Class extends question

Question

Hi Ive written a program in java3D and my class extends JFrame because i using swing for my GUI however i now want to use the mouse picking thing in java to click on shapes on my canvas which i see isnt 'too' hard but i cant now extend a second thing can i? is there a way around it? the code below is exactly what i want but it extends MouseAdapter which mine cant ?
import com.sun.j3d.utils.picking.*;
import com.sun.j3d.utils.universe.SimpleUniverse;
import com.sun.j3d.utils.geometry.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import java.awt.event.*;
import java.awt.*;
public class Pick extends MouseAdapter
  private PickCanvas pickCanvas;
public Pick()
    Frame frame = new Frame("Box and Sphere");
    GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();
    Canvas3D canvas = new Canvas3D(config);
    canvas.setSize(400, 400);
    SimpleUniverse universe = new SimpleUniverse(canvas);
    BranchGroup group = new BranchGroup();
    // create a color cube
    Vector3f vector = new Vector3f(-0.3f, 0.0f, 0.0f);
    Transform3D transform = new Transform3D();
    transform.setTranslation(vector);
    TransformGroup transformGroup = new TransformGroup(transform);
    ColorCube cube = new ColorCube(0.3);
    transformGroup.addChild(cube);
    group.addChild(transformGroup);
    //create a sphere
    Vector3f vector2 = new Vector3f(+0.3f, 0.0f, 0.0f);
    Transform3D transform2 = new Transform3D();
    transform2.setTranslation(vector2);
    TransformGroup transformGroup2 = new TransformGroup(transform2);
    Appearance appearance = new Appearance();
    appearance.setPolygonAttributes(new PolygonAttributes(PolygonAttributes.POLYGON_LINE, PolygonAttributes.CULL_BACK,0.0f));
    Sphere sphere = new Sphere(0.3f,appearance);
    transformGroup2.addChild(sphere);
    group.addChild(transformGroup2);
    universe.getViewingPlatform().setNominalViewingTransform();
    universe.addBranchGraph(group);
    frame.addWindowListener(new WindowAdapter() {
       public void windowClosing(WindowEvent winEvent) {
          System.exit(0);
    frame.add(canvas);
    pickCanvas = new PickCanvas(canvas, group);
    pickCanvas.setMode(PickCanvas.BOUNDS);
    canvas.addMouseListener(this);
    frame.pack();
    frame.show();
public static void main( String[] args )
    new Pick();
public void mouseClicked(MouseEvent e)
    pickCanvas.setShapeLocation(e);
    PickResult result = pickCanvas.pickClosest();
    if (result == null)
       System.out.println("Nothing picked");
    else
       Primitive p = (Primitive)result.getNode(PickResult.PRIMITIVE);
       Shape3D s = (Shape3D)result.getNode(PickResult.SHAPE3D);
       if (p != null)
          System.out.println(p.getClass().getName());
       else if (s != null)
             System.out.println(s.getClass().getName());
       else
          System.out.println("null");
}

Answer 1

hi,
first, you don't have to extend JFrame (even it seems convenient), try to honor the composition over the inheritance. second, if you listen to key or mouse events, usually it's enough and perfectly ok to implement proper listener interface and then implement its methods (fulfill the contract).
what you did (extnding some mouse listener) i would assume that you're trying to implement a new mouse listener with specific behavior. but what you actually want is just to use it.
this question is "on the edge" since it involves some general design decisions (so it could be in java programming section) and at the same time it touches the j3d apis (so it can be here).
hope it helped;)