private void showButtonClicked(ActionEvent e){
    if (rStart.isSelected()){     
      sort(new StartComparator()); 
    }
    else if (rName.isSelected()){
      sort(new NameComparator());
    }
    else if (rAge.isSelected()){
      sort(new AgeComparator());
    }
    else if (rTime.isSelected()){
      sort(new TimeComparator());
    }
    //kolla radiobutton.isSelected() else if  lägg till lyssnare på radiobuttons
    refreshList();
  }