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                                                                                                               实验六 继承定义与使用

                                                                                                                                                      实验时间 2018-9-28

1、实验目的与要求

(1) 理解继承的定义；

(2) 掌握子类的定义要求

(3) 掌握多态性的概念及用法；

(4) 掌握抽象类的定义及用途；

(5) 掌握类中4个成员访问权限修饰符的用途；

(6) 掌握抽象类的定义方法及用途；

(7)掌握Object类的用途及常用API；

(8) 掌握ArrayList类的定义方法及用法；

(9) 掌握枚举类定义方法及用途。

2、实验内容和步骤

实验1： 导入第5章示例程序，测试并进行代码注释。

测试程序1：

      在elipse IDE中编辑、调试、运行程序5-1 （教材152页-153页） ；

     掌握子类的定义及用法；

    结合程序运行结果，理解并总结OO风格程序构造特点，理解Employee和Manager类的关系子类的用途，并在代码中添加注释。

测试实验结果如下：

插入此程序的代码并对其进行注释，进行更深一步的理解

ManagerTest

package inheritance;/
public class ManagerTest
{public static void main(String[] args){// 构建管理者对象Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);boss.setBonus(5000);Employee[] staff = new Employee[3];//定义一个包含3个雇员的数组// 用管理者和员工对象填充员工数组staff[0] = boss;staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);staff[2] = new Employee("Tommy Tester", 40000, 1990, 3, 15);// 打印关于所有员工对象的信息for (Employee e : staff)System.out.println("name=" + e.getName() + ",salary=" + e.getSalary());//输出每个人的薪水}}

　　Manager

package inheritance;public class Manager extends Employee
{private double bonus;/*** @param name the employee's name* @param salary the salary* @param year the hire year* @param month the hire month* @param day the hire day*/public Manager(String name, double salary, int year, int month, int day){super(name, salary, year, month, day);bonus = 0;}public double getSalary(){double baseSalary = super.getSalary();return baseSalary + bonus;}public void setBonus(double b){bonus = b;}
}

Emloyee:

package inheritance;import java.time.*;public class Employee
{private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}
}

package inheritance;import java.time.*;public class Employee
{private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}
}

 

子类的定义：在有继承关系的类中extends前面的类则是子类。

超类和子类都是Java程序员常用的两个类。

测试程序2：

    编辑、编译、调试运行教材PersonTest程序（教材163页-165页)；

   掌握超类的定义及其使用要求；

   掌握利用超类扩展子类的要求；

  在程序中相关代码处添加新知识的注释。

  超类：如果在程序中没有明确的之处超类，Object就是被认为是这个类的超类，如：Public class Employee extebds Object.在java中，每个类都是Object类扩展而来的。当然也可以使用Object类型的变量引用任何类型的对象。

超类扩展子类的要求

 

代码的注释：

package abstractClasses;import java.time.*;public class Employee extends Person
{private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){super(name);this.salary = salary;hireDay = LocalDate.of(year, month, day);}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public String getDescription(){return String.format("an employee with a salary of $%.2f", salary);}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}
}

package abstractClasses;/*** This program demonstrates abstract classes.* @version 1.01 2004-02-21* @author Cay Horstmann*/
public class PersonTest
{public static void main(String[] args){Person[] people = new Person[2];// 用Student和Employee对象填充人员数组people[0] = new Employee("Harry Hacker", 50000, 1989, 10, 1);people[1] = new Student("Maria Morris", "computer science");// 打印所有person对象的名称和描述for (Person p : people)System.out.println(p.getName() + ", " + p.getDescription());}
}

package abstractClasses;public class Student extends Person
{private String major;/*** @param nama the student's name* @param major the student's major*/public Student(String name, String major){// 将n传递给父类函数
      super(name);this.major = major;}public String getDescription(){return "a student majoring in " + major;}
}

测试程序3：

    编辑、编译、调试运行教材程序5-8、5-9、5-10，结合程序运行结果理解程序（教材174页-177页）；

    掌握Object类的定义及用法；

    在程序中相关代码处添加新知识的注释。

Employee.java:

package equals;import java.time.*;
import java.util.Objects;public class Employee
{private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}public boolean equals(Object otherObject){// 看看这些对象是否相同if (this == otherObject) return true;// 如果显式参数为空，则必须返回falseif (otherObject == null) return false;// 如果类不匹配，它们就不能相等if (getClass() != otherObject.getClass()) return false;// 现在我们知道otherObject是一个非空雇员Employee other = (Employee) otherObject;// 测试字段是否具有相同的值return Objects.equals(name, other.name) && salary == other.salary && Objects.equals(hireDay, other.hireDay);}public int hashCode(){return Objects.hash(name, salary, hireDay); }public String toString(){return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay+ "]";}
}

