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AbstractCollection class in java.util
This class provides a skeletal implementation of the Collection interface, to minimize the effort required to implement this interface. To implement an unmodifiable collection, the programmer needs only to extend this class and provide implementations for the iterator and size metho ... more >
AbstractList class in java.utilThis class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "random access" data store (such as an array). For sequential access data (such as a linked list), AbstractSequentialList should be used in prefe ... more >
AbstractMap class in java.utilThis class provides a skeletal implementation of the Map interface, to minimize the effort required to implement this interface. To implement an unmodifiable map, the programmer needs only to extend this class and provide an implementation for the entrySet method, which returns a se ... more >
AbstractMethodError class in java.langThrown when an application tries to call an abstract method. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of some class has incompatibly changed since the currently executing method was last compiled.
AbstractQueue class in java.utilThis class provides skeletal implementations of some Queue operations. The implementations in this class are appropriate when the base implementation does not allow null elements. Methods add, remove, and element are based on offer, poll, and peek, respectively but throw exceptions i ... more >
AbstractSequentialList class in java.utilThis class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "sequential access" data store (such as a linked list). For random access data (such as an array), AbstractList should be used in preference to t ... more >
AbstractSet class in java.utilThis class provides a skeletal implementation of the Set interface to minimize the effort required to implement this interface. The process of implementing a set by extending this class is identical to that of implementing a Collection by extending AbstractCollection, except that a ... more >
AccessibleObject class in java.lang.reflectThe AccessibleObject class is the base class for Field, Method and Constructor objects. It provides the ability to flag a reflected object as suppressing default Java language access control checks when it is used. The access checks--for public, default (package) access, protected, a ... more >
AnnotatedElement interface in java.lang.reflectRepresents an annotated element of the program currently running in this VM. This interface allows annotations to be read reflectively. All annotations returned by methods in this interface are immutable and serializable. It is permissible for the caller to modify the arrays returne ... more >
Annotation interface in java.lang.annotationThe common interface extended by all annotation types. Note that an interface that manually extends this one does not define an annotation type. Also note that this interface does not itself define an annotation type.
Annotation class in java.textAn Annotation object is used as a wrapper for a text attribute value if the attribute has annotation characteristics. These characteristics are: The text range that the attribute is applied to is critical to the semantics of the range. That means, the attribute cannot be applied to su ... more >
AnnotationFormatError class in java.lang.annotationThrown when the annotation parser attempts to read an annotation from a class file and determines that the annotation is malformed.
AnnotationTypeMismatchException class in java.lang.annotationThrown to indicate that a program has attempted to access an element of an annotation whose type has changed after the annotation was compiled (or serialized).
Appendable interface in java.langAn object to which char sequences and values can be appended. The Appendable interface must be implemented by any class whose instances are intended to receive formatted output from a java.util.Formatter. The characters to be appended should be valid Unicode characters as described ... more >
ArithmeticException class in java.langThrown when an exceptional arithmetic condition has occurred. For example, an integer "divide by zero" throws an instance of this class.
Array class in java.lang.reflectThe Array class provides static methods to dynamically create and access Java arrays. Array permits widening conversions to occur during a get or set operation, but throws an IllegalArgumentException if a narrowing conversion would occur.
ArrayIndexOutOfBoundsException class in java.langThrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array.
ArrayList class in java.utilResizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store th ... more >
Arrays class in java.utilThis class contains various methods for manipulating arrays (such as sorting and searching). This class also contains a static factory that allows arrays to be viewed as lists. The methods in this class all throw a NullPointerException if the specified array reference is null, exce ... more >
ArrayStoreException class in java.langThrown to indicate that an attempt has been made to store the wrong type of object into an array of objects. For example, the following code generates an ArrayStoreException: Object x[] = new String[3]; x[0] = new Integer(0);
AssertionError class in java.langThrown to indicate that an assertion has failed. The seven one-argument public constructors provided by this class ensure that the assertion error returned by the invocation: new AssertionError(expression) has as its detail message the string conversion of expression (as d ... more >
AttributedCharacterIterator interface in java.textAn AttributedCharacterIterator allows iteration through both text and related attribute information. An attribute is a key/value pair, identified by the key. No two attributes on a given character can have the same key. The values for an attribute are immutable, or must not be m ... more >
AttributedCharacterIterator.Attribute class in java.textDefines attribute keys that are used to identify text attributes. These keys are used in AttributedCharacterIterator and AttributedString.
AttributedString class in java.textAn AttributedString holds text and related attribute information. It may be used as the actual data storage in some cases where a text reader wants to access attributed text through the AttributedCharacterIterator interface.
Attributes class in java.util.jarThe Attributes class maps Manifest attribute names to associated string values. Valid attribute names are case-insensitive, are restricted to the ASCII characters in the set [0-9a-zA-Z_-], and cannot exceed 70 characters in length. Attribute values can contain any characters and wil ... more >
Attributes.Name class in java.util.jarThe Attributes.Name class represents an attribute name stored in this Map. Valid attribute names are case-insensitive, are restricted to the ASCII characters in the set [0-9a-zA-Z_-], and cannot exceed 70 characters in length. Attribute values can contain any characters and will be ... more >
Authenticator class in java.netThe class Authenticator represents an object that knows how to obtain authentication for a network connection. Usually, it will do this by prompting the user for information. Applications use this class by overriding #getPasswordAuthentication() in a sub-class. This method will typ ... more >
Authenticator.RequestorType class in java.netThe type of the entity requesting authentication.
Bidi class in java.textThis class implements the Unicode Bidirectional Algorithm. A Bidi object provides information on the bidirectional reordering of the text used to create it. This is required, for example, to properly display Arabic or Hebrew text. These languages are inherently mixed directional, ... more >
BigDecimal class in java.mathImmutable, arbitrary-precision signed decimal numbers. A BigDecimal consists of an arbitrary precision integer unscaled value and a 32-bit integer scale. If zero or positive, the scale is the number of digits to the right of the decimal point. If negative, the unscaled value of the ... more >
BigInteger class in java.mathImmutable arbitrary-precision integers. All operations behave as if BigIntegers were represented in two's-complement notation (like Java's primitive integer types). BigInteger provides analogues to all of Java's primitive integer operators, and all relevant methods from java.lang.Math ... more >
BindException class in java.netSignals that an error occurred while attempting to bind a socket to a local address and port. Typically, the port is in use, or the requested local address could not be assigned.
BitSet class in java.utilThis class implements a vector of bits that grows as needed. Each component of the bit set has a boolean value. The bits of a BitSet are indexed by nonnegative integers. Individual indexed bits can be examined, set, or cleared. One BitSet may be used to modify the contents of anoth ... more >
Boolean class in java.langThe Boolean class wraps a value of the primitive type boolean in an object. An object of type Boolean contains a single field whose type is boolean. In addition, this class provides many methods for converting a boolean to a String and a String to a boolean, as well as other ... more >
BreakIterator class in java.textThe BreakIterator class implements methods for finding the location of boundaries in text. Instances of BreakIterator maintain a current position and scan over text returning the index of characters where boundaries occur. Internally, BreakIterator scans text using a CharacterIterator ... more >
BufferedInputStream class in java.ioA BufferedInputStream adds functionality to another input stream-namely, the ability to buffer the input and to support the mark and reset methods. When the BufferedInputStream is created, an internal buffer array is created. As bytes from the stream are read or skipped, the inter ... more >
BufferedOutputStream class in java.ioThe class implements a buffered output stream. By setting up such an output stream, an application can write bytes to the underlying output stream without necessarily causing a call to the underlying system for each byte written.
BufferedReader class in java.ioRead text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines. The buffer size may be specified, or the default size may be used. The default is large enough for most purposes. In general, each read requ ... more >
BufferedWriter class in java.ioWrite text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings. The buffer size may be specified, or the default size may be accepted. The default is large enough for most purposes. A newLine() me ... more >
Byte class in java.langThe Byte class wraps a value of primitive type byte in an object. An object of type Byte contains a single field whose type is byte. In addition, this class provides several methods for converting a byte to a String and a String to a byte, as well as other constants and methods ... more >
ByteArrayInputStream class in java.ioA ByteArrayInputStream contains an internal buffer that contains bytes that may be read from the stream. An internal counter keeps track of the next byte to be supplied by the read method. Closing a ByteArrayInputStream has no effect. The methods in this class can be called after ... more >
ByteArrayOutputStream class in java.ioThis class implements an output stream in which the data is written into a byte array. The buffer automatically grows as data is written to it. The data can be retrieved using toByteArray() and toString(). Closing a ByteArrayOutputStream has no effect. The methods in this class ... more >
CacheRequest class in java.netRepresents channels for storing resources in the ResponseCache. Instances of such a class provide an OutputStream object which is called by protocol handlers to store the resource data into the cache, and also an abort() method which allows a cache store operation to be interrupted and ... more >
CacheResponse class in java.netRepresent channels for retrieving resources from the ResponseCache. Instances of such a class provide an InputStream that returns the entity body, and also a getHeaders() method which returns the associated response headers.
Calendar class in java.utilThe Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, and so on, and for manipulating the calendar fields, such as getting the date of the next week. An insta ... more >
Character class in java.langThe Character class wraps a value of the primitive type char in an object. An object of type Character contains a single field whose type is char. In addition, this class provides several methods for determining a character's category (lowercase letter, digit, etc.) and for convert ... more >
Character.Subset class in java.langInstances of this class represent particular subsets of the Unicode character set. The only family of subsets defined in the Character class is UnicodeBlock. Other portions of the Java API may define other subsets for their own purposes.
Character.UnicodeBlock class in java.langA family of character subsets representing the character blocks in the Unicode specification. Character blocks generally define characters used for a specific script or purpose. A character is contained by at most one Unicode block.
