package b;
public class BB
{static abstract class Human{     }static class Man extends Human{   }static class Woman extends Human{      }public void sayHello(Human guy){System.out.println("hello guy");}public void sayHello(Man guy){System.out.println("hello man");}public void sayHello(Woman guy){System.out.println("hello woman");}public static void main(String[] args){BB b = new BB();Human man = new Man();//静态类型为HumanHuman woman = new Woman();b.sayHello(man);b.sayHello(woman);}
}

package b;
public class AA
{static abstract class Human{protected abstract void sayHello();}static class Man extends Human{@Overrideprotected void sayHello(){System.out.println("man say hello");}}static class Woman extends Human{@Overrideprotected void sayHello(){System.out.println("woman say hello");}}public static void main(String[] args){Human man = new Man();Human woman = new Woman();man.sayHello();woman.sayHello();man = new Woman();man.sayHello();}
}