.jar文件不断给我“找不到主类“。程序将退出 [英] .jar file keeps giving me " could not find the main class". Program will exit

问题描述

我一直在这两个netbeans和eclipse的问题，即使一个简单的文件，显示一个jframe的jlabel。我的netbeans的项目属性清楚设置testing2.hihi作为我的主类，我有干净，并生成它在我的dist文件夹中产生一个.jar文件。当我双击它，它给我的消息找不到主类，程序将退出。但是，如果我选择从命令提示符java -jar hello2.jar运行它，它会正常运行！

这是.jar文件文件。

  Manifest-Version：1.0 
 Ant版本：Apache Ant 1.8.3 
 Created- By：1.7.0_04-b20（Oracle Corporation）
类路径：
 X-COMMENT：src / hihi 
主类：testing2.hihi 
 
 b 
 $ b package testing2; 
 
 public class hihi extends javax.swing.JFrame {
 
 / ** 
 *创建新表单hihi 
 * / 
 public hihi （）{
 initComponents（）; 
} 
 
 / ** 
 *此方法从构造函数中调用以初始化表单。 
 *警告：请勿修改此代码。此方法的内容总是
 *由表单编辑器重新生成。 
 * / 
 @SuppressWarnings（unchecked）
 //< editor-fold defaultstate =collapseddesc =Generated Code> 
 private void initComponents（）{
 
 jLabel1 = new javax.swing.JLabel（）; 
 
 setDefaultCloseOperation（javax.swing.WindowConstants.EXIT_ON_CLOSE）; 
 
 jLabel1.setText（hihi）; 
 
 javax.swing.GroupLayout layout = new javax.swing.GroupLayout（getContentPane（））; 
 getContentPane（）。setLayout（layout）; 
 layout.setHorizo​​ntalGroup（
 layout.createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
 .addGroup（layout.createSequentialGroup（）
 .addGap（50，50，50） ）
 .addComponent（jLabel1）
 .addContainerGap（334，Short.MAX_VALUE））
）; 
 layout.setVerticalGroup（
 layout.createParallelGroup（javax.swing.GroupLayout.Alignment.LEADING）
 .addGroup（layout.createSequentialGroup（）
 .addGap（33，33，33 ）
 .addComponent（jLabel1）
 .addContainerGap（253，Short.MAX_VALUE））
）; 
 
 pack（）; 
} //< / editor-fold> 
 
 / ** 
 * @param参数命令行参数
 * / 
 public static void main（String args []）{
 / * 
 *设置Nimbus的外观和感觉
 * / 
 //< editor-fold defaultstate =collapseddesc =观感设置代码（可选）> 
 / * 
 *如果Nimbus（在Java SE 6中引入）不可用，保持
 *默认的外观和感觉。详情请参阅
 * 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 .getClassName（））; 
 break; 
} 
} 
} catch（ClassNotFoundException ex）{
 java.util.logging.Logger.getLogger（hihi.class.getName（））log（java.util。 logging.Level.SEVERE，null，ex）; 
} catch（InstantiationException ex）{
 java.util.logging.Logger.getLogger（hihi.class.getName（））。log（java.util.logging.Level.SEVERE，null，ex） ; 
} catch（IllegalAccessException ex）{
 java.util.logging.Logger.getLogger（hihi.class.getName（））。log（java.util.logging.Level.SEVERE，null，ex） ; 
} catch（javax.swing.UnsupportedLookAndFeelException ex）{
 java.util.logging.Logger.getLogger（hihi.class.getName（））。log（java.util.logging.Level.SEVERE， null，ex）; 
} 
 //< / editor-fold> 
 
 / * 
 *创建并显示表单
 * / 
 java.awt.EventQueue.invokeLater（new Runnable（）{
 
 public void run（）{
 new hihi（）。setVisible（true）; 
} 
}）; 
} 
 //变量声明 - 不要修改
 private javax.swing.JLabel jLabel1; 
 //变量声明结束
} 
  

解决方案>

我怀疑为Jar文件注册的打开命令未正确设置。这里有一个方法来检查从命令行（至少在Windows 7;我很确定它可以在Windows Vista上工作）：

1. 输入命令： assoc .jar


2. 它应该打印 .jar = jarfile 。如果找不到（根据您的症状极不可能），请使用命令 assoc .jar = jarfile 创建条目。


3. 输入命令： ftype jarfile


4. 它应该打印类似
   
   C ：\Program Files\Java\jre6\bin\javaw.exe-jar％1％*
   
   （路径 javaw.exe 可能在您的计算机上有所不同。）


5. 如果未定义或打印错误的值，
   ftype jarfile =C：\Program Files\Java\jre6\bin\javaw.exe-jar％1％*

您可能必须重新启动或至少打开一个新的Windows资源管理器窗口，看看是否双击.jar文件现在工作。

I have been having problems with this on both netbeans and eclipse even with a simple file that displays a jframe with a jlabel on it. My netbeans's project properties clearly sets testing2.hihi as my Main class and I have clean and build it which produces a .jar file in my dist folder. When I double click on it, it gives me the message" could not find the main class. Program will exit." However, if I choose to run it from the command prompt "java -jar hello2.jar" it will run as normal!

This is the manifest file inside the .jar file.

      Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.3
Created-By: 1.7.0_04-b20 (Oracle Corporation)
Class-Path: 
X-COMMENT: src/hihi
Main-Class: testing2.hihi



package testing2;

public class hihi extends javax.swing.JFrame {

/**
 * Creates new form hihi
 */
public hihi() {
    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.setText("hihi");

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(50, 50, 50)
            .addComponent(jLabel1)
            .addContainerGap(334, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(33, 33, 33)
            .addComponent(jLabel1)
            .addContainerGap(253, Short.MAX_VALUE))
    );

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

/**
 * @param args the command line arguments
 */
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(hihi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(hihi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(hihi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(hihi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /*
     * Create and display the form
     */
    java.awt.EventQueue.invokeLater(new Runnable() {

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

解决方案

I suspect that the open command registered for Jar files is not set up correctly. Here's a way to check from the command line (at least on Windows 7; I'm pretty sure it works on Windows Vista):

1. Enter the command: assoc .jar
2. It should print .jar=jarfile. If it is not found (highly unlikely, given your symptoms), create the entry with the command assoc .jar=jarfile.
3. Enter the command: ftype jarfile
4. It should print something like
   "C:\Program Files\Java\jre6\bin\javaw.exe" -jar "%1" %*
   (The path to javaw.exe might be different on your machine.)
5. If it isn't defined or prints the wrong value, fix it with:
   ftype jarfile="C:\Program Files\Java\jre6\bin\javaw.exe" -jar "%1" %*

You may have to reboot, or at least open a new Windows Explorer window, to see if double-clicking on the .jar file now works.

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