@Override
 public void itemStateChanged(ItemEvent e) {
   if (e.getItem() == "Free") {
     model.setChoiceFree();
   }
   if (e.getItem() == "Together") {
     model.setChoiceTogether();
   }
   if (e.getItem() == "Against") {
     model.setChoiceAganist();
   }
 }
 @Override
 public void actionPerformed(ActionEvent e) {
   String command = e.getActionCommand();
   switch (command) {
     case "Go":
       stop = !stop;
       start();
       break;
     case "New":
       model.startwerte();
       break;
     case "Spring +":
       model.setDPlus();
       stop = false;
       step = 0;
       model.startwerte();
       model.repaint();
       break;
     case "Spring -":
       model.setDMinus();
       stop = false;
       step = 0;
       model.startwerte();
       model.repaint();
       break;
     case "Friction ++":
       model.plusFriction();
       stop = false;
       step = 0;
       model.startwerte();
       model.repaint();
       break;
     case "Friction --":
       model.minusFriction();
       stop = false;
       step = 0;
       model.startwerte();
       model.repaint();
       break;
   }
 }