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/*
 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
 *
 * The original version of this source code and documentation
 * is copyrighted and owned by Taligent, Inc., a wholly-owned
 * subsidiary of IBM. These materials are provided under terms
 * of a License Agreement between Taligent and Sun. This technology
 * is protected by multiple US and International patents.
 *
 * This notice and attribution to Taligent may not be removed.
 * Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.text;

import java.lang.ref.SoftReference;
import java.text.spi.BreakIteratorProvider;
import java.util.Locale;
import sun.util.locale.provider.LocaleProviderAdapter;
import sun.util.locale.provider.LocaleServiceProviderPool;



The 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, and is thus able to scan text held by any object implementing that protocol. A StringCharacterIterator is used to scan String objects passed to setText. 
 You use the factory methods provided by this class to create instances of various types of break iterators. In particular, use getWordInstance, getLineInstance, getSentenceInstance, and getCharacterInstance to create BreakIterators that perform word, line, sentence, and character boundary analysis respectively. A single BreakIterator can work only on one unit (word, line, sentence, and so on). You must use a different iterator for each unit boundary analysis you wish to perform. 

Line boundary analysis determines where a text string can be
broken when line-wrapping. The mechanism correctly handles
punctuation and hyphenated words. Actual line breaking needs
to also consider the available line width and is handled by
higher-level software.


Sentence boundary analysis allows selection with correct interpretation
of periods within numbers and abbreviations, and trailing punctuation
marks such as quotation marks and parentheses.


Word boundary analysis is used by search and replace functions, as
well as within text editing applications that allow the user to
select words with a double click. Word selection provides correct
interpretation of punctuation marks within and following
words. Characters that are not part of a word, such as symbols
or punctuation marks, have word-breaks on both sides.


Character boundary analysis allows users to interact with characters
as they expect to, for example, when moving the cursor through a text
string. Character boundary analysis provides correct navigation
through character strings, regardless of how the character is stored.
The boundaries returned may be those of supplementary characters,
combining character sequences, or ligature clusters.
For example, an accented character might be stored as a base character
and a diacritical mark. What users consider to be a character can
differ between languages.

 The BreakIterator instances returned by the factory methods of this class are intended for use with natural languages only, not for programming language text. It is however possible to define subclasses that tokenize a programming language. 

Examples:

Creating and using text boundaries:



public static void main(String args[]) {
     if (args.length == 1) {
         String stringToExamine = args[0];
         //print each word in order
         BreakIterator boundary = BreakIterator.getWordInstance();
         boundary.setText(stringToExamine);
         printEachForward(boundary, stringToExamine);
         //print each sentence in reverse order
         boundary = BreakIterator.getSentenceInstance(Locale.US);
         boundary.setText(stringToExamine);
         printEachBackward(boundary, stringToExamine);
         printFirst(boundary, stringToExamine);
         printLast(boundary, stringToExamine);
     }
}




Print each element in order:



public static void printEachForward(BreakIterator boundary, String source) {
    int start = boundary.first();
    for (int end = boundary.next();
         end != BreakIterator.DONE;
         start = end, end = boundary.next()) {
         System.out.println(source.substring(start,end));
    }
}




Print each element in reverse order:



public static void printEachBackward(BreakIterator boundary, String source) {
    int end = boundary.last();
    for (int start = boundary.previous();
         start != BreakIterator.DONE;
         end = start, start = boundary.previous()) {
        System.out.println(source.substring(start,end));
    }
}




Print first element:



public static void printFirst(BreakIterator boundary, String source) {
    int start = boundary.first();
    int end = boundary.next();
    System.out.println(source.substring(start,end));
}




Print last element:



public static void printLast(BreakIterator boundary, String source) {
    int end = boundary.last();
    int start = boundary.previous();
    System.out.println(source.substring(start,end));
}




Print the element at a specified position:



public static void printAt(BreakIterator boundary, int pos, String source) {
    int end = boundary.following(pos);
    int start = boundary.previous();
    System.out.println(source.substring(start,end));
}




