Thread only running correctly if there is a System.out.println() inside the while true loop

Question

Basicly, I\'m making a game which to update the players position, it uses this thread:

@Override
public void run() {
    while(true) {
        System.out.pri         


        

Answer 1

A loop like

while(true) {
    updatePos(x, y);
}

would completely hog the CPU. Reason it starts behaving better with a println is probably because you yield a few hundred cycles per iteration for I/O.

I suggest you add a small sleep-method according to the desired frame rate:

while (true) {
    try {
        Thread.sleep(10); // for 100 FPS
    } catch (InterruptedException ignore) {
    }
    updatePos(x, y);
}

or, even better, go with an event driven approach with for instance a java.util.Timer. (That would be more Java idiomatic.)