Does using var with a literal result in a primitive or a primitive wrapper class?

Question

After reading and talking about Java 10s new reserved type name var (JEP 286: Local-Variable Type Inference), one question arose in the discussion.

When using it with literals like:

var number = 42;

is number now an int or an Integer? If you just use it with comparison operators or as a parameter it usually doesn't matter thanks to autoboxing and -unboxing. But due to Integers member functions it could matter.

So which type is created by var, a primitive int or class Integer?

Answer 1

var asks the compiler to infer the type of the variable from the type of the initializer, and the natural type of 42 is int. So number will be an int. That is what the JLS example says:

var a = 1;  // a has type 'int' 

And I would be surprised if it worked any other way, when I write something like this, I definitely expect a primitive.

If you need a var as boxed primitive, you could do:

var x = (Integer) 10;  // x is now an Integer