对象(DuoTaiDemo1)

//多态应用：package duixiang;abstract class Stu//供子类继承的相同属性{public abstract void study();public abstract void sleep();}class BaseStudent extends Stu{public void study(){System.out.println("base study");}public void sleep(){System.out.println("da sleep");}void play(){System.out.println("basketball");}}class AdvStudent extends Stu{public void study(){System.out.println("adv study");}public void sleep(){System.out.println("xiao sleep");}void watch(){System.out.println("movies");}}class Method//供主函数操作的方法类{public static void method(Stu s)//此方法可以提高代码的可扩展性，先用多态调用共同属性如：Stu s=new BaseStudent(){s.study();s.sleep();if(s instanceof BaseStudent)//instance比较是否为同一类((BaseStudent) s).play();//强制转换类型并调用特有属性else if(s instanceof AdvStudent)((AdvStudent) s).watch();}}public class DuoTaiDemo1 {public static void main(String [] args){Method.method(new BaseStudent());Method.method(new AdvStudent());}}