Cloned object is changing original object even with using a copy constructor

Question

I have a State object called state. I am trying to make a clone of it by calling a function applyMoveCloning() which creates a new State object called newState by using a copy constructor.

public State applyMoveCloning(State oldState, Move move) {
    State newState = new State(oldState); // Calls copy constructor
    applyMove(newState, move);            // Calls applyMove() on the newState
    return newState;
}

Here is where I call applyMoveCloning()

State clonedState = game.applyMoveCloning(state, moves.get(i));

The problem is, whenever I make changes to clonedState, it is changing the properties of my old state even though they are different objects (one just has the same properties as the other)

This is my copy constructor

public State(State another) {
    this.width = another.width;  
    this.height = another.height; 
    this.board = another.board; 
}

How can this be happening? It's not like I'm cloning by using State newState = state; so I don't understand.

What class should I show, there's not really anything else that deals with the copying. — Brejuro, Oct 12 '15 at 22:51
Hm, so how can I work around this so that they have separate boards? — Brejuro, Oct 12 '15 at 22:54

score 1 · Accepted Answer · answered Oct 12 '15 at 22:52

1

Which properties are affected?

Assuming width and height are integers, they are copied by value and not likely to change.

board, on the other hand, looks like a reference and your cloned state is sharing it with the old state.

answered Oct 12 '15 at 22:52

xiaofeng.li

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How could I fix it so that, they both have separate boards then? – Brejuro Oct 12 '15 at 22:54
@Brejuro: You're going to have to copy the board int[][] array value by value. – Gilbert Le Blanc Oct 12 '15 at 22:54

Cloned object is changing original object even with using a copy constructor

1 Answers1