java - 将 BoxLayout 设置为我的 JPanel 后，我的图像无法正常显示

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) {
    }
}

经销商面板:

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);
}
}

玩家面板:

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);
    }
}

我的程序正确显示，直到我调用 setLayout(newBoxLayout(this,BoxLayout.PAGE_AXIS));在 DealerPanel 的构造函数中。调用该函数后，我的整个程序向右扩展，显示空白。之前，它被设置为显示 600 x 600 的图像，并在底部添加按钮(OptionPanel)。谁能告诉我我做错了什么？

Answer 1

我认为这是因为您在构造函数中指定了 this (此 JPanel 可能未完全初始化)。尝试替换:

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

与:

setLayout(new BorderLayout());

注意:从我们在此处的代码中看到的情况来看，用 BorderLayout 替换此 BoxLayout 不会对此面板内的布局产生任何影响，因为您没有在代码中向此面板添加任何组件。如果不是这种情况，请阅读BorderLayout Javadoc。