Generics in Java

HI ,
  An Important link about Generics in Java.

http://www.javabeat.net/articles/33-generics-in-java-50-1.html


what is upper bound in Java Generics?
Ans: 

7.1) Upper Bound

The solution to this situation is the usage of wild-cards along with parametric bounding. Have a look over the following declaration.

List animals = new ArrayList();

It tells that a list is being declared with type being anything (?) that is 

extending the Animal class. Though it looks very similar to the above declaration

 it has some differences. The first thing is that it is now possible for the animals

 reference to point to a list that is holding any sub-type of Animal objects.

List dogs = new ArrayList();
dogs.add(new Dog()); dogs.add(new Dog());
 
animals = dogs;

One important difference is that, it is not possible to add elements to the 

animals list, though the only exception is adding null elements. This is

 called the Upper Bound for the animals list.