CollationElementIterator Class

Definition

[Android.Runtime.Register("android/icu/text/CollationElementIterator", ApiSince=24, DoNotGenerateAcw=true)]
public sealed class CollationElementIterator : Java.Lang.Object

[<Android.Runtime.Register("android/icu/text/CollationElementIterator", ApiSince=24, DoNotGenerateAcw=true)>]
type CollationElementIterator = class
    inherit Object

Inheritance

Object

Object

CollationElementIterator

Attributes

RegisterAttribute

Remarks

CollationElementIterator is an iterator created by a RuleBasedCollator to walk through a string. The return result of each iteration is a 32-bit collation element (CE) that defines the ordering priority of the next character or sequence of characters in the source string.

For illustration, consider the following in Slovak and in traditional Spanish collation: <blockquote>

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

</blockquote> And in German phonebook collation, <blockquote>

Since the character 'æ' is a composed character of 'a' and 'e', the
            iterator returns two collation elements for the single character 'æ'

            "æb" -> the first collation element is collation_element('a'), the
                         second collation element is collation_element('e'), and the
                         third collation element is collation_element('b').

</blockquote>

For collation ordering comparison, the collation element results can not be compared simply by using basic arithmetic operators, e.g. &lt;, == or &gt;, further processing has to be done. Details can be found in the ICU User Guide. An example of using the CollationElementIterator for collation ordering comparison is the class android.icu.text.StringSearch.

To construct a CollationElementIterator object, users call the method getCollationElementIterator() on a RuleBasedCollator that defines the desired sorting order.

Example: <blockquote>

String testString = "This is a test";
             RuleBasedCollator rbc = new RuleBasedCollator("&a<b");
             CollationElementIterator iterator = rbc.getCollationElementIterator(testString);
             int primaryOrder = iterator.IGNORABLE;
             while (primaryOrder != iterator.NULLORDER) {
                 int order = iterator.next();
                 if (order != iterator.IGNORABLE &&
                     order != iterator.NULLORDER) {
                     // order is valid, not ignorable and we have not passed the end
                     // of the iteration, we do something
                     primaryOrder = CollationElementIterator.primaryOrder(order);
                     System.out.println("Next primary order 0x" +
                                        Integer.toHexString(primaryOrder));
                 }
             }

</blockquote>

The method next() returns the collation order of the next character based on the comparison level of the collator. The method previous() returns the collation order of the previous character based on the comparison level of the collator. The Collation Element Iterator moves only in one direction between calls to reset(), setOffset(), or setText(). That is, next() and previous() can not be inter-used. Whenever previous() is to be called after next() or vice versa, reset(), setOffset() or setText() has to be called first to reset the status, shifting current position to either the end or the start of the string (reset() or setText()), or the specified position (setOffset()). Hence at the next call of next() or previous(), the first or last collation order, or collation order at the specified position will be returned. If a change of direction is done without one of these calls, the result is undefined.

This class is not subclassable.

Java documentation for android.icu.text.CollationElementIterator.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Fields

Properties

Methods

Explicit Interface Implementations

Extension Methods

Applies to