Manager.java:

package equals;public class Manager extends Employee//子类Manager继承父类Employee
{private double bonus;public Manager(String name, double salary, int year, int month, int day){super(name, salary, year, month, day);bonus = 0;}public double getSalary(){double baseSalary = super.getSalary();return baseSalary + bonus;}public void setBonus(double bonus){this.bonus = bonus;}public boolean equals(Object otherObject){if (!super.equals(otherObject)) return false;Manager other = (Manager) otherObject;// super.equals检查这个和其他属于同一个类return bonus == other.bonus;}public int hashCode(){return java.util.Objects.hash(super.hashCode(), bonus);}public String toString(){return super.toString() + "[bonus=" + bonus + "]";}
}

Equals.java:

package equals;/*** This program demonstrates the equals method.* @version 1.12 2012-01-26* @author Cay Horstmann*/
public class EqualsTest
{public static void main(String[] args){Employee alice1 = new Employee("Alice Adams", 75000, 1987, 12, 15);Employee alice2 = alice1;Employee alice3 = new Employee("Alice Adams", 75000, 1987, 12, 15);Employee bob = new Employee("Bob Brandson", 50000, 1989, 10, 1);System.out.println("alice1 == alice2: " + (alice1 == alice2));System.out.println("alice1 == alice3: " + (alice1 == alice3));System.out.println("alice1.equals(alice3): " + alice1.equals(alice3));System.out.println("alice1.equals(bob): " + alice1.equals(bob));System.out.println("bob.toString(): " + bob);Manager carl = new Manager("Carl Cracker", 80000, 1987, 12, 15);Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);boss.setBonus(5000);System.out.println("boss.toString(): " + boss);System.out.println("carl.equals(boss): " + carl.equals(boss));System.out.println("alice1.hashCode(): " + alice1.hashCode());System.out.println("alice3.hashCode(): " + alice3.hashCode());System.out.println("bob.hashCode(): " + bob.hashCode());System.out.println("carl.hashCode(): " + carl.hashCode());}
}

package equals;/*** This program demonstrates the equals method.* @version 1.12 2012-01-26* @author Cay Horstmann*/
public class EqualsTest
{public static void main(String[] args){Employee alice1 = new Employee("Alice Adams", 75000, 1987, 12, 15);Employee alice2 = alice1;Employee alice3 = new Employee("Alice Adams", 75000, 1987, 12, 15);Employee bob = new Employee("Bob Brandson", 50000, 1989, 10, 1);System.out.println("alice1 == alice2: " + (alice1 == alice2));System.out.println("alice1 == alice3: " + (alice1 == alice3));System.out.println("alice1.equals(alice3): " + alice1.equals(alice3));System.out.println("alice1.equals(bob): " + alice1.equals(bob));System.out.println("bob.toString(): " + bob);Manager carl = new Manager("Carl Cracker", 80000, 1987, 12, 15);Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);boss.setBonus(5000);System.out.println("boss.toString(): " + boss);System.out.println("carl.equals(boss): " + carl.equals(boss));System.out.println("alice1.hashCode(): " + alice1.hashCode());System.out.println("alice3.hashCode(): " + alice3.hashCode());System.out.println("bob.hashCode(): " + bob.hashCode());System.out.println("carl.hashCode(): " + carl.hashCode());}
}

 

测试程序4：

     在elipse IDE中调试运行程序5-11（教材182页），结合程序运行结果理解程序；

     掌握ArrayList类的定义及用法；

     在程序中相关代码处添加新知识的注释。

插入程序相关代码

ArrayList.java:

package arrayList;import java.util.*;/*** This program demonstrates the ArrayList class.* @version 1.11 2012-01-26* @author Cay Horstmann*/
public class ArrayListTest
{public static void main(String[] args){// 用三个Employee对象填充staff数组列表ArrayList<Employee> staff = new ArrayList<>();staff.add(new Employee("Carl Cracker", 75000, 1987, 12, 15));staff.add(new Employee("Harry Hacker", 50000, 1989, 10, 1));staff.add(new Employee("Tony Tester", 40000, 1990, 3, 15));// 把每个人的薪水提高5%for (Employee e : staff)e.raiseSalary(5);// 打印所有Employee对象的信息for (Employee e : staff)System.out.println("name=" + e.getName() + ",salary=" + e.getSalary() + ",hireDay="+ e.getHireDay());}
}

