<project name="myapp" default="jar">

  <!-- where the project source code is found -->

  <property name="sources" value="src"/>

  <!-- where compiled class files should be left -->

  <property name="classes" value="classes"/>

  <target name="jar" depends="pre-jar,classes"

      description="build release jar">

    <jar destfile="jar/${ant.project.name}.jar">

      <fileset dir="classes">

        <include name="**/*.class"/>

      </fileset>

    </jar>

  </target>

  <target name="pre-jar" depends="ensure-release">

    <property name="srcdir" value="jar/src"/>

    <mkdir dir="${srcdir}"/>

    <copy todir="${srcdir}">

      <fileset dir="${sources}">

        <include name="**/*.java"/>

      </fileset>

      <filterset>

        <filter token="RELEASE" value="${release}"/>

      </filterset>

    </copy>

  </target>

  <target name="ensure-release" unless="release">

    <fail message="You must define -Drelease=&lt;name&gt;"/>

  </target>

  <target name="classes" description="compile classes">

    <property name="srcdir" value="${sources}"/>

    <mkdir dir="${classes}"/>

    <echo message="srcdir=${srcdir}"/>

    <javacdestdir="${classes}" srcdir="${srcdir}">

    </javac>

  </target>

  <target name="clean" depends="tidy" description="delete all generated files">

    <delete dir="jar" quiet="true"/>

  </target>

  <target name="tidy" description="delete all intermediary files">

    <delete dir="jar/src" quiet="true"/>

    <delete dir="classes" quiet="true"/>

  </target>

</project>