Vector clone references the same objects??

Hi all
I'm developing a simple chess program.
Obviously, each move the user tries must be checked against the following sets of chess rules:
1.) Whether it is that colour player's turn to move
2.) Whether this move is valid for this specific piece (eg. 3 forward for a King --> invalid of course)
3.) Whether this move will jeopardize the player's king (put it in check)
If from any of the above the move is found to be invalid, the move is not executed.
My program structure is briefly this:
A. abstract super class 'ChessPiece' - subclassed by the various specific Chess Piece classes.
Each of the specific ChessPiece subclasses must implement an abstract method to check if a
proposed move is valid, and also a method to actually do the move...
B. 'PieceManager' class - has a Vector of ChessPieces:
This class checks whether the given move is valid:
For the piece: by calling the checking method (see A above)
For the general game: by making sure the given move doesn't put the player's king in check.
NOTE: In chess (for those who don't know), it is illegal to move any piece if, at the end of
the move, your king will be in check [possible to be captured by any enemy piece]
This last check I want to do in the following way:
1) copy/clone the entire PieceManager object
2) in this copied object, actually do the move
3) still in the copied/cloned object, see if the moving player's king is now in check
4) based on this evaluation, execute the move in the original PieceManger object or don't...
The Problem:
When I clone this PieceManager object, its 'pieces' Vector is obviously also cloned.
BUT it seems that the cloned 'pieces' Vector references the same ChessPiece objects
as those referenced by the original 'pieces' Vector; ie the 2 Vectors are sharing the same Objects.
Thus, when I actually execute the move in the test/cloned PieceManager object,
the original PieceManager's corresponding piece is moved too (well, it seems it is the same piece...).
I am pretty stuck with this.
I've tried the Vector clone method; it doesn't seem to copy the objects, but create another reference
to the same objects, as I've said.
I've tried cloning the entire object ; also not helping......
I'd love any comments, helpful pointers, suggestions.
Also any comments on my program structure... is a Vector the best tool for this job?
Thanks very much -
lutha

Hi all, OP here.
Ok thanks guys for all your posts...
two points:
1) I have tried the "copy constructor", and it seems to be doing the same thing. (ie 'shallow clone')
What's really frustrating me is that nothing I do seems to actually physically copy the Vector's objects
to new, separate copies of those objects...
I had my PieceManager class implement Cloneable (just in case - not too sure on that one; in fact I
commented that out later), and I overrode the clone method like this:
public Object clone ()
        PieceManager pm = new PieceManager ();
        Vector pcs = new Vector ();
        // Enumeration e = pieces.elements ();
        //while (e.hasMoreElements ())
        //    ChessPiece p = (ChessPiece) e.nextElement ();
        //pcs.add ();
        //} // still references the same objects!!
        pieces.trimToSize ();
        int size = pieces.size ();
        Object[] arr = new Object [size];
        Object[] initial = pieces.toArray ();
        System.arraycopy (initial, 0, arr, 0, size);
        for (int i = 0 ; i < size ; i++)
            ChessPiece p = (ChessPiece) arr ;
pcs.add (p);
pm.pieces = pcs;
return pm;
This all still does the same 'shallow cloning'...
2) m.winter, my ChessPiece objects are not immutable - they have a co-ordinate field that
changes as they are moved. This is for getting as called by another object, and for checking in
the ChessPiece's own internal method for checking whether the passed-in square co-ordinate
is a valid destination.
Anyway, I don't think that's the main issue here. How can I properly clone/copy a Vector, resulting
in :
a) the original Vector
b) a new, totally unrelated Vector.
Thanks again all for your input.
regards,
lutha

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