Find the next word:




public static int nextWordStartAfter(int pos, String text) {
    BreakIterator wb = BreakIterator.getWordInstance();
    wb.setText(text);
    int last = wb.following(pos);
    int current = wb.next();
    while (current != BreakIterator.DONE) {
        for (int p = last; p < current; p++) {
            if (Character.isLetter(text.codePointAt(p)))
                return last;
        }
        last = current;
        current = wb.next();
    }
    return BreakIterator.DONE;
 }


(The iterator returned by BreakIterator.getWordInstance() is unique in that
the break positions it returns don't represent both the start and end of the
thing being iterated over.  That is, a sentence-break iterator returns breaks
that each represent the end of one sentence and the beginning of the next.
With the word-break iterator, the characters between two boundaries might be a
word, or they might be the punctuation or whitespace between two words.  The
above code uses a simple heuristic to determine which boundary is the beginning
of a word: If the characters between this boundary and the next boundary
include at least one letter (this can be an alphabetical letter, a CJK ideograph,
a Hangul syllable, a Kana character, etc.), then the text between this boundary
and the next is a word; otherwise, it's the material between words.)



See Also:
Since:1.1
/**
 * The {@code BreakIterator} class implements methods for finding
 * the location of boundaries in text. Instances of {@code BreakIterator}
 * maintain a current position and scan over text
 * returning the index of characters where boundaries occur.
 * Internally, {@code BreakIterator} scans text using a
 * {@code CharacterIterator}, and is thus able to scan text held
 * by any object implementing that protocol. A {@code StringCharacterIterator}
 * is used to scan {@code String} objects passed to {@code setText}.
 *
 * <p>
 * You use the factory methods provided by this class to create
 * instances of various types of break iterators. In particular,
 * use {@code getWordInstance}, {@code getLineInstance},
 * {@code getSentenceInstance}, and {@code getCharacterInstance}
 * to create {@code BreakIterator}s that perform
 * word, line, sentence, and character boundary analysis respectively.
 * A single {@code BreakIterator} can work only on one unit
 * (word, line, sentence, and so on). You must use a different iterator
 * for each unit boundary analysis you wish to perform.
 *
 * <p><a id="line"></a>
 * Line boundary analysis determines where a text string can be
 * broken when line-wrapping. The mechanism correctly handles
 * punctuation and hyphenated words. Actual line breaking needs
 * to also consider the available line width and is handled by
 * higher-level software.
 *
 * <p><a id="sentence"></a>
 * Sentence boundary analysis allows selection with correct interpretation
 * of periods within numbers and abbreviations, and trailing punctuation
 * marks such as quotation marks and parentheses.
 *
 * <p><a id="word"></a>
 * Word boundary analysis is used by search and replace functions, as
 * well as within text editing applications that allow the user to
 * select words with a double click. Word selection provides correct
 * interpretation of punctuation marks within and following
 * words. Characters that are not part of a word, such as symbols
 * or punctuation marks, have word-breaks on both sides.
 *
 * <p><a id="character"></a>
 * Character boundary analysis allows users to interact with characters
 * as they expect to, for example, when moving the cursor through a text
 * string. Character boundary analysis provides correct navigation
 * through character strings, regardless of how the character is stored.
 * The boundaries returned may be those of supplementary characters,
 * combining character sequences, or ligature clusters.
 * For example, an accented character might be stored as a base character
 * and a diacritical mark. What users consider to be a character can
 * differ between languages.
 *
 * <p>
 * The {@code BreakIterator} instances returned by the factory methods
 * of this class are intended for use with natural languages only, not for
 * programming language text. It is however possible to define subclasses
 * that tokenize a programming language.
 *
 * <P>
 * <strong>Examples</strong>:<P>
 * Creating and using text boundaries:
 * <blockquote>
 * <pre>
 * public static void main(String args[]) {
 *      if (args.length == 1) {
 *          String stringToExamine = args[0];
 *          //print each word in order
