[hardwired]

Code:

public SpaceGame(int width, int height){
    ...
    addKeyListener(new MyKeyListener());
    // Keyboard input requires the listening component to have the focus.
    setFocusable(true);
    new Thread(this).start();
    ...
public static void main(String [] args){
    ...
    frame.add(g);
    // This should be last for proper/complete initialization.
    frame.setVisible(true);