201771010131孔维滢《面向对象程序设计（java）》第六周学习总结

理论知识学习部分

   类继承的格式： class  新类名  extends  已有类名（子类比超类拥有的功能更加丰富。）

   继承层次：Java不支持多继承。

   多态性：Java中，对象变量是多态的；不能把对超类的对象引用赋给子类对象变量。

   阻止继承：

          不允许继承的类称为final类，在类的定义中用final修饰 符加以说明。

                finalclass  Executive  extends Manager

                     {     ……          }

   抽象类：abstractclass Person {   

                        publicabstractString getDescription( );

                        …...      }

   Object：所有类的超类

                 （1）equals方法：Object类中的equals方法用于测试某个对象是否同另一 个对象相等。它在Object类中的实现是判断两个对象是 否具有相同的引用。如果两个对象具有相同的引用，它 们一定是相等的。

                （2）定义子类的equals方法时，可调用超类的equals方法。 super.equals（otherObject）

                （3）toString方法：Object类的toString方法返回一个代表该对象域值的字符串。

   泛型数组列表：Java中，利用ArrayList类，可允许程序在运行 时确定数组的大小。ArryList是一个采用类型参数的泛型类。为指定 数组列表保存元素的对象类型

                            ArryList<Employee> staff=new ArrayList<Employee>();

   枚举类：枚举类是一个类，它的隐含超类是java.lang.Enum

                 枚举值并不是整数或其它类型，是被声明的枚举类的 自身实例；

                 枚举类不能有public修饰的构造函数，构造函数都是 隐含private，编译器自动处理。枚举值隐含都是由public、static、final修饰的，无 须自己添加这些修饰符。

                 在比较两个枚举类型的值时，永远不需要调用equals 方法，直接使用"=="进行相等比较。

                 声明枚举类：publicenumGrade{A,B,C,D,E};

实验部分

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：

          ManagerTest.java

package inheritance;

/**
 * This program demonstrates inheritance.
 * @version 1.21 2004-02-21
 * @author Cay Horstmann
 */
public class ManagerTest
{
   public static void main(String[] args)
   {
      // 创建一个Manager对象
      Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
      boss.setBonus(5000);
      
      Employee[] staff = new Employee[3];

      // 将Manager和Employee填入数组

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

      // 打印所有员工信息
      for (Employee e : staff)
         System.out.println("name=" + e.getName() + ",salary=" + e.getSalary());
   }
}

Employee.java

package inheritance;

import java.time.*;

public class Employee
{
    //构建私有对象
   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;
   }
}

Manager.java

package inheritance;
//构造一个新的子类Manager继承父类Employee
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
    */
   //调用父类中的name，salary，year，month，day参数构造器
   public Manager(String name, double salary, int year, int month, int day)
   {
      super(name, salary, year, month, day);
      bonus = 0;
   }

   public double getSalary()
   {
       //子类访问父类中的方法
      double baseSalary = super.getSalary();
      return baseSalary + bonus;
   }
   
   public void setBonus(double b)
   {
      bonus = b;
   }
}

输出结果：

测试程序2：

PersonTest.java

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Person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对象的名称和个人描述
      for (Person p : people)
         System.out.println(p.getName() + ", " + p.getDescription());
   }
}

Person.java

package abstractClasses;
//定义抽象类Person
public abstract class Person
{
    //增加getDescription方法，添加对一个人的简短描述
   public abstract String getDescription();
   private String name;

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

   public String getName()
   {
      return name;
   }
}

Employee.java

package abstractClasses;

import java.time.*;
//构造新的子类Employee继承父类Person
public class Employee extends Person
{
    //构建私有对象
   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;
   }
}

Student.java

package abstractClasses;

public class Student extends Person
//构造新的子类Student继承父类Person
{
   private String major;

   /**
    * @param nama the student's name
    * @param major the student's major
    */
   public Student(String name, String major)
   {
      //将n传给父类构造器
      super(name);
      this.major = major;
   }

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

输出结果：

测试程序3：

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());
   }
}

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)
   {
      // 快速测试对象是否相同
      if (this == otherObject) return true;

      //如果显式参数为空必须返回false
      if (otherObject == null) return false;

      // if the classes don't match, they can't be equal如果类不匹配则它们不相等
      if (getClass() != otherObject.getClass()) return false;

      //现在已知otherObject是一个非空雇员
      Employee other = (Employee) otherObject;

      //测试字段是否具有相同值
      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
//构建子类Manager继承父类Employ
{
   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;
      //检查this和other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 + "]";
   }
}

输出结果：

测试程序4：

ArraryListTest.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)
   {
      //用三个雇员对象填充数组
      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));

      //将所有人的薪水增加5%
      for (Employee e : staff)
         e.raiseSalary(5);

      //打印所有雇员对象的信息
      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;
   }
}