CharacterIterator interface in java.textThis interface defines a protocol for bidirectional iteration over text. The iterator iterates over a bounded sequence of characters. Characters are indexed with values beginning with the value returned by getBeginIndex() and continuing through the value returned by getEndIndex()-1. ... more >
CharArrayReader class in java.ioThis class implements a character buffer that can be used as a character-input stream.
CharArrayWriter class in java.ioThis class implements a character buffer that can be used as an Writer. The buffer automatically grows when data is written to the stream. The data can be retrieved using toCharArray() and toString(). Note: Invoking close() on this class has no effect, and methods of this class can ... more >
CharConversionException class in java.ioBase class for character conversion exceptions.
CharSequence interface in java.langA CharSequence is a readable sequence of char values. This interface provides uniform, read-only access to many different kinds of char sequences. A char value represents a character in the Basic Multilingual Plane (BMP) or a surrogate. Refer to Unicode Character Representation for det ... more >
ChoiceFormat class in java.textA ChoiceFormat allows you to attach a format to a range of numbers. It is generally used in a MessageFormat for handling plurals. The choice is specified with an ascending list of doubles, where each item specifies a half-open interval up to the next item: X matches j if and only ... more >
Class class in java.langInstances of the class Class represent classes and interfaces in a running Java application. An enum is a kind of class and an annotation is a kind of interface. Every array also belongs to a class that is reflected as a Class object that is shared by all arrays with the same element ... more >
ClassCastException class in java.langThrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. For example, the following code generates a ClassCastException: Object x = new Integer(0); System.out.println((String)x);
ClassCircularityError class in java.langThrown when a circularity has been detected while initializing a class.
ClassDefinition class in java.lang.instrumentThis class serves as a parameter block to the Instrumentation.redefineClasses method. Serves to bind the Class that needs redefining together with the new class file bytes.
ClassFileTransformer interface in java.lang.instrumentAn agent provides an implementation of this interface in order to transform class files. The transformation occurs before the class is defined by the JVM. Note the term class file is used as defined in the chapter The class File Format of The Java Virtual Machine Specification, t ... more >
ClassFormatError class in java.langThrown when the Java Virtual Machine attempts to read a class file and determines that the file is malformed or otherwise cannot be interpreted as a class file.
ClassLoader class in java.langA class loader is an object that is responsible for loading classes. The class ClassLoader is an abstract class. Given the binary name of a class, a class loader should attempt to locate or generate data that constitutes a definition for the class. A typical strategy is to transform t ... more >
ClassLoadingMXBean interface in java.lang.managementThe management interface for the class loading system of the Java virtual machine. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the ManagementF ... more >
ClassNotFoundException class in java.langThrown when an application tries to load in a class through its string name using: The forName method in class Class. The findSystemClass method in class ClassLoader . The loadClass method in class ClassLoader. but no definition for the class with the specified name could ... more >
Cloneable interface in java.langA class implements the Cloneable interface to indicate to the java.lang.Object#clone() method that it is legal for that method to make a field-for-field copy of instances of that class. Invoking Object's clone method on an instance that does not implement the Cloneable interfa ... more >
CloneNotSupportedException class in java.langThrown to indicate that the clone method in class Object has been called to clone an object, but that the object's class does not implement the Cloneable interface. Applications that override the clone method can also throw this exception to indicate that an object could not o ... more >
Closeable interface in java.ioA Closeable is a source or destination of data that can be closed. The close method is invoked to release resources that the object is holding (such as open files).
CollationElementIterator class in java.textThe CollationElementIterator class is used as an iterator to walk through each character of an international string. Use the iterator to return the ordering priority of the positioned character. The ordering priority of a character, which we refer to as a key, defines how a character i ... more >
CollationKey class in java.textA CollationKey represents a String under the rules of a specific Collator object. Comparing two CollationKeys returns the relative order of the Strings they represent. Using CollationKeys to compare Strings is generally faster than using Collator.compare. Thus, when the Strings must ... more >
Collator class in java.textThe Collator class performs locale-sensitive String comparison. You use this class to build searching and sorting routines for natural language text. Collator is an abstract base class. Subclasses implement specific collation strategies. One subclass, RuleBasedCollator, is current ... more >
Collection interface in java.utilThe root interface in the collection hierarchy. A collection represents a group of objects, known as its elements. Some collections allow duplicate elements and others do not. Some are ordered and others unordered. The JDK does not provide any direct implementations of this interfa ... more >
Collections class in java.utilThis class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, "wrappers", which return a new collection backed by a specified collection, and a few other odds and ends. The methods of this cla ... more >
Comparable interface in java.langThis interface imposes a total ordering on the objects of each class that implements it. This ordering is referred to as the class's natural ordering, and the class's compareTo method is referred to as its natural comparison method. Lists (and arrays) of objects that implement this ... more >
Comparator interface in java.utilA comparison function, which imposes a total ordering on some collection of objects. Comparators can be passed to a sort method (such as Collections.sort) to allow precise control over the sort order. Comparators can also be used to control the order of certain data structures (such a ... more >
CompilationMXBean interface in java.lang.managementThe management interface for the compilation system of the Java virtual machine. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the ManagementFactor ... more >
Compiler class in java.langThe Compiler class is provided to support Java-to-native-code compilers and related services. By design, the Compiler class does nothing; it serves as a placeholder for a JIT compiler implementation. When the Java Virtual Machine first starts, it determines if the system property j ... more >
ConcurrentModificationException class in java.utilThis exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible. For example, it is not generally permissible for one thread to modify a Collection while another thread is iterating over it. In general, the re ... more >
ConnectException class in java.netSignals that an error occurred while attempting to connect a socket to a remote address and port. Typically, the connection was refused remotely (e.g., no process is listening on the remote address/port).
Constructor class in java.lang.reflectConstructor provides information about, and access to, a single constructor for a class. Constructor permits widening conversions to occur when matching the actual parameters to newInstance() with the underlying constructor's formal parameters, but throws an IllegalArgumentException ... more >
ContentHandler class in java.netThe abstract class ContentHandler is the superclass of all classes that read an Object from a URLConnection. An application does not generally call the getContent method in this class directly. Instead, an application calls the getContent method in class URL or in URLConnect ... more >
ContentHandlerFactory interface in java.netThis interface defines a factory for content handlers. An implementation of this interface should map a MIME type into an instance of ContentHandler. This interface is used by the URLStreamHandler class to create a ContentHandler for a MIME type.
CookieHandler class in java.netA CookieHandler object provides a callback mechanism to hook up a HTTP state management policy implementation into the HTTP protocol handler. The HTTP state management mechanism specifies a way to create a stateful session with HTTP requests and responses. A system-wide CookieHandler ... more >
Currency class in java.utilRepresents a currency. Currencies are identified by their ISO 4217 currency codes. See the ISO 4217 maintenance agency for more information, including a table of currency codes. The class is designed so that there's never more than one Currency instance for any given currency. Th ... more >
DatagramPacket class in java.netThis class represents a datagram packet. Datagram packets are used to implement a connectionless packet delivery service. Each message is routed from one machine to another based solely on information contained within that packet. Multiple packets sent from one machine to anothe ... more >
DatagramSocket class in java.netThis class represents a socket for sending and receiving datagram packets. A datagram socket is the sending or receiving point for a packet delivery service. Each packet sent or received on a datagram socket is individually addressed and routed. Multiple packets sent from one machine ... more >
DatagramSocketImpl class in java.netAbstract datagram and multicast socket implementation base class.
DatagramSocketImplFactory interface in java.netThis interface defines a factory for datagram socket implementations. It is used by the classes DatagramSocket to create actual socket implementations.
DataInput interface in java.ioThe DataInput interface provides for reading bytes from a binary stream and reconstructing from them data in any of the Java primitive types. There is also a facility for reconstructing a String from data in modified UTF-8 format. It is generally true of all the reading routin ... more >
DataInputStream class in java.ioA data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. An application uses a data output stream to write data that can later be read by a data input stream.
DataOutput interface in java.ioThe DataOutput interface provides for converting data from any of the Java primitive types to a series of bytes and writing these bytes to a binary stream. There is also a facility for converting a String into modified UTF-8 format and writing the resulting series of bytes. Fo ... more >
DataOutputStream class in java.ioA data output stream lets an application write primitive Java data types to an output stream in a portable way. An application can then use a data input stream to read the data back in.
Date class in java.utilThe class Date represents a specific instant in time, with millisecond precision. Prior to JDK 1.1, the class Date had two additional functions. It allowed the interpretation of dates as year, month, day, hour, minute, and second values. It also allowed the formatting and par ... more >
DateFormat class in java.textDateFormat is an abstract class for date/time formatting subclasses which formats and parses dates or time in a language-independent manner. The date/time formatting subclass, such as SimpleDateFormat, allows for formatting (i.e., date -> text), parsing (text -> date), and normalizatio ... more >
DateFormat.Field class in java.textDefines constants that are used as attribute keys in the AttributedCharacterIterator returned from DateFormat.formatToCharacterIterator and as field identifiers in FieldPosition. The class also provides two methods to map between its constants and the corresponding Calendar constants.
DateFormatSymbols class in java.textDateFormatSymbols is a public class for encapsulating localizable date-time formatting data, such as the names of the months, the names of the days of the week, and the time zone data. DateFormat and SimpleDateFormat both use DateFormatSymbols to encapsulate this information. Typi ... more >
DecimalFormat class in java.textDecimalFormat is a concrete subclass of NumberFormat that formats decimal numbers. It has a variety of features designed to make it possible to parse and format numbers in any locale, including support for Western, Arabic, and Indic digits. It also supports different kinds of numbers, ... more >
DecimalFormatSymbols class in java.textThis class represents the set of symbols (such as the decimal separator, the grouping separator, and so on) needed by DecimalFormat to format numbers. DecimalFormat creates for itself an instance of DecimalFormatSymbols from its locale data. If you need to change any of these symbols, ... more >
Deprecated interface in java.langA program element annotated @Deprecated is one that programmers are discouraged from using, typically because it is dangerous, or because a better alternative exists. Compilers warn when a deprecated program element is used or overridden in non-deprecated code.
