Question

I am making a basic game using a 2D array (4×4) in which the elements (of object type with ints 1 to 16) must be switched around to reach a particular goal state, this state must be compared with the current state, hence the need for copying.

So far I have:

public void cloneArray() throws CloneNotSupportedException
    {
        ClassName copy = (ClassName)super.clone();
        copy.tiles = (Tile[][]) tiles.clone();
    }

Does this appear to be right, or am I missing something out?

Answer 1

You’ll need to go one step further and do like so :

    ClassName copy = (ClassName)super.clone();
    copy.tiles = (Tile[][]) tiles.clone();
    for(int i = 0; i < copy.tiles.length; i++) {
        copy.tiles[i] = (Tile[]) tiles[i].clone();
    }

The reason is that clone makes a shallow copy of the top-level array, which is holding references to other arrays.