输出结果：

测试程序5：

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;
}

输出结果：

实验2：编程练习1

            ShapeTest.java

package shape;

import java.util.*;

public class ShapeTest {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        
        System.out.println("n的值为:");
        int n=in.nextInt();
        String Rectangle = "rect";
        String Circle = "cir";
        shape[] staff = new shape[n];
        for(int i=0;i<n;i++) {
            //System.out.println("图形形状为:");
            String input = in.next();
            if(input.equals("rect")) {
                //System.out.print("长方形的长和宽为：");
                double width = in.nextDouble();
                double length = in.nextDouble();
                System.out.println("Rectangle ["+"length="+length+"  width="+width+"]");
                staff[i] = new Rectangle(width,length);
            }
            if(input.equals("cir")) {
                //System.out.print("圆形半径为：");
                double radius = in.nextDouble();
                System.out.println("Circle ["+"radius="+radius+"]");
                staff[i] = new Circle(radius);
            }
        }
        ShapeTest rescult = new ShapeTest();
        System.out.println(rescult.sumAllPerimeter(staff));
        System.out.println(rescult.sumAllArea(staff));
    }
    public double sumAllPerimeter(shape staff[]) {
            double sum = 0;
            for(int i = 0;i<staff.length;i++) 
                sum+= staff[i].getPerimeter();
            return sum;
    }
    public double sumAllArea(shape staff[]) {
            double sum = 0;
            for(int i = 0;i<staff.length;i++)
                sum += staff[i].getArea();
            return sum;
    }
}

Shape.java

package shape;

public abstract class shape {
    public abstract double  getPerimeter();
    public abstract double  getArea();
    double PI = 3.14;
}

Rectangle.java

package shape;

public class Rectangle extends shape{
    private double width;
    private double length;
    public Rectangle(double x,double y) {
         this.width = x;
         this.length = y;
    }
    public double getPerimeter() {
             double Perimeter = (width+length)*2;
             return Perimeter;
    }
    public double getArea() {
         double Area = width*length;
         return Area;
    }
}

Circle.java

package shape;

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

输出结果：

实验3：编程练习2

IDcheck.java

package IDcheck;

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.Scanner;
import java.util.ArrayList;

public class IDcheck {
    private static ArrayList<Identify> identifylist;
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        File file = new File("E:\身份证号.txt");
        identifylist = new ArrayList<>();
        try {
            FileInputStream files = new FileInputStream(file);
            BufferedReader in = new BufferedReader(new InputStreamReader(files));
            String temp = null;
            
            while ((temp = in.readLine()) != null) {
                Scanner linescanner = new Scanner(temp);
                linescanner.useDelimiter(" ");    
                String name = linescanner.next();
                String IDnumber = linescanner.next();
                String sex = linescanner.next();
                String year = linescanner.next();
                String bornplace =linescanner.nextLine();
                Identify identify = new Identify();
                identify.setName(name);
                identify.setIDnumber(IDnumber);
                identify.setsex(sex);
                identify.setage(year);
                identify.setbornplace(bornplace);
                identifylist.add(identify);
            }
        }

        catch (FileNotFoundException e) {
            System.out.println("信息不存在");
            e.printStackTrace();
        }
        catch (IOException e) {
            System.out.println("信息读取错误");
            e.printStackTrace();
        }
        boolean isTrue = true;
        while (isTrue) {
            System.out.println("1.按身份证号查询");
            System.out.println("2.按姓名查询");
            System.out.println("3.退出");
            int nextInt = scanner.nextInt();
            switch (nextInt) {
            case 1:
                System.out.println("请输入身份证号:");
                String ID = scanner.next();
                Identify identify = findIdentifyByidnumber(ID);
                if (identify != null) {
                    System.out.println("姓名:"+ identify.getName()+
                                       "  身份证号:"+ identify.getnumber()+
                                       "   年龄:"+ identify.getage()+
                                       "   性别:"+ identify.getsex()+
                                       "   地址:"+ identify.getbornplace());
                } else {
                    System.out.println("查无此人");
                }break;
            case 2:
                System.out.println("请输入姓名:");
                String name = scanner.next();
                Identify fullname = findIdentifyByname(name);
                if (fullname != null) {
                    System.out.println("姓名:"+ fullname.getName() +
                                       "  身份证号:"+ fullname.getnumber() +
                                       "   年龄:"+ fullname.getage()+
                                       "   性别:"+ fullname.getsex()+
                                       "   地址:"+ fullname.getbornplace()
                            );
                } else {
                    System.out.println("查无此人");
                }
                break;
            case 3:
                isTrue = false;
                System.out.println("错误!");
                break;
            }
        }
    }
    private static Identify findIdentifyByidnumber(String ID) {
        Identify flag = null;
        for (Identify people : identifylist) {
            if(people.getnumber().equals(ID)) {
                flag = people;
            }
        }
        return flag;
    }
    private static Identify findIdentifyByname(String name) {
        Identify flag = null;
        for (Identify people : identifylist) {
            if(people.getName().equals(name)) {
                flag = people;
            }
        }
        return flag;
    }
}

Identify.java

package IDcheck;

public class Identify {

    private    String name;
    private    String IDnumber;
    private    String age;
    private    String sex;
    private    String bornplace;

    public String getName()
    {
        return name;
    }
    public void setName(String name) 
    {
        this.name = name;
    }
    public String getnumber() 
    {
        return IDnumber;
    }
    public void setIDnumber(String IDnumber)
    {
        this.IDnumber = IDnumber;
    }
    
    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 getbornplace() 
    {
        return bornplace;
    }
    public void setbornplace(String bornplace) 
    {
        this.bornplace = bornplace;
    }
}

输出结果：

    实验总结：通过对第五章的学习，我了解到了java中继承的作用，程序中有包含关系的类都可以使用继承，子类可以继承父类的所有属性和方法，继承可以提高代码的重用性和程序的拓展性。重写可以拓展父类的方法，更好的适应子类的需要。同时我也学到了一些继承的设计技巧，如将公共操作和域放在超类，但是除非继承的方法有意义，否则不使用继承......关于java我学习到了java支持面向对象编程的基础内容：类、继承，多态。但是我还是会不断地去完善自己的知识。