Object Copying in Java

What are the possible ways to copy an Object in java?
Ans: Possibility 1 : Using the shallow Copy
        Possibility 2 : Using the Deep Copy


What is Shallow Copy?
Ans: In Shallow Copy, both the original and copied or duplicate objects share the same 
references.Example: if the original object have an vector, then the duplicate object will 
point to the vector. That means it does not make any new copy of vector.
BUT,we can add a new elements to duplicate object, if required, and that elements are 
only visible to the duplicate objects.


Simply, Shallow copy is something, where original and duplicate are just the elements in
the  original object.


What is Deep Copy?
Ans: In this the Original and duplicate will have the distinct variable set which are used
by the  original set.So modifying one of the variable in the original Object, does not affect
the duplicate Object.


Sounds Good, Then How to Implement the Deep Copy?
Ans: Using Java Object Serialization [ JOS ].
The idea is simple: Write the object to an array using JOS’s ObjectOutputStream and 
then use ObjectInputStream to reconsistute a copy of the object. The result will be a completely distinct object, with completely distinct referenced objects.

Sample Program:

public class UnoptimizedDeepCopy {

    /**
     * Returns a copy of the object, or null if the object cannot
     * be serialized.
     */
    public static Object copy(Object orig) {
        Object obj = null;
        try {
            // Write the object out to a byte array
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ObjectOutputStream out = new ObjectOutputStream(bos);
            out.writeObject(orig);
            out.flush();
            out.close();

            // Make an input stream from the byte array and read
            // a copy of the object back in.
            ObjectInputStream in = new ObjectInputStream(
                new ByteArrayInputStream(bos.toByteArray()));
            obj = in.readObject();
        }
        catch(IOException e) {
            e.printStackTrace();
        }
        catch(ClassNotFoundException cnfe) {
            cnfe.printStackTrace();
        }
        return obj;
    }

}