Dictionary class in java.utilThe Dictionary class is the abstract parent of any class, such as Hashtable, which maps keys to values. Every key and every value is an object. In any one Dictionary object, every key is associated with at most one value. Given a Dictionary and a key, the associated element can be ... more >
Documented interface in java.lang.annotationIndicates that annotations with a type are to be documented by javadoc and similar tools by default. This type should be used to annotate the declarations of types whose annotations affect the use of annotated elements by their clients. If a type declaration is annotated with Docume ... more >
Double class in java.langThe Double class wraps a value of the primitive type double in an object. An object of type Double contains a single field whose type is double. In addition, this class provides several methods for converting a double to a String and a String to a double, as well as other constan ... more >
DuplicateFormatFlagsException class in java.utilUnchecked exception thrown when duplicate flags are provided in the format specifier. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
ElementType class in java.lang.annotationA program element type. The constants of this enumerated type provide a simple classification of the declared elements in a Java program. These constants are used with the Target meta-annotation type to specify where it is legal to use an annotation type.
EmptyStackException class in java.utilThrown by methods in the Stack class to indicate that the stack is empty.
Enum class in java.langThis is the common base class of all Java language enumeration types.
EnumConstantNotPresentException class in java.langThrown when an application tries to access an enum constant by name and the enum type contains no constant with the specified name.
Enumeration interface in java.utilAn object that implements the Enumeration interface generates a series of elements, one at a time. Successive calls to the nextElement method return successive elements of the series. For example, to print all elements of a vector v: for (Enumeration e = v.elements() ; e.has ... more >
EnumMap class in java.utilA specialized Map implementation for use with enum type keys. All of the keys in an enum map must come from a single enum type that is specified, explicitly or implicitly, when the map is created. Enum maps are represented internally as arrays. This representation is extremely compa ... more >
EnumSet class in java.utilA specialized Set implementation for use with enum types. All of the elements in an enum set must come from a single enum type that is specified, explicitly or implicitly, when the set is created. Enum sets are represented internally as bit vectors. This representation is extremely ... more >
EOFException class in java.ioSignals that an end of file or end of stream has been reached unexpectedly during input. This exception is mainly used by data input streams to signal end of stream. Note that many other input operations return a special value on end of stream rather than throwing an exception.
Error class in java.langAn Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. The ThreadDeath error, though a "normal" condition, is also a subclass of Error because most applications should not ... more >
EventListener interface in java.utilA tagging interface that all event listener interfaces must extend.
EventListenerProxy class in java.utilAn abstract wrapper class for an EventListener class which associates a set of additional parameters with the listener. Subclasses must provide the storage and accessor methods for the additional arguments or parameters. Subclasses of EventListenerProxy may be returned by getListeners ... more >
EventObject class in java.utilThe root class from which all event state objects shall be derived. All Events are constructed with a reference to the object, the "source", that is logically deemed to be the object upon which the Event in question initially occurred upon.
Exception class in java.langThe class Exception and its subclasses are a form of Throwable that indicates conditions that a reasonable application might want to catch.
ExceptionInInitializerError class in java.langSignals that an unexpected exception has occurred in a static initializer. An ExceptionInInitializerError is thrown to indicate that an exception occurred during evaluation of a static initializer or the initializer for a static variable. As of release 1.4, this exception has been ... more >
Externalizable interface in java.ioOnly the identity of the class of an Externalizable instance is written in the serialization stream and it is the responsibility of the class to save and restore the contents of its instances. The writeExternal and readExternal methods of the Externalizable interface are implemented b ... more >
Field class in java.lang.reflectA Field provides information about, and dynamic access to, a single field of a class or an interface. The reflected field may be a class (static) field or an instance field. A Field permits widening conversions to occur during a get or set access operation, but throws an IllegalArgu ... more >
FieldPosition class in java.textFieldPosition is a simple class used by Format and its subclasses to identify fields in formatted output. Fields can be identified in two ways: By an integer constant, whose names typically end with _FIELD. The constants are defined in the various subclasses of Format. ... more >
File class in java.ioAn abstract representation of file and directory pathnames. User interfaces and operating systems use system-dependent pathname strings to name files and directories. This class presents an abstract, system-independent view of hierarchical pathnames. An abstract pathname has two c ... more >
FileDescriptor class in java.ioInstances of the file descriptor class serve as an opaque handle to the underlying machine-specific structure representing an open file, an open socket, or another source or sink of bytes. The main practical use for a file descriptor is to create a FileInputStream or FileOutputStream t ... more >
FileFilter interface in java.ioA filter for abstract pathnames. Instances of this interface may be passed to the listFiles(FileFilter) method of the java.io.File class.
FileInputStream class in java.ioA FileInputStream obtains input bytes from a file in a file system. What files are available depends on the host environment. FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader.
FilenameFilter interface in java.ioInstances of classes that implement this interface are used to filter filenames. These instances are used to filter directory listings in the list method of class File, and by the Abstract Window Toolkit's file dialog component.
FileNameMap interface in java.netA simple interface which provides a mechanism to map between a file name and a MIME type string.
FileNotFoundException class in java.ioSignals that an attempt to open the file denoted by a specified pathname has failed. This exception will be thrown by the FileInputStream, FileOutputStream, and RandomAccessFile constructors when a file with the specified pathname does not exist. It will also be thrown by these con ... more >
FileOutputStream class in java.ioA file output stream is an output stream for writing data to a File or to a FileDescriptor. Whether or not a file is available or may be created depends upon the underlying platform. Some platforms, in particular, allow a file to be opened for writing by only one FileOutputStream (or ... more >
FilePermission class in java.ioThis class represents access to a file or directory. A FilePermission consists of a pathname and a set of actions valid for that pathname. Pathname is the pathname of the file or directory granted the specified actions. A pathname that ends in "/*" (where "/" is the file separator ... more >
FileReader class in java.ioConvenience class for reading character files. The constructors of this class assume that the default character encoding and the default byte-buffer size are appropriate. To specify these values yourself, construct an InputStreamReader on a FileInputStream. FileReader is meant for ... more >
FileWriter class in java.ioConvenience class for writing character files. The constructors of this class assume that the default character encoding and the default byte-buffer size are acceptable. To specify these values yourself, construct an OutputStreamWriter on a FileOutputStream. Whether or not a file i ... more >
FilterInputStream class in java.ioA FilterInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. The class FilterInputStream itself simply overrides all methods of InputStream with versions that p ... more >
FilterOutputStream class in java.ioThis class is the superclass of all classes that filter output streams. These streams sit on top of an already existing output stream (the underlying output stream) which it uses as its basic sink of data, but possibly transforming the data along the way or providing additional fun ... more >
FilterReader class in java.ioAbstract class for reading filtered character streams. The abstract class FilterReader itself provides default methods that pass all requests to the contained stream. Subclasses of FilterReader should override some of these methods and may also provide additional methods and fields.
FilterWriter class in java.ioAbstract class for writing filtered character streams. The abstract class FilterWriter itself provides default methods that pass all requests to the contained stream. Subclasses of FilterWriter should override some of these methods and may also provide additional methods and fields.
Float class in java.langThe Float class wraps a value of primitive type float in an object. An object of type Float contains a single field whose type is float. In addition, this class provides several methods for converting a float to a String and a String to a float, as well as other constants and met ... more >
Flushable interface in java.ioA Flushable is a destination of data that can be flushed. The flush method is invoked to write any buffered output to the underlying stream.
Format class in java.textFormat is an abstract base class for formatting locale-sensitive information such as dates, messages, and numbers. Format defines the programming interface for formatting locale-sensitive objects into Strings (the format method) and for parsing Strings back into objects (the parse ... more >
Format.Field class in java.textDefines constants that are used as attribute keys in the AttributedCharacterIterator returned from Format.formatToCharacterIterator and as field identifiers in FieldPosition.
FormatFlagsConversionMismatchException class in java.utilUnchecked exception thrown when a conversion and flag are incompatible. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
Formattable interface in java.utilThe Formattable interface must be implemented by any class that needs to perform custom formatting using the 's' conversion specifier of java.util.Formatter. This interface allows basic control for formatting arbitrary objects. For example, the following class prints out different re ... more >
FormattableFlags class in java.utilFomattableFlags are passed to the Formattable.formatTo() method and modify the output format for . Implementations of Formattable are responsible for interpreting and validating any flags.
Formatter class in java.utilAn interpreter for printf-style format strings. This class provides support for layout justification and alignment, common formats for numeric, string, and date/time data, and locale-specific output. Common Java types such as byte, BigDecimal, and Calendar are supported. Limited for ... more >
Formatter.BigDecimalLayoutForm class in java.utilFormatterClosedException class in java.utilUnchecked exception thrown when the formatter has been closed. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
GarbageCollectorMXBean interface in java.lang.managementThe management interface for the garbage collection of the Java virtual machine. Garbage collection is the process that the Java virtual machine uses to find and reclaim unreachable objects to free up memory space. A garbage collector is one type of memory manager. A Java virtu ... more >
GenericArrayType interface in java.lang.reflectGenericArrayType represents an array type whose component type is either a parameterized type or a type variable.
GenericDeclaration interface in java.lang.reflectA common interface for all entities that declare type variables.
GenericSignatureFormatError class in java.lang.reflectThrown when a syntactically malformed signature attribute is encountered by a reflective method that needs to interpret the generic signature information for a type, method or constructor.
