Looks like you are storing these in individual variables. The “normal” place to store groups of items like this would usually be in a list or array.
In this case, store them in a “set” data structure instead. It will not allow duplicates.
Set documentation:
http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Set.html
Set set = new HashSet();
while (set.size() < 10) {
set.add(r.nextInt(500));
}