java - Problem with Java GridLayout and adding Buttons

Question

I want to add 100 buttons into an GridLayout and my code works but sometimes it only adds one button and if I click where the other buttons belong the button where I clicked appears. it happens totally randomly and I don't get it. Here is my code:

    public class GamePanel extends JPanel {
    GameUI controler;
    GridLayout gameLayout = new GridLayout(10,10);
    JButton gameButtons[] = new JButton[100];
    ImageIcon ice;
    JButton startButton;
    JButton exitButton;
    ImageIcon startIcon;
    ImageIcon exitIcon;
    URL urlIcon;
    private int i;

    public GamePanel(GameUI controler) {
        this.setLayout(gameLayout);
        this.controler = controler;
        urlIcon = this.getClass().getResource("/icons/Overlay.png");
        ice = new ImageIcon(urlIcon);
        makeButtons();
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
    }

    public void makeButtons() {
        for(i = 0; i< 100; i++) {
            gameButtons[i] = new JButton(ice);
            this.add(gameButtons[i]);
            revalidate();   
        }
        repaint();
    }
}

update:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.net.URL;


public class GameUI extends JFrame {

ImageIcon i;
Image jFrameBackground;
JButton startButton;
JButton exitButton;
ImageIcon startIcon; 
ImageIcon exitIcon;


public GameUI() {
    setResizable(false);
    this.setSize(1200, 800);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    this.setLayout(null);








    BackGroundPanel backGroundPanel = new BackGroundPanel();
    GamePanel panel = new GamePanel(this);
    ButtonPanel buttonPanel = new ButtonPanel();

    panel.setSize(500,500);
    panel.setLocation(100, 150);
    backGroundPanel.setSize(this.getWidth(),this.getHeight());
    backGroundPanel.setLocation(0,0);
    buttonPanel.setSize(390,50);
    buttonPanel.setLocation(100,100);
    this.add(backGroundPanel);
    this.add(panel);
    this.add(buttonPanel);




    backGroundPanel.setBackground(Color.BLACK);



}





public static void main(String[] args) throws InvocationTargetException, InterruptedException {







    javax.swing.SwingUtilities.invokeAndWait(
                new Runnable(){

                    @Override
                    public void run() {



                        GameUI ui = new GameUI();
                        ui.setVisible(true);


                    }


                }

            );




}

}

标签： javaswingpanellayout-managergrid-layout

Answer 1

正如我在评论中提到的，您使用的是空布局，这是您问题的根源。

您正在使用 null 布局尝试将 JPanel 分层，一个在另一个之上，这不是它应该如何使用或它的用途，也不是您应该如何创建背景。这具有背景覆盖您的按钮的效果，直到您的鼠标悬停在它们上方。

相反，如果您希望创建背景图像，我建议您：

• 创建一个JPanel，比如说叫BackgroundPanel，
• 覆盖它的paintComponent方法，
• super.paintComponent(g);在你的方法的第一行调用它
• 然后绘制它应该显示的图像
• 然后给它一个像样的布局管理器
• 并向其中添加您的 GUI 组件
• 确保添加到其中的任何 JPanel 通过.setOpaque(false)

其他选项包括使用 JLayeredPane，但您真的不需要它来获得背景。

例如，以下代码产生：

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;

public class GameUI2 {

    private static final String IMG_PATH = "https://upload.wikimedia.org/wikipedia/commons/3/3f/"
            + "Butterfly_Nebula_in_narrow_band_Sulfur%2C_Hydrogen_and_Oxygen_Stephan_Hamel.jpg";
    private static final String BTN_IMG_PATH = "https://upload.wikimedia.org/wikipedia/commons/5/54/Crystal_Project_Games_kids.png";

    private static void createAndShowGui() {
        BufferedImage bgImg = null;
        BufferedImage btnImg = null;
        try {
            URL bgImgUrl = new URL(IMG_PATH);
            URL btnImgUrl = new URL(BTN_IMG_PATH);
            bgImg = ImageIO.read(bgImgUrl);
            btnImg = ImageIO.read(btnImgUrl);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(-1);
        }


        BackgroundPanel2 mainPanel = new BackgroundPanel2(bgImg);
        mainPanel.setLayout(new GridBagLayout());
        GamePanel2 gamePanel = new GamePanel2(btnImg); 
        mainPanel.add(gamePanel);        

        JFrame frame = new JFrame("Game");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.setResizable(false);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

@SuppressWarnings("serial")
class BackgroundPanel2 extends JPanel {
    private Image backgroundImg;

    public BackgroundPanel2(Image backgroundImg) {
        this.backgroundImg = backgroundImg;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (backgroundImg != null) {
            g.drawImage(backgroundImg, 0, 0, this);
        }
    }

    @Override
    public Dimension getPreferredSize() {
        if (isPreferredSizeSet() || backgroundImg == null) {
            return super.getPreferredSize();
        } else {
            int w = backgroundImg.getWidth(this);
            int h = backgroundImg.getHeight(this);
            return new Dimension(w, h);
        }
    }
}

@SuppressWarnings("serial")
class GamePanel2 extends JPanel {
    public static final int MAX_BUTTONS = 100;
    private static final int IMG_WIDTH = 40;
    JButton[] gameButtons = new JButton[MAX_BUTTONS];

    public GamePanel2(Image buttonImg) {
        setOpaque(false);
        if (buttonImg.getWidth(this) > IMG_WIDTH) {
            buttonImg = buttonImg.getScaledInstance(IMG_WIDTH, IMG_WIDTH, Image.SCALE_SMOOTH);
        }
        Icon icon = new ImageIcon(buttonImg);
        setLayout(new GridLayout(10, 10, 4, 4));
        for (int i = 0; i < gameButtons.length; i++) {
            int finalIndex = i;
            JButton btn = new JButton(icon);
            btn.addActionListener(e -> {
                String text = String.format("Button: %02d", finalIndex);
                System.out.println(text);
            });
            add(btn);
            gameButtons[i] = btn;            
        }
    }
}