GregorianCalendar class in java.utilGregorianCalendar is a concrete subclass of Calendar and provides the standard calendar system used by most of the world. GregorianCalendar is a hybrid calendar that supports both the Julian and Gregorian calendar systems with the support of a single discontinuity, which correspond ... more >
HashMap class in java.utilHash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This class mak ... more >
HashSet class in java.utilThis class implements the Set interface, backed by a hash table (actually a HashMap instance). It makes no guarantees as to the iteration order of the set; in particular, it does not guarantee that the order will remain constant over time. This class permits the null element. This ... more >
Hashtable class in java.utilThis class implements a hashtable, which maps keys to values. Any non-null object can be used as a key or as a value. To successfully store and retrieve objects from a hashtable, the objects used as keys must implement the hashCode method and the equals method. An instance of ... more >
HttpRetryException class in java.netThrown to indicate that a HTTP request needs to be retried but cannot be retried automatically, due to streaming mode being enabled.
HttpURLConnection class in java.netA URLConnection with support for HTTP-specific features. See the spec for details. Each HttpURLConnection instance is used to make a single request but the underlying network connection to the HTTP server may be transparently shared by other instances. Calling the close() met ... more >
IdentityHashMap class in java.utilThis class implements the Map interface with a hash table, using reference-equality in place of object-equality when comparing keys (and values). In other words, in an IdentityHashMap, two keys k1 and k2 are considered equal if and only if (k1==k2). (In normal Map implementations (li ... more >
IllegalAccessError class in java.langThrown if an application attempts to access or modify a field, or to call a method that it does not have access to. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
IllegalAccessException class in java.langAn IllegalAccessException is thrown when an application tries to reflectively create an instance (other than an array), set or get a field, or invoke a method, but the currently executing method does not have access to the definition of the specified class, field, method or constructor.
IllegalArgumentException class in java.langThrown to indicate that a method has been passed an illegal or inappropriate argument.
IllegalClassFormatException class in java.lang.instrumentThrown by an implementation of ClassFileTransformer.transform when its input parameters are invalid. This may occur either because the initial class file bytes were invalid or a previously applied transform corrupted the bytes.
IllegalFormatCodePointException class in java.utilUnchecked exception thrown when a character with an invalid Unicode code point as defined by Character#isValidCodePoint is passed to the Formatter. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
IllegalFormatConversionException class in java.utilUnchecked exception thrown when the argument corresponding to the format specifier is of an incompatible type. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
IllegalFormatException class in java.utilUnchecked exception thrown when a format string contains an illegal syntax or a format specifier that is incompatible with the given arguments. Only explicit subtypes of this exception which correspond to specific errors should be instantiated.
IllegalFormatFlagsException class in java.utilUnchecked exception thrown when an illegal combination flags is given. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
IllegalFormatPrecisionException class in java.utilUnchecked exception thrown when the precision is a negative value other than -1, the conversion does not support a precision, or the value is otherwise unsupported.
IllegalFormatWidthException class in java.utilUnchecked exception thrown when the format width is a negative value other than -1 or is otherwise unsupported.
IllegalMonitorStateException class in java.langThrown to indicate that a thread has attempted to wait on an object's monitor or to notify other threads waiting on an object's monitor without owning the specified monitor.
IllegalStateException class in java.langSignals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.
IllegalThreadStateException class in java.langThrown to indicate that a thread is not in an appropriate state for the requested operation. See, for example, the suspend and resume methods in class Thread.
IncompatibleClassChangeError class in java.langThrown when an incompatible class change has occurred to some class definition. The definition of some class, on which the currently executing method depends, has since changed.
IncompleteAnnotationException class in java.lang.annotationThrown to indicate that a program has attempted to access an element of an annotation type that was added to the annotation type definition after the annotation was compiled (or serialized). This exception will not be thrown if the new element has a default value.
IndexOutOfBoundsException class in java.langThrown to indicate that an index of some sort (such as to an array, to a string, or to a vector) is out of range. Applications can subclass this class to indicate similar exceptions.
Inet4Address class in java.netThis class represents an Internet Protocol version 4 (IPv4) address. Defined by RFC 790: Assigned Numbers, RFC 1918: Address Allocation for Private Internets, and RFC 2365: Administratively Scoped IP Multicast Textual representation of IP addresses Textual repr ... more >
Inet6Address class in java.netThis class represents an Internet Protocol version 6 (IPv6) address. Defined by RFC 2373: IP Version 6 Addressing Architecture. Textual representation of IP addresses Textual representation of IPv6 address used as input to methods takes one of the following forms: T ... more >
InetAddress class in java.netThis class represents an Internet Protocol (IP) address. An IP address is either a 32-bit or 128-bit unsigned number used by IP, a lower-level protocol on which protocols like UDP and TCP are built. The IP address architecture is defined by RFC 790: Assigned Numbers, RFC ... more >
InetSocketAddress class in java.netThis class implements an IP Socket Address (IP address + port number) It can also be a pair (hostname + port number), in which case an attempt will be made to resolve the hostname. If resolution fails then the address is said to be unresolved but can still be used on some circumstances ... more >
InheritableThreadLocal class in java.langThis class extends ThreadLocal to provide inheritance of values from parent thread to child thread: when a child thread is created, the child receives initial values for all inheritable thread-local variables for which the parent has values. Normally the child's values will be identic ... more >
Inherited interface in java.lang.annotationIndicates that an annotation type is automatically inherited. If an Inherited meta-annotation is present on an annotation type declaration, and the user queries the annotation type on a class declaration, and the class declaration has no annotation for this type, then the class's supe ... more >
InputMismatchException class in java.utilThrown by a Scanner to indicate that the token retrieved does not match the pattern for the expected type, or that the token is out of range for the expected type.
InputStream class in java.ioThis abstract class is the superclass of all classes representing an input stream of bytes. Applications that need to define a subclass of InputStream must always provide a method that returns the next byte of input.
InputStreamReader class in java.ioAn InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted. Each ... more >
InstantiationError class in java.langThrown when an application tries to use the Java new construct to instantiate an abstract class or an interface. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
InstantiationException class in java.langThrown when an application tries to create an instance of a class using the newInstance method in class Class, but the specified class object cannot be instantiated because it is an interface or is an abstract class.
Instrumentation interface in java.lang.instrumentThis class provides services needed to instrument Java programming language code. Instrumentation is the addition of byte-codes to methods for the purpose of gathering data to be utilized by tools. Since the changes are purely additive, these tools do not modify application state or ... more >
Integer class in java.langThe Integer class wraps a value of the primitive type int in an object. An object of type Integer contains a single field whose type is int. In addition, this class provides several methods for converting an int to a String and a String to an int, as well as other constants an ... more >
InternalError class in java.langThrown to indicate some unexpected internal error has occurred in the Java Virtual Machine.
InterruptedException class in java.langThrown when a thread is waiting, sleeping, or otherwise paused for a long time and another thread interrupts it using the interrupt method in class Thread.
InterruptedIOException class in java.ioSignals that an I/O operation has been interrupted. An InterruptedIOException is thrown to indicate that an input or output transfer has been terminated because the thread performing it was interrupted. The field #bytesTransferred indicates how many bytes were successfully transferred ... more >
InvalidClassException class in java.ioThrown when the Serialization runtime detects one of the following problems with a Class. The serial version of the class does not match that of the class descriptor read from the stream The class contains unknown datatypes The class does not have an accessible no-arg constructor
InvalidObjectException class in java.ioIndicates that one or more deserialized objects failed validation tests. The argument should provide the reason for the failure.
InvalidPropertiesFormatException class in java.utilThrown to indicate that an operation could not complete because the input did not conform to the appropriate XML document type for a collection of properties, as per the Properties specification. Note, that although InvalidPropertiesFormatException inherits Serializable interface ... more >
InvocationHandler interface in java.lang.reflectInvocationHandler is the interface implemented by the invocation handler of a proxy instance. Each proxy instance has an associated invocation handler. When a method is invoked on a proxy instance, the method invocation is encoded and dispatched to the invoke method of its invocation handler.
InvocationTargetException class in java.lang.reflectInvocationTargetException is a checked exception that wraps an exception thrown by an invoked method or constructor. As of release 1.4, this exception has been retrofitted to conform to the general purpose exception-chaining mechanism. The "target exception" that is provided at cons ... more >
IOException class in java.ioSignals that an I/O exception of some sort has occurred. This class is the general class of exceptions produced by failed or interrupted I/O operations.
Iterable interface in java.langImplementing this interface allows an object to be the target of the "foreach" statement.
Iterator interface in java.utilAn iterator over a collection. Iterator takes the place of Enumeration in the Java collections framework. Iterators differ from enumerations in two ways: Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined ... more >
JarEntry class in java.util.jarThis class is used to represent a JAR file entry.
JarException class in java.util.jarSignals that an error of some sort has occurred while reading from or writing to a JAR file.
JarFile class in java.util.jarThe JarFile class is used to read the contents of a jar file from any file that can be opened with java.io.RandomAccessFile. It extends the class java.util.zip.ZipFile with support for reading an optional Manifest entry. The Manifest can be used to specify meta-information about the j ... more >
JarInputStream class in java.util.jarThe JarInputStream class is used to read the contents of a JAR file from any input stream. It extends the class java.util.zip.ZipInputStream with support for reading an optional Manifest entry. The Manifest can be used to store meta-information about the JAR file and its entries.
JarOutputStream class in java.util.jarThe JarOutputStream class is used to write the contents of a JAR file to any output stream. It extends the class java.util.zip.ZipOutputStream with support for writing an optional Manifest entry. The Manifest can be used to specify meta-information about the JAR file and its entries.
JarURLConnection class in java.netA URL Connection to a Java ARchive (JAR) file or an entry in a JAR file. The syntax of a JAR URL is: jar:<url>!/{entry} for example: jar:http://www.foo.com/bar/baz.jar!/COM/foo/Quux.class Jar URLs should be used to refer to a JAR file or entries in a JAR f ... more >
LineNumberInputStream class in java.ioThis class is an input stream filter that provides the added functionality of keeping track of the current line number. A line is a sequence of bytes ending with a carriage return character ('\r'), a newline character ('\n'), or a carriage return character followed imm ... more >
LineNumberReader class in java.ioA buffered character-input stream that keeps track of line numbers. This class defines methods void setLineNumber(int) and int getLineNumber() for setting and getting the current line number respectively. By default, line numbering begins at 0. This number increments as data is ... more >
LinkageError class in java.langSubclasses of LinkageError indicate that a class has some dependency on another class; however, the latter class has incompatibly changed after the compilation of the former class.
