can you explain why both of these questions have different answers. I did both of them 2- which is wrong. can you explain. thank you

1.

What is y displayed in the following code?

public class Test {

public static void main(String[] args) {

int x = 1;

int y = x++ + x;

System.out.println("y is " + y);

}

}

2.

What is y displayed?

public class Test {

public static void main(String[] args) {

int x = 1;

int y = x + x++;

System.out.println("y is " + y);

}

}