import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JFrame {
Main() {
add(new ContentPanel());
setSize(500, 300);
}

public static void main(String[] args) {
Main jrframe = new Main();
jrframe.setVisible(true);
}

}

class ContentPanel extends JPanel {
Image bgimage = null;

ContentPanel() {
MediaTracker mt = new MediaTracker(this);
bgimage = Toolkit.getDefaultToolkit().getImage("a.jpg");
mt.addImage(bgimage, 0);
try {
mt.waitForAll();
} catch (InterruptedException e) {
e.printStackTrace();
}
}

protected void paintComponent(Graphics g) {
super.paintComponent(g);
int imwidth = bgimage.getWidth(null);
int imheight = bgimage.getHeight(null);
g.drawImage(bgimage, 1, 1, null);
}
}