Java SE (Java Platform, Standard Edition)

when try to compile my code
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import com.sun.j3d.utils.geometry.*;
import com.sun.j3d.utils.universe.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import java.awt.*;
public class Main
{
public Main()
{
Transform3D tf=new Transform3D();
TransformGroup trans=new TransformGroup();
Vector3f vec=new Vector3f(0.0f,-4.0f,0.2f);
SimpleUniverse su=new SimpleUniverse();
BranchGroup bg=new BranchGroup();
ColorCube cc=new ColorCube(0.10f);
tf.setTranslation(vec);
trans.setTransform(tf);
trans.addChild(cc);
bg.addChild(cc);
su.getViewingPlatform().setNominalViewingTransform();
su.addBranchGraph(bg);
}
public static void main(String[] args)
{
Main m=new Main();
}
}
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i get these exceptions
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javax.media.j3d.MultipleParentException: Group.addChild: child already has a parent
at javax.media.j3d.GroupRetained.checkValidChild(GroupRetained.java:397)
at javax.media.j3d.GroupRetained.addChild(GroupRetained.java:406)
at javax.media.j3d.Group.addChild(Group.java:261)
at Main.<init>(Main.java:19)
at Main.main(Main.java:25)
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someone can plz help me?