简单的Ant文件的 “Hello World”

Question

我试图运行Ant文件，我不断收到以下错误：

Exception in thread "main" java.lang.NoClassDefFoundError 

我的build.xml文件包含此：

<project name="Proj0" default="compile" basedir="."> 

    <description> 
    Proj0 build file 
    </description> 

    <!-- global properties for this build file --> 
    <property name="source.dir" location="src"/> 
    <property name="build.dir" location="bin"/> 
    <property name="doc.dir" location="doc"/> 
    <property name="main.class" value="proj0.Proj0.java"/> 

    <!-- set up some directories used by this project --> 
    <target name="init" description="setup project directories"> 
    <mkdir dir="${build.dir}"/> 
    <mkdir dir="${doc.dir}"/> 
    </target> 

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

    <!-- execute the program with the fully qualified name in ${build.dir} --> 
    <target name="run" description="run the project"> 
    <java dir="${build.dir}" classname="${main.class}" fork="yes"> 
     <arg line="${args}"/> 
    </java> 
    </target> 

    <!-- Delete the build & doc directories and Emacs backup (*~) files --> 
    <target name="clean" description="tidy up the workspace"> 
    <delete dir="${build.dir}"/> 
    <delete dir="${doc.dir}"/> 
    <delete> 
     <fileset defaultexcludes="no" dir="${source.dir}" includes="**/*~"/> 
    </delete> 
    </target> 

    <!-- Generate javadocs for current project into ${doc.dir} --> 
    <target name="doc" depends="init" description="generate documentation"> 
    <javadoc sourcepath="${source.dir}" destdir="${doc.dir}"/> 
    </target> 

</project> 

我如何解决这个错误？

编辑：这是我的Proj0.java文件和堆栈跟踪看起来像：

package proj0; 

public class Proj0 
{ 
    public static void main(String[] args) 
    { 
     System.out.println("Hello World"); 
    } 
} 

---

Buildfile: build.xml 

run: 
    [java] Exception in thread "main" java.lang.NoClassDefFoundError: proj0/Proj0 
    [java] Caused by: java.lang.ClassNotFoundException: proj0.Proj0 
    [java]  at java.net.URLClassLoader$1.run(URLClassLoader.java:217) 
    [java]  at java.security.AccessController.doPrivileged(Native Method) 
    [java]  at java.net.URLClassLoader.findClass(URLClassLoader.java:205) 
    [java]  at java.lang.ClassLoader.loadClass(ClassLoader.java:321) 
    [java]  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) 
    [java]  at java.lang.ClassLoader.loadClass(ClassLoader.java:266) 
    [java] Could not find the main class: proj0.Proj0. Program will exit. 
    [java] Java Result: 1 

BUILD SUCCESSFUL 
Total time: 0 seconds 

Answer 1

<property name="main.class" value="proj0.Proj0.java"/> 

这也许应该是

<property name="main.class" value="proj0.Proj0"/> 

（班级名称，不是th e源文件名）。