i need to create a domino-like game that has Tiles with each of it’s sides containing 3 integers, and, given a random tile, i can place a new square next to it only if the integers match. I use a grid of tiles, gamePanel, to represent the game.

In a class that extends JFrame, i have a nested class that extends JPanel and uses a square GridLayout , i also have a grid of JPanels that will associate each JPanel with a tile from gamePanel that will display it. since gamePanels is bigger i will start from a (x,y) and finish in (x+n,y+n). I also added a mouseListner to each tile that has a non-null neighbor.

here is the code to show the grid of panels.

        public void update(){
            game.afficher();
            reset();
            for(int i=0;i<gamePanels.length;i++){
                for (int j =0 ; j < gamePanels[i].length; j++) {
                    if(!game.valid(i+x))throw new ArrayIndexOutOfBoundsException(i+x);
                    if(!game.valid(j+y))throw new ArrayIndexOutOfBoundsException(j+y);
                    
                    if(game.table[i+x][j+y]!=null){
                        gamePanels[i][j]=affiche(game.table[i+x][j+y]);
                    }else if(game.voisin( i+x,j+y)){
                        gamePanels[i][j]=addVoisin(i+x,j+y);
                    }else {
                        JPanel carre=new JPanel();
                        // Border blackline = BorderFactory.createLineBorder(Color.black);
                        carre.setSize(bigSquare());
                        gamePanels[i][j]=carre;
                    }
                    this.add(gamePanels[i][j]);
                }
            }

        }

 public JPanel addVoisin(int x, int y){
            Border shadow = BorderFactory.createLineBorder(Color.GRAY, 5);
            JPanel panel=new JPanel();
            panel.setSize(bigSquare());
            panel.setBorder(new CompoundBorder(shadow, new EmptyBorder(1, 1,1,1)));
            panel.addMouseListener(new MouseInputListener() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    try {
                        System.out.println("("+x+","+y+"))");
                        Grid.this.game.place(x, y, Grid.this.players.get(Grid.this.playerIndex), Grid.this.players.get(Grid.this.playerIndex).current);
                        if(game.gameFinished()){
                            endGame();
                        }
                        players.get(playerIndex).give(null);
                        playerIndex=(playerIndex+1) % players.size();
                        players.get(playerIndex).give(game.pop());
                        update();
                        menu.update(players.get(playerIndex));
                    } catch (Exception exception) {
                        exception.printStackTrace();
                        JOptionPane.showMessageDialog(null, "Placement Invalide");
                    }
                }
                @Override
                public void mousePressed(MouseEvent e) {}
                @Override
                public void mouseReleased(MouseEvent e) {}
                @Override
                public void mouseEntered(MouseEvent e) {}
                @Override
                public void mouseExited(MouseEvent e) {}
                @Override
                public void mouseDragged(MouseEvent e) {}
                @Override
                public void mouseMoved(MouseEvent e) {}
            });
            return panel;
        }

And this is the code to

it seemes that instead of updating the main JPanel, it adds a new one next to it:

initial JPanel, i clicked on the left square, and this is what happens.

i wanted this to happen this