我不明白为什么这个工作

Question

public static void main(String args[]){

    Scanner s = new Scanner(System.in);
    int x;
    int y;
    int z = 0;
    x = s.nextInt();
    y = s.nextInt();

    while(y != 0){
        z += x;
        y--;
    }
    System.out.println(z);
}

This is all. This code calculates x*y but doesn't use *. It was just a (task ?) somebody told me. And my question is why this is working with negative numbers. That x can be negative is obvious but why can y be.

Edit: I wrote this code on my own so I know why it works without *. That's not the question. I can input 5 for x and -5 for y and i get -25. But why? Everytime he adds one more time x to zy goes 1 down. But after the 5th time it stops.

Answer 1

If you put the "z" print inside the while you will understand.

This code makes overflow. Reach the maximum value that the int permit and decrease again from there

Answer 2

This code makes multiple sums. So it can sum the number 2, 3 times, and thats how it does 2*3.

The y can be negative because the if is seeing != than 0, not < than 0.