Is 1/0 a legal Java expression?

Question

The following compiles fine in my Eclipse:

final int j = 1/0;
// compiles fine!!!
// throws ArithmeticException: / by zero at run-time

Java

Answer 1

It's legal because no where is it a given that the compiler is supposed to fold constant expressions at compile time.

A "smart" compiler might compile:

a = 1 + 2

as

a = 3

But there's nothing that says the compiler HAS to do that. Other than that, 1/0 is a legal expression just like:

int a;
int b;

a = a/b;

is a legal expression.

At RUNTIME it throws an exception, but that's a runtime error for a reason.