001    /* ListResourceBundle -- a resource bundle build around a list
002       Copyright (C) 1998, 1999, 2001, 2002, 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     * A <code>ListResouceBundle</code> provides an easy way, to create your own
043     * resource bundle. It is an abstract class that you can subclass. You should
044     * then overwrite the getContents method, that provides a key/value list.
045     *
046     * <p>The key/value list is a two dimensional list of Object.  The first
047     * dimension ranges over the resources. The second dimension ranges from
048     * zero (key) to one (value). The keys must be of type String, and they are
049     * case-sensitive. For example:
050     *
051    <br><pre>public class MyResources
052      extends ListResourceBundle
053    {
054      public Object[][] getContents()
055      {
056        return contents;
057      }
058    
059      static final Object[][] contents =
060      {
061        // LOCALIZED STRINGS
062        {"s1", "The disk \"{1}\" contains {0}."},  // MessageFormat pattern
063        {"s2", "1"},                       // location of {0} in pattern
064        {"s3", "My Disk"},                 // sample disk name
065        {"s4", "no files"},                // first ChoiceFormat choice
066        {"s5", "one file"},                // second ChoiceFormat choice
067        {"s6", "{0,number} files"}         // third ChoiceFormat choice
068        {"s7", "3 Mar 96"},                // sample date
069        {"s8", new Dimension(1,5)}         // real object, not just string
070        // END OF LOCALIZED MATERIAL
071      };
072    }</pre>
073     *
074     * @author Jochen Hoenicke
075     * @author Eric Blake (ebb9@email.byu.edu)
076     * @see Locale
077     * @see PropertyResourceBundle
078     * @since 1.1
079     * @status updated to 1.4
080     */
081    public abstract class ListResourceBundle extends ResourceBundle
082    {
083      /**
084       * The constructor. It does nothing special.
085       */
086      public ListResourceBundle()
087      {
088      }
089    
090      /**
091       * Gets a resource for a given key. This is called by <code>getObject</code>.
092       *
093       * @param key the key of the resource
094       * @return the resource for the key, or null if it doesn't exist
095       */
096      public final Object handleGetObject(String key)
097      {
098        Object[][] contents = getContents();
099        int i = contents.length;
100        while (--i >= 0)
101          if (key.equals(contents[i][0]))
102            return contents[i][1];
103        return null;
104      }
105    
106      /**
107       * This method should return all keys for which a resource exists.
108       *
109       * @return an enumeration of the keys
110       */
111      public Enumeration<String> getKeys()
112      {
113        // We make a new Set that holds all the keys, then return an enumeration
114        // for that. This prevents modifications from ruining the enumeration,
115        // as well as ignoring duplicates.
116        final Object[][] contents = getContents();
117        Set<String> s = new HashSet<String>();
118        int i = contents.length;
119        while (--i >= 0)
120          s.add((String) contents[i][0]);
121        ResourceBundle bundle = parent;
122        // Eliminate tail recursion.
123        while (bundle != null)
124          {
125            Enumeration<String> e = bundle.getKeys();
126            while (e.hasMoreElements())
127              s.add(e.nextElement());
128            bundle = bundle.parent;
129          }
130        return Collections.enumeration(s);
131      }
132    
133      /**
134       * Gets the key/value list. You must override this method, and should not
135       * provide duplicate keys or null entries.
136       *
137       * @return a two dimensional list of String key / Object resouce pairs
138       */
139      protected abstract Object[][] getContents();
140    } // class ListResourceBundle