Question about post-increment

Question

Hey! I got the following answer in the quiz:

int x = 1;
x += x++;
System.out.println(x);

x is 2 in the end.

My question:
1 += 1++;
Shouldn't the post-increment be added now? Inbetween the calculation and out.print?
So the result should be 3?

Answer 1

I would say that this expression is undefinded.

An example with two variables:

int x = 1;
int y = 1;

y += x++
first add value of x to y -> y is now 2
than increment x -> x is now 2