CODEWITHSUNDEEP
java
Neha Choudhary
Neha Choudhary

Reputation: 4870

Clone() body for deep cloning?

I'm stuck at this since a very long time.

tell me if the following code makes a clone or not?

class A
{  
 int i;
    int j;  
    String str;  
    A()  
    {  
      i=10;  
      j=30;  
      str="Hello";  
    }  
    A(A a)  
   {  
      this.i=a.i;  
      this.j=a.j;  
      this.str=a.str;  
   }  
}  
class B
{  
   public static void main(String args[])  
   {
      A a  = new A();  
      A a1 = new A(a);
      /* I want to make clone like this. */  
      } 
}

when I run this code and when I print hashcode of a and a1, they are different. But some of my friends say that this is not the correct way to make a clone. You have to implement the Cloneable interface, is that really necessary? In my opinion, it can be a good approach if I want to make a deep copy even in case of derived reference variable. Thank you.

Upvotes: 1

Views: 249

Answers (1)

combinatorics
combinatorics

Reputation: 535

You need to implement the Clonable interface in order to clone an object. What you have implemented is called a copy constructor. Copy constructors are preferable to implementing Clonable.

The reason your copied object has a different hashcode/equals from the object it is copied from is because you haven't overridden the hashcode or equals functions in your A class so it's checking for identity rather than just equality (the exact same object, not an object with the same values). By overriding hashcode/equals you can make your class compare the values of it's properties instead.

Upvotes: 2

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