 *          BreakIterator boundary = BreakIterator.getWordInstance();
 *          boundary.setText(stringToExamine);
 *          printEachForward(boundary, stringToExamine);
 *          //print each sentence in reverse order
 *          boundary = BreakIterator.getSentenceInstance(Locale.US);
 *          boundary.setText(stringToExamine);
 *          printEachBackward(boundary, stringToExamine);
 *          printFirst(boundary, stringToExamine);
 *          printLast(boundary, stringToExamine);
 *      }
 * }
 * </pre>
 * </blockquote>
 *
 * Print each element in order:
 * <blockquote>
 * <pre>
 * public static void printEachForward(BreakIterator boundary, String source) {
 *     int start = boundary.first();
 *     for (int end = boundary.next();
 *          end != BreakIterator.DONE;
 *          start = end, end = boundary.next()) {
 *          System.out.println(source.substring(start,end));
 *     }
 * }
 * </pre>
 * </blockquote>
 *
 * Print each element in reverse order:
 * <blockquote>
 * <pre>
 * public static void printEachBackward(BreakIterator boundary, String source) {
 *     int end = boundary.last();
 *     for (int start = boundary.previous();
 *          start != BreakIterator.DONE;
 *          end = start, start = boundary.previous()) {
 *         System.out.println(source.substring(start,end));
 *     }
 * }
 * </pre>
 * </blockquote>
 *
 * Print first element:
 * <blockquote>
 * <pre>
 * public static void printFirst(BreakIterator boundary, String source) {
 *     int start = boundary.first();
 *     int end = boundary.next();
 *     System.out.println(source.substring(start,end));
 * }
 * </pre>
 * </blockquote>
 *
 * Print last element:
 * <blockquote>
 * <pre>
 * public static void printLast(BreakIterator boundary, String source) {
 *     int end = boundary.last();
 *     int start = boundary.previous();
 *     System.out.println(source.substring(start,end));
 * }
 * </pre>
 * </blockquote>
 *
 * Print the element at a specified position:
 * <blockquote>
 * <pre>
 * public static void printAt(BreakIterator boundary, int pos, String source) {
 *     int end = boundary.following(pos);
 *     int start = boundary.previous();
 *     System.out.println(source.substring(start,end));
 * }
 * </pre>
 * </blockquote>
 *
 * Find the next word:
 * <blockquote>
 * <pre>{@code
 * public static int nextWordStartAfter(int pos, String text) {
 *     BreakIterator wb = BreakIterator.getWordInstance();
 *     wb.setText(text);
 *     int last = wb.following(pos);
 *     int current = wb.next();
 *     while (current != BreakIterator.DONE) {
 *         for (int p = last; p < current; p++) {
 *             if (Character.isLetter(text.codePointAt(p)))
 *                 return last;
 *         }
 *         last = current;
 *         current = wb.next();
 *     }
 *     return BreakIterator.DONE;
 * }
 * }</pre>
 * (The iterator returned by BreakIterator.getWordInstance() is unique in that
 * the break positions it returns don't represent both the start and end of the
 * thing being iterated over.  That is, a sentence-break iterator returns breaks
 * that each represent the end of one sentence and the beginning of the next.
 * With the word-break iterator, the characters between two boundaries might be a
 * word, or they might be the punctuation or whitespace between two words.  The
 * above code uses a simple heuristic to determine which boundary is the beginning
 * of a word: If the characters between this boundary and the next boundary
 * include at least one letter (this can be an alphabetical letter, a CJK ideograph,
 * a Hangul syllable, a Kana character, etc.), then the text between this boundary
 * and the next is a word; otherwise, it's the material between words.)
 * </blockquote>
 *
 * @since 1.1
 * @see CharacterIterator
 *
 */

public abstract class BreakIterator implements Cloneable
{
    
Constructor. BreakIterator is stateless and has no default behavior.

/**
     * Constructor. BreakIterator is stateless and has no default behavior.
     */
    protected BreakIterator()
    {
    }

    
Create a copy of this iterator

Returns:A copy of this
/**
     * Create a copy of this iterator
     * @return A copy of this
     */
    @Override
    public Object clone()
    {
        try {
            return super.clone();
        }
        catch (CloneNotSupportedException e) {
            throw new InternalError(e);
        }
    }

    
DONE is returned by previous(), next(), next(int), preceding(int)
and following(int) when either the first or last text boundary has been
reached.

