public E remove(String name, int uid) {
     SparseArray<E> uids = mMap.get(name);
     if (uids != null) {
         final E old = uids.removeReturnOld(uid);
         if (uids.size() == 0) {
             mMap.remove(name);
         }
         return old;
     }
     return null;
 }