[Chapter 16] CollationElementIterator

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| Chapter 16 The java.text Package |

# CollationElementIterator

## Name

CollationElementIterator

## Synopsis

Class Name:

  `java.text.CollationElementIterator`

Superclass:

  `java.lang.Object`

Immediate Subclasses:

  None

Interfaces Implemented:

  None

Availability:

  New as of JDK 1.1

## Description

A `RuleBasedCollator` object creates an instance of the `CollationElementIterator` class to iterate through the characters of a string and determine their relative collation sequence. A `CollationElementIterator` object performs callbacks to the `RuleBasedCollator` that created it to get the information it needs to recognize groups of characters that are treated as single collation characters. For example, a `RuleBasedCollator` for a Spanish language locale would be set up to treat `ch' as a single letter. A `CollationElementIterator` object also gets information from its `RuleBasedCollator` that is used to determine the collation ordering priority for characters.

A collation-ordering priority of a character is a composite integer value that determines how the character is collated. This priority is comprised of:

- A primary order that distinguishes between different letters. Characters that are considered to be different letters, such as `e' and `f', have different primary orders. Different forms of the same letter, such as `e' and `E', or an accented form of `e', have the same primary order. Primary orders are short values.

- A secondary order that distinguishes between accented forms of the same letter. An unaccented `e' has a different secondary order than forms of `e' that have different accents. `E' and `e' have the same secondary order, as do upper- and lowercase forms of `e' that have the same accent. Secondary orders are byte values.

- A tertiary order that distinguishes between case differences. `E' and `e' have different tertiary orders. Tertiary orders are byte values.

The `next()` method returns the collation-ordering priority of the next logical character. Primary, secondary, and tertiary orders are extracted from an ordering priority with the `primaryOrder()`, `secondaryOrder()`, and `tertiaryOrder()` methods.

## Class Summary

    public final class java.text.CollationElementIterator
                       extends java.lang.Object {
       // Constants
       public static final int NULLORDER;

      // Class Methods
       public static final int primaryOrder(int order);
       public static final short secondaryOrder(int order);
       public static final short tertiaryOrder(int order);

      // Instance Methods
       public int next();
       public void reset();
    }

## Constants

### NULLORDER

#### public final static int NULLORDER

Description

  A constant that is returned by `next()` if the end of the string has been reached.

## Class Methods

### primaryOrder

#### public static final int primaryOrder(int order)

Returns

  The primary order component of the given order key.

Description

  This method extracts the primary order value from the given order key.

### secondaryOrder

#### public static final short secondaryOrder(int order)

Returns

  The secondary order component of the given order key.

Description

  This method extracts the secondary order value from the given order key.

### tertiaryOrder

#### public static final short tertiaryOrder(int order)

Returns

  The tertiary order component of the given order key.

Description

  This method extracts the tertiary order value from the given order key.

## Instance Methods

### next

#### public int next()

Returns

  The order value of the next character in the string.

Description

  This method returns the order key for the next character in the string. The returned value can be broken apart using the `primaryOrder()`, `secondaryOrder()`, and `tertiaryOrder()` methods.

### reset

#### public void reset()

Description

  This method resets the position of this `CollationElementIterator` to the beginning of the string.

## Inherited Methods

Method | Inherited From | Method | Inherited From
--- | --- | --- | ---
`clone()` | `Object` | `equals(Object)` | `Object`
`finalize()` | `Object` | `getClass()` | `Object`
`hashCode()` | `Object` | `notify()` | `Object`
`notifyAll()` | `Object` | `toString()` | `Object`
`wait()` | `Object` | `wait(long)` | `Object`
`wait(long, int)` | `Object` |  |

## See Also

`Collator`, `RuleBasedCollator`, `String`

ChoiceFormat |  | CollationKey