This is now drying me mad. I have a javaApplet on top of a asp.net page. Within this javaApplet I must detect the user preferred language FireFox-Tools-Options-Content-Languages-Choose.I have 3 languages in there and the firstOne is Spanish/Spain[es-ES]by doing the following String locale= System.getProperty("user.language")+"-"+System.getProperty("user.region"); I expect locale to be "es-ES" but I always get "en-null" and user.language is always "en" How do you get the userPreferred language in Java? The correct result should be "es-ES" Any suggestions#? thanks a lot