Employee.java:

package arrayList;import java.time.*;public class Employee
{private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}
}

package arrayList;import java.time.*;public class Employee
{private String name;private double salary;private LocalDate hireDay;public Employee(String name, double salary, int year, int month, int day){this.name = name;this.salary = salary;hireDay = LocalDate.of(year, month, day);}public String getName(){return name;}public double getSalary(){return salary;}public LocalDate getHireDay(){return hireDay;}public void raiseSalary(double byPercent){double raise = salary * byPercent / 100;salary += raise;}
}

程序测试结果如下：

测试程序5：

    编辑、编译、调试运行程序5-12（教材189页），结合运行结果理解程序；

   掌握枚举类的定义及用法；

   在程序中相关代码处添加新知识的注释。

插入实例程序的代码：

package enums;import java.util.*;/*** This program demonstrates enumerated types.* @version 1.0 2004-05-24* @author Cay Horstmann*/
public class EnumTest
{  public static void main(String[] args){  Scanner in = new Scanner(System.in);System.out.print("Enter a size: (SMALL, MEDIUM, LARGE, EXTRA_LARGE) ");String input = in.next().toUpperCase();Size size = Enum.valueOf(Size.class, input);System.out.println("size=" + size);System.out.println("abbreviation=" + size.getAbbreviation());if (size == Size.EXTRA_LARGE)System.out.println("Good job--you paid attention to the _.");      }
}enum Size
{SMALL("S"), MEDIUM("M"), LARGE("L"), EXTRA_LARGE("XL");private Size(String abbreviation) { this.abbreviation = abbreviation; }public String getAbbreviation() { return abbreviation; }private String abbreviation;
}

测试结果如下：

实验2：编程练习1

    定义抽象类Shape：

  属性：不可变常量double PI，值为3.14；

  方法：public double getPerimeter()；public double getArea())。

  让Rectangle与Circle继承自Shape类。

    编写double sumAllArea方法输出形状数组中的面积和和double sumAllPerimeter方法输出形状数组中的周长和。

  main方法中

1）输入整型值n，然后建立n个不同的形状。如果输入rect，则再输入长和宽。如果输入cir，则再输入半径。
2） 然后输出所有的形状的周长之和，面积之和。并将所有的形状信息以样例的格式输出。
3） 最后输出每个形状的类型与父类型，使用类似shape.getClass()(获得类型)，shape.getClass().getSuperclass()(获得父类型);

思考sumAllArea和sumAllPerimeter方法放在哪个类中更合适？

输入样例:

3

rect

1 1

rect

2 2

cir

1

输出样例:

18.28

8.14

[Rectangle [width=1, length=1], Rectangle [width=2, length=2], Circle [radius=1]]

class Rectangle,class Shape

class Rectangle,class Shape

class Circle,class Shape

 程序相关代码：

shape:

package shape;
import java.util.Scanner;
public class Test {public static void main(String[] args) {Scanner in = new Scanner(System.in);System.out.println("个数");int a = in.nextInt();System.out.println("种类");String rect="rect";String cir="cir";Shape[] num=new Shape[a];for(int i=0;i<a;i++){String input=in.next();if(input.equals(rect)) {System.out.println("长和宽");int length = in.nextInt();int width = in.nextInt();num[i]=new Rectangle(width,length);System.out.println("Rectangle["+"length:"+length+"  width:"+width+"]");}if(input.equals(cir)) {System.out.println("半径");int radius = in.nextInt();num[i]=new Circle(radius);System.out.println("Circle["+"radius:"+radius+"]");}}Test c=new Test();System.out.println("求和");System.out.println(c.sumAllPerimeter(num));System.out.println(c.sumAllArea(num));for(Shape s:num) {System.out.println(s.getClass()+","+s.getClass().getSuperclass());}}public double sumAllArea(Shape score[]){double sum=0;for(int i=0;i<score.length;i++)sum+= score[i].getArea();return sum;}public double sumAllPerimeter(Shape score[]){double sum=0;for(int i=0;i<score.length;i++)sum+= score[i].getPerimeter();return sum;}    
}

Test:

package shape;
import java.util.Scanner;
public class Test {public static void main(String[] args) {Scanner in = new Scanner(System.in);System.out.println("个数");int a = in.nextInt();System.out.println("种类");String rect="rect";String cir="cir";Shape[] num=new Shape[a];for(int i=0;i<a;i++){String input=in.next();if(input.equals(rect)) {System.out.println("长和宽");int length = in.nextInt();int width = in.nextInt();num[i]=new Rectangle(width,length);System.out.println("Rectangle["+"length:"+length+"  width:"+width+"]");}if(input.equals(cir)) {System.out.println("半径");int radius = in.nextInt();num[i]=new Circle(radius);System.out.println("Circle["+"radius:"+radius+"]");}}Test c=new Test();System.out.println("求和");System.out.println(c.sumAllPerimeter(num));System.out.println(c.sumAllArea(num));for(Shape s:num) {System.out.println(s.getClass()+","+s.getClass().getSuperclass());}}public double sumAllArea(Shape score[]){double sum=0;for(int i=0;i<score.length;i++)sum+= score[i].getArea();return sum;}public double sumAllPerimeter(Shape score[]){double sum=0;for(int i=0;i<score.length;i++)sum+= score[i].getPerimeter();return sum;}    
}

