Java MOD operator returns negative value

Question

I have this method:

private static int generateNo(int randomNo, int value){
    return   ((randomNo*value)%256);
}

in my example randomNo = 17719 qValue = 197920

When I calculate it with calculator the returned value should be 224, however, when I run the program it returns -32.

can anyone explain it please.

Answer 1

A little hint. If you have unexpected negative value when multiply (or sum) numbers, mostly this is number overflow:

private static int generateNo(int randomNo, int value) {
    return (int)(((long)randomNo * value) % 256);
}