Question

这是我得到的错误：

Using directory  file:/D:/CCSF%20Docs/CS111B/Java%20Projects/LabelDemo2.java/bin/ 
Image url is null 
Exception in thread "main" java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(Unknown Source) 
    at LabelDemo2.<init>(LabelDemo2.java:23) 
    at LabelDemo2.main(LabelDemo2.java:46)

有谁可以告诉我为什么我无法加载图片？ java.jpg图像位于D:/CCSF%20Docs/CS111B/Java%20Projects/LabelDemo2.java/bin/

我不知道为什么我会收到空的异常/错误。

import java.awt.*;
import javax.swing.*;

public class LabelDemo2 extends JFrame {
    private ImageIcon image1;
    private JLabel label1;
    private ImageIcon image2;
    private JLabel label2;
    private ImageIcon image3;
    private JLabel label3;
    private static final long serialVersionUID = 1L;

    LabelDemo2() {
        setLayout(new FlowLayout());

        System.out.println("Using directory " + getClass().getResource(""));         
        System.out.println("Image url is " + getClass().getResource("java.jpg"));         
        image1 = new ImageIcon(getClass().getResource("java.jpg"));
        label1 = new JLabel(image1);
        add(label1);


        label1 = new JLabel(image1);
        add(label1);

        image2 = new ImageIcon(getClass().getResource("java.jpg"));

        label2 = new JLabel(image2);
        add(label2);

        image3 = new ImageIcon(getClass().getResource("java.jpg"));

        label3 = new JLabel(image3);
        add(label3);
    }

    public static void main (String args[]) {
        LabelDemo2 gui = new LabelDemo2();
        gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        gui.setVisible(true);
        gui.pack();
        gui.setTitle("Label Demo");
    }
}

Answer 1

如果image位于您的源文件夹中，那么您确实如下所示阅读Image

getClass().getResource("/java.jpg")

只需添加/或\\

即可

如果它在您的源文件夹之外，那么您可以通过InputStream以绝对路径

来阅读它

Answer 2

你可以尝试

ClassLoader classLoader = this.getClass().getClassLoader();
InputStream in = classLoader.getResourceAsStream(path);

OR

ClassPathResource fileReference = new ClassPathResource(filename);  
InputStream in = fileReference.getInputStream();

OR

this.getClass().getResourceAsStream(filename);

进一步阅读Different ways of loading a file as an InputStream

如何使用getClass和getResource？

2 个答案: