The following example will create c:/project.jar file after compiling the files present in the src folder.

<?xml version="1.0"?>
  <project name="Ant Tutorial" basedir="." default="compile">

  <property name="build" location="c:/testingProject"/>
  <property name="jarname" location="c:/project.jar"/>

  <target name="create" depends="delete">
    <mkdir dir="${build}"/>

  </target>

  <target name="delete">

    <delete dir="${build}"/>

  </target>

  <target name="compile" depends="create">
    <javac srcdir="src" destdir="${build}"/>
    <jar jarfile="${jarname}" basedir="${build}"/>
  </target>
</project>