实验二 继承与接口实验

1、.实验二 继承与接口一、实验目的1. 掌握类的继承机制。2. 熟悉类中成员变量和方法的访问控制。3. 掌握接口与包的使用，熟悉方法的多态性。二、实验内容1. 定义父类及子类，在子类中重写父类的方法2. 练习接口与包的使用三、.实验步骤与要求第1题 继承编写一个Java应用程序，除了主类外，该程序中还有4个类：People, ChinaPeople, AmericanPeople 和 BeijingPeople类。此四个类的继承关系如下图所示：要求ChinaPeople，American类均重写其父类People类的speakHello, averageHeight, averageWeight

2、方法，BeijingPeople类重写其父类ChinaPeople类的speakHello, averageHeight, averageWeight方法。People类 变量 方法protected double height public void speak Hello() protected double weight public void averageHeight() public void averageWeight()ChinaPeople类方法： public void chinaGongfu()AmericanPeople类方法：Public void americanB

3、oxing()BeijingPeople类方法：Public void beijingOpera()源代码：package people;class peopleprotected double height ; protected double weight ; public void speakHello() /问候语的函数System.out.println(hello);public void averageHeight()/人们的平均身高 height=170;System.out.println(+height);public void averageWeight()/人们的平均体

4、重 weight=120;System.out.println(+weight);class Chinapeople extends peoplepublic void speakHello() System.out.println(你好);public void averageHeight() height=172;System.out.println(+height);public void averageWeight() weight=115;System.out.println(+weight);public void chinaGongfu()/中国功夫的方法System.out.p

5、rintln(中国功夫);class Americanpeople extends peoplepublic void speakHello() System.out.println(hello);public void averageHeight() height=180;System.out.println(+height);public void averageWeight() weight=150;System.out.println(+weight);public void americanBoxing()/美国拳击的方法System.out.println(americanBoxi

6、ng);class Beijingpeople extends Chinapeoplepublic void speakHello() System.out.println(北京欢迎你);public void averageHeight() height=168;System.out.println(+height);public void averageWeight() weight=125;System.out.println(+weight);class Examplepublic static void main(String args)people p =new people();

7、Chinapeople c=new Chinapeople();Americanpeople a=new Americanpeople();Beijingpeople b=new Beijingpeople();p.averageHeight();p.averageWeight();p.speakHello();c.averageHeight();c.averageWeight();c.chinaGongfu();c.speakHello();a.averageHeight();a.averageWeight();a.americanBoxing();a.speakHello();b.aver

8、ageHeight();b.averageWeight();b.speakHello();结果截图：第2题 上转型对象要求有一个abstract类，类名为Employee。Employee的子类有YearWorker,MonthWorker和WeekWorker。YearWorker按年领取薪水，MonthWorker按月领取薪水，WeekWorker按周领取薪水。Employee类有一个abstract方法：public abstract earnings();子类必须重写父类的earnings()方法，给出各自领取报酬的具体方式。有一个Company类，该类用employee数组作为成员，

9、employee数组的单元可以是YearWorker对象的上转型对象、MonthWorker对象的上转型对象或WeekWorker对象的上转型对象。程序能输出Company对象一年需要支付的薪水总额。源代码：package people; abstract class Employee int salary;public abstract void earnings();class YearWorker extends Employee public void earnings() salary=200;System.out.println(年薪： +salary*365);class Mon

10、thWorker extends Employee public void earnings() salary=100;System.out.println(月薪：+salary*30+ 一年薪水： +salary*30*12);class WeekWorker extends Employee public void earnings() salary=80;System.out.println(周薪：+salary*7+ 一年薪水： +salary*365);public class Company public static void main(String args) Employee

11、 e=new Employee3; e0=new YearWorker(); e0.earnings(); e1=new MonthWorker(); e1.earnings(); e2=new WeekWorker(); e2.earnings(); 结果截图：第3题 接口回调要求有一个ComputeTotalSales接口，该接口中有一个方法：public double totalSalesByYear()，有三个实现该接口的类：Television,Computer和Mobile。这三个类通过实现接口computeTotalSales，给出自己的年销售额。有一个Shop类，该类用comp

12、uteTotalSales数组作为成员，computeTotalSales数组的单元可以存放Television对象的引用、Computer对象的引用或Mobile对象的引用。程序能输出Shop对象的年销售额。源代码：package people;interface ComputeTotalSalespublic double totalSalesByYear();class Television implements ComputeTotalSalespublic double totalSalesByYear()double sale=100;return sale*365;class c

13、omputer implements ComputeTotalSalespublic double totalSalesByYear()double sale=200;return sale*365;class Mobile implements ComputeTotalSalespublic double totalSalesByYear()double sale=220;return sale*365;public class shop public static void main(String args) ComputeTotalSales c; c=new ComputeTotalSales3; c0=new Television(); System.out.println(电视机的年销售量：+c0.totalSalesByYear(); c1=new computer(); System.out.println(电脑的年销售量：+c1.totalSalesByYear(); c2=