Question

我正在运行此代码，并且它返回了以下堆栈跟踪：

Uncaught error fetching image:
java.lang.NullPointerException
at sun.awt.image.URLImageSource.getConnection(URLImageSource.java:115)
at sun.awt.image.URLImageSource.getDecoder(URLImageSource.java:125)
at sun.awt.image.InputStreamImageSource.doFetch(InputStreamImageSource.java:263)
at sun.awt.image.ImageFetcher.fetchloop(ImageFetcher.java:205)
at sun.awt.image.ImageFetcher.run(ImageFetcher.java:169)

我不知道我输错Null Pointer异常的地方。关于如何解决这个问题的提示？

import java.awt.BorderLayout;  
import java.awt.EventQueue;  
import java.awt.Graphics;  
import java.awt.Image;  
import java.awt.Toolkit;  
import javax.swing.JFrame;  
import javax.swing.JPanel;  
import javax.swing.border.EmptyBorder;  

public class MyFrame extends JFrame {  
     private JPanel contentPane;  

     public static void main(String[] args) {  
          EventQueue.invokeLater(new Runnable() {  
              public void run() {  
                    try {  
                         MyFrame frame = new MyFrame();  
              frame.setVisible(true);  
               } catch (Exception e) {  
                         e.printStackTrace();  
                   }  
               }  
        });  
     }   
   public MyFrame() {  
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
        setBounds(100, 100, 450, 300);  
        contentPane = new JPanel() {  
             public void paintComponent(Graphics g) {  
                  Image img = Toolkit.getDefaultToolkit().getImage(  
                           MyFrame.class.getResource("/images/Ella and Louis_front.jpg"));  
                 g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);  
             }  
        };  
       contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));  
        contentPane.setLayout(new BorderLayout(0, 0));  
        setContentPane(contentPane);         }

}

Answer 1

获取资源时：MyFrame.class.getResource("/images/Ella and Louis_front.jpg") 它返回一个null，我建议做一个检查：我建议做一个检查：

URL url = MyFrame.class.getResource("/images/Ella and Louis_front.jpg")
if (url != null) {
    Image img = Toolkit.getDefaultToolkit().getImage(url);
}

从.jar加载图像，Null Pointer Exception

1 个答案: