[Chapter 29] The java.text Package

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| Chapter 29 |

# 29. The java.text Package

Contents:
java.text.CharacterIterator (JDK 1.1)
java.text.ChoiceFormat (JDK 1.1)
java.text.CollationElementIterator (JDK 1.1)
java.text.CollationKey (JDK 1.1)
java.text.Collator (JDK 1.1)
java.text.DateFormat (JDK 1.1)
java.text.DateFormatSymbols (JDK 1.1)
java.text.DecimalFormat (JDK 1.1)
java.text.DecimalFormatSymbols (JDK 1.1)
java.text.FieldPosition (JDK 1.1)
java.text.Format (JDK 1.1)
java.text.MessageFormat (JDK 1.1)
java.text.NumberFormat (JDK 1.1)
java.text.ParseException (JDK 1.1)
java.text.ParsePosition (JDK 1.1)
java.text.RuleBasedCollator (JDK 1.1)
java.text.SimpleDateFormat (JDK 1.1)
java.text.StringCharacterIterator (JDK 1.1)

The `java.text` package consists of classes and interfaces that are useful for writing internationalized programs that handle local customs, such as date and time formatting and string alphabetization, correctly. This package is new in Java 1.1. Figure 29.1 shows its class hierarchy.

The `NumberFormat` class formats numbers, monetary quantities, and percentages as appropriate for the default or specified locale. `DateFormat` formats dates and times in a locale-specific way. The concrete `DecimalFormat` and `SimpleDateFormat` subclasses of these classes can be used for customized number, date, and time formatting. `MessageFormat` allows substitution of dynamic values, including formatted numbers and dates, into static message strings. `ChoiceFormat` formats a number using an enumerated set of string values. `Collator` compares strings according to the customary sorting order for a locale. `BreakIterator` scans text to find word, line, and sentence boundaries following locale-specfic rules.

#### Figure 29.1: The java.text package

## 29.1 java.text.BreakIterator (JDK 1.1)

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This class is used to determine character, word, sentence, and line breaks in a block of text in a way that is independent of locale and text-encoding. As an abstract class, `BreakIterator` cannot be instantiated directly. Instead, you must use one of the class methods `getCharacterInstance()`, `getWordInstance()`, `getSentenceInstance()`, or `getLineInstance()` to return an instance of a nonabstract subclass of `BreakIterator`. These various "factory" methods return a `BreakIterator` object that is configured to locate the requested boundary types, and is localized to work for the optionally specified locale.

Once you have obtained an appropriate `BreakIterator` object, you use `setText()` to specify the text that it is to locate boundaries in. To locate boundaries in a Java `String` object, simply specify the string. To locate boundaries in text that uses some other encoding, you must specify a `CharacterIterator` object for that text so that the `BreakIterator` object can locate the individual characters of the text.

Having set the text to be searched, you can determine the character positions of characters, words, sentences, or line breaks with the `first()`, `last()`, `next()`, `previous()`, `current()`, and `following()` methods, which perform the obvious functions. Note that these methods do not return text itself, but merely the position of the appropriate word, sentence, or line break.

    public abstract class BreakIterator extends Object implements Cloneable, Serializable {
        // Protected Constructor
                protected BreakIterator();
        // Constants
                public static final int DONE;
        // Class Methods
                public static synchronized Locale[] getAvailableLocales();
                public static BreakIterator getCharacterInstance();
                public static BreakIterator getCharacterInstance(Locale where);
                public static BreakIterator getLineInstance();
                public static BreakIterator getLineInstance(Locale where);
                public static BreakIterator getSentenceInstance();
                public static BreakIterator getSentenceInstance(Locale where);
                public static BreakIterator getWordInstance();
                public static BreakIterator getWordInstance(Locale where);
        // Public Instance Methods
                public Object clone();  // Overrides Object
                public abstract int current();
                public abstract int first();
                public abstract int following(int offset);
                public abstract CharacterIterator getText();
                public abstract int last();
                public abstract int next(int n);
                public abstract int next();
                public abstract int previous();
                public void setText(String newText);
                public abstract void setText(CharacterIterator newText);
    }

### Returned By:

BreakIterator.getCharacterInstance(), BreakIterator.getLineInstance(), BreakIterator.getSentenceInstance(), BreakIterator.getWordInstance()

java.net.URLStreamHandlerFactory (JDK 1.0) |  | java.text.CharacterIterator (JDK 1.1)