LinkedHashMap class in java.utilHash table and linked list implementation of the Map interface, with predictable iteration order. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is normally ... more >
LinkedHashSet class in java.utilHash table and linked list implementation of the Set interface, with predictable iteration order. This implementation differs from HashSet in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is the order ... more >
LinkedList class in java.utilLinked list implementation of the List interface. Implements all optional list operations, and permits all elements (including null). In addition to implementing the List interface, the LinkedList class provides uniformly named methods to get, remove and insert an element at the beg ... more >
List interface in java.utilAn ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list. Unlike sets, lists typi ... more >
ListIterator interface in java.utilAn iterator for lists that allows the programmer to traverse the list in either direction, modify the list during iteration, and obtain the iterator's current position in the list. A ListIterator has no current element; its cursor position always lies between the element that wou ... more >
ListResourceBundle class in java.utilListResourceBundle is an abstract subclass of ResourceBundle that manages resources for a locale in a convenient and easy to use list. See ResourceBundle for more information about resource bundles in general. Subclasses must override getContents and provide an array, where each i ... more >
Locale class in java.utilA Locale object represents a specific geographical, political, or cultural region. An operation that requires a Locale to perform its task is called locale-sensitive and uses the Locale to tailor information for the user. For example, displaying a number is a locale-sensitive operation ... more >
Long class in java.langThe Long class wraps a value of the primitive type long in an object. An object of type Long contains a single field whose type is long. In addition, this class provides several methods for converting a long to a String and a String to a long, as well as other constants and met ... more >
MalformedParameterizedTypeException class in java.lang.reflectThrown when a semantically malformed parameterized type is encountered by a reflective method that needs to instantiate it. For example, if the number of type arguments to a parameterized type is wrong.
MalformedURLException class in java.netThrown to indicate that a malformed URL has occurred. Either no legal protocol could be found in a specification string or the string could not be parsed.
ManagementFactory class in java.lang.managementThe ManagementFactory class is a factory class for getting managed beans for the Java platform. This class consists of static methods each of which returns one or more platform MXBean(s) representing the management interface of a component of the Java virtual machine. An app ... more >
ManagementPermission class in java.lang.managementThe permission which the SecurityManager will check when code that is running with a SecurityManager calls methods defined in the management interface for the Java platform. The following table provides a summary description of what the permission allows, and discusses the risks of ... more >
Manifest class in java.util.jarThe Manifest class is used to maintain Manifest entry names and their associated Attributes. There are main Manifest Attributes as well as per-entry Attributes. For information on the Manifest format, please see the Manifest format specification.
Map interface in java.utilAn object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value. This interface takes the place of the Dictionary class, which was a totally abstract class rather than an interface. The Map interface provides three collection views, w ... more >
Map.Entry interface in java.utilA map entry (key-value pair). The Map.entrySet method returns a collection-view of the map, whose elements are of this class. The only way to obtain a reference to a map entry is from the iterator of this collection-view. These Map.Entry objects are valid only for the duration of th ... more >
Math class in java.langThe class Math contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions. Unlike some of the numeric methods of class StrictMath, all implementations of the equivalent functions of class Math are ... more >
MathContext class in java.mathImmutable objects which encapsulate the context settings which describe certain rules for numerical operators, such as those implemented by the BigDecimal class. The base-independent settings are: precision: the number of digits to be used for an operation; results are rounded t ... more >
Member interface in java.lang.reflectMember is an interface that reflects identifying information about a single member (a field or a method) or a constructor.
MemoryManagerMXBean interface in java.lang.managementThe management interface for a memory manager. A memory manager manages one or more memory pools of the Java virtual machine. A Java virtual machine has one or more memory managers. An instance implementing this interface is an MXBean that can be obtained by calling the Manageme ... more >
MemoryMXBean interface in java.lang.managementThe management interface for the memory system of the Java virtual machine. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the ManagementFactory#get ... more >
MemoryNotificationInfo class in java.lang.managementThe information about a memory notification. A memory notification is emitted by MemoryMXBean when the Java virtual machine detects that the memory usage of a memory pool is exceeding a threshold value. The notification emitted will contain the memory notification information a ... more >
MemoryPoolMXBean interface in java.lang.managementThe management interface for a memory pool. A memory pool represents the memory resource managed by the Java virtual machine and is managed by one or more memory managers. A Java virtual machine has one or more instances of the implementation class of this interface. An instance ... more >
MemoryType class in java.lang.managementTypes of memory pools.
MemoryUsage class in java.lang.managementA MemoryUsage object represents a snapshot of memory usage. Instances of the MemoryUsage class are usually constructed by methods that are used to obtain memory usage information about individual memory pool of the Java virtual machine or the heap or non-heap memory of the Java virtual ... more >
MessageFormat class in java.textMessageFormat provides a means to produce concatenated messages in language-neutral way. Use this to construct messages displayed for end users. MessageFormat takes a set of objects, formats them, then inserts the formatted strings into the pattern at the appropriate places. N ... more >
MessageFormat.Field class in java.textDefines constants that are used as attribute keys in the AttributedCharacterIterator returned from MessageFormat.formatToCharacterIterator.
Method class in java.lang.reflectA Method provides information about, and access to, a single method on a class or interface. The reflected method may be a class method or an instance method (including an abstract method). A Method permits widening conversions to occur when matching the actual parameters to invoke ... more >
MissingFormatArgumentException class in java.utilUnchecked exception thrown when there is a format specifier which does not have a corresponding argument or if an argument index refers to an argument that does not exist. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a Nul ... more >
MissingFormatWidthException class in java.utilUnchecked exception thrown when the format width is required. Unless otherwise specified, passing a null argument to anyg method or constructor in this class will cause a NullPointerException to be thrown.
MissingResourceException class in java.utilSignals that a resource is missing.
Modifier class in java.lang.reflectThe Modifier class provides static methods and constants to decode class and member access modifiers. The sets of modifiers are represented as integers with distinct bit positions representing different modifiers. The values for the constants representing the modifiers are taken from ... more >
MulticastSocket class in java.netThe multicast datagram socket class is useful for sending and receiving IP multicast packets. A MulticastSocket is a (UDP) DatagramSocket, with additional capabilities for joining "groups" of other multicast hosts on the internet. A multicast group is specified by a class D IP addr ... more >
NegativeArraySizeException class in java.langThrown if an application tries to create an array with negative size.
NetPermission class in java.netThis class is for various network permissions. A NetPermission contains a name (also referred to as a "target name") but no actions list; you either have the named permission or you don't. The target name is the name of the network permission (see below). The naming convention foll ... more >
NetworkInterface class in java.netThis class represents a Network Interface made up of a name, and a list of IP addresses assigned to this interface. It is used to identify the local interface on which a multicast group is joined. Interfaces are normally known by names such as "le0".
NoClassDefFoundError class in java.langThrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found. The searched-for class definition ... more >
NoRouteToHostException class in java.netSignals that an error occurred while attempting to connect a socket to a remote address and port. Typically, the remote host cannot be reached because of an intervening firewall, or if an intermediate router is down.
NoSuchElementException class in java.utilThrown by the nextElement method of an Enumeration to indicate that there are no more elements in the enumeration.
NoSuchFieldError class in java.langThrown if an application tries to access or modify a specified field of an object, and that object no longer has that field. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
NoSuchFieldException class in java.langSignals that the class doesn't have a field of a specified name.
NoSuchMethodError class in java.langThrown if an application tries to call a specified method of a class (either static or instance), and that class no longer has a definition of that method. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has in ... more >
NoSuchMethodException class in java.langThrown when a particular method cannot be found.
NotActiveException class in java.ioThrown when serialization or deserialization is not active.
NotSerializableException class in java.ioThrown when an instance is required to have a Serializable interface. The serialization runtime or the class of the instance can throw this exception. The argument should be the name of the class.
NullPointerException class in java.langThrown when an application attempts to use null in a case where an object is required. These include: Calling the instance method of a null object. Accessing or modifying the field of a null object. Taking the length of null as if it were an array. Accessing or modifying the sl ... more >
Number class in java.langThe abstract class Number is the superclass of classes BigDecimal, BigInteger, Byte, Double, Float, Integer, Long, and Short. Subclasses of Number must provide methods to convert the represented numeric value to byte, double, float, int, long, and short.
NumberFormat class in java.textNumberFormat is the abstract base class for all number formats. This class provides the interface for formatting and parsing numbers. NumberFormat also provides methods for determining which locales have number formats, and what their names are. NumberFormat helps you to format and ... more >
NumberFormat.Field class in java.textDefines constants that are used as attribute keys in the AttributedCharacterIterator returned from NumberFormat.formatToCharacterIterator and as field identifiers in FieldPosition.
NumberFormatException class in java.langThrown to indicate that the application has attempted to convert a string to one of the numeric types, but that the string does not have the appropriate format.
Object class in java.langClass Object is the root of the class hierarchy. Every class has Object as a superclass. All objects, including arrays, implement the methods of this class.
ObjectInput interface in java.ioObjectInput extends the DataInput interface to include the reading of objects. DataInput includes methods for the input of primitive types, ObjectInput extends that interface to include objects, arrays, and Strings.
ObjectInputStream class in java.ioAn ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream. ObjectOutputStream and ObjectInputStream can provide an application with persistent storage for graphs of objects when used with a FileOutputStream and FileInputStream respec ... more >
ObjectInputStream.GetField class in java.ioProvide access to the persistent fields read from the input stream.
