面向对象第五章课后作业

面向对象第五章课后作业 1打印机 package tang.biao; public abstract class Printer { public abstract void print(); } package tang.biao; public class DotMatrixtPrinter extends Printer{ public void print() { System.out.println("针式打印机打印"); } } package tang.biao; public class InkpetPrinter extends Printer{ public void print() { System.out.println("一个喷墨打印机打印"); } } package tang.biao; public class LaserPrinter extends Printer{ public void print(){ System.out.println("一个激光打印机打印"); } } package tang.biao; public class TestPrinter { public static void main(String[] args){ Printer per=new DotMatrixtPrinter(); per.print(); Printer per1=new InkpetPrinter(); per1.print(); Printer per2 =new LaserPrinter(); per2.print(); } } 2.招待朋友 package com.bdqn.dome; //牛犇类 public class Niu { public void feed(Visit visit) { visit.eat(); } public void play(Visit visit) { visit.play(); } } package com.bdqn.dome; public abstract class Visit { //请吃东西 public abstract void eat(); //玩耍 public abstract void play(); } package com.bdqn.dome; public class China extends Visit{ public void eat(){ System.out.println("吃四川菜"); } public void play(){ System.out.println("去打太极"); } } package com.bdqn.dome; public class Usa extends Visit{ public void eat(){ System.out.println("吃披萨"); } public void play(){ System.out.println("打橄榄球"); } }package com.bdqn.dome; public class Testniu { public static void main(String[] args) { Niu niu = new Niu(); Visit visit = new China(); niu.feed(visit); niu.play(visit); visit=new Usa(); niu.feed(visit); niu.play(visit); } }