/**
     * DONE is returned by previous(), next(), next(int), preceding(int)
     * and following(int) when either the first or last text boundary has been
     * reached.
     */
    public static final int DONE = -1;

    
Returns the first boundary. The iterator's current position is set
to the first text boundary.

Returns:The character index of the first text boundary.
/**
     * Returns the first boundary. The iterator's current position is set
     * to the first text boundary.
     * @return The character index of the first text boundary.
     */
    public abstract int first();

    
Returns the last boundary. The iterator's current position is set
to the last text boundary.

Returns:The character index of the last text boundary.
/**
     * Returns the last boundary. The iterator's current position is set
     * to the last text boundary.
     * @return The character index of the last text boundary.
     */
    public abstract int last();

    
Returns the nth boundary from the current boundary. If either the first or last text boundary has been reached, it returns BreakIterator.DONE and the current position is set to either the first or last text boundary depending on which one is reached. Otherwise, the iterator's current position is set to the new boundary. For example, if the iterator's current position is the mth text boundary and three more boundaries exist from the current boundary to the last text boundary, the next(2) call will return m + 2. The new text position is set to the (m + 2)th text boundary. A next(4) call would return BreakIterator.DONE and the last text boundary would become the new text position. 
Params:
  • n – which boundary to return.  A value of 0
does nothing.  Negative values move to previous boundaries
and positive values move to later boundaries.
Returns:The character index of the nth boundary from the current position or BreakIterator.DONE if either first or last text boundary has been reached.
/**
     * Returns the nth boundary from the current boundary. If either
     * the first or last text boundary has been reached, it returns
     * {@code BreakIterator.DONE} and the current position is set to either
     * the first or last text boundary depending on which one is reached. Otherwise,
     * the iterator's current position is set to the new boundary.
     * For example, if the iterator's current position is the mth text boundary
     * and three more boundaries exist from the current boundary to the last text
     * boundary, the next(2) call will return m + 2. The new text position is set
     * to the (m + 2)th text boundary. A next(4) call would return
     * {@code BreakIterator.DONE} and the last text boundary would become the
     * new text position.
     * @param n which boundary to return.  A value of 0
     * does nothing.  Negative values move to previous boundaries
     * and positive values move to later boundaries.
     * @return The character index of the nth boundary from the current position
     * or {@code BreakIterator.DONE} if either first or last text boundary
     * has been reached.
     */
    public abstract int next(int n);

    
Returns the boundary following the current boundary. If the current boundary is the last text boundary, it returns BreakIterator.DONE and the iterator's current position is unchanged. Otherwise, the iterator's current position is set to the boundary following the current boundary. 
See Also:
Returns:The character index of the next text boundary or BreakIterator.DONE if the current boundary is the last text boundary. Equivalent to next(1).
/**
     * Returns the boundary following the current boundary. If the current boundary
     * is the last text boundary, it returns {@code BreakIterator.DONE} and
     * the iterator's current position is unchanged. Otherwise, the iterator's
     * current position is set to the boundary following the current boundary.
     * @return The character index of the next text boundary or
     * {@code BreakIterator.DONE} if the current boundary is the last text
     * boundary.
     * Equivalent to next(1).
     * @see #next(int)
     */
    public abstract int next();

    
Returns the boundary preceding the current boundary. If the current boundary is the first text boundary, it returns BreakIterator.DONE and the iterator's current position is unchanged. Otherwise, the iterator's current position is set to the boundary preceding the current boundary. 
Returns:The character index of the previous text boundary or BreakIterator.DONE if the current boundary is the first text boundary.
/**
     * Returns the boundary preceding the current boundary. If the current boundary
     * is the first text boundary, it returns {@code BreakIterator.DONE} and
     * the iterator's current position is unchanged. Otherwise, the iterator's
     * current position is set to the boundary preceding the current boundary.
     * @return The character index of the previous text boundary or
     * {@code BreakIterator.DONE} if the current boundary is the first text
     * boundary.
     */
    public abstract int previous();

