为什么我的董事会不出现？ 用Java创建游戏

Question

First off I would like to say that I understand I am asking a lot so any help would be appreciated and I thank you for your time. I am extremely grateful.

Anyway I am creating a game for my A2 coursework, most commonly known as Checkers. I have completed my code and everything works as I had planned except that the CheckerBoard itself as well as the checkerpieces do not appear to be showing.

The section of were my board should be present is just a black space. Although my board does not appear to be displaying, all of the actions I perform on it such as clicking certain section produces the planned response, and although I've checked through my code I cannot work out what I've done wrong.

Anyway if anyone could possibly spot my mistake or perhaps give me some advice I would be extremely grateful. Thank you

As I of course can't upload my entire code I will do snippets of where I think the problem might lie or just important sections. Thank you

CheckerBoard content = new CheckerBoard(); // Sets the CheckerBoard values into the content to be used in the next line
        application.setContentPane(content); // Container holds the values together, Content pane of the CheckerBoard
        application.pack();  // Use preferred size of content to set size of application.
        Dimension screensize = Toolkit.getDefaultToolkit().getScreenSize();
        application.setLocation( (screensize.width - application.getWidth())/2,
                (screensize.height - application.getHeight())/2 );
        application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); // Sets so that the application can be exited when the application is closed
        application.setResizable(false);  // This makes it so that the user can't change the application's size.
        application.setVisible(true); // Sets it so that the application can actually be seen

The code above is placed within a "public static void main(String[] args)"

Then below that I have:

public CheckerBoard()  {
// This is going to be a constructor, this constructor will set the layout manager for the panel to be null, it will then add components to the panel
// and it will set their bounds.

    setLayout(null);  // So that it will match my requirement specification, I will do the layout myself
    setBackground(new Color(0,120,0));  // Dark Green Background colour.
    setPreferredSize(new Dimension(350,250)); // The size of the Panel

    BoardComplete checkerboardData = new BoardComplete();
    add(checkerboardData); // This will create the components and add them to the content pane
    add(NewGameButton);
    add(ResignButton);
    add(MessageDisplay);

 // I will now have to produce a method to set the position and size of each component by calling its setBounds() method
    checkerboardData.setBounds(20,20,164,164); // Sets the board dimensions
    NewGameButton.setBounds(210, 60, 120, 30); 
    ResignButton.setBounds(210, 120, 120, 30); 
    MessageDisplay.setBounds(20, 200, 350, 30); 
    }   

And then finally I have a another public class called BoardComplete which contains all the relevant code involving the actionlistners ect. used:

 BoardComplete() {
        setBackground(Color.BLACK);
        addMouseListener(this);
        ResignButton = new JButton("Resign");
        ResignButton.addActionListener(this);
        NewGameButton = new JButton("New Game");
        NewGameButton.addActionListener(this);
        MessageDisplay = new JLabel("",JLabel.CENTER);
        MessageDisplay.setFont(new  Font("Serif", Font.BOLD, 14));
        MessageDisplay.setForeground(Color.green);
        checkerboardData = new DataForCheckers();
        MakeaNewGame();
    }       

I understand that this is a lot to ask but any help would be greatly appreciate and I would be extremely grateful. Thank you.

Edit due to comment: This is the code for my Paint Class:

    public void PaintCheckerBoard(Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // This will draw a two-pixel black border around the edges of the canvas. 

        g.setColor(Color.black);
        g.drawRect(0,0,getSize().width-1,getSize().height-1);
        g.drawRect(1,1,getSize().width-3,getSize().height-3);

        // Draw the squares of the checkerboard and the checkers.

        for (int row = 0; row < 8; row++) {
            for (int col = 0; col < 8; col++) {
                if ( row % 2 == col % 2 )
                    g.setColor(Color.LIGHT_GRAY);
                else
                    g.setColor(Color.GRAY);
                g.fillRect(2 + col*20, 2 + row*20, 20, 20);
                switch (checkerboardData.PieceLocation(row,col)) {
                case DataForCheckers.RED:
                    g.setColor(Color.RED);
                    g.fillOval(4 + col*20, 4 + row*20, 15, 15);
                    break;
                case DataForCheckers.BLACK:
                    g.setColor(Color.BLACK);
                    g.fillOval(4 + col*20, 4 + row*20, 15, 15);
                    break;
                case DataForCheckers.RED_KING:
                    g.setColor(Color.RED);
                    g.fillOval(4 + col*20, 4 + row*20, 15, 15);
                    g.setColor(Color.WHITE);
                    g.drawString("K", 7 + col*20, 16 + row*20);
                    break;
                case DataForCheckers.BLACK_KING:
                    g.setColor(Color.BLACK);
                    g.fillOval(4 + col*20, 4 + row*20, 15, 15);
                    g.setColor(Color.WHITE);
                    g.drawString("K", 7 + col*20, 16 + row*20);
                    break;
                }
            }
        }

        // If there is a game in progress, highlight the legal moves that the player can make.
        // It can be seen that in this process, LegalMoves is never null while a game is in progress     

        if (CheckerMatchInProgress) {
            /* First, draw a 2-pixel cyan border around the pieces that can be moved. */
            g.setColor(Color.cyan);
            for (int i = 0; i < LegalMoves.length; i++) {
                g.drawRect(2 + LegalMoves[i].fromCol*20, 2 + LegalMoves[i].fromRow*20, 19, 19);
                g.drawRect(3 + LegalMoves[i].fromCol*20, 3 + LegalMoves[i].fromRow*20, 17, 17);
            }
            // If a piece is selected to be moved, for example if ChosenRow>=0, then
            // draw a 2-pixel white border around that piece, and draw a green border
            // around each square that the piece can be legally moved to.

            if (ChosenRow >= 0) {
                g.setColor(Color.white);
                g.drawRect(2 + ChosenColumn*20, 2 + ChosenRow*20, 19, 19);
                g.drawRect(3 + ChosenColumn*20, 3 + ChosenRow*20, 17, 17);
                g.setColor(Color.green);
                for (int i = 0; i < LegalMoves.length; i++) {
                    if (LegalMoves[i].fromCol == ChosenColumn && LegalMoves[i].fromRow == ChosenRow) {
                        g.drawRect(2 + LegalMoves[i].toCol*20, 2 + LegalMoves[i].toRow*20, 19, 19);
                        g.drawRect(3 + LegalMoves[i].toCol*20, 3 + LegalMoves[i].toRow*20, 17, 17);
                    }
                }
            }
        }

    }  // end PaintCheckerBoard()

Answer 1

So looking through your code on the other site, your custom paint method never seems to be getting called from anywhere. You're supposed to override the paintComponent method from the Component class (JPanel is a subclass of Component). This paintComponent method will be called whenever swing thinks, or is told to redraw something.

So, add this code to your BoardComplete class:

@Override
public void paintComponent(Graphics g){
    super.paintComponent(g);
    PaintCheckerBoard(g);
} 

super.paintComponent will do anything swing would do to paint this component (which at this point is just drawing the background). And then you pass the Graphics object to your own custom paint method, that method will draw your entire game on the Graphics object, and swing will display whatever is drawn on there for you.

So now you have to remember also to call repaint() every time something in your game changes. The repaint() method will just tell swing he should repaint something (note: this tells the awt thread it should repaint the component, so it happens asynchronously from where youre calling repaint()).

If youre still confused, you should probably look up some information or tutorials on how to draw with awt/swing using this method.