Java generics: Use this type as return type?

Question

I'm trying to make an API as user friendly as possible.

Let's have:

class B extends A {}

class A {
    A setX(){ ...; return this; }
}

Now this

B b = new B().setX();

is invalid, has to be casted:

B b = (B) new B().setX();

Is there a way using generics in A to make compiler aware of "this" type and accept the first way - without casting and without passing type parameter at the place where used? (I.e. not new B<B>().setX(), that's ugly.)

I KNOW why Java needs retyping in this case. Please no answers explaing that setX() returns A. I know that. I am asking if generics can solve this.

And for those still wanting to tell me that "this is how static typing works" and "not even generics can help with that", consider this valid Java code:

Map<String, String> map = new HashMap(){{ put( "foo", new RuntimeException() );
String foo = map.get("foo");  // ClassCastException!!

So you can see that generics DO allow you get a CCE without actual type cast appearing in the code.
That's the reason why I expect generics to allow getting rid of the explicit type cast.

Also, IIRC C++ allows that.

Answer 1

Try this in class A:

public <T extends A> T setX() {
    return (T) this;
}

And you can use it like this

B b = new B().setX();