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interface

michael ngangom
Greenhorn

Joined: Aug 24, 2010
Posts: 5

What is the difference between the following two?

List l=new ArrayList();

and

ArrayList al=new ArrayList();

??


Michael.
gurpeet singh
Ranch Hand

Joined: Apr 04, 2012
Posts: 924
    
    1

michael ngangom wrote:What is the difference between the following two?

List l=new ArrayList();

and

ArrayList al=new ArrayList();

??


in case of List l = new ArrayList(); the reference variable l is of type List which is an interface whereas in ArrayList al = new ArrayList(); al is of type ArrayList which is a class. well that was obvious you could say. it is said that it is a good practice to code in terms of interfaces. why ? suppose you have a method which takes list argument as follows :
method2(List list){} now this method can take any type of List. it can take ArrayList. suppose later you changed your implementation and supplied LinkedList , it will work. this flexibility does not come with the second option .
michael ngangom
Greenhorn

Joined: Aug 24, 2010
Posts: 5

Thanks! That clears my doubt!!
 
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subject: interface