What`s the problem?

[Anurag Chand]

  class X< T extends List<S>, S  extends Number > { 
   public void someMethod(T t, S s) { 
    t.add(new Long(0L));    // error 
    t.add(s);
    //Number n = t.remove(0);   //ok
  } 
} 
 
class  Generics3{ 
  public static void main(String[] args) { 
     X<ArrayList< Long >, Long>   x1 = new X<ArrayList<Long>, Long>();  
     ArrayList< Long >  list = new ArrayList< Long > ();
     Long l = 10L;
     x1.someMethod(list, l);
     System.out.println(list);
  } 
} 
  

Why is that error coming up when we are adding a Long.But its adding Long which is passed?

[Deepak Bala]

What is the error message and where did you get this question from ?