Can't figure out how to fix error. Please help.

Question

When I try to run the program I compiled, this is the error I recieved:
Exception in thread "main" java.lang.NullPointerException: Canvas3D: null GraphicsConfiguration
at javax.media.j3d.Canvas3D.checkForValidGraphicsConfig(Canvas3D.java:963)
at javax.media.j3d.Canvas3D.<init>(Canvas3D.java:1006)
at HelloJava3Da.<init>(HelloJava3Da.java:16)
at HelloJava3Da.main(HelloJava3Da.java:45)
Any thoughts about how to fix?

Answer 1

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.*;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.ColorCube;
import javax.media.j3d.*;
import javax.vecmath.*;
public class HelloJava3Da extends Applet
     public HelloJava3Da()
          setLayout(new BorderLayout());
          Canvas3D canvas3D = new Canvas3D(null);
          add("Center", canvas3D);
          BranchGroup scene = createSceneGraph();
          scene.compile();
          SimpleUniverse simpleU = new SimpleUniverse(canvas3D);
          simpleU.getViewingPlatform().setNominalViewingTransform();
          simpleU.addBranchGraph(scene);
     public BranchGroup createSceneGraph()
          BranchGroup objRoot = new BranchGroup();
          objRoot.addChild(new ColorCube(0.4));
          return objRoot;
public static void main(String[] args)
Frame frame = new MainFrame(new HelloJava3Da(), 256, 256);
}