public void  scr0100_pbo()
{
   .....
}

public void  scr0100_PAI()
{
   .....
}

  abstract public class Screen
  {
         ...........
         abstract public void event_pbo();
         abstract public void event_pbo_subscreen();
         abstract public void event_pbo_finished();
         abstract public void event_pai();
         abstract public void event_pai_subscreen();
         abstract public void event_pai_finished();
         ...........
  }

  class Screen1 extends Screen
  {
         ...........
  }

  class Screen2 extends Screen
  {
         ...........
  }

  ........

  class ScreenN extends Screen
  {
         ...........
  }

  ........

  Screen[] screen = new Screen[5];
  Screen[0] = new Screen1();
  Screen[1] = new Screen2();
  Screen[N] = new ScreenN();

  ........

  Screen[N].event_pbo();

  ........