UnitLocale.java
package org.djunits.locale;
import java.io.Serializable;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import org.djutils.exceptions.Throw;
/**
* Localization object for language specific reporting of units.
* <p>
* Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
* BSD-style license. See <a href="https://djunits.org/docs/license.html">DJUNITS License</a>
* </p>
* @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
* @author <a href="https://tudelft.nl/pknoppers">Peter Knoppers</a>
*/
public class UnitLocale implements Serializable
{
/** */
private static final long serialVersionUID = 20200118L;
/** filename without .properties, to be found in the /resources folder. */
private final String bundleNamePrefix;
/** the resource bundle. */
private transient ResourceBundle resourceBundle;
/** current locale. */
private Locale currentLocale = null;
/** the fallback resource bundle. */
private final transient ResourceBundle fallbackResourceBundle;
/** fallback locale. */
private final Locale fallbackLocale;
/**
* Create a localization object for units and unit systems. The prefix is right now either "unit" or "unitsystem".
* @param prefix String; the prefix of the properties files to use.
*/
public UnitLocale(final String prefix)
{
Throw.whenNull(prefix, "prefix cannot be null");
this.bundleNamePrefix = prefix;
this.fallbackLocale = new Locale("en");
this.fallbackResourceBundle = ResourceBundle.getBundle("resources/locale/" + prefix, this.fallbackLocale);
}
/**
* Reload the resource bundle if necessary.
*/
public void checkReload()
{
if (this.currentLocale == null || !this.currentLocale.equals(Locale.getDefault(Locale.Category.DISPLAY)))
{
this.currentLocale = Locale.getDefault(Locale.Category.DISPLAY);
try
{
this.resourceBundle = ResourceBundle.getBundle("resources/locale/" + this.bundleNamePrefix, this.currentLocale);
}
catch (MissingResourceException e)
{
this.resourceBundle = null;
}
}
}
/**
* Retrieve a string from a resource bundle. If retrieval fails, try the fallbackLocale. If that fails as well, return the
* value of key string, surrounded by exclamation marks. When the DefaultLocale has changed, load a new ResourceBundle.
* @param key String; the key for the locale in the currently valid resource bundle
* @return String; localized string, or, if the key could not be found, the key surrounded by exclamation marks
*/
public final String getString(final String key)
{
checkReload();
if (null == this.resourceBundle)
{
// Failed to find the resourceBundle (on a previous call to getString)
return getFallbackString(key);
}
try
{
return this.resourceBundle.getString(key);
}
catch (MissingResourceException e)
{
return getFallbackString(key);
}
}
/**
* Retrieve a string from the falback bundle. If retrieval fails, return the value of key string, surrounded by exclamation
* marks.
* @param key String; the key for the fallback locale to look up in the resource bundle
* @return String; localized string, or, if the key could not be found, the key surrounded by exclamation marks
*/
public final String getFallbackString(final String key)
{
try
{
return this.fallbackResourceBundle.getString(key);
}
catch (MissingResourceException e)
{
return '!' + key.substring(key.indexOf('.') + 1) + '!';
}
}
@Override
public String toString()
{
return "Localization [bundleNamePrefix=" + this.bundleNamePrefix + ", currentLocale=" + this.currentLocale
+ ", fallbackLocale=" + this.fallbackLocale + "]";
}
}