Thanks a lot.I have a lot to learn.....

public      Scene s = null;
     bjectFile f = new ObjectFile(flags,
       (float)(creaseAngle * Math.PI / 180.0));

      s = f.load(filename);
and when  I want to change the  obj file ,first i use the "objTrans.removeChild(s.getSceneGroup()); "
then the wrong appear: (please help me)

javax.media.j3d.CapabilityNotSetException: Group: no capability to remove children()
     at javax.media.j3d.Group.removeChild(Group.java:349)()
     at ObjLoad.change(ObjLoad.java:257)()
     at ObjLoad.actionPerformed(ObjLoad.java:249)()
     at java.awt.Button.processActionEvent(Button.java:381)()
     at java.awt.Button.processEvent(Button.java:350)()
     at java.awt.Component.dispatchEventImpl(Component.java:3639)()
     at java.awt.Component.dispatchEvent(Component.java:3480)()
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)()
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)()
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)()
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)()
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)()
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)()

TransformGroup objTrans = new TransformGroup();
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
       objScale.addChild(objTrans);
   
   BranchGroup b = new  objLoad("cig.obj");
   objTrans.addChild(b);

******************************
if i want to change a file,do i have to "objTrans.Remove(b)"
and I objTrans.addChild(c); (c-- the other )
but i fail.
can you help me
Thanks in advance