Question

When you instantiate an object, why do you specify the class twice?

OddEven number = new OddEven();

Why can’t you just say number = new OddEven();? When I declare a string, I only say String once:

String str = "abc";

Actually, my question is not “why do you do it this way” — obviously, you do it because you have to — but rather, why did the creators choose to make Java syntax work like this?

My thoughts are:

1. There is something fundamental to the way Java operates at a low level that necessitates typing the name twice, or
2. The creators freely choose to do it this way to keep some aspect of the syntax uniform — declare the type first? Or was it to be more like its predecessors?

Answer 1

Because you can do this:

Superclass x = new Subclass();

The type of the reference can be a superclass of the actual object being declared, so you need to specify both. For example, you can do:

List<String> stringList = new ArrayList<String>();

Your program interacts with objects that implement List, and you don’t care about the implementation.,