类型擦除会干扰多态性

Question

I was reading Core Java Volume I and I encounter a question in translating generic expression. Here is what the book said.

I don't understand why there is a interfere. For the highlighted sentence, why setSecond(Object) method is called? Shouldn't it be setSecond(Date) method since interval is a DateInterval object?

Answer 1

The main problem, I think, is that all that comes between brackets (in this case ) only exists when you're writing the code. It's a compilation-time checking. That's what the type erasure is all about. When you compile the code, all you have are references to Object and these bridge methods in the bytecodes.