importance of formal type parameters?

[Roshan Rai]

what is the importance of formal type parameters..??

why are they used..??

class Queue<T> {
   private LinkedList<T> items = new LinkedList<T>();
   public void enqueue(T item) {
      items.addLast(item);
   }

please help...
thanks in advance..

[Ankit Dan]

Suppose you have a non-generic method

  static void iAmNonGeneric(Object k, Object[] array){
    //rest of the code
  }

now this is too general in the sense that it does not express any relationship between k and array this kind of dependency can be achieved using formal type parameter

  static <E> void iAmGeneric(E k, E[] array){
    //rest of the code
  }

so now when a generic method is called you can specify the E as you wish like Integer and hence k and array will be of type Integer, for example

ClassName.<Integer>iAmGeneric(20, intArray);

this means the call signature is : iAmGeneric(Integer, Integer[])


i hope you got it

Ankit