https://openjdk.java.net/ 
/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * (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.io.Serializable;


Format is an abstract base class for formatting locale-sensitive
information such as dates, messages, and numbers.


Format defines the programming interface for formatting
locale-sensitive objects into Strings (the
format method) and for parsing Strings back
into objects (the parseObject method).


Generally, a format's parseObject method must be able to parse
any string formatted by its format method. However, there may
be exceptional cases where this is not possible. For example, a
format method might create two adjacent integer numbers with
no separator in between, and in this case the parseObject could
not tell which digits belong to which number.

Subclassing



The Java Platform provides three specialized subclasses of Format--
DateFormat, MessageFormat, and
NumberFormat--for formatting dates, messages, and numbers,
respectively.


Concrete subclasses must implement three methods:

    

  1.  format(Object obj, StringBuffer toAppendTo, FieldPosition pos)

  2.  formatToCharacterIterator(Object obj)

  3.  parseObject(String source, ParsePosition pos)


These general methods allow polymorphic parsing and formatting of objects
and are used, for example, by MessageFormat.
Subclasses often also provide additional format methods for
specific input types as well as parse methods for specific
result types. Any parse method that does not take a
ParsePosition argument should throw ParseException
when no text in the required format is at the beginning of the input text.


Most subclasses will also implement the following factory methods:

    

  1. 
getInstance for getting a useful format object appropriate
for the current locale

  2. 
getInstance(Locale) for getting a useful format
object appropriate for the specified locale


In addition, some subclasses may also implement other
getXxxxInstance methods for more specialized control. For
example, the NumberFormat class provides
getPercentInstance and getCurrencyInstance
methods for getting specialized number formatters.


Subclasses of Format that allow programmers to create objects
for locales (with getInstance(Locale) for example)
must also implement the following class method:



public static Locale[] getAvailableLocales()






And finally subclasses may define a set of constants to identify the various
fields in the formatted output. These constants are used to create a FieldPosition
object which identifies what information is contained in the field and its
position in the formatted result. These constants should be named
item_FIELD where item identifies
the field. For examples of these constants, see ERA_FIELD and its friends in DateFormat. 
Synchronization



Formats are generally not synchronized.
It is recommended to create separate format instances for each thread.
If multiple threads access a format concurrently, it must be synchronized
externally.

