java面板的背景图片为什么显示不出来？下面是程序代码？

Question

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

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

public class Exam9_4 extends JPanel{
private Image image;
Exam9_4(){
super();
image=Toolkit.getDefaultToolkit().getImage("AB.jpg");
}
public void paintComponent(Graphics g){//绘制此容器中的每个组件
super.paintComponent(g);
g.drawImage(image, 0, 0, this.getWidth(),this.getHeight(),this);
}//图片会自动缩放
public static void main(String[] args) {
JFrame frame=new JFrame("添加了背景的面板");
Exam9_4 panel = new Exam9_4();
frame.add(panel);//将面板添加到JFrame上
frame.setVisible(true);
frame.setBounds(300, 300, 400, 500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

}

Answer 1

image=Toolkit.getDefaultToolkit().getImage("AB.jpg");
调试下这个图片路径是否正确，有没有加载图片