ObjectInputValidation interface in java.ioCallback interface to allow validation of objects within a graph. Allows an object to be called when a complete graph of objects has been deserialized.
ObjectOutput interface in java.ioObjectOutput extends the DataOutput interface to include writing of objects. DataOutput includes methods for output of primitive types, ObjectOutput extends that interface to include objects, arrays, and Strings.
ObjectOutputStream class in java.ioAn ObjectOutputStream writes primitive data types and graphs of Java objects to an OutputStream. The objects can be read (reconstituted) using an ObjectInputStream. Persistent storage of objects can be accomplished by using a file for the stream. If the stream is a network socket str ... more >
ObjectOutputStream.PutField class in java.ioProvide programmatic access to the persistent fields to be written to ObjectOutput.
ObjectStreamClass class in java.ioSerialization's descriptor for classes. It contains the name and serialVersionUID of the class. The ObjectStreamClass for a specific class loaded in this Java VM can be found/created using the lookup method. The algorithm to compute the SerialVersionUID is described in Object Se ... more >
ObjectStreamConstants interface in java.ioConstants written into the Object Serialization Stream.
ObjectStreamException class in java.ioSuperclass of all exceptions specific to Object Stream classes.
ObjectStreamField class in java.ioA description of a Serializable field from a Serializable class. An array of ObjectStreamFields is used to declare the Serializable fields of a class.
Observable class in java.utilThis class represents an observable object, or "data" in the model-view paradigm. It can be subclassed to represent an object that the application wants to have observed. An observable object can have one or more observers. An observer may be any object that implements interface ... more >
Observer interface in java.utilA class can implement the Observer interface when it wants to be informed of changes in observable objects.
OperatingSystemMXBean interface in java.lang.managementThe management interface for the operating system on which the Java virtual machine is running. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the M ... more >
OptionalDataException class in java.ioException indicating the failure of an object read operation due to unread primitive data, or the end of data belonging to a serialized object in the stream. This exception may be thrown in two cases: An attempt was made to read an object when the next element in the stream ... more >
OutOfMemoryError class in java.langThrown when the Java Virtual Machine cannot allocate an object because it is out of memory, and no more memory could be made available by the garbage collector.
OutputStream class in java.ioThis abstract class is the superclass of all classes representing an output stream of bytes. An output stream accepts output bytes and sends them to some sink. Applications that need to define a subclass of OutputStream must always provide at least a method that writes one byte ... more >
OutputStreamWriter class in java.ioAn OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted. Each ... more >
Override interface in java.langIndicates that a method declaration is intended to override a method declaration in a superclass. If a method is annotated with this annotation type but does not override a superclass method, compilers are required to generate an error message.
Pack200 class in java.util.jarTransforms a JAR file to or from a packed stream in Pack200 format. Please refer to Network Trasfer Format JSR 200 Specification at http://jcp.org/aboutJava/communityprocess/review/jsr200/index.html Typically the packer engine is used by application developers to deploy or host JAR ... more >
Pack200.Packer interface in java.util.jarThe packer engine applies various transformations to the input JAR file, making the pack stream highly compressible by a compressor such as gzip or zip. An instance of the engine can be obtained using #newPacker. The high degree of compression is achieved by using a number of techniq ... more >
Pack200.Unpacker interface in java.util.jarThe unpacker engine converts the packed stream to a JAR file. An instance of the engine can be obtained using #newUnpacker. Every JAR file produced by this engine will include the string "PACK200" as a zip file comment. This allows a deployer to detect if a JAR archive was packed a ... more >
Package class in java.langPackage objects contain version information about the implementation and specification of a Java package. This versioning information is retrieved and made available by the ClassLoader instance that loaded the class(es). Typically, it is stored in the manifest that is distributed wit ... more >
ParameterizedType interface in java.lang.reflectParameterizedType represents a parameterized type such as Collection<String>. A parameterized type is created the first time it is needed by a reflective method, as specified in this package. When a parameterized type p is created, the generic type declaration that p instantia ... more >
ParseException class in java.textSignals that an error has been reached unexpectedly while parsing.
ParsePosition class in java.textParsePosition is a simple class used by Format and its subclasses to keep track of the current position during parsing. The parseObject method in the various Format classes requires a ParsePosition object as an argument. By design, as you parse through a string with different forma ... more >
PasswordAuthentication class in java.netThe class PasswordAuthentication is a data holder that is used by Authenticator. It is simply a repository for a user name and a password.
PhantomReference class in java.lang.refPhantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. Phantom references are most often used for scheduling pre-mortem cleanup actions in a more flexible way than is possible with the Java finalization mechanism. ... more >
PipedInputStream class in java.ioA piped input stream should be connected to a piped output stream; the piped input stream then provides whatever data bytes are written to the piped output stream. Typically, data is read from a PipedInputStream object by one thread and data is written to the corresponding PipedOu ... more >
PipedOutputStream class in java.ioA piped output stream can be connected to a piped input stream to create a communications pipe. The piped output stream is the sending end of the pipe. Typically, data is written to a PipedOutputStream object by one thread and data is read from the connected PipedInputStream by som ... more >
PipedReader class in java.ioPiped character-input streams.
PipedWriter class in java.ioPiped character-output streams.
PortUnreachableException class in java.netSignals that an ICMP Port Unreachable message has been received on a connected datagram.
PrintStream class in java.ioA PrintStream adds functionality to another output stream, namely the ability to print representations of various data values conveniently. Two other features are provided as well. Unlike other output streams, a PrintStream never throws an IOException; instead, exceptional situations ... more >
PrintWriter class in java.ioPrint formatted representations of objects to a text-output stream. This class implements all of the print methods found in PrintStream. It does not contain methods for writing raw bytes, for which a program should use unencoded byte streams. Unlike the PrintStream class, if automa ... more >
PriorityQueue class in java.utilAn unbounded priority based on a priority heap. This queue orders elements according to an order specified at construction time, which is specified either according to their natural order (see Comparable), or according to a java.util.Comparator, depending on which constructor is use ... more >
Process class in java.langThe ProcessBuilder#start() and Runtime.exec methods create a native process and return an instance of a subclass of Process that can be used to control the process and obtain information about it. The class Process provides methods for performing input from the process, performing ou ... more >
ProcessBuilder class in java.langThis class is used to create operating system processes. Each ProcessBuilder instance manages a collection of process attributes. The #start() method creates a new Process instance with those attributes. The #start() method can be invoked repeatedly from the same instance to create ... more >
Properties class in java.utilThe Properties class represents a persistent set of properties. The Properties can be saved to a stream or loaded from a stream. Each key and its corresponding value in the property list is a string. A property list can contain another property list as its "defaults"; this second p ... more >
PropertyPermission class in java.utilThis class is for property permissions. The name is the name of the property ("java.home", "os.name", etc). The naming convention follows the hierarchical property naming convention. Also, an asterisk may appear at the end of the name, following a ".", or by itself, to signify a ... more >
PropertyResourceBundle class in java.utilPropertyResourceBundle is a concrete subclass of ResourceBundle that manages resources for a locale using a set of static strings from a property file. See ResourceBundle for more information about resource bundles. See Properties for more information about properties files, in partic ... more >
ProtocolException class in java.netThrown to indicate that there is an error in the underlying protocol, such as a TCP error.
Proxy class in java.lang.reflectProxy provides static methods for creating dynamic proxy classes and instances, and it is also the superclass of all dynamic proxy classes created by those methods. To create a proxy for some interface Foo: InvocationHandler handler = new MyInvocationHandler(...); Class p ... more >
Proxy class in java.netThis class represents a proxy setting, typically a type (http, socks) and a socket address. A Proxy is an immutable object.
Proxy.Type class in java.netRepresents the proxy type.
ProxySelector class in java.netSelects the proxy server to use, if any, when connecting to the network resource referenced by a URL. A proxy selector is a concrete sub-class of this class and is registered by invoking the setDefault method. The currently registered proxy selector can be retrieved by calling getDefa ... more >
PushbackInputStream class in java.ioA PushbackInputStream adds functionality to another input stream, namely the ability to "push back" or "unread" one byte. This is useful in situations where it is convenient for a fragment of code to read an indefinite number of data bytes that are delimited by a particular byte ... more >
PushbackReader class in java.ioA character-stream reader that allows characters to be pushed back into the stream.
Queue interface in java.utilA collection designed for holding elements prior to processing. Besides basic Collection operations, queues provide additional insertion, extraction, and inspection operations. Queues typically, but do not necessarily, order elements in a FIFO (first-in-first-out) manner. Among the ... more >
Random class in java.utilAn instance of this class is used to generate a stream of pseudorandom numbers. The class uses a 48-bit seed, which is modified using a linear congruential formula. (See Donald Knuth, The Art of Computer Programming, Volume 2, Section 3.2.1.) If two instances of Random are creat ... more >
RandomAccess interface in java.utilMarker interface used by List implementations to indicate that they support fast (generally constant time) random access. The primary purpose of this interface is to allow generic algorithms to alter their behavior to provide good performance when applied to either random or sequentia ... more >
RandomAccessFile class in java.ioInstances of this class support both reading and writing to a random access file. A random access file behaves like a large array of bytes stored in the file system. There is a kind of cursor, or index into the implied array, called the file pointer; input operations read bytes sta ... more >
Readable interface in java.langA Readable is a source of characters. Characters from a Readable are made available to callers of the read method via a CharBuffer.
Reader class in java.ioAbstract class for reading character streams. The only methods that a subclass must implement are read(char[], int, int) and close(). Most subclasses, however, will override some of the methods defined here in order to provide higher efficiency, additional functionality, or both.
Reference class in java.lang.refAbstract base class for reference objects. This class defines the operations common to all reference objects. Because reference objects are implemented in close cooperation with the garbage collector, this class may not be subclassed directly.
ReferenceQueue class in java.lang.refReference queues, to which registered reference objects are appended by the garbage collector after the appropriate reachability changes are detected.
