Background dans java

import java.awt.image.BufferedImage;
import java.io.File;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
..............
public class firstPage extends JFrame implements ActionListener{
    
    firstPage()
    {
       
        String imagePath = "C:/balance.jpg";
	ImageFond fond = new ImageFond(imagePath);
        fond.pack();
	fond.setVisible(true);
        setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        setSize(2000,1000);
       .....................
        JPanel p1 = new JPanel();
         .............
        ............       
        
        pack();
        setVisible(true);
    }
    
  
    class ImageFond extends JFrame {
	private Container c;
	private JPanel imagePanel;
	private String filePath;

	public ImageFond(String filePath) {
		super("Image de fond");
		this.filePath = filePath;
		initialize();
	}

	private void initialize() {
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		c = getContentPane();
		imagePanel = new JPanel() {
			public void paintComponent(Graphics g) {
				try {
                                    
					BufferedImage image = ImageIO.read(new File(filePath));
					g.drawImage(image, 0, 0, null);
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		};
		imagePanel.setPreferredSize(new Dimension(1000,2000));
		c.add(imagePanel);
                
	
	}

class ImagePanel extends JPanel
{
	private final BufferedImage img;
	
	public ImagePanel(String filename) throws IOException
	{
		img = ImageIO.read(new File(filename));
		setPreferredSize(new Dimension(img.getWidth(),img.getHeight()));
	}
	
	@Override
	public void paint(Graphics g)
	{
		g.drawImage(img, 0, 0, null);
	};
}

class ImageFrame extends JFrame
{
	public ImageFrame(String filename) throws IOException 
	{
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setSize(500,500);
		add(new ImagePanel(filename));		
	}
}

public class Test
{
	public static void main(String...args) throws IOException
	{
		new ImageFrame("D:\\test.png").setVisible(true);
	}
}