201771010108 -韩腊梅-第六周学习总结

第六周实验总结

一、知识点总结

1、继承的概述：在多个类中存在相同的属性和行为，把这些相同的部分抽取到一个单独的类中，把这个单独的类叫作父类，也叫基类或者超类，把其他被抽取的类叫作子类，并且父类的所有属性和方法（除private修饰的私有属性和方法外），子类都可以调用。这样的一种行为就叫做继承。（相同的东西在父类，不同的东西在子类）

2、继承的关键字：extends

3、继承的格式：class 子类名 extends 父类名{ }

4、在代码中使用继承提高了代码的复用性和维护性，让类与类直接产生了关系。

5、继承的注意点：

①子类只能继承父类所有的非私有的成员方法和成员变量，private修饰的不能继承。

②子类不能继承父类的构造方法，但可以通过 super 关键字去访问父类的构造方法。（先初始化父类，再执行自己）

③不同包不能继承。

6、在使用 super 的时候，我们还需要了解关键字 super 和 this 的区别：

super ：到父类中去找方法，没有引用的作用；也可以用于其他方法中；与this调用构造方的重载一样，用于第一行。

this：是指当前正在初始化的这个对象的引用。

二、实验名称：实验六——继承定义与使用

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、实验内容和步骤及结果

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。

package inheritance;

/**
 * This program demonstrates inheritance.
 * @version 1.21 2004-02-21
 * @author Cay Horstmann
 */
public class ManagerTest
{
   public static void main(String[] args)
   {
      // 构建一个Manager项目
      Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
     //生成Manager对象
      boss.setBonus(5000);//setBonus（）：更改器

      Employee[] staff = new Employee[3];//创建一个名为staff，大小为3的对象数组

      // 用管理者和雇员对象填充工作人员数组

      staff[0] = boss;
      staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
      staff[2] = new Employee("Tommy Tester", 40000, 1990, 3, 15);

      // 输出所有员工对象的信息
      for (Employee e : staff)
         System.out.println("name=" + e.getName() + ",salary=" + e.getSalary());
   }
}

package inheritance;

import java.time.*;

public class Employee
{
   private String name;//构建三个私有对象
   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;

public class Manager extends Employee//关键字extends表示继承。
{
   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);
//调用超类中含有name,salary,year,month,day参数的构造器。
      bonus = 0;
   }

   public double getSalary()
   { 
      double baseSalary = super.getSalary();
 //子类要想访问要想访问超类中的方法需要使用特定的关键字super。
      return baseSalary + bonus;
   }

   public void setBonus(double b)
   {
      bonus = b;
   }
}

测试结果：

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。

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];
// 抽象类的声明。父类引用可以引用子类对象，但反之不行。

      // 用学生和雇员填充人物数组
      people[0] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
      people[1] = new Student("Maria Morris", "computer science");

      // 输出所有人对象的名称和描述
      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)
   {
      //构造函数
      super(name);
      this.major = major;
   }

   public String getDescription()
   {
      return "a student majoring in " + major;
   }
}

package abstractClasses;

public abstract class Person
{
     //包含一个或多个抽象方法的类被称为抽象类，由abstract关键字修饰
   public abstract String getDescription();
   private String name;

   public Person(String name)
   {
      this.name = name;
   }

   public String getName()
   {
      return name;
   }
}

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;
   }
}

测试结果：

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。

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;

public class Manager extends 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;
      return bonus == other.bonus;
   }

   public int hashCode()
   {
      return java.util.Objects.hash(super.hashCode(), bonus);
   }

   public String toString()
   {
      return super.toString() + "[bonus=" + bonus + "]";
   }
}

package equals;

public class Manager extends 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;
      return bonus == other.bonus;
   }

   public int hashCode()
   {
      return java.util.Objects.hash(super.hashCode(), bonus);
   }

   public String toString()
   {
      return super.toString() + "[bonus=" + bonus + "]";
   }
}

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)
   {
      // 快速检查对象是否相同
      if (this == otherObject) return true;
      if (otherObject == null) return false;
     //  getClass()：得到对象的类。
      if (getClass() != otherObject.getClass()) return false;

      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); 
   }
// toString()方法
   public String toString()
   {
      return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay
            + "]";
   }
}

测试结果：

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。

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)
   {
      // 用三个雇员对象填充工作人员数组列表
      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);

      // 输出所有员工对象的信息
      for (Employee e : staff)
         System.out.println("name=" + e.getName() + ",salary=" + e.getSalary() + ",hireDay="
               + e.getHireDay());
   }
}

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;
}
}

测试结果：

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。

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：

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:

rect

1 1

rect

2 2

cir

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 Circle,class Shape

package em;

import java.util.*;
import em.abc;
import em.Rectangle;
import em.Circle;
import java.math.*;

public class abc {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String rect = "rect";
        String cir = "cir";
        System.out.print("");
        int n = in.nextInt();
        Shape[] score = new Shape[n];

        for (int i = 0; i < n; i++) {

            String input = in.next();
            if (input.equals(rect)) {// System.out.print("rect:");
                double length = in.nextDouble();
                double width = in.nextDouble();
                score[i] = new Rectangle(width, length);
            }
            if (input.equals(cir)) {// System.out.print("cir:");
                double radius = in.nextDouble();
                score[i] = new Circle(radius);
            }

