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實驗七 繼承附加實驗

相同 vat oid 定義類 快速 package 繼承 add emp

實驗七繼承附加實驗

實驗時間 2018-10-11

1、實驗目的與要求

(1)進一步理解4個成員訪問權限修飾符的用途;

(2)掌握Object類的常用API用法;

(3)掌握ArrayList類用法與常用API;

(4)掌握枚舉類使用方法;

(5)結合本章知識,理解繼承與多態性兩個面向對象程序設計特征,並體會其優點;

(6)熟練掌握Java語言中基於類、繼承技術構造程序的語法知識(ch1-ch5);

(7)利用已掌握Java語言程序設計知識,學習設計開發含有1個主類、2個以上用戶自定義類的應用程序。

2、實驗內容和步驟

實驗1 補充以下程序中主類內main方法體,以驗證四種權限修飾符的用法。

public class TEST1 {

private String t1 = "這是TEST1的私有屬性";

public String t2 = "這是TEST1的公有屬性";

protected String t3 = "這是TEST1受保護的屬性";

String t4 = "這是TEST1的默認屬性";

private void tese1() {

System.out.println("我是TEST1用private修飾符修飾的方法");

}

public void tese2() {

System.out.println("我是TEST1用public修飾符修飾的方法");

}

protected void tese3() {

System.out.println("我是TEST1用protected修飾符修飾的方法");

}

void tese4() {

System.out.println("我是TEST1無修飾符修飾的方法");

}

}

public class TEST2 extends TEST1{

private String e1 = "這是TEST2的私有屬性";

public String e2 = "這是TEST2的公有屬性";

protected String e3 = "這是TEST2受保護的屬性";

String e4 = "這是TEST2的默認屬性";

public void demo1() {

System.out.println("我是TEST2用public修飾符修飾的方法");

}

private void demo2() {

System.out.println("我是TEST2用private修飾符修飾的方法");

}

protected void demo3() {

System.out.println("我是TEST2用protected修飾符修飾的方法");

}

void demo4() {

System.out.println("我是TEST2無修飾符修飾的方法");

}

}

public class Main {

public static void main(String[] args) {

TEST2 test2 = new TEST2();

/*以下設計代碼分別調用 demo1 demo2 demo3 demo4 test1 test2 test3 test4方法和t1 t2 t3 t3 e1 e2 e3 e4屬性,結合程序運行結果理解繼承和權限修飾符的用法與區別*/

}

}

技術分享圖片

實驗2 第五章測試程序反思,繼承知識總結。

測試程序1:

? 編輯、編譯、調試運行教材程序5-8、5-9、5-10(教材174頁-177頁);

? 結合程序運行結果,理解程序代碼,掌握Object類的定義及用法;

技術分享圖片

package equals;

import java.time.*;
import java.util.Objects;

public class Employee
{
   private String name;
   private double salary;
   private LocalDate hireDay;   //屬性

   public Employee(String name, double salary, int year, int month, int day)
   {
      this.name = name;
      this.salary = salary;
      hireDay = LocalDate.of(year, month, day);
   }        //構造器

   public String getName()
   {
      return name;
   }        //訪問器

   public double getSalary()
   {
      return salary;
   }          //訪問器
public LocalDate getHireDay() { return hireDay; } //訪問器 public void raiseSalary(double byPercent) { double raise = salary * byPercent / 100; salary += raise; } //完成漲工資的計算 public boolean equals(Object otherObject) { //快速測試,看看這些對象是否相同
if (this == otherObject) return true; // 如果顯式參數為空,則必須返回false
if (otherObject == null) return false; // 如果類不匹配,它們就不能相等 if (getClass() != otherObject.getClass()) return false; // 現在我們知道otherObject是一個非空雇員
Employee other = (Employee) otherObject; // 測試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() //hashcode返回散列碼 { return Objects.hash(name, salary, hireDay); } public String toString() //返回類對象的狀態信息 { 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());
   }
}
 1 package equals;
 2 
 3 public class Manager extends Employee
 4 {
 5    private double bonus;
 6 
 7    public Manager(String name, double salary, int year, int month, int day)
 8    {
 9       super(name, salary, year, month, day);
10       bonus = 0;
11    }
12 
13    public double getSalary()
14    {
15       double baseSalary = super.getSalary();
16       return baseSalary + bonus;
17    }
18 
19    public void setBonus(double bonus)
20    {
21       this.bonus = bonus;
22    }
23 
24    public boolean equals(Object otherObject)
25    {
26       if (!super.equals(otherObject)) return false;
27       Manager other = (Manager) otherObject;
28       //super.equals檢查這個和其他屬於同一個類
29 return bonus == other.bonus; 30 } 31 32 public int hashCode() 33 { 34 return java.util.Objects.hash(super.hashCode(), bonus); 35 } 36 37 public String toString() 38 { 39 return super.toString() + "[bonus=" + bonus + "]"; 40 } 41 }

