在抽象超類中覆蓋克隆

Question

=================================在編輯之前======= =================================

我對Java有點新，所以請耐心等待:)

我創建了一個超類。

public abstract class Employee 

我嘗試做覆蓋對象克隆以下

@Override 
    public Employee clone() 
    { 
     Employee foo; 

     try 
     { 
      foo = (Employee) super.clone(); 
     } 
     catch (CloneNotSupportedException e) 
     { 
      throw new AssertionError(e); 
     } 

     return foo; 
    } 

我創建了一個子類

public class Employee_Subclass extends Employee 

由於只有一個構造函數。

在上面，我有我的主程序。

從主程序我試圖克隆Employee_Subclass的對象，但未成功。

是否可以在超類中克隆一個子類的對象只有克隆函數？

我不斷收到我

Exception in thread "main" java.lang.AssertionError: java.lang.CloneNotSupportedException: test_project.Employee_Subclass 
    at test_project.Employee.clone(Employee.java:108) 
    at test_project.Test_Project.main(Test_Project.java:22) 
Caused by: java.lang.CloneNotSupportedException: test_project.Employee_Subclass 
    at java.lang.Object.clone(Native Method) 
    at test_project.Employee.clone(Employee.java:104) 
    ... 1 more 
Java Result: 1 

任何想法，我怎麼能做到這一點正確拋出的AssertionError的？

謝謝。

============================================== ====================================

好吧，我添加了可克隆的，這就是我有

public abstract class Employee implements Cloneable 
    { 
     private String firstName; 
     private String lastName; 
     private String socialSecurityNumber; 
     private Date_Of_Birth Date_Of_Birth_Inst; 

     // three-argument constructor 
     public Employee(String first, String last, String ssn, int Day, 
          int Month, int Year) 
     { 
      firstName = first; 
      lastName = last; 
      socialSecurityNumber = ssn; 
      Date_Of_Birth_Inst = new Date_Of_Birth(Day, Month, Year); 
     } 

     .... 
     Some Get and Set functions. 
     .... 

     @Override 
     protected Employee clone() throws CloneNotSupportedException { 
      Employee clone = (Employee) super.clone(); 
      return clone; 
     } 
    } 

這裏是子類

public class Employee_Subclass extends Employee{ 

    public Employee_Subclass(String first, String last, String ssn, int Day, 
         int Month, int Year) 
    { 
      super(first, last, ssn, Day, Month, Year); 
     } 

} 

只有構造。

這裏是主文件。

public class Test_Project { 

    /** 
    * @param args the command line arguments 
    */ 
    public static void main(String[] args) throws CloneNotSupportedException { 

     Employee_Subclass Employee_Inst = new Employee_Subclass("Hello", "World", 
                "066499402", 7, 6, 1984); 

     Employee_Subclass Employee_Inst1; 

     Employee_Inst1 = (Employee_Subclass) Employee_Inst.clone(); 
    }   

} 

我不得不添加throws CloneNotSupportedException否則將無法正常工作。

所以我的問題是它是如何工作的？

當我調用Employee_Inst.clone（）時，它會調用Employee中的克隆函數，對吧？

現在，這個函數返回一個Employee對象，所以我怎樣才能將它插入到子類對象中呢？

至於深度克隆，我做對了嗎？ Date_Of_Birth_Inst呢，它複製正確嗎？

非常感謝。

Answer 1

你只是忘了讓你的Employee類實現Cloneable。

Answer 2

你需要implement Cloneable在Employee類

Answer 3

我建議你實現，而不是使用Cloneable接口拷貝構造函數。進一步的細節見Joshua J. Bloch explanation。

Answer 4

您需要實現Cloneable接口。下面的例子可能會幫助你理解和深入克隆和淺層克隆。

import java.util.ArrayList; 
import java.util.List; 

public class DeepCopy implements Cloneable { 
    private List<String> hobbiesList; 
    private int age; 
    private String name; 
    private float salary; 

    public static void main(String[] args) throws CloneNotSupportedException { 
     DeepCopy original = new DeepCopy(); 
     original.name = "AAA"; 
     original.age = 20; 
     original.salary = 10000; 
     original.hobbiesList = new ArrayList<String>(); 
     original.hobbiesList.add("Cricket"); 
     original.hobbiesList.add("Movies"); 
     original.hobbiesList.add("Guitar"); 
     original.hobbiesList.add("Eating"); 

     DeepCopy cloned = (DeepCopy) original.clone(); 
     System.out.println("original:=" + original); 
     System.out.println("cloned :=" + cloned); 
     System.out.println("After adding two more hobbies in 'original' which untimately reflected in 'cloned'"); 
     cloned.name = "BBB"; 
     cloned.age = 27; 
     cloned.salary = 18237; 
     cloned.hobbiesList.add("Trecking"); 
     System.out.println("original  :=" + original); 
     System.out.println("cloned changed:=" + cloned); 
    } 

    @Override 
    protected DeepCopy clone() throws CloneNotSupportedException { 
     DeepCopy clone = (DeepCopy) super.clone(); 
     clone.hobbiesList = new ArrayList<String>(clone.hobbiesList); 
     return clone; 
    } 

    @Override 
    public String toString() { 
     return "My name is (String)" + name + " having age (int)" + age + ". I earned (float)" + salary + " and hobbies are (ArrayList)" + hobbiesList; 
    } 
}