private String call (Object obj, String m, String param)
    {
        String result;
        Class cls = obj.getClass ();
        try 
        {
            Method met = cls.getMethod (m, String.class);
            Object answer = met.invoke (obj, param);
            result = "" + answer;
        } 
        catch (Exception ex) 
        {
            result = "exception: " + ex;
        } 
        return result;
    }
 
    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        String m = jTextField1.getText ();
 
        String param = jTextField2.getText ();
 
        String v = call (jButton1, m, param);
 
        jTextField3.setText (v);
    }