If your class exetends Applet you could use
com.sun.j3d.utils.applet.MainFrame class.
For example:
public class Cube3D extends Applet{
// ...
}
import com.sun.j3d.utils.applet.MainFrame;
public class Main {
public static void main(String[] args) {
Frame frame = new MainFrame(new Cube3D(), 256, 256);
}
}
This is a code how to initialize 3D Applet:
public class Cube3D extends Applet{
public Cube3D() {
setLayout(new BorderLayout());
GraphicsConfiguration conf = SimpleUniverse.getPreferredConfiguration();
Canvas3D canvas3D = new Canvas3D(SimpleUniverse.getPreferredConfiguration());
add(BorderLayout.CENTER, canvas3D);
BranchGroup scene = createSceneGraph();
scene.compile();
SimpleUniverse simpleUniverse = new SimpleUniverse(canvas3D);
simpleUniverse.getViewingPlatform().setNominalViewingTransform();
simpleUniverse.addBranchGraph(scene);
}
public BranchGroup createSceneGraph() {
BranchGroup rootGroup = new BranchGroup();
// insert your code hear
return rootGroup;
}