Question

I am writing a program for my IB Math internal assessment.

I have the classes Calc, Gamble, Inventory, Player, and Test.
I have a field instance variable Players (instantiated in the constructor) and the method playrounds and that is where the problem is.
The source for the method is below:

    ArrayList<Player> Players;

    public ArrayList<ArrayList<ArrayList<Player>>> playrounds(boolean randombets, double initialmoney, double initialbet,
        double betrange, int numberofrounds){

    ArrayList<Player> winningPlayers = new ArrayList<>(0);
    ArrayList<ArrayList<Player>> m = new ArrayList<>(0);
    for(int b = 0; b < numberofrounds; b++){
        if(firstround){
            firstround = false;
            preparePlayersfirst(randombets, initialmoney, initialbet, betrange);
            winningPlayers.clear();
            winningPlayers.trimToSize();
            m.clear();
            m.trimToSize();
        }
        else{
            preparePlayersnext(randombets, initialbet, betrange);
        }
        for(int a = 0; a < playingPlayers.size(); a++){
            Player u = playingPlayers.get(a);
            u.rolldice();
            u.checkdice();
            Players.set(a, u);
            playingPlayers.set(a, u);
        }
        Player t = getwinningPlayer();
        for(int a = 0; a < playingPlayers.size(); a++){
            Player u = playingPlayers.get(a);
            u.setprofits(t, this);
            Players.set(a, u);
            playingPlayers.set(a, u);
        }
        distributegainslosses();
        removebankruptPlayers();
        winningPlayers.add(t);
        m.add(Players);
        for(int x = 0; x < m.size(); x++){
            for(Player y: m.get(x)){
                for(int z = 0; z < y.getdice().size(); z++){
                    System.out.print(y.getdie(z) + " ");
                }
                System.out.print("\t");
            }
            System.out.println();
        }
        System.out.println();
    }
    ArrayList<ArrayList<ArrayList<Player>>> results = new ArrayList<>(0);
    ArrayList<ArrayList<Player>> t = new ArrayList<>(0);
    t.add(winningPlayers);
    results.add(t);
    results.add(m);

    return results;

}

The for loop to print the values inside the variable m gives an output like this:
2 3

6 4
6 4

5 5
5 5
5 5

6 1
6 1
6 1
6 1

The expected output is something like this:
2 3

2 3
6 4

2 3
6 4
5 5

2 3
6 4
5 5
6 1

I know that the way I print the values is not wrong. It doesn’t print duplicates.
The if(firstround) and the else does not have to do with the problem.
Any help would be greatly appreciated.

-Edit-
@NPE: I tried one of the solutions from the place you suggested to look at. It still doesn’t work. Here’s the code for what I did:

    public ArrayList<Player> clonePlayers(){

        ArrayList<Player> clone = new ArrayList<>(0);
        for(Player a: Players){
            clone.add(new Player(a));
        }

        return clone;

    }

Did I do something wrong?

Answer 1

The problem is that you insert the same reference into m over and over again:

   m.add(Players);

If you need the entries of m to be independent of one another they have to be different objects, not references to the same object.