Question

Jpanel 背景图片不能显示

package 窗口;

import javax.swing.*;
import java.awt.*;
import java.net.*;
public class beijing {
JFrame f;
Container c;
public beijing(){
f=new JFrame("背景");
f.setSize(400,300);
c=f.getContentPane();
c.setLayout(new BorderLayout());
newjpanl p=new newjpanl();
c.add(p,BorderLayout.SOUTH);
p.add(new JTextField(10));
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String args[]){
new beijing();

}

}
class newjpanl extends JPanel{
public void paintComponent(Graphics g){
int x=0,y=0;
URL url=getClass().getResource("C:/Documents and Settings/Administrator/桌面/000.gif");
ImageIcon icon =new ImageIcon(url);
g.drawImage(icon.getImage(), x, y, getSize().width, getSize().height, this);
while(true )
{
g.drawImage(icon.getImage(), x, y, this);
if(x>getSize().width&&y>getSize().height) break;
if(x>getSize().width){x=0;y+=icon.getIconHeight();}
else x+=icon.getIconHeight();
}
}
}

编译问题：Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(Unknown Source)
at ??.newjpanl.paintComponent(beijing.java:30)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JLayeredPane.paint(Unknown Source)
at javax.swing.JComponent.paintChildren(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.BufferStrategyPaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at java.awt.GraphicsCallback$PaintCallback.run(Unknown Source)
at sun.awt.SunGraphicsCallback.runOneComponent(Unknown Source)
at sun.awt.SunGraphicsCallback.runComponents(Unknown Source)
at java.awt.Container.paint(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.seqPaintDirtyRegions(Unknown Source)
at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
275403088@qq.com 谢谢了

Answer 1

又是你哈，看来问题还没解决哈。

其实呢，我比较倾向推荐使用相对路径，这样程序才好移植。

如你之前程序里图片路径“/image/123.gif”，“/”指的是当前目录的根目录，当前java文件的目录是“窗口”，它的根目录也就是上一级目录一般为src，所以image这个文件夹便在src下，与“窗口”目录同级。

如图所示，即为image的位置。希望能对你有所帮助。 

这样好了，你把邮箱地址给我，我直接把工程打包发给你，看问题出在什么地方 。