Why can't the compiler/JVM just make autoboxing “just work”?

Question

Autoboxing is rather scary. While I fully understand the difference between == and .equals I can\'t but help have the follow bug the hell out of m

Answer 1

When you write

foo.get(0)

the compiler does not matter how you created the List. It only looks at the compile-time type of the List foo. So, if that is a List, it will treat that as a List, as it is supposed to do, and a List's get() always returns an Integer. If you want to use the == then you have to write

System.out.println(foo.get(0).intValue() == bar.get(0).intValue());

not

System.out.println(foo.get(0) == bar.get(0));

because that has a totally different meaning.