    
Returns the first boundary following the specified character offset. If the specified offset is equal to the last text boundary, it returns BreakIterator.DONE and the iterator's current position is unchanged. Otherwise, the iterator's current position is set to the returned boundary. The value returned is always greater than the offset or the value BreakIterator.DONE. 
Params:
  • offset – the character offset to begin scanning.
Throws:
  • IllegalArgumentException – if the specified offset is less than
the first text boundary or greater than the last text boundary.
Returns:The first boundary after the specified offset or BreakIterator.DONE if the last text boundary is passed in as the offset.
/**
     * Returns the first boundary following the specified character offset. If the
     * specified offset is equal to the last text boundary, it returns
     * {@code BreakIterator.DONE} and the iterator's current position is unchanged.
     * Otherwise, the iterator's current position is set to the returned boundary.
     * The value returned is always greater than the offset or the value
     * {@code BreakIterator.DONE}.
     * @param offset the character offset to begin scanning.
     * @return The first boundary after the specified offset or
     * {@code BreakIterator.DONE} if the last text boundary is passed in
     * as the offset.
     * @throws     IllegalArgumentException if the specified offset is less than
     * the first text boundary or greater than the last text boundary.
     */
    public abstract int following(int offset);

    
Returns the last boundary preceding the specified character offset. If the specified offset is equal to the first text boundary, it returns BreakIterator.DONE and the iterator's current position is unchanged. Otherwise, the iterator's current position is set to the returned boundary. The value returned is always less than the offset or the value BreakIterator.DONE. 
Params:
  • offset – the character offset to begin scanning.
Throws:
  • IllegalArgumentException – if the specified offset is less than
the first text boundary or greater than the last text boundary.
Returns:The last boundary before the specified offset or BreakIterator.DONE if the first text boundary is passed in as the offset.
Since:1.2
/**
     * Returns the last boundary preceding the specified character offset. If the
     * specified offset is equal to the first text boundary, it returns
     * {@code BreakIterator.DONE} and the iterator's current position is unchanged.
     * Otherwise, the iterator's current position is set to the returned boundary.
     * The value returned is always less than the offset or the value
     * {@code BreakIterator.DONE}.
     * @param offset the character offset to begin scanning.
     * @return The last boundary before the specified offset or
     * {@code BreakIterator.DONE} if the first text boundary is passed in
     * as the offset.
     * @throws      IllegalArgumentException if the specified offset is less than
     * the first text boundary or greater than the last text boundary.
     * @since 1.2
     */
    public int preceding(int offset) {
        // NOTE:  This implementation is here solely because we can't add new
        // abstract methods to an existing class.  There is almost ALWAYS a
        // better, faster way to do this.
        int pos = following(offset);
        while (pos >= offset && pos != DONE) {
            pos = previous();
        }
        return pos;
    }

    
Returns true if the specified character offset is a text boundary.

Params:
  • offset – the character offset to check.
Throws:
  • IllegalArgumentException – if the specified offset is less than
the first text boundary or greater than the last text boundary.
Returns:true if "offset" is a boundary position, false otherwise.
Since:1.2
/**
     * Returns true if the specified character offset is a text boundary.
     * @param offset the character offset to check.
     * @return {@code true} if "offset" is a boundary position,
     * {@code false} otherwise.
     * @throws      IllegalArgumentException if the specified offset is less than
     * the first text boundary or greater than the last text boundary.
     * @since 1.2
     */
    public boolean isBoundary(int offset) {
        // NOTE: This implementation probably is wrong for most situations
        // because it fails to take into account the possibility that a
        // CharacterIterator passed to setText() may not have a begin offset
        // of 0.  But since the abstract BreakIterator doesn't have that
        // knowledge, it assumes the begin offset is 0.  If you subclass
        // BreakIterator, copy the SimpleTextBoundary implementation of this
        // function into your subclass.  [This should have been abstract at
        // this level, but it's too late to fix that now.]
        if (offset == 0) {
            return true;
        }
        int boundary = following(offset - 1);
        if (boundary == DONE) {
            throw new IllegalArgumentException();
        }
        return boundary == offset;
    }

