Parameter Substitution In Resource Bundles

If you use Java resource bundles to translate your application into several languages, it is sometimes necessary to use parameters in the properties of resource bundles. The JDK does not offer the feature to use parameters directly in resource bundles. This article shows how to use parameters in resource bundles.

Resource bundle property example

messages.properties (English):

...
itemservice.item.added = User {0} added new item {1} to group {2}.
...


messages_de.properties (German):

...
itemservice.item.added = Das Objekt {1} wurde von Benutzer {0} zur Gruppe {2} hinzugef\u00FCgt.
...


The example shows that parameters are used in English and German in different order. Therefore it is necessary to use parameters at all. To replace parameters by values, you have to use method java.text.MessageFormat.format(String text, Object … arguments). Add a small wrapper class to you project:

public class Messages {
    // property file is: package/name/messages.properties
    private static final String BUNDLE_NAME = "package.name.messages";
    private static final ResourceBundle RESOURCE_BUNDLE = ResourceBundle.getBundle(BUNDLE_NAME);
    private Messages() {
    }
    public static String getString(String key) {
        try {
            return RESOURCE_BUNDLE.getString(key);
        } catch (MissingResourceException e) {
            return '!' + key + '!';
        }
    }
    public static String getString(String key, Object... params  ) {
        try {
            return MessageFormat.format(RESOURCE_BUNDLE.getString(key), params);
        } catch (MissingResourceException e) {
            return '!' + key + '!';
        }
    }
}

You can now use the properties from the example above:

Messages.getString( "itemservice.item.added", user.getName(), item.getTitle(), group.getName());

2010

04/23

CATEGORY

Java

TAGS

resource bundle

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