ReflectPermission class in java.lang.reflectThe Permission class for reflective operations. A ReflectPermission is a named permission and has no actions. The only name currently defined is suppressAccessChecks, which allows suppressing the standard Java language access checks -- for public, default (package) access, protected, ... more >
ResourceBundle class in java.utilResource bundles contain locale-specific objects. When your program needs a locale-specific resource, a String for example, your program can load it from the resource bundle that is appropriate for the current user's locale. In this way, you can write program code that is largely inde ... more >
ResponseCache class in java.netRepresents implementations of URLConnection caches. An instance of such a class can be registered with the system by doing ResponseCache.setDefault(ResponseCache), and the system will call this object in order to: store resource data which has been retrieved from an ext ... more >
Retention interface in java.lang.annotationIndicates how long annotations with the annotated type are to be retained. If no Retention annotation is present on an annotation type declaration, the retention policy defaults to RetentionPolicy.CLASS. A Target meta-annotation has effect only if the meta-annotated type is use dir ... more >
RetentionPolicy class in java.lang.annotationAnnotation retention policy. The constants of this enumerated type describe the various policies for retaining annotations. They are used in conjunction with the Retention meta-annotation type to specify how long annotations are to be retained.
RoundingMode class in java.mathSpecifies a rounding behavior for numerical operations capable of discarding precision. Each rounding mode indicates how the least significant returned digit of a rounded result is to be calculated. If fewer digits are returned than the digits needed to represent the exact numerical r ... more >
RuleBasedCollator class in java.textThe RuleBasedCollator class is a concrete subclass of Collator that provides a simple, data-driven, table collator. With this class you can create a customized table-based Collator. RuleBasedCollator maps characters to sort keys. RuleBasedCollator has the following restrictions ... more >
Runnable interface in java.langThe Runnable interface should be implemented by any class whose instances are intended to be executed by a thread. The class must define a method of no arguments called run. This interface is designed to provide a common protocol for objects that wish to execute code while they are ... more >
Runtime class in java.langEvery Java application has a single instance of class Runtime that allows the application to interface with the environment in which the application is running. The current runtime can be obtained from the getRuntime method. An application cannot create its own instance of this class.
RuntimeException class in java.langRuntimeException is the superclass of those exceptions that can be thrown during the normal operation of the Java Virtual Machine. A method is not required to declare in its throws clause any subclasses of RuntimeException that might be thrown during the execution of the metho ... more >
RuntimeMXBean interface in java.lang.managementThe management interface for the runtime system of the Java virtual machine. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the ManagementFactory#ge ... more >
RuntimePermission class in java.langThis class is for runtime permissions. A RuntimePermission contains a name (also referred to as a "target name") but no actions list; you either have the named permission or you don't. The target name is the name of the runtime permission (see below). The naming convention follows ... more >
Scanner class in java.utilA simple text scanner which can parse primitive types and strings using regular expressions. A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace. The resulting tokens may then be converted into values of different types using the ... more >
SecureCacheResponse class in java.netRepresents a cache response originally retrieved through secure means, such as TLS.
SecurityException class in java.langThrown by the security manager to indicate a security violation.
SecurityManager class in java.langThe security manager is a class that allows applications to implement a security policy. It allows an application to determine, before performing a possibly unsafe or sensitive operation, what the operation is and whether it is being attempted in a security context that allows the ... more >
SequenceInputStream class in java.ioA SequenceInputStream represents the logical concatenation of other input streams. It starts out with an ordered collection of input streams and reads from the first one until end of file is reached, whereupon it reads from the second one, and so on, until end of file is reached on ... more >
Serializable interface in java.ioSerializability of a class is enabled by the class implementing the java.io.Serializable interface. Classes that do not implement this interface will not have any of their state serialized or deserialized. All subtypes of a serializable class are themselves serializable. The serializ ... more >
SerializablePermission class in java.ioThis class is for Serializable permissions. A SerializablePermission contains a name (also referred to as a "target name") but no actions list; you either have the named permission or you don't. The target name is the name of the Serializable permission (see below). The follow ... more >
ServerSocket class in java.netThis class implements server sockets. A server socket waits for requests to come in over the network. It performs some operation based on that request, and then possibly returns a result to the requester. The actual work of the server socket is performed by an instance of the Soc ... more >
Set interface in java.utilA collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the mathematical set abstraction. The Set interface places additional sti ... more >
Short class in java.langThe Short class wraps a value of primitive type short in an object. An object of type Short contains a single field whose type is short. In addition, this class provides several methods for converting a short to a String and a String to a short, as well as other constants and ... more >
SimpleDateFormat class in java.textSimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date -> text), parsing (text -> date), and normalization. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formattin ... more >
SimpleTimeZone class in java.utilSimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar. The class holds an offset from GMT, called raw offset, and start and end rules for a daylight saving time schedule. Since it only holds single values for each, it cannot ha ... more >
Socket class in java.netThis class implements client sockets (also called just "sockets"). A socket is an endpoint for communication between two machines. The actual work of the socket is performed by an instance of the SocketImpl class. An application, by changing the socket factory that creates the sock ... more >
SocketAddress class in java.netThis class represents a Socket Address with no protocol attachment. As an abstract class, it is meant to be subclassed with a specific, protocol dependent, implementation. It provides an immutable object used by sockets for binding, connecting, or as returned values.
SocketException class in java.netThrown to indicate that there is an error in the underlying protocol, such as a TCP error.
SocketImpl class in java.netThe abstract class SocketImpl is a common superclass of all classes that actually implement sockets. It is used to create both client and server sockets. A "plain" socket implements these methods exactly as described, without attempting to go through a firewall or proxy.
SocketImplFactory interface in java.netThis interface defines a factory for socket implementations. It is used by the classes Socket and ServerSocket to create actual socket implementations.
SocketOptions interface in java.netInterface of methods to get/set socket options. This interface is implemented by: SocketImpl and DatagramSocketImpl. Subclasses of these should override the methods of this interface in order to support their own options. The methods and constants which specify options in this int ... more >
SocketPermission class in java.netThis class represents access to a network via sockets. A SocketPermission consists of a host specification and a set of "actions" specifying ways to connect to that host. The host is specified as host = (hostname | IPv4address | iPv6reference) [:portrange] portrange = portnu ... more >
SocketTimeoutException class in java.netSignals that a timeout has occurred on a socket read or accept.
SoftReference class in java.lang.refSoft reference objects, which are cleared at the discretion of the garbage collector in response to memory demand. Soft references are most often used to implement memory-sensitive caches. Suppose that the garbage collector determines at a certain point in time that an object is so ... more >
SortedMap interface in java.utilA map that further guarantees that it will be in ascending key order, sorted according to the natural ordering of its keys (see the Comparable interface), or by a comparator provided at sorted map creation time. This order is reflected when iterating over the sorted map's collection v ... more >
SortedSet interface in java.utilA set that further guarantees that its iterator will traverse the set in ascending element order, sorted according to the natural ordering of its elements (see Comparable), or by a Comparator provided at sorted set creation time. Several additional operations are provided to take adva ... more >
Stack class in java.utilThe Stack class represents a last-in-first-out (LIFO) stack of objects. It extends class Vector with five operations that allow a vector to be treated as a stack. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to te ... more >
StackOverflowError class in java.langThrown when a stack overflow occurs because an application recurses too deeply.
StackTraceElement class in java.langAn element in a stack trace, as returned by Throwable#getStackTrace(). Each element represents a single stack frame. All stack frames except for the one at the top of the stack represent a method invocation. The frame at the top of the stack represents the execution point at which th ... more >
StreamCorruptedException class in java.ioThrown when control information that was read from an object stream violates internal consistency checks.
StreamTokenizer class in java.ioThe StreamTokenizer class takes an input stream and parses it into "tokens", allowing the tokens to be read one at a time. The parsing process is controlled by a table and a number of flags that can be set to various states. The stream tokenizer can recognize identifiers, numbers, quot ... more >
StrictMath class in java.langThe class StrictMath contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions. To help ensure portability of Java programs, the definitions of some of the numeric functions in this package req ... more >
String class in java.langThe String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class. Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String object ... more >
StringBuffer class in java.langA thread-safe, mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls. String buffers ... more >
StringBufferInputStream class in java.ioThis class allows an application to create an input stream in which the bytes read are supplied by the contents of a string. Applications can also read bytes from a byte array by using a ByteArrayInputStream. Only the low eight bits of each character in the string are used by this class.
StringBuilder class in java.langA mutable sequence of characters. This class provides an API compatible with StringBuffer, but with no guarantee of synchronization. This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is gene ... more >
StringCharacterIterator class in java.textStringCharacterIterator implements the CharacterIterater protocol for a String. The StringCharacterIterator class iterates over the entire String.
StringIndexOutOfBoundsException class in java.langThrown by String methods to indicate that an index is either negative or greater than the size of the string. For some methods such as the charAt method, this exception also is thrown when the index is equal to the size of the string.
StringReader class in java.ioA character stream whose source is a string.
StringTokenizer class in java.utilThe string tokenizer class allows an application to break a string into tokens. The tokenization method is much simpler than the one used by the StreamTokenizer class. The StringTokenizer methods do not distinguish among identifiers, numbers, and quoted strings, nor do they recogni ... more >
StringWriter class in java.ioA character stream that collects its output in a string buffer, which can then be used to construct a string. Closing a StringWriter has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.
SuppressWarnings interface in java.langIndicates that the named compiler warnings should be suppressed in the annotated element (and in all program elements contained in the annotated element). Note that the set of warnings suppressed in a given element is a superset of the warnings suppressed in all containing elements. F ... more >
SyncFailedException class in java.ioSignals that a sync operation has failed.
