Changing locale at runtime in Swing

Question

I would like to be able to change the locale in my Swing application at runtime and have all the text elements on the screen update themselves with localized text from a ResourceBundle of the new locale.

Can this be done without customizing swing components or creating UIDelegates for all components that handle rendering localized text?

If no, then what is a good solution I can consider implementing?

Answer 1

use ResourceBundle.getBundle(BUNDLE_NAME).getString(key); to access the Strings.

when updating the Default Locale e.g. via Locale.setDefault(Locale.GERMAN); clear the Resourcebundle cache: ResourceBundle.clearCache();

the next call of ResourceBundle.getBundle(BUNDLE_NAME).getString(key); should the return the localized String of the chosen Locale.

Answer 2

1. You have a method that is used to change app locale (and probably persist the new value) and another one to get localized strings.

2. Create an interface:

   interface LocaleChangeListener {
       void onLocaleChange();
   }
   

   Implement it by UI components that need to be able to change locale at runtime and set the new values in overrides onLocaleChange().

3. Now, have a list of listeners that will be notified on locale change by the first method.

Answer 3

You may want to save the language preference out, and then require a restart of the app for changes to take effect.

Then, you should be able to use Locale.setDefault(Locale.<desired language>); on startup, prior to rendering the GUI. That should properly switch your locale, which will result in the desired .properties file(s) being loaded.