Why is x == (x = y) not the same as (x = y) == x?

Question

Consider the following example:

class Quirky {
    public static void main(String[] args) {
        int x = 1;
        int y = 3;

        System.out.println(x =         


        

Answer 1

== is a binary equality operator.

The left-hand operand of a binary operator appears to be fully evaluated before any part of the right-hand operand is evaluated.

^{Java 11 Specification > Evaluation Order > Evaluate Left-Hand Operand First}