It depends on your code like if you are getting null/default on selecting a default locale
then accordingly you can make a check and load the desired locale.
For ex ,In my case :
String cc=req.getParameter("country");
String ln=req.getParameter("language");
Locale l=null;
if(cc==null)
l=new Locale("en","US");
else
l=new Locale(ln,cc);
ResourceBundle rb=ResourceBundle.getBundle("ApplicationResources",l);
req.setAttribute("resource", rb);