// 演示動態方法分配
class Sup {
  void who() {
    System.out.println("who() in Sup");
  }
}
class Sub1 extends Sup {
  void who() {
    System.out.println("who() in Sub1");
  }
}
class Sub2 extends Sup {
  void who() {
    System.out.println("who() in Sub2");
  }
}
class DynDispDemo {
  public static void main(String args[]) {
    Sup superOb = new Sup();
    Sub1 subOb1 = new Sub1();
    Sub2 subOb2 = new Sub2();
    Sup supRef; 
    supRef = superOb;    
    supRef.who();
    supRef = subOb1; 
    supRef.who();
    supRef = subOb2; 
    supRef.who();
  }
}