java.lang.Object
  └ java.text.CollationElementIterator

The 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 is collated in the given collation object.

For example, consider the following in Spanish:

 "ca" -> the first key is key('c') and second key is key('a').
 "cha" -> the first key is key('ch') and second key is key('a').
 

And in German,

 "?b"-> the first key is key('a'), the second key is key('e'), and
 the third key is key('b').
 

The key of a character is an integer composed of primary order(short), secondary order(byte), and tertiary order(byte). Java strictly defines the size and signedness of its primitive data types. Therefore, the static functions primaryOrder, secondaryOrder, and tertiaryOrder return int, short, and short respectively to ensure the correctness of the key value.

Example of the iterator usage,

  String testString = "This is a test";
  RuleBasedCollator ruleBasedCollator = (RuleBasedCollator)Collator.getInstance();
  CollationElementIterator collationElementIterator = ruleBasedCollator.getCollationElementIterator(testString);
  int primaryOrder = CollationElementIterator.primaryOrder(collationElementIterator.next());
 

CollationElementIterator.next returns the collation order of the next character. A collation order consists of primary order, secondary order and tertiary order. The data type of the collation order is int. The first 16 bits of a collation order is its primary order; the next 8 bits is the secondary order and the last 8 bits is the tertiary order.