Difference between ArrayList and List?

List is an interface and ArrayList is an implementation of the List interface. The ArrayList class has only a few methods in addition to the methods available in the List interface.

There is not much difference in this. The only difference is, you are creating a reference of the parent interface in the first one and a reference of the class which implements the List (i.e) the ArrayList class in the second. If you use the first, you will be able to call the methods available in the List interface and you cannot make calls to the new methods available in the ArrayList class. Where as, you are free to use all the methods available in the ArrayList, if you use the second one.