如何在 JFrame 中放置背景图像？

Question

I'm trying a little JFrame because I have to make the flappy bird project and there's a bug in my code.

When I run it, it opens at maximized window but the background picture doesn't load. I have to minimize the window then maximize it for it to work.

package com.company;

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class Main extends JFrame{
    JButton button;
    JLabel text;
    JFrame frame;
    JPanel panel;

    public static void main(String[] args) {
        new Main();
    }

    public Main(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("flappyBird");
        setLocationRelativeTo(null);
        setVisible(true);
        setSize(new Dimension(100,100));
        setExtendedState(JFrame.MAXIMIZED_BOTH);

        BufferedImage img = null;
        try {
            img = ImageIO.read(new File("C:\\Users\\m11\\Documents\\FlappyBird\\spirit\\base.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        Image dimg = img.getScaledInstance(800, 508, Image.SCALE_SMOOTH);
        ImageIcon imageIcon = new ImageIcon(dimg);
        setContentPane(new JLabel(imageIcon));
    }
}

How can I fix it?

Answer 1

Try this example:

JFrame f = new JFrame();
try {
    f.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("test.jpg")))));
} catch (IOException e) {
    e.printStackTrace();
}
f.pack();
f.setVisible(true);

Alternatively, another great way to achieve your goal would be to use Background Panel .

And please, try to avoid using absolute paths, they almost always break the Application when changing directories or systems.

Let me know if that helped:)