What's the difference between these ways of initializing a HashMap?

Question

I used a HashMap for my program and it works fine, but I don\'t understand the difference between these initializations of HashMap.

Let\'s say I\'m implementing a Ha

Answer 1

You missed the right choice:

Map alphabet1 = new HashMap();

1. Generics declaration allows compiler to check your 'alphabet1' usages during compile-time.
2. Map/HashMap on left side declares how your 'alphabet1' variable should be considered: either as Map (interface) or HashMap (instance of concrete class). Of course interface is preferred - it makes your code more robust to further changes.