build.xml

<project name="HelloWorld" basedir="." default="main"> 
 
    <property name="src.dir"     value="src"/> 
 
    <property name="build.dir"   value="build"/>     <property name="classes.dir" value="${build.dir}/classes"/>     <property name="jar.dir"     value="${build.dir}/jar"/> 
 
    <property name="main-class"  value="oata.HelloWorld"/> 
 
 
    <target name="clean">         <delete dir="${build.dir}"/>     </target> 
 
    <target name="compile">         <mkdir dir="${classes.dir}"/>         <javac srcdir="${src.dir}" destdir="${classes.dir}"/>     </target> 
 
    <target name="jar" depends="compile">         <mkdir dir="${jar.dir}"/>         <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}">             <manifest>                 <attribute name="Main-Class" value="${main-class}"/>             </manifest>         </jar>     </target> 
 
    <target name="run" depends="jar">         <java jar="${jar.dir}/${ant.project.name}.jar" fork="true"/>     </target> 
 
    <target name="clean-build" depends="clean,jar"/> 
 
    <target name="main" depends="clean,run"/> 
 
</project>