How do i choose the language when running my application?

[Luuk]

I have created a piece of java-code, with eclipse, and WindowBuilder.

When i test this in eclipse, i see, with default settings, English labels. When i choose 'nl_NL' (externalize setting), i see my labels in Dutch.

When i create a runnable jar, i can only see my text in English.

Question: How do i choose the Dutch language when running my application? (I also want users to be able to choose English)

I already tried adding this:

Locale.setDefault(new Locale("nl_NL"));

but that 'did not help' ;-)