Android runs on ant script on the device, executing test cases and generating a code coverage report

Question

I am very new to ANT script. I am working on an android application and I have created the corresponding Junit android test application. Now I have the following in my build.xml file of my test project

<property name="src.dir" location="src" />
    <property name="test.dir" location="tests" />

    <property name="build.dir" location="bin" />
    <property name="build.test.dir" location="bin/tests" />

    <!-- Variables used for JUnit testin -->

    <property name="test.report.dir" location="testreport" />

    <!-- Define the classpath which includes the junit.jar and the classes after compiling-->
    <path id="junit.class.path">
        <pathelement location="libs/junit.jar" />
        <pathelement location="lib/hamcrest-core-1.3.jar" />
        <pathelement location="${build.dir}" />
    </path>


    <!-- Deletes the existing build, docs and dist directory-->
    <target name="clean">
        <delete dir="${build.dir}" />
        <delete dir="${test.report.dir}" />
    </target>

    <!-- Creates the  build, docs and dist directory-->
    <target name="makedir">
        <mkdir dir="${build.dir}" />
        <mkdir dir="${build.test.dir}" />
        <mkdir dir="${test.report.dir}" />
    </target>

    <!-- Compiles the java code (including the usage of library for JUnit -->
    <target name="compile" depends="clean, makedir">
        <echo>compile:clean, makedir</echo>
        <javac srcdir="${src.dir}" destdir="${build.dir}">
            <classpath refid="junit.class.path" />
        </javac>

        <javac srcdir="${test.dir}" destdir="${build.test.dir}">
            <classpath refid="junit.class.path" />
        </javac>

    </target>

    <!-- Run the JUnit Tests -->
    <!-- Output is XML, could also be plain-->
    <target name="junit" depends="compile">
          <echo>junit: compile</echo>
        <junit printsummary="on" fork="true" haltonfailure="yes">
            <classpath refid="junit.class.path" />
            <classpath>
                <pathelement location="${build.test.dir}"/>
              </classpath>
            <formatter type="xml" />
            <batchtest todir="${test.report.dir}">
                <fileset dir="${test.dir}">
                    <include name="**/*Test*.java" />
                </fileset>
            </batchtest>
        </junit>
    </target>

    <target name="main" depends="compile, junit">
        <description>Main target</description>
    </target>

When I run the above code right click on build.xml->run as ant, I can execute Junit test scripts, but the test case results are alwasys errors or crashes. I probably need to run these test scripts on the device. How can I run these test scripts on the device, and at the same time I need to also get a code coverage report. Please help me with this.