clone still pointing to original object

Posted on 2005-03-28
Medium Priority
Last Modified: 2010-03-31
I cloned an object of my own class, but it still points to the same object.  I mean, when I make changes to the cloned object the original is changed as well.  How do I do this properly.  I implemented Cloneable and and overid clone().  So whats wrong.

public Object clone() {
        try {
            return super.clone();
        catch (CloneNotSupportedException e) {
            throw new InternalError(e.toString());


players = (Player[])playersInfo.clone();

Question by:turtletimer
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LVL 15

Expert Comment

ID: 13649169
players = (Player[])playersInfo.clone(); -> this does not clone Player object but rather clone the array of players.
the cloned array will point to the same objects.
LVL 15

Accepted Solution

aozarov earned 2000 total points
ID: 13649174
If you want to clone the whole array then you should do
Player[] newPlayers = new Player[playersInfo.length];
for (int i = 0; i < playersInfo.length; i++)
newPlayers[i] = (Player) playersInfo[i].clone();

Expert Comment

ID: 13649387
The default/conventional behavior of clone() is to do a shallow copy. You can either override clone() to do a deep copy or provide a separate method to do a deep clone.

The simplest approach to deep cloning is to use Java serialization, where you serialize and deserialize the object and return the deserialized version. This will be a deep copy/clone, assuming everything in the tree is serializable. If everything is not serializable, you'll have to implement the deep cloning behavior yourself.

Assuming everything is serializable, the following should create a complete deep copy of the current class instance:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bais);
Object deepCopy = ois.readObject();

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