Adding elements into generic list doubt

[Andry Dub]

Hi, dear ranchers! I am very confused. Why I can add Integer or Short into list, that must contain only parants of Number. And I cannot insert Object while Object is superclass of Number.

class A {
public static void main(String[] args) {
 
List<? super Number> list = new ArrayList<Object>();
list.add(new Integer(3));
list.add(new Short((short) 2));
                // list.add(new Object());
for(Object i: list){
System.out.println(i);
}
}
}

[Fu Dong Jia]

hi!
for List<? super Number>,you can use add()method,but you can only add those objects which is-a Number.