API java : BreakIterator

java.text
Class BreakIterator

java.lang.Object
  java.text.BreakIterator

All Implemented Interfaces:: Cloneable

public abstract class BreakIterator
extends Object
implements Cloneable
extends Object
implements Cloneable

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 getWordIterator, getLineIterator, getSentenceIterator, and getCharacterIterator 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.

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 of through character strings, regardless of how the character is stored. 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.

BreakIterator is intended for use with natural languages only. Do not use this class to 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:: CharacterIterator

Field Summary

static int DONE
          DONE is returned by previous() and next() after all valid boundaries have been returned.

Constructor Summary

protected BreakIterator()
          Constructor.

Method Summary

Object clone()
          Create a copy of this iterator

abstract int current()
          Return character index of the text boundary that was most recently returned by next(), previous(), first(), or last()

abstract int first()
          Return the first boundary.

abstract int following(int offset)
          Return the first boundary following the specified offset.

static Locale[] getAvailableLocales()
          Returns an array of all locales for which the get*Instance methods of this class can return localized instances.

static BreakIterator getCharacterInstance()
          Create BreakIterator for character-breaks using default locale Returns an instance of a BreakIterator implementing character breaks.

static BreakIterator getCharacterInstance(Locale where)
          Create BreakIterator for character-breaks using specified locale Returns an instance of a BreakIterator implementing character breaks.

protected static int getInt(byte[] buf, int offset)


static BreakIterator getLineInstance()
          Create BreakIterator for line-breaks using default locale.

static BreakIterator getLineInstance(Locale where)
          Create BreakIterator for line-breaks using specified locale.

protected static long getLong(byte[] buf, int offset)


static BreakIterator getSentenceInstance()
          Create BreakIterator for sentence-breaks using default locale Returns an instance of a BreakIterator implementing sentence breaks.

static BreakIterator getSentenceInstance(Locale where)
          Create BreakIterator for sentence-breaks using specified locale Returns an instance of a BreakIterator implementing sentence breaks.

protected static short getShort(byte[] buf, int offset)


abstract CharacterIterator getText()
          Get the text being scanned

static BreakIterator getWordInstance()
          Create BreakIterator for word-breaks using default locale.

static BreakIterator getWordInstance(Locale where)
          Create BreakIterator for word-breaks using specified locale.

boolean isBoundary(int offset)
          Return true if the specified position is a boundary position.

abstract int last()
          Return the last boundary.

abstract int next()
          Return the boundary following the current boundary.

abstract int next(int n)
          Return the nth boundary from the current boundary

int preceding(int offset)
          Return the last boundary preceding the specfied offset.

abstract int previous()
          Return the boundary preceding the current boundary.

abstract void setText(CharacterIterator newText)
          Set a new text for scanning.

void setText(String newText)
          Set a new text string to be scanned.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Summary
`static int`	`DONE` DONE is returned by previous() and next() after all valid boundaries have been returned.

Constructor Summary
`protected`	`BreakIterator()` Constructor.

Method Summary
`Object`	`clone()` Create a copy of this iterator
`abstract int`	`current()` Return character index of the text boundary that was most recently returned by next(), previous(), first(), or last()
`abstract int`	`first()` Return the first boundary.
`abstract int`	`following(int offset)` Return the first boundary following the specified offset.
`static Locale[]`	`getAvailableLocales()` Returns an array of all locales for which the `get*Instance` methods of this class can return localized instances.
`static BreakIterator`	`getCharacterInstance()` Create BreakIterator for character-breaks using default locale Returns an instance of a BreakIterator implementing character breaks.
`static BreakIterator`	`getCharacterInstance(Locale where)` Create BreakIterator for character-breaks using specified locale Returns an instance of a BreakIterator implementing character breaks.
`protected static int`	`getInt(byte[] buf, int offset)`
`static BreakIterator`	`getLineInstance()` Create BreakIterator for line-breaks using default locale.
`static BreakIterator`	`getLineInstance(Locale where)` Create BreakIterator for line-breaks using specified locale.
`protected static long`	`getLong(byte[] buf, int offset)`
`static BreakIterator`	`getSentenceInstance()` Create BreakIterator for sentence-breaks using default locale Returns an instance of a BreakIterator implementing sentence breaks.
`static BreakIterator`	`getSentenceInstance(Locale where)` Create BreakIterator for sentence-breaks using specified locale Returns an instance of a BreakIterator implementing sentence breaks.
`protected static short`	`getShort(byte[] buf, int offset)`
`abstract CharacterIterator`	`getText()` Get the text being scanned
`static BreakIterator`	`getWordInstance()` Create BreakIterator for word-breaks using default locale.
`static BreakIterator`	`getWordInstance(Locale where)` Create BreakIterator for word-breaks using specified locale.
`boolean`	`isBoundary(int offset)` Return true if the specified position is a boundary position.
`abstract int`	`last()` Return the last boundary.
`abstract int`	`next()` Return the boundary following the current boundary.
`abstract int`	`next(int n)` Return the nth boundary from the current boundary
`int`	`preceding(int offset)` Return the last boundary preceding the specfied offset.
`abstract int`	`previous()` Return the boundary preceding the current boundary.
`abstract void`	`setText(CharacterIterator newText)` Set a new text for scanning.
`void`	`setText(String newText)` Set a new text string to be scanned.

