JButton僅在我將鼠標懸停在它們上方時才會顯示。 當我調整窗口大小時也消失

Question

JButton僅在我將鼠標懸停在它們上方時才會顯示。 調整窗口大小時也消失。 錯誤在於此處的構造函數中。 我正在擴展一個JFrame。 刪除JPanel不能修復它。 請幫忙。

public GameBoard(String title, int width, int height)
{
    super();
    this.boardWidth = width;
    this.boardHeight = height;

    // Create game state
    this.board = new GameSquare[width][height];

    // Set up window
    setTitle(title);
    setSize(720,720);
    setContentPane(boardPanel);
    setLocationRelativeTo(null);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    boardPanel.setLayout(new GridLayout(height,width));

    int decorator = 0;
    for (int y = 0; y<height; y++){
        decorator++;
        for (int x = 0; x<width; x++){
            if (decorator % 2 == 0)
                board[x][y] = new GameSquare(x, y, "BLACK");
            else
                board[x][y] = new GameSquare(x, y, "WHITE");

            board[x][y].addActionListener(this);
            boardPanel.add(board[x][y]);
            decorator++;
        }
    }
    // make our window visible
    setVisible(true);
}

MCV示例。

package chess;

public class GameBoard extends JFrame implements ActionListener
{
private JPanel boardPanel = new JPanel();

private int boardHeight;
private int boardWidth;
private GameSquare[][] board; 

public static void main(String[] args) {

    SwingUtilities.invokeLater(new Runnable() {

  @Override
  public void run() {
    GameBoard gameBoard = new GameBoard("The Revolutionary War",8,8);
  }
    });
}


/**
 * Create a new game board of the given size.
 * As soon as an instance of this class is created, it is visualised
 * on the screen.
 * 
 * @param title the name printed in the window bar.
 * @param width the width of the game area, in squares.
 * @param height the height of the game area, in squares.
 */
public GameBoard(String title, int width, int height)
{
    super();
    this.boardWidth = width;
    this.boardHeight = height;

    // Create game state
    this.board = new GameSquare[width][height];

    // Set up window
    setTitle(title);
    setSize(720,720);
    setContentPane(boardPanel);
    setLocationRelativeTo(null);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    boardPanel.setLayout(new GridLayout(height,width));

    for (int y = 0; y<height; y++){
        for (int x = 0; x<width; x++){

            board[x][y] = new GameSquare(x, y, this);
            board[x][y].setEnabled(true);
            board[x][y].addActionListener(this);

            boardPanel.add(board[x][y]);
        }
    }
    // make our window visible
    setVisible(true);
}

/**
 * Returns the GameSquare instance at a given location. 
 * @param x the x co-ordinate of the square requested.
 * @param y the y co-ordinate of the square requested.
 * @return the GameSquare instance at a given location 
 * if the x and y co-ordinates are valid - null otherwise. 
 */
public GameSquare getSquareAt(int x, int y)
{
    if (x < 0 || x >= boardWidth || y < 0 || y >= boardHeight)
        return null;

    return (GameSquare) board[x][y];
}

public void actionPerformed(ActionEvent e)
{
    // The button that has been pressed.s
    GameSquare square = (GameSquare)e.getSource();

}

//BufferedImage background = ImageIO.read(new File("/path/to/image.jpg"));
}

另一個類在這里：

package chess;

public class GameSquare extends JButton {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private int x;
private int y;
private ChessPiece chessPiece;
private boolean selected;
private ImageIcon icon;

GameSquare(int xPos, int yPos, GameBoard board){
    super();
    x = xPos;
    y = yPos;
    chessPiece = null; 
    selected = false;

    // Test to see colour of the base tile
    if ((xPos+yPos) % 2 == 1){
        icon = new ImageIcon(getClass().getResource("/pics/black.png"));
        this.setIcon(icon);
    }
    else if ((xPos+yPos) % 2 == 0) {
        icon = new ImageIcon(getClass().getResource("/pics/white.png"));
        this.setIcon(icon);
    }
}

public int getX(){
    return x;
}

public int getY(){
    return y;
}

public void setChessPiece(ChessPiece piece){
    chessPiece = piece;
}

public ChessPiece getChessPiece(){
    return chessPiece;
}

public void setImage(){
    setIcon(chessPiece.getIcon());
}

public void select(){
    selected = true;
    setIcon(new ImageIcon(getClass().getResource("pics/selected.png")));
}

public void deselect(){
    selected = false;
    if (chessPiece == null) setIcon(icon);
    else setImage();
}

}

Answer 1

您的問題是由於您重寫了JPanel的getX()和getY() 。 容器的布局管理器使用這些方法來幫助放置組件，並且通過覆蓋這些關鍵方法，您可以弄亂布局的功能。 請將那些方法的名稱更改為不會覆蓋該類的鍵方法的名稱。 如果這是一個國際象棋廣場，則將變量重命名為等級和文件，並具有getRank()和getFile()方法。

public class GameSquare extends JButton {
    private int file;
    private int rank;
    // ....

    GameSquare(int xPos, int yPos, GameBoard board){
        super();
        file = xPos;
        rank = yPos;
        chessPiece = null; 
        selected = false;

        // .....
    }

    public int getFile(){
        return file;
    }

    public int getRank(){
        return rank;
    }

    // .....
}

Answer 2

加

pack();

在GameBoard類中，然后將其設置為可見。 這將確保大小正確，並為懸於邊緣的任何按鈕留出空間...這將使框架的大小與JPanel的大小完全相同，即添加所有對象后呈現的大小。

也可能

setResizable(false);

因為它會阻止您調整窗口的大小，如果使用圖像，這可能會導致按鈕消失以及用戶意外單擊側面時重新出現。 我將其放在下面： setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);