导出后Java Eclipse项目出现问题

Question

我已经为学校做了几个星期的Java项目，几天前我完成了它。这是一个数据库管理员软件，设计用于运行Access数据库，在本例中是我学校的数据库。在EclipseIDE中，所有工作正常，显示0个错误，0个警告。然后，当我导出导出的菜单时，我也没有得到任何错误，但是当我打开项目时，菜单的6个按钮中只有2个起作用。菜单有6个按钮。5与Access连接并显示不同的数据，其中只有一个可用，另一个选项卡可用其退出按钮。因此，我在cmd中运行了导出的程序，以获得更精确的错误，并弹出了此日志

C:\Users\IVAN>java -jar prueba.jar
consulta busar registro: SELECT * FROM StudentsAbsences ORDER BY Id;
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.ImageIcon.<init>(Unknown Source)
        at ModificarAlumno.getCancelar_btn(ModificarAlumno.java:199)
        at ModificarAlumno.getJContentPane(ModificarAlumno.java:385)
        at ModificarAlumno.initialize(ModificarAlumno.java:310)
        at ModificarAlumno.<init>(ModificarAlumno.java:298)
        at Menu$4.actionPerformed(Menu.java:127)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
        at java.awt.EventQueue.access$000(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.awt.EventQueue$4.run(Unknown Source)
        at java.awt.EventQueue$4.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

我是stackoverflow的新手，从来没有使用过这个问答网页，所以我不确定是否必须发布其他内容。星期二我得交工作项目，所以我很忙。任何帮助都是感激的，如果你需要更多关于该项目的信息，请告诉我，我会尽快发布。多谢各位

Answer 1

下面的代码似乎抛出了NullPointerException

    at javax.swing.ImageIcon.<init>(Unknown Source)
    at ModificarAlumno.getCancelar_btn(ModificarAlumno.java:199)

这意味着在ModificarAlumno。getCancelar_btn（）您正在构造一个新的ImageIcon，在其构造函数中抛出异常。可能是图像在导出后没有正确加载吗？如果这没有帮助，请发布其他代码

Answer 2

如果该程序在Eclipse内部工作，但不在Eclipse外部工作，请检查两件事：

1. 在你的代码中寻找你在文件系统中硬编码位置的地方，比如图像和其他文件。在不同的计算机上，这些位置可能会发生变化

2. 导出jar默认只导出java类。如果程序中包含非java文件，请确保将导出和生成向导配置为导出/生成这些文件