Methods inherited from class java.lang.Object
`equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

DONE

public static final int DONE

DONE is returned by previous() and next() after all valid boundaries have been returned.

See Also:: Constant Field Values

Constructor Detail

BreakIterator

protected BreakIterator()

Constructor. BreakIterator is stateless and has no default behavior.

Method Detail

clone

public Object clone()

Create a copy of this iterator

Overrides:: clone in class Object

Returns:: A copy of this
See Also:: Cloneable

first

public abstract int first()

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

Returns:: The character index of the first text boundary.

last

public abstract int last()

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

Returns:: The character index of the last text boundary.

public abstract int next(int n)

Return the nth boundary from the current boundary

Parameters:: 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 index of the nth boundary from the current position.

public abstract int next()

Return the boundary following the current boundary.

Returns:: The character index of the next text boundary or DONE if all boundaries have been returned. Equivalent to next(1).

public abstract int previous()

Return the boundary preceding the current boundary.

Returns:: The character index of the previous text boundary or DONE if all boundaries have been returned.

following

public abstract int following(int offset)

Return the first boundary following the specified offset. The value returned is always greater than the offset or the value BreakIterator.DONE

Parameters:: offset - the offset to begin scanning. Valid values are determined by the CharacterIterator passed to setText(). Invalid values cause an IllegalArgumentException to be thrown.
Returns:: The first boundary after the specified offset.

preceding

public int preceding(int offset)

Return the last boundary preceding the specfied offset. The value returned is always less than the offset or the value BreakIterator.DONE.

Parameters:: offset - the offset to begin scanning. Valid values are determined by the CharacterIterator passed to setText(). Invalid values cause an IllegalArgumentException to be thrown.
Returns:: The last boundary before the specified offset.
Since:: 1.2

isBoundary

public boolean isBoundary(int offset)

Return true if the specified position is a boundary position.

Parameters:: offset - the offset to check.
Returns:: True if "offset" is a boundary position.
Since:: 1.2

current

public abstract int current()

Return character index of the text boundary that was most recently returned by next(), previous(), first(), or last()

Returns:: The boundary most recently returned.

getText

public abstract CharacterIterator getText()

Get the text being scanned

Returns:: the text being scanned

setText

public void setText(String newText)

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

Parameters:: newText - new text to scan.

setText

public abstract void setText(CharacterIterator newText)

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

Parameters:: newText - new text to scan.

getWordInstance

public static BreakIterator getWordInstance()

Create BreakIterator for word-breaks using default locale. Returns an instance of a BreakIterator implementing word breaks. WordBreak is usefull for word selection (ex. double click)

Returns:: A BreakIterator for word-breaks
See Also:: Locale.getDefault()

getWordInstance

public static BreakIterator getWordInstance(Locale where)

Create BreakIterator for word-breaks using specified locale. Returns an instance of a BreakIterator implementing word breaks. WordBreak is usefull for word selection (ex. double click)

Parameters:: where - the local. If a specific WordBreak is not avaliable for the specified locale, a default WordBreak is returned.
Returns:: A BreakIterator for word-breaks

getLineInstance

public static BreakIterator getLineInstance()

Create BreakIterator for line-breaks using default locale. Returns an instance of a BreakIterator implementing line breaks. Line breaks are logically possible line breaks, actual line breaks are usually determined based on display width. LineBreak is useful for word wrapping text.

Returns:: A BreakIterator for line-breaks
See Also:: Locale.getDefault()

getLineInstance

public static BreakIterator getLineInstance(Locale where)

Create BreakIterator for line-breaks using specified locale. Returns an instance of a BreakIterator implementing line breaks. Line breaks are logically possible line breaks, actual line breaks are usually determined based on display width. LineBreak is useful for word wrapping text.

Parameters:: where - the local. If a specific LineBreak is not avaliable for the specified locale, a default LineBreak is returned.
Returns:: A BreakIterator for line-breaks

getCharacterInstance

public static BreakIterator getCharacterInstance()

Create BreakIterator for character-breaks using default locale Returns an instance of a BreakIterator implementing character breaks. Character breaks are boundaries of combining character sequences.