測試程序2:

? 編輯、編譯、調試運行教材程序5-11(教材182頁);

? 結合程序運行結果,理解程序代碼,掌握ArrayList類的定義及用法;

技術分享圖片

代碼如下

 1 package arrayList;
 2 
 3 import java.util.*;
 4 
 5 /**
 6  * This program demonstrates the ArrayList class.
 7  * @version 1.11 2012-01-26
 8  * @author Cay Horstmann
 9  */
10 public class ArrayListTest
11 {
12    public static void main(String[] args)
13    {
14       // 用三個Employee對象填充staff數組列表
15 ArrayList<Employee> staff = new ArrayList<>(); 16 17 staff.add(new Employee("Carl Cracker", 75000, 1987, 12, 15)); 18 staff.add(new Employee("Harry Hacker", 50000, 1989, 10, 1)); 19 staff.add(new Employee("Tony Tester", 40000, 1990, 3, 15)); 20 21 // 把每個人的工資提升百分之五
22 for (Employee e : staff) 23 e.raiseSalary(5); 24 25 // 輸出所有雇員對象的信息
26 for (Employee e : staff) 27 System.out.println("name=" + e.getName() + ",salary=" + e.getSalary() + ",hireDay=" 28 + e.getHireDay()); 29 } 30 }
 1 package arrayList;
 2 
 3 import java.time.*;
 4 
 5 public class Employee
 6 {
 7    private String name;
 8    private double salary;
 9    private LocalDate hireDay;
10 
11    public Employee(String name, double salary, int year, int month, int day)
12    {
13       this.name = name;
14       this.salary = salary;
15       hireDay = LocalDate.of(year, month, day);
16    }
17 
18    public String getName()
19    {
20       return name;
21    }
22 
23    public double getSalary()
24    {
25       return salary;
26    }
27 
28    public LocalDate getHireDay()
29    {
30       return hireDay;
31    }
32 
33    public void raiseSalary(double byPercent)
34    {
35       double raise = salary * byPercent / 100;
36       salary += raise;
37    }
38 }

測試程序3:

? 編輯、編譯、調試運行程序5-12(教材189頁);

? 結合運行結果,理解程序代碼,掌握枚舉類的定義及用法;

技術分享圖片

代碼如下

 1 package enums;
 2 
 3 import java.util.*;
 4 
 5 /**
 6  * This program demonstrates enumerated types.
 7  * @version 1.0 2004-05-24
 8  * @author Cay Horstmann
 9  */
10 public class EnumTest
11 {  
12    public static void main(String[] args)
13    {  
14       Scanner in = new Scanner(System.in);
15       System.out.print("Enter a size: (SMALL, MEDIUM, LARGE, EXTRA_LARGE) ");
16       String input = in.next().toUpperCase();
17       Size size = Enum.valueOf(Size.class, input);
18       System.out.println("size=" + size);
19       System.out.println("abbreviation=" + size.getAbbreviation());
20       if (size == Size.EXTRA_LARGE)
21          System.out.println("Good job--you paid attention to the _.");      
22    }
23 }
24 
25 enum Size
26 {
27    SMALL("S"), MEDIUM("M"), LARGE("L"), EXTRA_LARGE("XL");
28 
29    private Size(String abbreviation) { this.abbreviation = abbreviation; }
30    public String getAbbreviation() { return abbreviation; }
31 
32    private String abbreviation;
33 }

實驗3:采用個人賬號登錄https://pintia.cn/,完成《2018秋季西北師範大學面向對象程序設計(Java)(ch1-ch5)測試題2》,測試時間60分鐘;

實驗4: 課後完成實驗3未完成的測試內容。

實驗總結:這次附加實驗在上次實驗的基礎上,對第五章的內容有了更加深入的了解,尤其是對於四種權限修飾符的使用。此外掌握Object類的常用API用法,掌握ArrayList類用法與和枚舉類使用方法;

有所提高,仍需努力。

實驗七 繼承附加實驗