Java Generic query

[PaulStat]

Ok given we can do this

import java.util.*;
class Animal {}
class Dog extends Animal {}
public class Generics {
   public static void main(String... args) {
      List<Animal> animalList = new ArrayList<Animal>();
      animalList.add(new Dog());
      animalList.add(new Dog());
      addAnimals(animalList);
   }
   public static void addAnimals(List<? super Dog> list) {
       list.add(new Dog());    
   }
}

What use could you get from the following generic code

List<? super Dog> animalList = new ArrayList<Animal>();

You can't afterall then say

animalList.add(new Animal());

You can only do the following

animalList.add(new Dog());

So yeah I'm curious, there's nothing wrong with the syntax of this example, it just doesn't seem to have any use?

 

[Nimble]

Well in your example it's clearly not of any additional use, but it's obviously capable of different things because it will match any superclass of Dog. List<? super Dog> could be matched with List<Object>, List<Animal> and List<Dog>. This tutorial has some good examples of using wildcards.