class Base {
  int i = 99;
  public void amethod(){ System.out.println("Base.amethod()"+i);}
    Base() { amethod(); }
}
public class Derived extends Base{
  int i = -1;        
  public static void main(String argv[]){
          Base b = new Derived(); 
            //Derived无构造函数，所以默认构造函数调用super()，即先执行Base的构造函数，
           //Base中调用函数amethod(),该amethod()调用的是Derived中的amethod()
          System.out.println(b.i); //i为Base中i的值
          b.amethod(); //amethod()调用的是Derived中的amethod
    }  
    public void amethod(){ System.out.println("Derived.amethod()"+i); }
} 
运行结果：Derived.amethod()0
              99
              Derived.amethod()-1