Author:      Mark Davis
See Also:
Since:1.1
/**
 * <code>Format</code> is an abstract base class for formatting locale-sensitive
 * information such as dates, messages, and numbers.
 *
 * <p>
 * <code>Format</code> defines the programming interface for formatting
 * locale-sensitive objects into <code>String</code>s (the
 * <code>format</code> method) and for parsing <code>String</code>s back
 * into objects (the <code>parseObject</code> method).
 *
 * <p>
 * Generally, a format's <code>parseObject</code> method must be able to parse
 * any string formatted by its <code>format</code> method. However, there may
 * be exceptional cases where this is not possible. For example, a
 * <code>format</code> method might create two adjacent integer numbers with
 * no separator in between, and in this case the <code>parseObject</code> could
 * not tell which digits belong to which number.
 *
 * <h3>Subclassing</h3>
 *
 * <p>
 * The Java Platform provides three specialized subclasses of <code>Format</code>--
 * <code>DateFormat</code>, <code>MessageFormat</code>, and
 * <code>NumberFormat</code>--for formatting dates, messages, and numbers,
 * respectively.
 * <p>
 * Concrete subclasses must implement three methods:
 * <ol>
 * <li> <code>format(Object obj, StringBuffer toAppendTo, FieldPosition pos)</code>
 * <li> <code>formatToCharacterIterator(Object obj)</code>
 * <li> <code>parseObject(String source, ParsePosition pos)</code>
 * </ol>
 * These general methods allow polymorphic parsing and formatting of objects
 * and are used, for example, by <code>MessageFormat</code>.
 * Subclasses often also provide additional <code>format</code> methods for
 * specific input types as well as <code>parse</code> methods for specific
 * result types. Any <code>parse</code> method that does not take a
 * <code>ParsePosition</code> argument should throw <code>ParseException</code>
 * when no text in the required format is at the beginning of the input text.
 *
 * <p>
 * Most subclasses will also implement the following factory methods:
 * <ol>
 * <li>
 * <code>getInstance</code> for getting a useful format object appropriate
 * for the current locale
 * <li>
 * <code>getInstance(Locale)</code> for getting a useful format
 * object appropriate for the specified locale
 * </ol>
 * In addition, some subclasses may also implement other
 * <code>getXxxxInstance</code> methods for more specialized control. For
 * example, the <code>NumberFormat</code> class provides
 * <code>getPercentInstance</code> and <code>getCurrencyInstance</code>
 * methods for getting specialized number formatters.
 *
 * <p>
 * Subclasses of <code>Format</code> that allow programmers to create objects
 * for locales (with <code>getInstance(Locale)</code> for example)
 * must also implement the following class method:
 * <blockquote>
 * <pre>
 * public static Locale[] getAvailableLocales()
 * </pre>
 * </blockquote>
 *
 * <p>
 * And finally subclasses may define a set of constants to identify the various
 * fields in the formatted output. These constants are used to create a FieldPosition
 * object which identifies what information is contained in the field and its
 * position in the formatted result. These constants should be named
 * <code><em>item</em>_FIELD</code> where <code><em>item</em></code> identifies
 * the field. For examples of these constants, see <code>ERA_FIELD</code> and its
 * friends in {@link DateFormat}.
 *
 * <h4><a id="synchronization">Synchronization</a></h4>
 *
 * <p>
 * Formats are generally not synchronized.
 * It is recommended to create separate format instances for each thread.
 * If multiple threads access a format concurrently, it must be synchronized
 * externally.
 *
 * @see          java.text.ParsePosition
 * @see          java.text.FieldPosition
 * @see          java.text.NumberFormat
 * @see          java.text.DateFormat
 * @see          java.text.MessageFormat
 * @author       Mark Davis
 * @since 1.1
 */
public abstract class Format implements Serializable, Cloneable {

    private static final long serialVersionUID = -299282585814624189L;

    
Sole constructor.  (For invocation by subclass constructors, typically
implicit.)

/**
     * Sole constructor.  (For invocation by subclass constructors, typically
     * implicit.)
     */
    protected Format() {
    }

    
Formats an object to produce a string. This is equivalent to

 format(obj,
        new StringBuffer(), new FieldPosition(0)).toString();



Params:
  • obj –    The object to format
Throws:
Returns:      Formatted string.
/**
     * Formats an object to produce a string. This is equivalent to
     * <blockquote>
     * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,
     *         new StringBuffer(), new FieldPosition(0)).toString();</code>
     * </blockquote>
     *
     * @param obj    The object to format
     * @return       Formatted string.
     * @exception IllegalArgumentException if the Format cannot format the given
     *            object
     */
    public final String format (Object obj) {
        return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
    }

    
Formats an object and appends the resulting text to a given string
buffer.
If the pos argument identifies a field used by the format,
then its indices are set to the beginning and end of the first such
field encountered.

Params:
  • obj –    The object to format
  • toAppendTo –    where the text is to be appended
  • pos –    A FieldPosition identifying a field
              in the formatted text
Throws:
Returns:      the string buffer passed in as toAppendTo,
              with formatted text appended
/**
     * Formats an object and appends the resulting text to a given string
     * buffer.
     * If the <code>pos</code> argument identifies a field used by the format,
     * then its indices are set to the beginning and end of the first such
     * field encountered.
     *
     * @param obj    The object to format
     * @param toAppendTo    where the text is to be appended
     * @param pos    A <code>FieldPosition</code> identifying a field
     *               in the formatted text
     * @return       the string buffer passed in as <code>toAppendTo</code>,
     *               with formatted text appended
     * @exception NullPointerException if <code>toAppendTo</code> or
     *            <code>pos</code> is null
     * @exception IllegalArgumentException if the Format cannot format the given
     *            object
     */
    public abstract StringBuffer format(Object obj,
                    StringBuffer toAppendTo,
                    FieldPosition pos);

    
Formats an Object producing an AttributedCharacterIterator.
You can use the returned AttributedCharacterIterator
to build the resulting String, as well as to determine information
about the resulting String.


