001    /* Formattable.java -- Objects which can be passed to a Formatter
002       Copyright (C) 2005 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010     
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.util;
040    
041    /** 
042     * <p>
043     * The <code>Formattable</code> interface is used to provide customised
044     * formatting to arbitrary objects via the {@link Formatter}.  The
045     * {@link #formatTo} method is called for <code>Formattable</code>
046     * objects used with the 's' conversion operator, allowing the object
047     * to provide its own formatting of its internal data.
048     * </p>
049     * <p>
050     * Thread safety is left up to the implementing class.  Thus,
051     * {@link Formattable} objects are not guaranteed to be thread-safe,
052     * and users should make their own provisions for multiple thread access.
053     * </p>
054     *
055     * @author Tom Tromey (tromey@redhat.com)
056     * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
057     * @since 1.5 
058     */
059    public interface Formattable
060    {
061    
062      /**
063       * Formats the object using the supplied formatter to the specification
064       * provided by the given flags, width and precision.
065       *
066       * @param formatter the formatter to use for formatting the object.
067       *                  The formatter gives access to the output stream
068       *                  and locale via {@link Formatter#out()} and
069       *                  {@link Formatter#locale()} respectively.
070       * @param flags a bit mask constructed from the flags in the
071       *              {@link FormattableFlags} class.  When no flags
072       *              are set, the implementing class should use its
073       *              defaults.
074       * @param width the minimum number of characters to include.
075       *              A value of -1 indicates no minimum.  The remaining
076       *              space is padded with ' ' either on the left
077       *              (the default) or right (if left justification is
078       *              specified by the flags).
079       * @param precision the maximum number of characters to include.
080       *              A value of -1 indicates no maximum.  This value
081       *              is applied prior to the minimum (the width).  Thus,
082       *              a value may meet the minimum width initially, but
083       *              not when the width value is applied, due to
084       *              characters being removed by the precision value.
085       * @throws IllegalFormatException if there is a problem with
086       *                                the syntax of the format
087       *                                specification or a mismatch
088       *                                between it and the arguments.
089       */
090      public void formatTo(Formatter formatter, int flags, int width,
091                           int precision);
092    }