JLabel图片显示问题

Question

我目前正在尝试在 JFrame 中简单地显示图像。我试过使用下面的代码，但它似乎不起作用。我不知道哪里出了问题 - 有什么想法吗？

这是控制台中显示的错误信息：

Exception in thread "main" java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(Unknown Source)
    at Day1.PictureTester.<init>(PictureTester.java:22)
    at Day1.PictureTester.main(PictureTester.java:14)

代码如下：

import java.awt.GridLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class PictureTester extends JFrame{

    private static final long serialVersionUID = 1L;

    public static void main(String[] args) {
        new PictureTester().setVisible(true);
    }

    public PictureTester(){
        super();
        setSize(600, 600);
        setLayout(new GridLayout());
        java.net.URL imgUrl = PictureTester.class.getResource("C:\Users\Harry\Desktop\LearnJava\pug-image3.jpg");
        ImageIcon image = new ImageIcon(imgUrl);    
        JLabel display = new JLabel(image);

        add (display);
    }
}

Answer 1

You can do it like the following example, by using just an image and a label. also you can remove all the extra code if you intend to use this image only once.

import java.awt.GridLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class PictureTester extends JFrame{

    private static final long serialVersionUID = 1L;

    public static void main(String[] args) {
        new PictureTester().setVisible(true);
    }

    public PictureTester(){
        super();
        setSize(600, 600);
        setLayout(new GridLayout());
        add(new JLabel(new ImageIcon("Path/To/Your/Image.png")));
    }
}

Answer 2

当然不行。阅读 Class.getResource() 的 javadoc。它使用 ClassLoader 从 classpath 加载资源，使用 slash分隔路径。

将您的图像与 PictureTester class 放在同一个包中，然后使用

PictureTester.class.getResource("pug-image3.jpg");

或者将它放在源文件夹的某个随机包中（如 com.foo.bar），然后使用

加载它

PictureTester.class.getResource("/com/foo/bar/pug-image3.jpg");

Answer 3

这段代码解决了它，它帮助我思考在新项目中创建它：

package NewAppIdea;

import java.awt.BorderLayout;
import java.awt.FlowLayout;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;


    public class PictureSplash extends JFrame {

        private static final long serialVersionUID = 1L;
        JLabel l1;

        PictureSplash(){
        setTitle("Pic");
        setSize(400,400);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
        setLayout(new BorderLayout());
        setContentPane(new JLabel(new ImageIcon("C:\Users\Harry\Desktop\LearnJava\pug-image3.jpg")));
        setLayout(new FlowLayout());
        setSize(399,399);
        setSize(400,400);
        }

        public static void main(String args[]) {
            new PictureSplash();
        }   
    }

Answer 4

        Icon i=new ImageIcon("src//pics//scope.jpg");
        JLabel l1=new JLabel(i);

像这样简单地使用JLabel或ImageIcon

JLabel图片显示问题

JLabel picture display issue

java

swing

image

jlabel

embedded-resource