        }
        for (int i = 0; i < n; i++) {
            System.out.println(score[i]);
        }

        abc c = new abc();
        System.out.println(c.sumAllPerimeter(score));
        System.out.println(c.sumAllArea(score));
        for (Shape s : score) {
            // System.out.println(s.getArea()+s.getPerimeter());
            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;
    }

}

package em;

import java.util.*;
import em.abc;
import em.Rectangle;
import em.Circle;
import java.math.*;

public class abc {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String rect = "rect";
        String cir = "cir";
        System.out.print("");
        int n = in.nextInt();
        Shape[] score = new Shape[n];

        for (int i = 0; i < n; i++) {

            String input = in.next();
            if (input.equals(rect)) {// System.out.print("rect:");
                double length = in.nextDouble();
                double width = in.nextDouble();
                score[i] = new Rectangle(width, length);
            }
            if (input.equals(cir)) {// System.out.print("cir:");
                double radius = in.nextDouble();
                score[i] = new Circle(radius);
            }

        }
        for (int i = 0; i < n; i++) {
            System.out.println(score[i]);
        }

        abc c = new abc();
        System.out.println(c.sumAllPerimeter(score));
        System.out.println(c.sumAllArea(score));
        for (Shape s : score) {
            // System.out.println(s.getArea()+s.getPerimeter());
            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;
    }

}

package em;

public class Circle extends Shape{

    private double radius;
    public Circle(double r)
    {
        radius=r;
    }
    public double getPerimeter()
    {
        double Perimeter=2*PI*radius;
        return Perimeter;
    }
    public double getArea()
    {
        double Area=PI*radius*radius;
        return Area;
    }

    public double getr()
    {
        return radius;
    }
    
    public String toString()
    {
          return  getClass().getName() + "[radius=" + radius + "]";
    }
       
}

package em;

public class Rectangle extends Shape{
    private double width;
    private double length;
    public Rectangle(double w,double l)
    {
        this.width=w;
        this.length=l;
    }
    public double getPerimeter()
    {
        double Perimeter=(width+length)*2;
        return Perimeter;
    }
    public double getArea()
    {
        double Area=width*length;
        return Area;
    }
    public double getw()
    {
        return width;
    }
    public double getl()
    {
        return length;
    }
    public String toString()
    {
          return getClass().getName() + "[ width=" +  width + "]"+ "[length=" + length + "]";
    }
    
}

package em;

public class Rectangle extends Shape{
    private double width;
    private double length;
    public Rectangle(double w,double l)
    {
        this.width=w;
        this.length=l;
    }
    public double getPerimeter()
    {
        double Perimeter=(width+length)*2;
        return Perimeter;
    }
    public double getArea()
    {
        double Area=width*length;
        return Area;
    }
    public double getw()
    {
        return width;
    }
    public double getl()
    {
        return length;
    }
    public String toString()
    {
          return getClass().getName() + "[ width=" +  width + "]"+ "[length=" + length + "]";
    }
    
}

package em;

public abstract class  Shape {

    public interface abc {

    }

    double PI=3.14;
    
    public abstract double  getPerimeter();

    public abstract double  getArea();
    

}

实验中构建的类，如下图：

实验结果：

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。

package idcard;

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 ddd{
    private static ArrayList<cccccc> studentlist;
    public static void main(String[] args) {
        studentlist = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        File file = new File("E:/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 age = linescanner.next();
                String province =linescanner.nextLine();
                cccccc student = new cccccc();
                student.setName(name);
                student.setnumber(number);
                student.setsex(sex);
                student.setage(age);
                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("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).getage()+"  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("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 ).getage()+"   地址:"
                            +studentlist.get(idint ).getprovince()
                            );
                } else {
                    System.out.println("不存在该学生");
                }
                break;
            case 3:
                isTrue = false;
                System.out.println("感谢使用");
                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;

    }
    
    
}

package idcard;

public class cccccc {

    private String name;
    private    String number ;
    private    String sex ;
    private    String age;
    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 getage() {
        return age;
    }
    public void setage(String age ) {
        this.age=age ;
    }
    public String getprovince() {
        return province;
    }
    public void setprovince(String province) {
        this.province=province ;
    }


}

package idcard;

public class cccccc {

    private String name;
    private    String number ;
    private    String sex ;
    private    String age;
    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 getage() {
        return age;
    }
    public void setage(String age ) {
        this.age=age ;
    }
    public String getprovince() {
        return province;
    }
    public void setprovince(String province) {
        this.province=province ;
    }


}

实验中构建的类，如下图：

实验结果：

三、实验总结

通过本次实验，我进一步理解继承的定义，更好的掌握子类的定义、多态性的概念及用法、抽象类的定义及用途。

在实验中有很多不理解的地方，实验注释也完成的不好，自己会尽力完善，实验自己完全写代码还是有很大困难，希望通过之后的学习，可以更好的锻炼自己的逻辑思维以及对Java语言实际应用的能力。

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原文地址：https://www.cnblogs.com/hanlamei/p/9749931.html