实验结果如下所示：

实验3： 编程练习2

编制一个程序，将身份证号.txt 中的信息读入到内存中，输入一个身份证号或姓名，查询显示查询对象的姓名、身份证号、年龄、性别和出生地。

 插入程序代码：

Main :

package id1;import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Scanner;public class Main{private static ArrayList<Student> studentlist;public static void main(String[] args) {studentlist = new ArrayList<>();Scanner scanner = new Scanner(System.in);File file = new File("D:/身份证号.txt");try {FileInputStream fis = new FileInputStream(file);BufferedReader in = new BufferedReader(new InputStreamReader(fis));String temp = null;while ((temp = in.readLine()) != null) {Scanner linescanner = new Scanner(temp);linescanner.useDelimiter(" ");    String name = linescanner.next();String number = linescanner.next();String sex = linescanner.next();String year = linescanner.next();String province =linescanner.nextLine();Student student = new Student();student.setName(name);student.setnumber(number);student.setsex(sex);student.setyear(year);student.setprovince(province);studentlist.add(student);}} catch (FileNotFoundException e) {System.out.println("学生信息文件找不到");e.printStackTrace();} catch (IOException e) {System.out.println("学生信息文件读取错误");e.printStackTrace();}boolean isTrue = true;while (isTrue) {System.out.println("1.按姓名查询");System.out.println("2.按身份证号查询");System.out.println("3.退出");int nextInt = scanner.nextInt();switch (nextInt) {case 1:System.out.println("请输入姓名");String studentname = scanner.next();int nameint = findStudentByname(studentname);if (nameint != -1) {System.out.println("查找信息为：身份证号:"+ studentlist.get(nameint).getnumber() + "    姓名:"+ studentlist.get(nameint).getName() +"    性别:"+studentlist.get(nameint).getsex()   +"    年龄:"+studentlist.get(nameint).getyaer()+"  地址:"+studentlist.get(nameint).getprovince());} else {System.out.println("不存在该学生");}break;case 2:System.out.println("请输入身份证号");String studentid = scanner.next();int idint = findStudentByid(studentid);if (idint != -1) {System.out.println("查找信息为：身份证号:"+ studentlist.get(idint ).getnumber() + "    姓名:"+ studentlist.get(idint ).getName() +"    性别:"+studentlist.get(idint ).getsex()   +"    年龄:"+studentlist.get(idint ).getyaer()+"   地址:"+studentlist.get(idint ).getprovince());} else {System.out.println("不存在该学生");}break;case 3:isTrue = false;System.out.println("程序已退出!");break;default:System.out.println("输入有误");}}}public static int findStudentByname(String name) {int flag = -1;int a[];for (int i = 0; i < studentlist.size(); i++) {if (studentlist.get(i).getName().equals(name)) {flag= i;}}return flag;}public static int findStudentByid(String id) {int flag = -1;for (int i = 0; i < studentlist.size(); i++) {if (studentlist.get(i).getnumber().equals(id)) {flag = i;}}return flag;}   
}

Student:

package id1;public class Student {private String name;private String number ;private String sex ;private String year;private String province;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getnumber() {return number;}public void setnumber(String number) {this.number = number;}public String getsex() {return sex ;}public void setsex(String sex ) {this.sex =sex ;}public String getyaer() {return year;}public void setyear(String year ) {this.year=year ;}public String getprovince() {return province;}public void setprovince(String province) {this.province=province ;}
}

实验结果如下所示：

 本周学习总结：

        通过将近一周的学习以及自己在后期的自学过程当中，我深入了解了什么叫做继承，以及在继承中所包含的类型有哪些。继承是用已有类来构建新类的一种机制，当定义了一个新类继承了一个类时，这个新类继承一个类时，这个新类就继承了这个类的方法和域。而且继承是具有层次的，其代码也是可重用的，可以轻松定义子类。首先在学习过程当中我们学习了类，超类和子类的定义，让我明白了父类和子类时相对的。还学习了泛型数组列表与对象包装器与自动装箱，在后面还介绍了反射的概念，它是在程序运行期间发现更多的类及其属性的能力。