Returns:: A BreakIterator for character-breaks
See Also:: Locale.getDefault()

getCharacterInstance

public static BreakIterator getCharacterInstance(Locale where)

Create BreakIterator for character-breaks using specified locale Returns an instance of a BreakIterator implementing character breaks. Character breaks are boundaries of combining character sequences.

Parameters:: where - the local. If a specific character break is not avaliable for the specified local, a default character break is returned.
Returns:: A BreakIterator for character-breaks

getSentenceInstance

public static BreakIterator getSentenceInstance()

Create BreakIterator for sentence-breaks using default locale Returns an instance of a BreakIterator implementing sentence breaks.

Returns:: A BreakIterator for sentence-breaks
See Also:: Locale.getDefault()

getSentenceInstance

public static BreakIterator getSentenceInstance(Locale where)

Create BreakIterator for sentence-breaks using specified locale Returns an instance of a BreakIterator implementing sentence breaks.

Parameters:: where - the local. If a specific SentenceBreak is not avaliable for the specified local, a default SentenceBreak is returned.
Returns:: A BreakIterator for sentence-breaks

getAvailableLocales

public static Locale[] getAvailableLocales()

Returns an array of all locales for which the get*Instance methods of this class can return localized instances. The array returned must contain at least a Locale instance equal to Locale.US.

Returns:: An array of locales for which localized BreakIterator instances are available.

getLong

protected static long getLong(byte[] buf,
                              int offset)

getInt

protected static int getInt(byte[] buf,
                            int offset)

getShort

protected static short getShort(byte[] buf,
                                int offset)

Package :

Ces informations proviennent du site de http://java.sun.com

Remarques

Contenu

Le contenu de cette page provient du site de Sun, et est généré depuis un cache sur l'infobrol après certains traitements automatisés. La présentation peut donc différer du document original, mais le contenu aussi. Vous pouvez utiliser ce bouton pour afficher la page originale du site de Sun :

Quels sont les motivations de cette démarche?

Maintenir les pages en cache sur différents sites peut offrir plus de disponibilité.

Chaque page est indexée dans la base de donnée, ce qui permet de retrouver facilement les informations, au moyen des sommaires, du moteur de recherche interne, etc.

Des facilités sont mises en place pour que les membres de l'infobrol puissent effectuer des traductions en français des différents documents. Ceci devrait permettre aux débutants en programmation Java de consulter les API en français s'ils maîtrisent moins bien la langue de Shakespeare. Dans le cas où une traduction a été soumise, elle est disponible au moyen d'un lien en bas de page. Si la traduction a été validée, la page s'affiche par défaut en français, et un lien en bas de page permet d'atteindre la version en anglais.

Le code sur l'infobrol est automatiquement coloré selon la syntaxe, et les différents mots clés sont transformés en liens pour accéder rapidement aux informations.

Vous avez la possibilité de partager vos expériences en proposant vos propres extraits de code en utilisant le bouton "ajouter un commentaire" en bas de page. Si vous visitez simplement l'infobrol, vous avez déjà accès à cette fonction, mais si vous étes membre du brol, vous pouvez en plus utiliser des boutons supplémentaires de mise en forme, dont la coloration automatique de vos extraits de codes.

<- BoxView BrokenBarrierException ->

Réseaux sociaux

|Plus d'options...

Vous pouvez modifier vos préférences dans votre profil pour ne plus afficher les interactions avec les réseaux sociaux sur ces pages.

Nuage de mots clés

5 mots clés dont 0 définis manuellement (plus d'information...).

Avertissement

Cette page ne possède pas encore de mots clés manuels, ceci est donc un exemple automatique (les niveaux de pertinence sont fictifs, mais les liens sont valables). Pour tester le nuage avec une page qui contient des mots définis manuellement, vous pouvez cliquer ici.

Vous pouvez modifier vos préférences dans votre profil pour ne plus afficher le nuage de mots clés.

Structure du document

Réseaux sociaux
Nuage de mots clés
- Avertissement :

Astuce pour imprimer les couleurs des cellules de tableaux : http://www.gaudry.be/ast-rf-450.html

Aucun commentaire pour cette page

tection. Enregistrement IDDN n° 5329-3494
Document créé le 16/09/06 03:53, dernière modification le Vendredi 17 Juin 2011, 12:12
Source du document imprimé : http://www.gaudry.be/java-api-rf-java/text/BreakIterator.html Document affiché 1 fois ce mois de Juin.
St.Gaudry©07.01.02