Question

I am having issues figuring out why I’m getting a nullpointerexception thrown. It doesn’t really affect anything (I don’t think at least) since everything still gets painted out properly, but I don’t like error messages.

As you can see, paint() calls this.game.paint(g2). To try to debug, everything in this.game.print has been commented out – the function does nothing so it shouldn’t be a part of the problem.

public class Application extends JFrame {

private Game game;///<stores the rules for the game and facilitates interactions

public Application() throws RoyException {
    this.game = new Game(this, 2);
}


//   @Override
public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    try{
    this.game.paint(g2);
    }catch(Exception e)
    {
        System.out.println("CAUGHT " + e.getMessage());
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    try {
        Application app = new Application();
    } catch (RoyException e) {
        System.out.println("An error occurred while running the program: " + e.getMessage());
        System.out.print("Stack trace: ");
        e.getStackTrace();
    }
}

}

And here’s the stacktrace – Application.java:153 is this.game.paint(g2);

CAUGHT null java.lang.NullPointerException
    at bullshitakemushrooms.Application.paint(Application.java:153)
   Game created.
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:781)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:728)
    at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677)
    at javax.swing.RepaintManager.access$700(RepaintManager.java:59)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1621)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:701)
    at java.awt.EventQueue.access$000(EventQueue.java:102)
    at java.awt.EventQueue$3.run(EventQueue.java:662)
    at java.awt.EventQueue$3.run(EventQueue.java:660)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:671)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)

Answer 1

Apparently it is a bad idea to set the window’s iconimage after setting visibility/size.

After moving this line

this.app.setIconImage(new ImageIcon("mushy.jpg").getImage());

before

    this.app.setSize(this.maxX, this.maxY);
    this.mmenu.setVisible(true);
    app.setVisible(true);
    app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    app.setAlwaysOnTop(true);

the nullpointerexception throw stopped. Lesson learned: set window icon first.