在Java中,每次我向JPanel添加多个东西时,第二件事都没有创建？

Question

我创建了一个JPanel并添加了几个简单的按钮,并附加了监听器.然后我决定将一个Image添加到我的面板的背景中,所以我将我的JPanel切换到了ImagePanel.按钮正在JPanel上工作,但现在我为要显示的背景图像添加了一堆代码,按钮不再显示.我没有更改任何按钮添加代码,所以我很困惑为什么按钮不再显示.这也发生在我单独的GameFrame类中.我在面板中添加了2个矩形组件,然后是3个按钮.对于该面板,只有按钮显示,尽管在添加按钮之前矩形工作.我可以每个面板只有一种类型的JComponent吗？我真的不明白为什么这样做.感谢您的时间.

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class TitleFrame extends JFrame
{
    private ImagePanel panel;
    private JButton mage;
    private JButton rogue;
    private JButton warrior;
    private Image image;

    public TitleFrame()
    {
        JFrame frame = new JFrame();

        frame.setSize(1024, 768);
        frame.setTitle("Title Screen");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

        createMageButton();
        createRogueButton();
        createWarriorButton();
        ImagePanel panel = new ImagePanel(new ImageIcon("C:/Users/Derek Reitz/Documents/Eclipse Projects/GameApp/src/background.jpg").getImage());
        panel.add(mage);
        panel.add(rogue);
        panel.add(warrior);
        panel.paintComponent(frame.getGraphics());
        frame.getContentPane().add(panel);
    }

    private void createRogueButton() {
        rogue = new JButton("Select Rogue");

        class AddButtonListener implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
                moveToNextFrame('r');
            }
        }

        ActionListener listener = new AddButtonListener();
        rogue.addActionListener(listener);
    }

    private void createWarriorButton() {
        warrior = new JButton("Select Warrior");

        class AddButtonListener implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
                moveToNextFrame('w');
            }

        }

        ActionListener listener = new AddButtonListener();
        warrior.addActionListener(listener);
    }

    private void createMageButton() {
        mage = new JButton("Select Mage");

        class AddButtonListener implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
                moveToNextFrame('m');
            }
        }

        ActionListener listener = new AddButtonListener();
        mage.addActionListener(listener);
    }

    public void moveToNextFrame(char c) 
    {
        GameFrame game = new GameFrame(c);
    }

    class ImagePanel extends JPanel 
    {

        private Image img;

        public ImagePanel(Image img) {
            this.img = img;
            Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
            setPreferredSize(size);
            setMinimumSize(size);
            setMaximumSize(size);
            setSize(size);
            setLayout(null);
        }

        public void paintComponent(Graphics g) {
            g.drawImage(img, 0, 0, null);
        }

    }
}

Answer 1

您需要使用LayoutManager.

然后,您应该能够将ImagePanel和按钮添加到contentPane,并将它们全部展开并可见.

尝试下面的内容:

JFrame frame = new JFrame();
frame.setTitle("Title Screen");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

createMageButton();
createRogueButton();
createWarriorButton();

ImagePanel panel = new ImagePanel(new ImageIcon(".../background.jpg").getImage());
panel.setLayout(new FlowLayout());

panel.add(mage);
panel.add(rogue);
panel.add(warrior);

frame.getContentPane().add(panel);
frame.pack();
frame.setVisible(true);