Reputation: 29
=================================Before Edit========================================
I'm a bit new to Java so please bear with me :)
I've created a superclass.
public abstract class Employee
I try to override the object clone by doing the following
@Override
public Employee clone()
{
Employee foo;
try
{
foo = (Employee) super.clone();
}
catch (CloneNotSupportedException e)
{
throw new AssertionError(e);
}
return foo;
}
I've created a subclass
public class Employee_Subclass extends Employee
With only a constructor.
Above that I have my main program.
From the main program I'm trying to clone an object of Employee_Subclass
, unsuccessfully.
Is it possible to clone an object of a subclass with only clone function in the superclass?
I keep getting the AssertionError thrown at me
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
Any idea how can I do that correctly?
Thanks.
==================================================================================
Ok so I added clonable, this is what I have
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;
}
}
Here is the subclass
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);
}
}
Only a constructor.
And here is the main file.
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();
}
}
I had to add throws CloneNotSupportedException
otherwise it wouldn't work.
So my question is how does it exactly works?
When I call Employee_Inst.clone(), it calls the clone function in Employee, right?
Now, this function return an object of Employee, so how can I insert it into the subclass object?
And as for the deep clone, did I do it correctly? what about Date_Of_Birth_Inst, was it copied correctly?
Thanks a lot.
Upvotes: 0
Views: 935
Reputation: 10553
You need to implement Cloneable
interface. Following example might help you to understand and deep cloning and shallow cloning.
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;
}
}
Upvotes: 0
Reputation: 48837
I suggest you implement a copy-constructor instead of using the Cloneable interface. See Joshua J. Bloch explanation for further details.
Upvotes: 0
Reputation: 692281
You simply forgot to make your Employee class implement Cloneable.
Upvotes: 2