错误：未捕获的错误获取图像：java.lang.NullPointerException
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error : Uncaught error fetching image: java.lang.NullPointerException
提问by Raj
The image path is all correct only, I don't know why this error is coming. Any one have any idea?
仅图像路径全部正确，我不知道为什么会出现此错误。任何人有任何想法？
Code is for putting a background image in a frame and add button over that image
代码用于将背景图像放入框架中并在该图像上添加按钮
The error is
错误是
Uncaught error fetching image:
java.lang.NullPointerException
at sun.awt.image.URLImageSource.getConnection(URLImageSource.java:99)
at sun.awt.image.URLImageSource.getDecoder(URLImageSource.java:113)
at sun.awt.image.InputStreamImageSource.doFetch(InputStreamImageSource.java:240)
at sun.awt.image.ImageFetcher.fetchloop(ImageFetcher.java:172)
at sun.awt.image.ImageFetcher.run(ImageFetcher.java:136)
Code
代码
Error is coming while running the code :
运行代码时出现错误：
public class BackgroundImg extends JPanel {
private Image img;
public BackgroundImg (String img)
{
this(new ImageIcon(img).getImage());
}
public BackgroundImg (Image img)
{
this.img = img;
Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
setPreferredSize(size);
setMinimumSize(size);
setMaximumSize(size);
setSize(size);
//setLayout(null);
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(img, 0, 0, null);
}
}
public class ApplicationFrame {
public static void main(String[] args) throws ImageAccessException {
BackgroundImg panel = new BackgroundImg(Toolkit.getDefaultToolkit().createImage(ApplicationFrame.class.getResource("C:\test.png")));
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 600);
frame.getContentPane().add(panel);
ApplicationContents.addContentsToPane(panel);
frame.setVisible(true);
// frame.setVisible(true);
}
}
}
public class ApplicationContents {
public static void addContentsToPane(Container pane)
{
//pane.setLayout(null);
pane.setLayout(new FlowLayout());
JButton b1 = new JButton("Test");
pane.add(b1);
//Insets insets = pane.getInsets();
//Dimension size = new Dimension(120,32);
// b1.setBounds(0 + insets.left, 0 + insets.top,
// size.width, size.height);
b1.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
JOptionPane.showMessageDialog(null, "Test" , "Test", JOptionPane.ERROR_MESSAGE);
}
}
);
}
}
回答by eis
getResource() loads a resource from classpath, not an OS path, so even if "C:\test.png" would be correct you cannot load it that way.
getResource() 从类路径加载资源，而不是操作系统路径，因此即使 "C:\test.png" 是正确的，您也无法以这种方式加载它。
Also, please check the return value of getResource() before using it so you'd catch these kinds of errors.
另外，请在使用 getResource() 之前检查它的返回值，以便您可以捕获这些类型的错误。
You might want to bundle the image as a resource within your jar and load it using path that specifies the location within your jar.
您可能希望将图像捆绑为 jar 中的资源，并使用指定 jar 中位置的路径加载它。
回答by MaVRoSCy
You have to use Toolkit.getDefaultToolkit().createImage("c:\\tmp\\test.png");to get the image from a static folder, or if you want to include the image inside your jar, set the image path relatively to the .class file.
你必须使用Toolkit.getDefaultToolkit().createImage("c:\\tmp\\test.png"); 要从静态文件夹中获取图像，或者如果要将图像包含在 jar 中，请设置相对于 .class 文件的图像路径。
