java - 我是 java 新手，尝试使用 JFrameb 添加图像，但我收到错误 Exception in thread "AWT-EventQueue-0"java.lang.NullPointerException

Question

我使用 netbeans 来创建代码，因为我不明白如何添加图像，但每当我在 Jcreator 中运行它时，我都会收到以下错误:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(ImageIcon.java:167)
    at org.me.myimageapp.ImageDisplay.initComponents(ImageDisplay.java:38)
    at org.me.myimageapp.ImageDisplay.<init>(ImageDisplay.java:21)
    at org.me.myimageapp.ImageDisplay$1.run(ImageDisplay.java:68)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641)
    at java.awt.EventQueue.access$000(EventQueue.java:84)
    at java.awt.EventQueue$1.run(EventQueue.java:602)
    at java.awt.EventQueue$1.run(EventQueue.java:600)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:611)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

这是我的代码:

    package org.me.myimageapp;


    public class ImageDisplay extends javax.swing.JFrame {

    /** Creates new form ImageDisplay */
    public ImageDisplay() {
    initComponents();
    }

    /** This method is called from within the constructor to
    * initialize the form.
    * WARNING: Do NOT modify this code. The content of this method is
    * always regenerated by the Form Editor.
    */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

    jLabel1 = new javax.swing.JLabel();


    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/org/me/myimageapp    /resources/1406_animado.gif"))); // NOI18N
    jLabel1.setText("jLabel1");

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(110, Short.MAX_VALUE)
            .addComponent(jLabel1)
            .addGap(102, 102, 102))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(82, 82, 82)
            .addComponent(jLabel1)
            .addContainerGap(88, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {

        public void run() {
            new ImageDisplay().setVisible(true);
        }
    });
}
// Variables declaration - do not modify
private javax.swing.JLabel jLabel1;
// End of variables declaration

}

Answer 1

您正在尝试加载不存在于以下位置的图像:

jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/org/me/myimageapp/resources/1406_animado.gif"))); // NOI18N

由于 getClass().getResource( xyz ) 返回 null，因此您会得到该异常。

您可以将包含图像的文件夹(以“/org/me/”等开头的结构)添加到类路径中，这样就可以了。