Why does giving explicit type arguments to a non-generic method or constructor compile?

Question

When instantiating ArrayLists I am used to seeing code like this

ArrayList arr = new ArrayList();

or

Answer 1

I've just tried:

ArrayList arr = new ArrayList();

And got the same warning (not an error!). Looks like the compiler ignores¹ the generics after the new keyword and before the ArrayList. It's just like writing:

ArrayList arr = new ArrayList();

¹ I'm not sure if it really "ignores" that, I'll be glad if someone confirms/correct me