    
Returns character index of the text boundary that was most recently returned by next(), next(int), previous(), first(), last(), following(int) or preceding(int). If any of these methods returns BreakIterator.DONE because either first or last text boundary has been reached, it returns the first or last text boundary depending on which one is reached. 
See Also:
Returns:The text boundary returned from the above methods, first or last
text boundary.
/**
     * Returns character index of the text boundary that was most
     * recently returned by next(), next(int), previous(), first(), last(),
     * following(int) or preceding(int). If any of these methods returns
     * {@code BreakIterator.DONE} because either first or last text boundary
     * has been reached, it returns the first or last text boundary depending on
     * which one is reached.
     * @return The text boundary returned from the above methods, first or last
     * text boundary.
     * @see #next()
     * @see #next(int)
     * @see #previous()
     * @see #first()
     * @see #last()
     * @see #following(int)
     * @see #preceding(int)
     */
    public abstract int current();

    
Get the text being scanned

Returns:the text being scanned
/**
     * Get the text being scanned
     * @return the text being scanned
     */
    public abstract CharacterIterator getText();

    
Set a new text string to be scanned.  The current scan
position is reset to first().

Params:
  • newText – new text to scan.
/**
     * Set a new text string to be scanned.  The current scan
     * position is reset to first().
     * @param newText new text to scan.
     */
    public void setText(String newText)
    {
        setText(new StringCharacterIterator(newText));
    }

    
Set a new text for scanning.  The current scan
position is reset to first().

Params:
  • newText – new text to scan.
/**
     * Set a new text for scanning.  The current scan
     * position is reset to first().
     * @param newText new text to scan.
     */
    public abstract void setText(CharacterIterator newText);

    private static final int CHARACTER_INDEX = 0;
    private static final int WORD_INDEX = 1;
    private static final int LINE_INDEX = 2;
    private static final int SENTENCE_INDEX = 3;

    @SuppressWarnings("unchecked")
    private static final SoftReference<BreakIteratorCache>[] iterCache = (SoftReference<BreakIteratorCache>[]) new SoftReference<?>[4];

    
Returns a new BreakIterator instance for word breaks for the default locale. 
Returns:A break iterator for word breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#word">word breaks</a>
     * for the {@linkplain Locale#getDefault() default locale}.
     * @return A break iterator for word breaks
     */
    public static BreakIterator getWordInstance()
    {
        return getWordInstance(Locale.getDefault());
    }

    
Returns a new BreakIterator instance for word breaks
for the given locale.

Params:
  • locale – the desired locale
Throws:
Returns:A break iterator for word breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#word">word breaks</a>
     * for the given locale.
     * @param locale the desired locale
     * @return A break iterator for word breaks
     * @throws    NullPointerException if {@code locale} is null
     */
    public static BreakIterator getWordInstance(Locale locale)
    {
        return getBreakInstance(locale, WORD_INDEX);
    }

    
Returns a new BreakIterator instance for line breaks for the default locale. 
Returns:A break iterator for line breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#line">line breaks</a>
     * for the {@linkplain Locale#getDefault() default locale}.
     * @return A break iterator for line breaks
     */
    public static BreakIterator getLineInstance()
    {
        return getLineInstance(Locale.getDefault());
    }

    
Returns a new BreakIterator instance for line breaks
for the given locale.

Params:
  • locale – the desired locale
Throws:
Returns:A break iterator for line breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#line">line breaks</a>
     * for the given locale.
     * @param locale the desired locale
     * @return A break iterator for line breaks
     * @throws    NullPointerException if {@code locale} is null
     */
    public static BreakIterator getLineInstance(Locale locale)
    {
        return getBreakInstance(locale, LINE_INDEX);
    }

    
Returns a new BreakIterator instance for character breaks for the default locale. 
Returns:A break iterator for character breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#character">character breaks</a>
     * for the {@linkplain Locale#getDefault() default locale}.
     * @return A break iterator for character breaks
     */
    public static BreakIterator getCharacterInstance()
    {
        return getCharacterInstance(Locale.getDefault());
    }

    
Returns a new BreakIterator instance for character breaks
for the given locale.

