Language change - Web dynpro Java

Dear All,

We have a Web Dynpro Java application (CE 7.1 SP11), where we have internationalization (defined using xlf) which is working fine (for EN and DE language) when we pass a URL parameter sap-locale (sap-locale=EN or sap-locale=DE) in Web dynpro application url.

Now, when the application is loaded with English language, we have button in Web dynpro view (button "Change Language"), on click of the Button it has to load in German (DE) language.

Please suggest how we can achiev this.

Thanks and regards,