Each attribute key of the AttributedCharacterIterator will be of type
Field. It is up to each Format implementation
to define what the legal values are for each attribute in the
AttributedCharacterIterator, but typically the attribute
key is also used as the attribute value.

The default implementation creates an
AttributedCharacterIterator with no attributes. Subclasses
that support fields should override this and create an
AttributedCharacterIterator with meaningful attributes.

Params:
  • obj – The object to format
Throws:
Returns:AttributedCharacterIterator describing the formatted value.
Since:1.4
/**
     * Formats an Object producing an <code>AttributedCharacterIterator</code>.
     * You can use the returned <code>AttributedCharacterIterator</code>
     * to build the resulting String, as well as to determine information
     * about the resulting String.
     * <p>
     * Each attribute key of the AttributedCharacterIterator will be of type
     * <code>Field</code>. It is up to each <code>Format</code> implementation
     * to define what the legal values are for each attribute in the
     * <code>AttributedCharacterIterator</code>, but typically the attribute
     * key is also used as the attribute value.
     * <p>The default implementation creates an
     * <code>AttributedCharacterIterator</code> with no attributes. Subclasses
     * that support fields should override this and create an
     * <code>AttributedCharacterIterator</code> with meaningful attributes.
     *
     * @exception NullPointerException if obj is null.
     * @exception IllegalArgumentException when the Format cannot format the
     *            given object.
     * @param obj The object to format
     * @return AttributedCharacterIterator describing the formatted value.
     * @since 1.4
     */
    public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
        return createAttributedCharacterIterator(format(obj));
    }

    
Parses text from a string to produce an object.


The method attempts to parse text starting at the index given by
pos.
If parsing succeeds, then the index of pos is updated
to the index after the last character used (parsing does not necessarily
use all characters up to the end of the string), and the parsed
object is returned. The updated pos can be used to
indicate the starting point for the next call to this method.
If an error occurs, then the index of pos is not
changed, the error index of pos is set to the index of
the character where the error occurred, and null is returned.

Params:
  • source – A String, part of which should be parsed.
  • pos – A ParsePosition object with index and error
           index information as described above.
Throws:
Returns:An Object parsed from the string. In case of
        error, returns null.
/**
     * Parses text from a string to produce an object.
     * <p>
     * The method attempts to parse text starting at the index given by
     * <code>pos</code>.
     * If parsing succeeds, then the index of <code>pos</code> is updated
     * to the index after the last character used (parsing does not necessarily
     * use all characters up to the end of the string), and the parsed
     * object is returned. The updated <code>pos</code> can be used to
     * indicate the starting point for the next call to this method.
     * If an error occurs, then the index of <code>pos</code> is not
     * changed, the error index of <code>pos</code> is set to the index of
     * the character where the error occurred, and null is returned.
     *
     * @param source A <code>String</code>, part of which should be parsed.
     * @param pos A <code>ParsePosition</code> object with index and error
     *            index information as described above.
     * @return An <code>Object</code> parsed from the string. In case of
     *         error, returns null.
     * @throws NullPointerException if {@code source} or {@code pos} is null.
     */
    public abstract Object parseObject (String source, ParsePosition pos);

    
Parses text from the beginning of the given string to produce an object.
The method may not use the entire text of the given string.