Params:
  • locale – the desired locale
Throws:
Returns:A break iterator for character breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#character">character breaks</a>
     * for the given locale.
     * @param locale the desired locale
     * @return A break iterator for character breaks
     * @throws    NullPointerException if {@code locale} is null
     */
    public static BreakIterator getCharacterInstance(Locale locale)
    {
        return getBreakInstance(locale, CHARACTER_INDEX);
    }

    
Returns a new BreakIterator instance for sentence breaks for the default locale. 
Returns:A break iterator for sentence breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#sentence">sentence breaks</a>
     * for the {@linkplain Locale#getDefault() default locale}.
     * @return A break iterator for sentence breaks
     */
    public static BreakIterator getSentenceInstance()
    {
        return getSentenceInstance(Locale.getDefault());
    }

    
Returns a new BreakIterator instance for sentence breaks
for the given locale.

Params:
  • locale – the desired locale
Throws:
Returns:A break iterator for sentence breaks
/**
     * Returns a new {@code BreakIterator} instance
     * for <a href="BreakIterator.html#sentence">sentence breaks</a>
     * for the given locale.
     * @param locale the desired locale
     * @return A break iterator for sentence breaks
     * @throws    NullPointerException if {@code locale} is null
     */
    public static BreakIterator getSentenceInstance(Locale locale)
    {
        return getBreakInstance(locale, SENTENCE_INDEX);
    }

    private static BreakIterator getBreakInstance(Locale locale, int type) {
        if (iterCache[type] != null) {
            BreakIteratorCache cache = iterCache[type].get();
            if (cache != null) {
                if (cache.getLocale().equals(locale)) {
                    return cache.createBreakInstance();
                }
            }
        }

        BreakIterator result = createBreakInstance(locale, type);
        BreakIteratorCache cache = new BreakIteratorCache(locale, result);
        iterCache[type] = new SoftReference<>(cache);
        return result;
    }

    private static BreakIterator createBreakInstance(Locale locale,
                                                     int type) {
        LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(BreakIteratorProvider.class, locale);
        BreakIterator iterator = createBreakInstance(adapter, locale, type);
        if (iterator == null) {
            iterator = createBreakInstance(LocaleProviderAdapter.forJRE(), locale, type);
        }
        return iterator;
    }

    private static BreakIterator createBreakInstance(LocaleProviderAdapter adapter, Locale locale, int type) {
        BreakIteratorProvider breakIteratorProvider = adapter.getBreakIteratorProvider();
        BreakIterator iterator = null;
        switch (type) {
        case CHARACTER_INDEX:
            iterator = breakIteratorProvider.getCharacterInstance(locale);
            break;
        case WORD_INDEX:
            iterator = breakIteratorProvider.getWordInstance(locale);
            break;
        case LINE_INDEX:
            iterator = breakIteratorProvider.getLineInstance(locale);
            break;
        case SENTENCE_INDEX:
            iterator = breakIteratorProvider.getSentenceInstance(locale);
            break;
        }
        return iterator;
    }

    
Returns an array of all locales for which the get*Instance methods of this class can return localized instances. The returned array represents the union of locales supported by the Java runtime and by installed BreakIteratorProvider implementations. It must contain at least a Locale instance equal to Locale.US. 
Returns:An array of locales for which localized BreakIterator instances are available.
/**
     * Returns an array of all locales for which the
     * {@code get*Instance} methods of this class can return
     * localized instances.
     * The returned array represents the union of locales supported by the Java
     * runtime and by installed
     * {@link java.text.spi.BreakIteratorProvider BreakIteratorProvider} implementations.
     * It must contain at least a {@code Locale}
     * instance equal to {@link java.util.Locale#US Locale.US}.
     *
     * @return An array of locales for which localized
     *         {@code BreakIterator} instances are available.
     */
    public static synchronized Locale[] getAvailableLocales()
    {
        LocaleServiceProviderPool pool =
            LocaleServiceProviderPool.getPool(BreakIteratorProvider.class);
        return pool.getAvailableLocales();
    }

    private static final class BreakIteratorCache {

        private BreakIterator iter;
        private Locale locale;

        BreakIteratorCache(Locale locale, BreakIterator iter) {
            this.locale = locale;
            this.iter = (BreakIterator) iter.clone();
        }

        Locale getLocale() {
            return locale;
        }

        BreakIterator createBreakInstance() {
            return (BreakIterator) iter.clone();
        }
    }
}