How is the generic type getting inferred here?

Question

public static void main(String[] args) {
    Map>> map = getHashMap();
}

static  Map getHashM         


        

Answer 1

class XX
  static  T foo(){ return null; }

String  s = XX.foo();
Integer i = XX.foo();

Java infers that T is String in the 1st case, Integer in the 2nd case.

What does "infer" mean? It means that Java guesses that in the two statements, the programmer most like wants T==String in the 1st case, T==Integer for the 2nd case, being a nice guy, Java takes these guesses as fact, and programmers do not have to manually specify the Ts

    String  s = XX. foo();
    Integer i = XX.foo();

But really, Java dictates that the return type T must be determined like that.

I find this thing very fishy, not sure what's the reason behind the design. Probably, when (if) Java adds reifiable types(i.e. the real class of T is available at runtime), the design makes more sense:

class XX
  static  T foo(){ return new T(); }

String  s = XX.foo();
Integer i = XX.foo();

I still don't like the fact that the type of a method is context dependent.