JButton的2D数组未出现

Question

So I'm working an an assignment and I seemed to be stuck on a bug I can't seem to overcome. Essentially when trying to create a 10x10 grid, it isn't appearing while everything else (eg. title and menu) is when I'm running the application. Here's the essential part of what I've done so far

public class minesweeperGUI extends JFrame{

    private JFrame gameGUI;
    private JPanel board;
    private JButton[][] boardButtons = new JButton [10][10];

    public minesweeperGUI(){

        gameGUI = new JFrame("Enhanced Minesweeper"); //Title of the Window
        gameGUI.setVisible(true); //We want (true) to set it visible
        gameGUI.setSize(400,550); //400 550
        gameGUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //This will close the frame when you press X. IMPORTANT
        gameGUI.getContentPane().setBackground(Color.CYAN);
        gameGUI.setLayout(null);

        //Panel for minesweeper board
        board = new JPanel();
        GridLayout experimentLayout = new GridLayout(10, 10);
        board.setLayout(experimentLayout);
        board.setSize(400,550);

        for(int x=0;x<boardButtons.length;x++){
            for(int y=0;y<boardButtons[x].length;y++){

                boardButtons[x][y] = new JButton();
                board.add(boardButtons[x][y]);
                }
        }

        gameGUI.add(board);



    }

    public static void main(String[] args) {

        minesweeperGUI mainInterface = new minesweeperGUI();

    }
}

Any type of help would be greatly appreciated :)

Answer 1

gameGUI.setVisible(true); //We want (true) to set it visible

• yes but its should be last code line in minesweeperGUI() , otherwise you added JComponent s to the already visible Swing Gui (missing notifier for automatical refresh, repaint)

---

minesweeperGUI mainInterface = new minesweeperGUI();

• should be wrapped into invokeLater , more in Oracle trail Initial Thread

• class name should be MinesweeperGUI , search for Java Namings Convention

---

gameGUI.setLayout(null); and board.setSize(400,550);

• missing there setBounds for board.setSize(400,550); (placing JPanel to JFrame , because JPanel has zero Dimension )

• there no reason to use null layout , remove gameGUI.setLayout(null);

  1. override getPreferredSize for private JPanel board;

  2. remove code lines gameGUI.setLayout(null); and board.setSize(400,550);

  3. add code line pack() before setVisible(true) , for proper sizing for JFrame (based on getPreferredSize for private JPanel board; )

Answer 2

Remove the gameGUI.setLayout(null); call and move the next line to be after buttons adding

    gameGUI.setSize(400,550); //400 550
    gameGUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //This will close the frame when you press X. IMPORTANT
    gameGUI.getContentPane().setBackground(Color.CYAN);

    gameGUI.setVisible(true); //We want (true) to set it visible

Answer 3

I think one Problem is that you mix up your instances...

public static void main(String[] args) {
    minesweeperGUI mainInterface = new minesweeperGUI();
}

makes a new Instance of your minesweeperGUI wich extends JFrame - so this simply makes a new JFrame...

but in your construktor you create another JFrame instance private JFrame gameGUI; and gameGUI = new JFrame("Enhanced Minesweeper"); ...

i suggest you remove the private variable gameGUI ( private JFrame gameGUI; ) and use simply this for your layout...

//private JFrame gameGUI; //remove this one!
private JPanel board;
private JButton[][] boardButtons = new JButton [10][10];
public minesweeperGUI(){

    super("Enhanced Minesweeper"); //construktor from superclass
    this.setVisible(true); //use of this
    this.setSize(400,550); //use of this
    ...        

    //Panel for minesweeper board
    board = new JPanel();
    GridLayout experimentLayout = new GridLayout(10, 10);
    board.setLayout(experimentLayout);
    board.setSize(400,550);

    for(int x=0;x<boardButtons.length;x++){
        for(int y=0;y<boardButtons[x].length;y++){

            boardButtons[x][y] = new JButton();
            board.add(boardButtons[x][y]);
            }
    }
    this.add(board); //use of this

}

you don't HAVE to write this.setXXX() you can also simply write setVisible(true) for instance...