将BoxLayout设置为JPanel后，我的图像不能正确显示

Question

package BlackjackPanels;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
public class MainPanel extends JFrame implements ActionListener {
    private JPanel background;
    BufferedImage backgroundImage=ImageIO.read(new File("src/BlackjackImages/blackjackBackground.jpg"));
    public MainPanel() throws IOException { 
        super("Alan's Blackjack");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        background = new JPanel() 
        {
            @Override
            protected void paintComponent(Graphics g)
            {       
                super.paintComponent(g);
                g.drawImage(backgroundImage, 0, 0, this);
            }
        };
        add(background);
        loadGame();
        pack();
        setLocationRelativeTo(null);
        setResizable(false);
        setVisible(true);
    }

    public void loadGame() throws IOException {
        background.setLayout(new BorderLayout(0,0));
        PlayerPanel player=new PlayerPanel();
        DealerPanel dealer=new DealerPanel();
        OptionPanel option= new OptionPanel();
            dealer.setBox();
        JPanel gameBoard=new JPanel();
        gameBoard.setOpaque(false);
        gameBoard.setLayout(new BoxLayout(gameBoard,BoxLayout.PAGE_AXIS));
        gameBoard.add(dealer);
        gameBoard.add(player);
        background.add(gameBoard, BorderLayout.CENTER);
        background.add(option, BorderLayout.PAGE_END);
    }
    public static void main(String [] args) throws IOException {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                try {
                    MainPanel game = new MainPanel();
                } 
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }
    @Override
    public void actionPerformed(ActionEvent e) {
    }
}

DealerPanel:

public class DealerPanel extends JPanel {
private JLabel moneyAmt;
private JLabel betAmt;
private JPanel status;
public DealerPanel() {
    super();
    setPreferredSize(new Dimension(600,300));
    setOpaque(false);
    setFocusable(true);
    setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.DARK_GRAY), "DEALER"));
    moneyAmt = new JLabel("Your money:");
    betAmt = new JLabel("Your bet:");
    moneyAmt.setForeground(Color.red);
    betAmt.setForeground(Color.red);
}
public void setBox() {
    setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
    add(moneyAmt);
    add(betAmt);
}
}

PlayerPanel:

package BlackjackPanels;
public class PlayerPanel extends JPanel {
    Image cardImg=Card.loadCardImage();
    public PlayerPanel() throws IOException {
        super();
        setPreferredSize(new Dimension(600,300));
        setOpaque(false);
        setFocusable(true);
        setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.DARK_GRAY), "PLAYER"));
    }
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(cardImg,0,0,this);
    }
}

我的程序显示正确，直到我调用setLayout(newBoxLayout(this,BoxLayout.PAGE_AXIS));在DealerPanel的构造函数中。在我调用这个函数之后，我的整个程序被向右扩展，显示空白。在此之前，它被设置为显示600 * 600的图像，并在底部添加按钮(OptionPanel)。有人能告诉我我做错了什么吗?

Answer 1

我认为这是因为您在构造函数中指定了this(这个JPanel可能没有完全初始化)。试着更换:

setLayout(new BoxLayout(this,BoxLayout.PAGE_AXIS));

:

setLayout(new BorderLayout());

注意:从我们在这里看到的代码中，用BorderLayout替换这个BoxLayout应该不会对这个面板内的布局产生任何影响，因为你没有在代码中向这个面板添加任何组件。如果不是这样，请阅读BorderLayout Javadoc。