Question

How can I draw something in JPanel that will stay the same and not be repainted, I am doing a traffic simulation program and I want the road to be drawn once because It will not change. Thanks

Answer 1

I’m not sure you actually want your road to never be repainted – repaint events fire (for example) when your window is resized, or when it becomes visible following another window obstructing it. If your panel never repaints then it’ll look peculiar.

As far as I remember, Swing will only fire appropriate paint events for these circumstances, so you should be OK following the usual method of subclassing JPanel with a suitable override:

public class RoadPanel extends JPanel {      @Override     public void paintComponent(Graphics g) {         super.paintComponent(g);         // your drawing code here     } } 

If you cache your road into an image or another graphics format (to save calculating the display data multiple times) once drawn once, this might save you some time on subsequent paints.