实验5 继承、多态、接口和异常处理.doc

实验5 继承、多态、接口和异常处理一、实验目的1、掌握Java的类和对象的声明和使用方法2、掌握Java的类的继承和实现方法；3、掌握多态性在类的继承中的运用；4、掌握接口的定义与使用。5、掌握基本异常的处理机制 6、熟悉try语句与catch语句的搭配使用 7、了解有异常处理与没有异常处理的差别 8、多重catch语句的使用9、使用Throws声明异常和Throw抛出异常二、实验环境1、PC微机；2、DOS操作系统或 Windows 操作系统；3、Java sdk程序开发环境、eclipse集成环境。三、实验内容1. 设计三个类，分别是学生类Student，本科生类UnderGraduate，研究生类Postjgraduate，其中Student类是一个抽象类，它包含学生的基本信息如姓名、所学课程、课程成绩等，而Undergraduate类和Postgraduate类都是Student类的子类，这两个类计算课程成绩等级的方法有所不同，如下表所示。假设某班级里既有研究生又有本科生，编写程序统计出全班学生的成绩等级并打印出来。要求：将程序空白部分补充完整。本科生标准研究生标准80100 优秀90100 优秀7080 良好8090 良好6070 一般7080 一般5060 及格6070 及格50以下 不及格60以下 不及格abstract class Student final static int CourseNo = 3; String name;String type; int courses; String courseGrade; public Student(String name) = name; courses = new intCourseNo; 代码1 courseGrade = ; /初始化courseGrade为空串 public abstract void calculateGrade(); public String getName( ) return name; public String getType( ) 代码2 return type; /返回学生类型 public String getCourseGrade( ) return courseGrade; public int getCourseScore(int courseNumber) return coursescourseNumber; public void setName(String name) = name; public void setType(String type) this.type = type; public void setCourseScore(int courseNumber, int courseScore) 代码3 this.coursescourseNumber = courseScore; /按课程索引号设置课程成绩 class Undergraduate extends Student public Undergraduate(String name ) super(name);type = 本科生; public void calculateGrade() int total = 0; double average = 0; for (int i = 0; i =80&average=70&average=60&average=50&average60) courseGrade = 及格; else courseGrade = 不及格; class Postgraduate extends Student public Postgraduate(String name) super(name); type = 研究生; public void calculateGrade() int total = 0; double average = 0; for (int i = 0; i =90&average=80&average=70&average=60&average70) courseGrade = 及格; else courseGrade = 不及格; public class Polymorphism public static void main(String args) Student students = new Student5; students0 = new Undergraduate(陈建平); students1 = new Undergraduate(鲁向东); students2 = new Postgraduate(匡晓华); students3 = new Undergraduate(周丽娜); 代码5 students4 = new Postgraduate(梁欣欣); / 创建姓名为梁欣欣的Postgraduate对象students4 for (int i=0; i5 ;i+) studentsi.setCourseScore(0,87); studentsi.setCourseScore(1,90); studentsi.setCourseScore(2,78); for (int i=0; i5 ;i+) studentsi.calculateGrade(); System.out.println(姓名 + 类型 + 成绩); System.out.println(-); for (int i=0; i5 ;i+) System.out.println(studentsi.getName( )+ + studentsi.getType( )+ + studentsi.getCourseGrade( ); 2. 设计实现一个Soundable接口，该接口由三个类Radio、Walkman和Mobilephone具体实现，并设计一个应用程序类来使用这些类。将下面程序补充完整。import java.util.Scanner;interface Soundable public void increaseVolume( ); public void decreaseVolume( ); public void stopSound( ); public void playSound( );class Radio implements Soundable public void increaseVolume( ) System.out.println(增大收音机音量); public void decreaseVolume( ) System.out.println(减小收音机音量); public void stopSound( ) System.out.println(关闭收音机); public void playSound( ) System.out.println(收音机播放广播); class Walkman implements Soundable public void increaseVolume( ) System.out.println(增大随声听音量); public void decreaseVolume( ) 代码1 System.out.println(减小随声听音量); / 输出减小随声听音量 public void stopSound( ) System.out.println(关闭随声听); public void playSound( ) System.out.println(随声听发出音乐); class Mobilephone implements Soundable public void increaseVolume( ) System.out.println(增大手机音量); public void decreaseVolume( ) System.out.println(减小手机音量); public void stopSound( ) System.out.println(关闭手机); public void playSound( ) System.out.println(手机发出来电铃声); class People private String name; private int age; public void listen(Soundable s) s.playSound( ); public class InterfaceTest public static void main(String args) int i; People sportsman = new People( ); Scanner scanner = new Scanner(System.in); Soundable soundDevice = new Soundable3; /往声音设备数组中放入能发声的设备 soundDevice0 = new Radio( ); soundDevice1 = new Walkman( ); 代码2 soundDevice2 = new Mobilephone( ); /创建手机对象并赋值给soundDevice2 System.out.println(你想听什么? 请输入选择：0-收音机 1-随声听 2-手机); i = scanner.nextInt( ); /开始听声音 sportsman.listen(soundDevicei); soundDevicei.increaseVolume( ); 代码3 soundDevicei.stopSound( ); /调用stopSound( )方法 3要求设计一个GUI图形窗口程序，该程序让用户输入一个星期中的任意一天的数字1到7，然后输出该数字所对应的是星期几。 程序的运行效果如图1 图1但是当用户输入的数字不在1到7范围内时，程序应该弹出一个对话框以显示发生了异常，如图2和图3所示。 图2 图3package myjava;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.*;public class GUIGraphicsWindow public static void main(String args) / TODO Auto-generated method stubBoundary frame = new Boundary();frame.setSize(350,100);frame.setTitle(日子数与星期几转换);frame.setLocationRelativeTo(null);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.setVisible(true);class Boundary extends JFrame private static JTextField Jtnum = new JTextField(10);private static JTextField Jtday = new JTextField(10);public Boundary() JPanel p1 = new JPanel();JPanel p2 = new JPanel();p1.setLayout(new GridLayout(2,2);setLayout(new GridLayout(1,1);p1.add(new JLabel(输入数字);p1.add(Jtnum);p1.add(new JLabel(星期几);p1.add(Jtday);p2.add(new JLabel();add(p2);add(p1);ActionListener listener = new TextFiledListener();Jtnum.addActionListener(listener);public static JTextField getJtnum() return Jtnum;public static void setJtnum(JTextField jtnum) Jtnum = jtnum;public static JTextField getJtday() return Jtday;public static void setJtday(JTextField jtday) Jtday = jtday;class TextFiledListener implements ActionListener public void actionPerformed(ActionEvent e) int num = Integer.parseInt(Boundary.getJtnum().getText();String day = ;try day = handle(num);Boundary.getJtday().setText(day); catch (Exception e1) JOptionPane.showMessageDialog(null, BadDataException:您输入的日子数不是1.7, 无效日期,JOptionPane.WARNING_MESSAGE); public String handle(