public void setUpGame(){
        MainGame game = new MainGame();
               
        game.setLayout(new BoxLayout(game, BoxLayout.Y_AXIS) );
               
        playPanel = new PlayPanel();   // don't worry about this.. it's a subclass of JPanel.
        playPanel.setPreferredSize( new Dimension(playPanel.width, playPanel.height) );       
        game.add(playPanel);
 
        JPanel collections = new JPanel();
        collections.setLayout(new FlowLayout() );
        collections.setPreferredSize( new Dimension( 1280, 256));
 
        miniMapPanel = new MiniMapPanel();   // subclass of JPanel.
        miniMapPanel.setPreferredSize( new Dimension(miniMapPanel.width, miniMapPanel.height) );
        collections.add(miniMapPanel);
 
        statsPanel = new StatsPanel();
        statsPanel.setPreferredSize( new Dimension(statsPanel.width , statsPanel.height ) );
        collections.add(statsPanel);
 
        ... // I do the same thing for StatsPanel and CommandPanel objects
 
        game.add(collections);
        add(game);
 
        // referencing to the JFrame object
        this.pack();
        setVisible(true);
        setFocusable(true);
}