Detecting that a button's function is completed

I placed an actionListener on some JButtons I created. It is such that if the user clicks a button, another class is called-up. I want to detect if that class has finished its function... for more clarity, here is my code:

Quest.addActionListener(new ActionListener(){
  public void actionPerformed(ActionEvent iq) {

        JButton source = (JButton) iq.getSource();

             if (point.equals(points.get(0))){

         q1 = new Quest1();  //class called up
         source.setEnabled(false);

         //This is where my problem lies.... I want to be able to detect when the button's action is finished...than some other action takes place!
}
});

please help me.....