System class in java.langThe System class contains several useful class fields and methods. It cannot be instantiated. Among the facilities provided by the System class are standard input, standard output, and error output streams; access to externally defined properties and environment variables; a means o ... more >
Target interface in java.lang.annotationIndicates the kinds of program element to which an annotation type is applicable. If a Target meta-annotation is not present on an annotation type declaration, the declared type may be used on any program element. If such a meta-annotation is present, the compiler will enforce the sp ... more >
Thread class in java.langA thread is a thread of execution in a program. The Java Virtual Machine allows an application to have multiple threads of execution running concurrently. Every thread has a priority. Threads with higher priority are executed in preference to threads with lower priority. Each th ... more >
Thread.State class in java.langA thread state. A thread can be in one of the following states: #NEW A thread that has not yet started is in this state. #RUNNABLE A thread executing in the Java virtual machine is in this state. #BLOCKED A thread that is blocked waiting for a monitor ... more >
Thread.UncaughtExceptionHandler interface in java.langInterface for handlers invoked when a Thread abruptly terminates due to an uncaught exception. When a thread is about to terminate due to an uncaught exception the Java Virtual Machine will query the thread for its UncaughtExceptionHandler using Thread#getUncaughtExceptionHandler ... more >
ThreadDeath class in java.langAn instance of ThreadDeath is thrown in the victim thread when the stop method with zero arguments in class Thread is called. An application should catch instances of this class only if it must clean up after being terminated asynchronously. If ThreadDeath is caught by a metho ... more >
ThreadGroup class in java.langA thread group represents a set of threads. In addition, a thread group can also include other thread groups. The thread groups form a tree in which every thread group except the initial thread group has a parent. A thread is allowed to access information about its own thread ... more >
ThreadInfo class in java.lang.managementThread information. ThreadInfo contains the information about a thread including: General thread information Thread ID. Name of the thread. Execution information Thread state. The object upon which the thread is blocked waiting to enter a synchronization bloc ... more >
ThreadLocal class in java.langThis class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields i ... more >
ThreadMXBean interface in java.lang.managementThe management interface for the thread system of the Java virtual machine. A Java virtual machine has a single instance of the implementation class of this interface. This instance implementing this interface is an MXBean that can be obtained by calling the ManagementFactory#get ... more >
Throwable class in java.langThe Throwable class is the superclass of all errors and exceptions in the Java language. Only objects that are instances of this class (or one of its subclasses) are thrown by the Java Virtual Machine or can be thrown by the Java throw statement. Similarly, only this class or one of it ... more >
Timer class in java.utilA facility for threads to schedule tasks for future execution in a background thread. Tasks may be scheduled for one-time execution, or for repeated execution at regular intervals. Corresponding to each Timer object is a single background thread that is used to execute all of the ti ... more >
TimerTask class in java.utilA task that can be scheduled for one-time or repeated execution by a Timer.
TimeZone class in java.utilTimeZone represents a time zone offset, and also figures out daylight savings. Typically, you get a TimeZone using getDefault which creates a TimeZone based on the time zone where the program is running. For example, for a program running in Japan, getDefault creates a TimeZone ob ... more >
TooManyListenersException class in java.utilThe TooManyListenersException Exception is used as part of the Java Event model to annotate and implement a unicast special case of a multicast Event Source. The presence of a "throws TooManyListenersException" clause on any given concrete implementation of the normally multica ... more >
TreeMap class in java.utilRed-Black tree based implementation of the SortedMap interface. This class guarantees that the map will be in ascending key order, sorted according to the natural order for the key's class (see Comparable), or by the comparator provided at creation time, depending on which constructor ... more >
TreeSet class in java.utilThis class implements the Set interface, backed by a TreeMap instance. This class guarantees that the sorted set will be in ascending element order, sorted according to the natural order of the elements (see Comparable), or by the comparator provided at set creation time, depending on ... more >
Type interface in java.lang.reflectType is the common superinterface for all types in the Java programming language. These include raw types, parameterized types, array types, type variables and primitive types.
TypeNotPresentException class in java.langThrown when an application tries to access a type using a string representing the type's name, but no definition for the type with the specified name can be found. This exception differs from ClassNotFoundException in that ClassNotFoundException is a checked exception, whereas this e ... more >
TypeVariable interface in java.lang.reflectTypeVariable is the common superinterface for type variables of kinds. A type variable is created the first time it is needed by a reflective method, as specified in this package. If a type variable t is referenced by a type (i.e, class, interface or annotation type) T, and T is declar ... more >
UndeclaredThrowableException class in java.lang.reflectThrown by a method invocation on a proxy instance if its invocation handler's invoke method throws a checked exception (a Throwable that is not assignable to RuntimeException or Error) that is not assignable to any of the exception types declared in the throws clause of the method tha ... more >
UnknownError class in java.langThrown when an unknown but serious exception has occurred in the Java Virtual Machine.
UnknownFormatConversionException class in java.utilUnchecked exception thrown when an unknown conversion is given. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
UnknownFormatFlagsException class in java.utilUnchecked exception thrown when an unknown flag is given. Unless otherwise specified, passing a null argument to any method or constructor in this class will cause a NullPointerException to be thrown.
UnknownHostException class in java.netThrown to indicate that the IP address of a host could not be determined.
UnknownServiceException class in java.netThrown to indicate that an unknown service exception has occurred. Either the MIME type returned by a URL connection does not make sense, or the application is attempting to write to a read-only URL connection.
UnmodifiableClassException class in java.lang.instrumentThrown by an implementation of Instrumentation.redefineClasses when one of the specified classes cannot be modified.
UnsatisfiedLinkError class in java.langThrown if the Java Virtual Machine cannot find an appropriate native-language definition of a method declared native.
UnsupportedClassVersionError class in java.langThrown when the Java Virtual Machine attempts to read a class file and determines that the major and minor version numbers in the file are not supported.
UnsupportedEncodingException class in java.ioThe Character Encoding is not supported.
UnsupportedOperationException class in java.langThrown to indicate that the requested operation is not supported. This class is a member of the Java Collections Framework.
URI class in java.netRepresents a Uniform Resource Identifier (URI) reference. Aside from some minor deviations noted below, an instance of this class represents a URI reference as defined by RFC 2396: Uniform Resource Identifiers (URI): Generic Syntax, amended by RFC 2732: Format for Litera ... more >
URISyntaxException class in java.netChecked exception thrown to indicate that a string could not be parsed as a URI reference.
URL class in java.netClass URL represents a Uniform Resource Locator, a pointer to a "resource" on the World Wide Web. A resource can be something as simple as a file or a directory, or it can be a reference to a more complicated object, such as a query to a database or to a search engine. More informatio ... more >
URLClassLoader class in java.netThis class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be opened as needed. The A ... more >
URLConnection class in java.netThe abstract class URLConnection is the superclass of all classes that represent a communications link between the application and a URL. Instances of this class can be used both to read from and to write to the resource referenced by the URL. In general, creating a connection to a URL ... more >
URLDecoder class in java.netUtility class for HTML form decoding. This class contains static methods for decoding a String from the application/x-www-form-urlencoded MIME format. To conversion process is the reverse of that used by the URLEncoder class. It is assumed that all characters in the encoded string a ... more >
URLEncoder class in java.netUtility class for HTML form encoding. This class contains static methods for converting a String to the application/x-www-form-urlencoded MIME format. For more information about HTML form encoding, consult the HTML specification. When encoding a String, the following rules apply: ... more >
URLStreamHandler class in java.netThe abstract class URLStreamHandler is the common superclass for all stream protocol handlers. A stream protocol handler knows how to make a connection for a particular protocol type, such as http, ftp, or gopher. In most cases, an instance of a URLStreamHandler subclass is not cr ... more >
URLStreamHandlerFactory interface in java.netThis interface defines a factory for URL stream protocol handlers. It is used by the URL class to create a URLStreamHandler for a specific protocol.
UTFDataFormatException class in java.ioSignals that a malformed string in modified UTF-8 format has been read in a data input stream or by any class that implements the data input interface. See the DataInput class description for the format in which modified UTF-8 strings are read and written.
UUID class in java.utilA class that represents an immutable universally unique identifier (UUID). A UUID represents a 128-bit value. There exist different variants of these global identifiers. The methods of this class are for manipulating the Leach-Salz variant, although the constructors allow the creati ... more >
Vector class in java.utilThe Vector class implements a growable array of objects. Like an array, it contains components that can be accessed using an integer index. However, the size of a Vector can grow or shrink as needed to accommodate adding and removing items after the Vector has been created. Each ... more >
VerifyError class in java.langThrown when the "verifier" detects that a class file, though well formed, contains some sort of internal inconsistency or security problem.
VirtualMachineError class in java.langThrown to indicate that the Java Virtual Machine is broken or has run out of resources necessary for it to continue operating.
Void class in java.langThe Void class is an uninstantiable placeholder class to hold a reference to the Class object representing the Java keyword void.
WeakHashMap class in java.utilA hashtable-based Map implementation with weak keys. An entry in a WeakHashMap will automatically be removed when its key is no longer in ordinary use. More precisely, the presence of a mapping for a given key will not prevent the key from being discarded by the garbage collector, tha ... more >
WeakReference class in java.lang.refWeak reference objects, which do not prevent their referents from being made finalizable, finalized, and then reclaimed. Weak references are most often used to implement canonicalizing mappings. Suppose that the garbage collector determines at a certain point in time that an object ... more >
WildcardType interface in java.lang.reflectWildcardType represents a wildcard type expression, such as ?, ? extends Number, or ? super Integer.
WriteAbortedException class in java.ioSignals that one of the ObjectStreamExceptions was thrown during a write operation. Thrown during a read operation when one of the ObjectStreamExceptions was thrown during a write operation. The exception that terminated the write can be found in the detail field. The stream is rese ... more >
Writer class in java.ioAbstract class for writing to character streams. The only methods that a subclass must implement are write(char[], int, int), flush(), and close(). Most subclasses, however, will override some of the methods defined here in order to provide higher efficiency, additional functionality, or both.
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