Java 使用Ant编译和运行时出现NoClassDefFoundError

我正试图使用Ant编译和运行一个项目，结果发现一个NoClassDefFoundError。这是我的OutlookToGmailCalendarSync.java文件，位于src文件夹中：

package sample.calendar;
public class OutlookToGmailCalendarSync {
    public static void main(String[] args) {
        System.out.println("hi");
    }
}

这是我的build.xml文件：

<project name="MyCalendarSample" default="run" basedir=".">
<description>
    simple example build file
</description>
<!-- set global properties for this build -->
<property name="src" location="src"/>
<property name="build" location="build"/>
<property name="dist"  location="dist"/>

<path id="path.class">
   <pathelement location="build/sample/calendar"/>
</path>

<target name="run" depends="compile"
   description="Runs the complied project">
   <!-- Run -->
   <java fork="true" classname="OutlookToGmailCalendarSync">
   <classpath>
     <path refid="path.class"/>
   </classpath>
</java>
</target>

<target name="compile" depends="init"
    description="compile the source " >
    <!-- Compile the java code from ${src} into ${build} -->
    <javac srcdir="${src}" destdir="${build}"/>
</target>

<target name="init">
    <!-- Create the time stamp -->
    <tstamp/>
    <!-- Create the build directory structure used by compile -->
    <mkdir dir="${build}"/>
</target>

<target name="clean"
    description="clean up" >
    <!-- Delete the ${build} directory trees -->
    <delete dir="${build}"/>
</target>

</project>

---

即使在阅读了其他论坛的帖子后，我仍然不明白为什么这会发生在我身上。在运行时，编译的类位于build/sample/calendar中，这是类路径设置的位置，因此我看不出问题。

尝试以下更改：

类路径设置为生成类的根目录，并为java命令提供类的打包名称

<path id="path.class">
<pathelement location="build"/>
</path>

<target name="run" depends="compile"
description="Runs the complied project">
<!-- Run -->
<java fork="true" classname="sample.calendar.OutlookToGmailCalendarSync" >
<classpath refid="path.class"/>
</java>
</target>

希望这会有所帮助

<path id="path.class">
<pathelement location="build"/>
</path>

<target name="run" depends="compile"
description="Runs the complied project">
<!-- Run -->
<java fork="true" classname="sample.calendar.OutlookToGmailCalendarSync" >
<classpath refid="path.class"/>
</java>
</target>