build.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="acra" default="help">

<!-- The local.properties file is created and updated by the 'android'
     tool.
     It contains the path to the SDK. It should *NOT* be checked into
     Version Control Systems. -->
    <property file="local.properties" />

   <property file="build.properties" />

    <!-- The default.properties file is created and updated by the 'android'
         tool, as well as ADT.
         This file is an integral part of the build system for your
         application and should be checked into Version Control Systems. -->
    <property file="default.properties" />

    <!-- Custom Android task to deal with the project target, and import the
         proper rules.
         This requires ant 1.6.0 or above. -->
    <path id="android.antlibs">
        <pathelement path="${sdk.dir}/tools/lib/anttasks.jar" />
        <pathelement path="${sdk.dir}/tools/lib/sdklib.jar" />
        <pathelement path="${sdk.dir}/tools/lib/androidprefs.jar" />
    </path>

    <taskdef name="setup"
        classname="com.android.ant.SetupTask"
        classpathref="android.antlibs" />
   <setup />

   <property name="acra.jar.file" value="${out.dir}/${ant.project.name}.jar" />
   <target name="jar" depends="compile" description="build the acra jar file">
    <jar basedir="${out.classes.dir}" destfile="${acra.jar.file}" />
   </target>
</project>