Params:
  • source – A String whose beginning should be parsed.
Throws:
Returns:An Object parsed from the string.
/**
     * Parses text from the beginning of the given string to produce an object.
     * The method may not use the entire text of the given string.
     *
     * @param source A <code>String</code> whose beginning should be parsed.
     * @return An <code>Object</code> parsed from the string.
     * @exception ParseException if the beginning of the specified string
     *            cannot be parsed.
     * @throws NullPointerException if {@code source} is null.
     */
    public Object parseObject(String source) throws ParseException {
        ParsePosition pos = new ParsePosition(0);
        Object result = parseObject(source, pos);
        if (pos.index == 0) {
            throw new ParseException("Format.parseObject(String) failed",
                pos.errorIndex);
        }
        return result;
    }

    
Creates and returns a copy of this object.

Returns:a clone of this instance.
/**
     * Creates and returns a copy of this object.
     *
     * @return a clone of this instance.
     */
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            // will never happen
            throw new InternalError(e);
        }
    }

    //
    // Convenience methods for creating AttributedCharacterIterators from
    // different parameters.
    //

    
Creates an AttributedCharacterIterator for the String
s.

Params:
  • s – String to create AttributedCharacterIterator from
Returns:AttributedCharacterIterator wrapping s
/**
     * Creates an <code>AttributedCharacterIterator</code> for the String
     * <code>s</code>.
     *
     * @param s String to create AttributedCharacterIterator from
     * @return AttributedCharacterIterator wrapping s
     */
    AttributedCharacterIterator createAttributedCharacterIterator(String s) {
        AttributedString as = new AttributedString(s);

        return as.getIterator();
    }

    
Creates an AttributedCharacterIterator containing the
concatenated contents of the passed in
AttributedCharacterIterators.

Params:
  • iterators – AttributedCharacterIterators used to create resulting
                 AttributedCharacterIterators
Returns:AttributedCharacterIterator wrapping passed in
        AttributedCharacterIterators
/**
     * Creates an <code>AttributedCharacterIterator</code> containing the
     * concatenated contents of the passed in
     * <code>AttributedCharacterIterator</code>s.
     *
     * @param iterators AttributedCharacterIterators used to create resulting
     *                  AttributedCharacterIterators
     * @return AttributedCharacterIterator wrapping passed in
     *         AttributedCharacterIterators
     */
    AttributedCharacterIterator createAttributedCharacterIterator(
                       AttributedCharacterIterator[] iterators) {
        AttributedString as = new AttributedString(iterators);

        return as.getIterator();
    }

    
Returns an AttributedCharacterIterator with the String
string and additional key/value pair key,
value.

Params:
  • string – String to create AttributedCharacterIterator from
  • key – Key for AttributedCharacterIterator
  • value – Value associated with key in AttributedCharacterIterator
Returns:AttributedCharacterIterator wrapping args
/**
     * Returns an AttributedCharacterIterator with the String
     * <code>string</code> and additional key/value pair <code>key</code>,
     * <code>value</code>.
     *
     * @param string String to create AttributedCharacterIterator from
     * @param key Key for AttributedCharacterIterator
     * @param value Value associated with key in AttributedCharacterIterator
     * @return AttributedCharacterIterator wrapping args
     */
    AttributedCharacterIterator createAttributedCharacterIterator(
                      String string, AttributedCharacterIterator.Attribute key,
                      Object value) {
        AttributedString as = new AttributedString(string);

        as.addAttribute(key, value);
        return as.getIterator();
    }

    
Creates an AttributedCharacterIterator with the contents of
iterator and the additional attribute key
value.

