Question

我在JButton上制作了30 * 30 JPanel，但是当我启动该应用程序时，直到将鼠标悬停在它们上方时，这些按钮才会显示。

我发现此问题主要是在layout设置为null的情况下发生的，我没有这个问题，也没有找到有关此问题的更多信息。我已经尝试过repaint()和validate()，但没有一个起作用。

JPanel：

public class Board extends JPanel implements PropertyChangeListener{

private static final int SIZE_IN_PX = 600; 
private GObject[][] field = new GObject[SIZE_IN_PX / 20][SIZE_IN_PX / 20];
private ArrayList<GObject> minesList = new ArrayList<>();
private GridLayout layout = new GridLayout(SIZE_IN_PX / 20, SIZE_IN_PX / 20);


public Board() {
    setSize(SIZE_IN_PX, SIZE_IN_PX);
    setLayout(layout);
    initBoard();
    initMines();
}


@Override
public void propertyChange(PropertyChangeEvent arg0) {
    return;
}

private void initBoard() {
    for (int y = 0; y < SIZE_IN_PX / 20; y++) {
        for (int x = 0; x < SIZE_IN_PX / 20; x++) {
            field[x][y] = new GObject(x, y, false);
            add(field[x][y]);
        }
    }
}

private void initMines() {
    int minesCount = 12;
    for (int i = 0; i < minesCount; i++) {
        int x = (int)(Math.random() * 30);
        int y = (int)(Math.random() * 30);
        field[x][y].setMine(true);
        System.out.println("x:" + x + ", x:" + y);
    }
}
}

JFrame：

public class Window extends javax.swing.JFrame {

public Window() {
    initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    board1 = new minesweeper.Board();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle("MineSweeper");

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(board1, javax.swing.GroupLayout.PREFERRED_SIZE, 600, javax.swing.GroupLayout.PREFERRED_SIZE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addComponent(board1, javax.swing.GroupLayout.DEFAULT_SIZE, 600, Short.MAX_VALUE)
    );

    pack();
    setLocationRelativeTo(null);
}// </editor-fold>                        

// Variables declaration - do not modify                     
private minesweeper.Board board1;
// End of variables declaration                   

}

JButton：

public class GObject extends JButton{

// vlastnosti
private int y;
public int getY() {
    return y;
}
public void setY(int y) {
    this.y = y;
}

private boolean mine;
public boolean isMine() {
    return mine;
}
public void setMine(boolean mine) {
    this.mine = mine;
}

private int x;
public int getX() {
    return x;
}
public void setX(int x) {
    this.x = x;
}

// konstruktor
public GObject(int x, int y, boolean mine) {
    setY(y);
    setMine(mine);
    setX(x);
    setActionListener();
}

当我启动应用程序并将鼠标从左上角放到中心位置时：

JButton在启动时不显示，但在鼠标悬停时显示

0 个答案: