Question

我的Jar文件均未运行。我创建了一个在Netbeans中运行良好的项目，但是Jar没有显示任何内容。通过cmd运行它会显示noclassdeffounderror等。我创建了一个简单的项目，该类具有将JFrame设置为可见的类，该项目仅显示“ MY FIRST APP”。JFrame具有绝对布局，可在Netbeans项目中添加库，但jar没有该库，因此抛出错误

package app;
import app.Look;
public class App 
{
    public static void main(String[] args) 
    {
        System.out.println("Run");
        Look n = new Look();
        n.setVisible(true);
    }
}

和JFrame文件代码

package app;
public class Look extends javax.swing.JFrame {
    public Look() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        jPanel1.setBackground(new java.awt.Color(0, 0, 0));
        jPanel1.setBorder(new javax.swing.border.SoftBevelBorder(javax.swing.border.BevelBorder.RAISED));
        jPanel1.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());

        jLabel1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        jLabel1.setForeground(new java.awt.Color(255, 255, 255));
        jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel1.setText("MY FIRST APP");
        jPanel1.add(jLabel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(240, 140, 230, 70));

        getContentPane().add(jPanel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 10, 730, 340));

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

    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Look.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Look.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Look.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Look.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(() -> {
            new Look().setVisible(true);
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;

线程“ AWT-EventQueue-0”中的异常java.lang.NoClassDefFoundError：org / netbeans / lib / awtextra / AbsoluteLayout 在app.Look.initComponents（Look.java:15）....

Answer 1

我用您的文件制作了一个Netbeans项目，一切正常。步骤如下。

首先，创建一个新的Java项目，添加两个文件并根据以下说明导入适当的库（也许您已经这样做了）：

https://www.youtube.com/watch?v=B0prYbtdKNI

然后通过“清理并生成”来生成项目。在项目级别，您将获得一个“ dist”文件夹，其中包含以下内容：

dist/lib/AbsoluteLayout.jar
dist/README.TXT
dist/StackOverflow1.jar

我将项目命名为“ Stackoverflow1”。因此，可以从命令行运行它：

cd <project_dir>/dist
java -jar StackOverflow1.jar

如果要移动.jar，例如，将其移动到上方一个目录，则可以通过以下方式运行它：

cd <project_dir>
copy dist/StackOverflow1.jar ./
java -cp dist/lib/AbsoluteLayout.jar;StackOverflow1.jar app.App

您不能通过以下方式进行操作，这将为您报告错误

java -cp dist/lib/AbsoluteLayout.jar -jar StackOverflow1.jar

诀窍是，如果使用-jar选项，则仅通过StackOverflow1.jar清单文件中的条目“ Class-Path：”定义类路径。因此，为了从另一个位置使用AbsoluteLayout.jar，必须将AbsoluteLayout.jar和StackOverflow1.jar都放在类路径中，然后通过调用主类来调用应用程序。在这里查看更多

Differences between "java -cp" and "java -jar"?

如何创建一个可以识别AbsoluteLayout而不抛出NoClassDefFoundError的jar？

1 个答案: