Here is a quick Ant skeleton build file, based on the Ant manual.

• Install and configure Ant (you must set a few environment variables)
• Save the following file as ‘build.xml’ in your base directory (noted as ‘.’).
• Replace PROJECTNAME with what you want and MAINCLASSNAME with the class that must be launched in your resulting jar (the class with a static void main(String[]) method).
• Put your source files in ./src, and any external libraries (jar files) in ./lib. Ant will then compile the classes in ./build/classes and store them as a jar file in ./build/jar.
• Run Ant in the base directory with the command ‘ant’ or ‘ant main’, it will execute the directives in build.xml (it will clean, compile, package and run your program).

<project name="PROJECTNAME" basedir="." default="main">

  <!-- set global properties for this build -->
  <property name="main-class"  value="MAINCLASSNAME"/>
  <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="lib.dir"     value="lib"/>

  <!-- adds every jar in the lib directory to the classpath-->
  <path id="classpath">
  <fileset dir="${lib.dir}" includes="**/*.jar"/>
  </path>

  <target name="clean">
    <delete dir="${build.dir}"/>
  </target>

  <target name="compile">
    <mkdir dir="${classes.dir}"/>
    <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="classpath"/>
  </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 fork="true" classname="${main-class}">
      <classpath>
        <path refid="classpath"/>
        <path location="${jar.dir}/${ant.project.name}.jar"/>
      </classpath>
    </java>
  </target>

  <target name="clean-build" depends="clean,jar"/>

  <target name="main" depends="clean,run"/>
</project>