Params:
  • iterator – Initial AttributedCharacterIterator to add arg to
  • key – Key for AttributedCharacterIterator
  • value – Value associated with key in AttributedCharacterIterator
Returns:AttributedCharacterIterator wrapping args
/**
     * Creates an AttributedCharacterIterator with the contents of
     * <code>iterator</code> and the additional attribute <code>key</code>
     * <code>value</code>.
     *
     * @param iterator Initial AttributedCharacterIterator to add arg to
     * @param key Key for AttributedCharacterIterator
     * @param value Value associated with key in AttributedCharacterIterator
     * @return AttributedCharacterIterator wrapping args
     */
    AttributedCharacterIterator createAttributedCharacterIterator(
              AttributedCharacterIterator iterator,
              AttributedCharacterIterator.Attribute key, Object value) {
        AttributedString as = new AttributedString(iterator);

        as.addAttribute(key, value);
        return as.getIterator();
    }


    
Defines constants that are used as attribute keys in the
AttributedCharacterIterator returned
from Format.formatToCharacterIterator and as
field identifiers in FieldPosition.

Since:1.4
/**
     * Defines constants that are used as attribute keys in the
     * <code>AttributedCharacterIterator</code> returned
     * from <code>Format.formatToCharacterIterator</code> and as
     * field identifiers in <code>FieldPosition</code>.
     *
     * @since 1.4
     */
    public static class Field extends AttributedCharacterIterator.Attribute {

        // Proclaim serial compatibility with 1.4 FCS
        private static final long serialVersionUID = 276966692217360283L;

        
Creates a Field with the specified name.

Params:
  • name – Name of the attribute
/**
         * Creates a Field with the specified name.
         *
         * @param name Name of the attribute
         */
        protected Field(String name) {
            super(name);
        }
    }


    
FieldDelegate is notified by the various Format
implementations as they are formatting the Objects. This allows for
storage of the individual sections of the formatted String for
later use, such as in a FieldPosition or for an
AttributedCharacterIterator.


Delegates should NOT assume that the Format will notify
the delegate of fields in any particular order.

See Also:
/**
     * FieldDelegate is notified by the various <code>Format</code>
     * implementations as they are formatting the Objects. This allows for
     * storage of the individual sections of the formatted String for
     * later use, such as in a <code>FieldPosition</code> or for an
     * <code>AttributedCharacterIterator</code>.
     * <p>
     * Delegates should NOT assume that the <code>Format</code> will notify
     * the delegate of fields in any particular order.
     *
     * @see FieldPosition#getFieldDelegate
     * @see CharacterIteratorFieldDelegate
     */
    interface FieldDelegate {
        
Notified when a particular region of the String is formatted. This
method will be invoked if there is no corresponding integer field id
matching attr.

Params:
  • attr – Identifies the field matched
  • value – Value associated with the field
  • start – Beginning location of the field, will be >= 0
  • end – End of the field, will be >= start and <= buffer.length()
  • buffer – Contains current formatted value, receiver should
       NOT modify it.
/**
         * Notified when a particular region of the String is formatted. This
         * method will be invoked if there is no corresponding integer field id
         * matching <code>attr</code>.
         *
         * @param attr Identifies the field matched
         * @param value Value associated with the field
         * @param start Beginning location of the field, will be >= 0
         * @param end End of the field, will be >= start and <= buffer.length()
         * @param buffer Contains current formatted value, receiver should
         *        NOT modify it.
         */
        public void formatted(Format.Field attr, Object value, int start,
                              int end, StringBuffer buffer);

        
Notified when a particular region of the String is formatted.

Params:
  • fieldID – Identifies the field by integer
  • attr – Identifies the field matched
  • value – Value associated with the field
  • start – Beginning location of the field, will be >= 0
  • end – End of the field, will be >= start and <= buffer.length()
  • buffer – Contains current formatted value, receiver should
       NOT modify it.
/**
         * Notified when a particular region of the String is formatted.
         *
         * @param fieldID Identifies the field by integer
         * @param attr Identifies the field matched
         * @param value Value associated with the field
         * @param start Beginning location of the field, will be >= 0
         * @param end End of the field, will be >= start and <= buffer.length()
         * @param buffer Contains current formatted value, receiver should
         *        NOT modify it.
         */
        public void formatted(int fieldID, Format.Field attr, Object value,
                              int start, int end, StringBuffer buffer);
    }
}