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

Expressions are evaluated from left to right. In this case:

int x = 1;
int y = 3;

---

x == (x = y)) // false
x ==    t

- left x = 1
- let t = (x = y) => x = 3
- x == (x = y)
  x == t
  1 == 3 //false

---

(x = y) == x); // true
   t    == x

- left (x = y) => x = 3
           t    =      3 
-  (x = y) == x
-     t    == x
-     3    == 3 //true