Why don't Java's +=, -=, *=, /= compound assignment operators require casting?

Question

Until today, I thought that for example:

i += j;

Was just a shortcut for:

i = i + j;

But if we try this:<

Answer 1

The problem here involves type casting.

When you add int and long,

1. The int object is casted to long & both are added and you get long object.
2. but long object cannot be implicitly casted to int. So, you have to do that explicitly.

But += is coded in such a way that it does type casting. i=(int)(i+m)