Source for gnu.java.locale.LocaleHelper

   1: /* LocaleHelper.java -- helper routines for localization
   2:    Copyright (C) 2004, 2005 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.java.locale;
  40: 
  41: import java.text.Collator;
  42: import java.util.Locale;
  43: import java.util.MissingResourceException;
  44: import java.util.ResourceBundle;
  45: 
  46: /**
  47:  * This class provides common helper methods
  48:  * for handling localized data.
  49:  *
  50:  * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
  51:  *
  52:  * @see java.util.Locale
  53:  * @see java.util.ResourceBundle
  54:  */
  55: public class LocaleHelper
  56: {
  57:   /**
  58:    * <p>
  59:    * This method is used by the localized name lookup methods to
  60:    * retrieve the next locale to try.  The next locale is derived
  61:    * from the supplied locale by applying the first applicable
  62:    * rule from the following:
  63:    * </p>
  64:    * <ol>
  65:    * <li>If the variant contains a <code>'_'</code>, then
  66:    * this and everything following it is trimmed.</li>
  67:    * <li>If the variant is non-empty, it is converted to
  68:    * an empty string.</li>
  69:    * <li>If the country is non-empty, it is converted to
  70:    * an empty string.</li>
  71:    * <li>If the language is non-empty, it is converted to
  72:    * an empty string (forming {@link java.util.Locale#ROOT})</li>
  73:    * </ol>
  74:    * <p>
  75:    * The base fallback locale is {@link java.util.Locale#ROOT}.
  76:    * </p>
  77:    *
  78:    * @param locale the locale for which a localized piece of
  79:    *               data could not be obtained.
  80:    * @return the next fallback locale to try.
  81:    */
  82:   public static Locale getFallbackLocale(Locale locale)
  83:   {
  84:     String language = locale.getLanguage();
  85:     String country = locale.getCountry();
  86:     String variant = locale.getVariant();
  87:     int uscore = variant.indexOf('_');
  88:     if (uscore != -1)
  89:       return new Locale(language, country,
  90:             variant.substring(0, uscore));
  91:     if (!variant.isEmpty())
  92:       return new Locale(language, country, "");
  93:     if (!country.isEmpty())
  94:       return new Locale(language, "", "");
  95:     return Locale.ROOT;
  96:   }
  97: 
  98:   /**
  99:    * Return an array of all the locales for which there is a
 100:    * {@link Collator} instance.  A new array is returned each time. 
 101:    */
 102:   public static Locale[] getCollatorLocales()
 103:   {
 104:     // For now we don't bother caching.  This is probably
 105:     // not called very frequently.  And, we would have to
 106:     // clone the array anyway.
 107:     if (LocaleData.collatorLocaleNames.length == 0)
 108:       return new Locale[] { Locale.US };
 109:     Locale[] result = new Locale[LocaleData.collatorLocaleNames.length];
 110:     for (int i = 0; i < result.length; ++i)
 111:       {
 112:         String language;
 113:         String region = "";
 114:         String variant = "";
 115:         String name = LocaleData.collatorLocaleNames[i];
 116: 
 117:         language = name.substring(0, 2);
 118: 
 119:         if (name.length() > 2)
 120:           region = name.substring(3);
 121: 
 122:         int index = region.indexOf("_");
 123:         if (index > 0)
 124:           {
 125:             variant = region.substring(index + 1);
 126:             region = region.substring(0, index - 1);
 127:           }
 128: 
 129:         result[i] = new Locale(language, region, variant);
 130:       }
 131:     return result;
 132:   }
 133: 
 134:   /**
 135:    * Return the number of locales we know of.
 136:    */
 137:   public static int getLocaleCount()
 138:   {
 139:     return LocaleData.localeNames.length;
 140:   }
 141: 
 142:   /**
 143:    * Return the Nth locale name.
 144:    */
 145:   public static String getLocaleName(int n)
 146:   {
 147:     return LocaleData.localeNames[n];
 148:   }
 149: }