苏浪浪 201771010120 《面向对象程序设计（java）》第七章学习总结

第七周

1、实验目的与要求

（1）进一步理解4个成员访问权限修饰符的用途；

（2）掌握Object类的常用API用法；

（3）掌握ArrayList类用法与常用API；

（4）掌握枚举类使用方法；

（5）结合本章知识，理解继承与多态性两个面向对象程序设计特征，并体会其优点；

（6）熟练掌握Java语言中基于类、继承技术构造程序的语法知识（ch1-ch5）；

（7）利用已掌握Java语言程序设计知识，学习设计开发含有1个主类、2个以上用户自定义类的应用程序。

2、实验内容和步骤

实验1  补充以下程序中主类内main方法体，以验证四种权限修饰符的用法。

public class TEST1 {

private String t1 = "这是TEST1的私有属性";

public String t2 = "这是TEST1的公有属性";

protected String t3 = "这是TEST1受保护的属性";

String t4 = "这是TEST1的默认属性";

private void tese1() {

System.out.println("我是TEST1用private修饰符修饰的方法");

}

public void tese2() {

System.out.println("我是TEST1用public修饰符修饰的方法");

}

protected void tese3() {

System.out.println("我是TEST1用protected修饰符修饰的方法");

}

void tese4() {

System.out.println("我是TEST1无修饰符修饰的方法");

}

}

public class TEST2 extends TEST1{

private String e1 = "这是TEST2的私有属性";

public String e2 = "这是TEST2的公有属性";

protected String e3 = "这是TEST2受保护的属性";

String e4 = "这是TEST2的默认属性";

public void demo1() {

System.out.println("我是TEST2用public修饰符修饰的方法");

}

private void demo2() {

System.out.println("我是TEST2用private修饰符修饰的方法");

}

protected void demo3() {

System.out.println("我是TEST2用protected修饰符修饰的方法");

}

void demo4() {

System.out.println("我是TEST2无修饰符修饰的方法");

}

}

public class Main {

public static void main(String[] args) {

TEST2 test2 = new TEST2();

/*以下设计代码分别调用 demo1 demo2 demo3 demo4 test1 test2 test3 test4方法和t1 t2 t3 t3 e1 e2 e3 e4属性，结合程序运行结果理解继承和权限修饰符的用法与区别*/

}

}

package 小浪浪;

public class bbb {
        public static void main(String[] args) {
            TEST2 test2 = new TEST2();
            test2.demo1();
            test2.demo3();
            test2.demo4();
            test2.test2();
            test2.test3();
            test2.test4();
            String e2=test2.e2;
            String e3=test2.e3;
            String e4=test2.e4;
            System.out.println(e2);
            System.out.println(e3);
            System.out.println(e4);
            System.out.println(test2.t2);
            System.out.println(test2.t3);
            System.out.println(test2.t4);
            }
    }

package 小浪浪;

public class TEST1 {
        private String t1 = "这是TEST1的私有属性";
        public String t2 = "这是TEST1的公有属性";
        protected String t3 = "这是TEST1受保护的属性";
        String t4 = "这是TEST1的默认属性";
        private void test1() {
            System.out.println("我是TEST1用private修饰符修饰的方法");
        }
        public void test2() {
            System.out.println("我是TEST1用public修饰符修饰的方法");
        }
        protected void test3() {
            System.out.println("我是TEST1用protected修饰符修饰的方法");
        }
        void test4() {
            System.out.println("我是TEST1无修饰符修饰的方法");
        }
    }

package 小浪浪;

    public class TEST2 extends TEST1{
        private String e1 = "这是TEST2的私有属性";
        public String e2 = "这是TEST2的公有属性";
        protected String e3 = "这是TEST2受保护的属性";
        String e4 = "这是TEST1的默认属性";
        public void demo1() {
            System.out.println("我是TEST2用public修饰符修饰的方法");
        }
        private void demo2() {
            System.out.println("我是TEST2用private修饰符修饰的方法");
        }
        protected void demo3() {
            System.out.println("我是TEST2用protected修饰符修饰的方法");
        }
        void demo4() {
            System.out.println("我是TEST2无修饰符修饰的方法");
        }
    }

实验2  第五章测试程序反思，继承知识总结。

测试程序1：

Ÿ   编辑、编译、调试运行教材程序5-8、5-9、5-10（教材174页-177页）；

Ÿ   结合程序运行结果，理解程序代码，掌握Object类的定义及用法；

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，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false
      if (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d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
            + "]";
   }
}

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;
      // super.equals checked that this and other belong to the same class
      return bonus == other.bonus;
   }

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

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

测试程序2：

Ÿ   编辑、编译、调试运行教材程序5-11（教材182页）；

Ÿ   结合程序运行结果，理解程序代码，掌握ArrayList类的定义及用法；

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)
   {
      // fill the staff array list with three Employee objects
      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));

      // raise everyone's salary by 5%
      for (Employee e : staff)
         e.raiseSalary(5);

      // print out information about all Employee objects
      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;
   }
}

测试程序3：

Ÿ   编辑、编译、调试运行程序5-12（教材189页）；

Ÿ   结合运行结果，理解程序代码，掌握枚举类的定义及用法；

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;
}

实验3：采用个人账号登录https://pintia.cn/，完成《2018秋季西北师范大学面向对象程序设计（Java）（ch1-ch5）测试题2》，测试时间60分钟；

实验4: 课后完成实验3未完成的测试内容

实验总结：

在学长的指导之下进一步理解4个成员访问权限修饰符的用途；在老师的讲解以及实验测试下掌握了Object类的常用API用法、ArrayList类用法与常用API、枚举类使用方法；大概理解了继承与多态性两个面向对象程序设计特征，掌握了Java语言中基于类、继承技术构造程序的语法知识；