How to include external libraries in Ant build.xml file?

Question

In my Java source-code I want to use different classes from java archives (.jar) stored in my application's "lib" directory. But if I do "ant run" then I always get a "java.lang.NoClassDefFoundError" message. I tried several things to fix it but nothing worked... Maybe someone here can help me?

This is my build.properties file:

app.name=MyApplication
app.version=1.0
main.class=mypackage.MyMain
build.dir=build
classes.dir=${build.dir}/classes
jar.dir=${build.dir}/jar
dist.dir=dist
src.dir=src
test.dir=test
lib.dir=lib

This is my build.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<project name="My Project" default="run" basedir=".">
  <description>My description.</description>

  <property file="build.properties" />
  <path id="classpath">
    <fileset dir="${lib.dir}" includes="*.jar"/>
  </path>

    <!-- Initialization -->
  <target name="init" description="Prepare needed directories.">
    <mkdir dir="${build.dir}" />
    <mkdir dir="${classes.dir}" />
    <mkdir dir="${jar.dir}" />
    <mkdir dir="${dist.dir}" />
    <mkdir dir="${lib.dir}" />
  </target>

    <!-- Cleanup -->
  <target name="clean" description="Remove all files created by the build/test process.">
    <delete dir="${classes.dir}" />
    <delete dir="${dist.dir}" />
  </target>

    <!-- Compile application -->
  <target name="compile">
    <mkdir dir="${classes.dir}"/>
    <javac srcdir="${src.dir}" 
       destdir="${classes.dir}" 
       debug="yes"
       includeantruntime="false">
      <!-- <classpath refid="classpath" /> -->
    </javac>
  </target>

    <!-- Java Archive -->
  <target name="jar" depends="compile">
    <!--<delete file="${jar.dir}/${app.name}-${app.version}.jar"/>-->
    <delete dir="${jar.dir}"/>
    <mkdir dir="${jar.dir}"/>
    <jar destfile="${jar.dir}/${app.name}-${app.version}.jar" basedir="${classes.dir}">
      <manifest>
        <attribute name="Class-Path" value="${lib.dir}"/>
        <attribute name="Main-Class" value="${main.class}"/>
      </manifest>
    </jar>
  </target>

    <!-- Run application -->
  <target name="run" depends="jar">

    <java jar="${jar.dir}/${app.name}-${app.version}.jar" 
        fork="true">
    </java>
    <!--
    <java fork="true" classname="${main.class}">
      <classpath>
         <path refid="classpath"/>
         <path location="${jar.dir}/${app.name}-${app.version}.jar"/>
      </classpath>
    </java>
    -->
  </target>
</project>

It would be nice if anyone could help.

Cheers!

Benny

Solution 1

Replacing classes.dir=${build.dir}/classes with classes.dir=build/classes and jar.dir=${build.dir}/jar with jar.dir=build/jar from your build.properties file will work.

Solution 2

Please edit target jar as follows. I am sure it will work.

<target name="jar" depends="compile">

<delete dir="${jar.dir}"/>
<mkdir dir="${jar.dir}"/>
<jar destfile="${jar.dir}/${app.name}-${app.version}.jar" basedir="${classes.dir}">
  <manifest>
    <attribute name="Class-Path" value="${lib.dir}"/>
    <attribute name="Main-Class" value="${main.class}"/>
  </manifest>
   <zipgroupfileset  dir="${lib.dir}"/>

</jar>

Comments

[Mads Hansen]

what does your lib directory look like? Are all of the jar files dumped in that directory, or are there subdirectories?

[Benny Neugebauer]

All jar files are in that directory (without any sub-directories). The structure looks like: ./lib/log4j-1.2.9.jar, ./lib/cobertura.jar, ./lib/easymock-3.0.jar, ... How can I include those libraries in my jar file?

[Benny Neugebauer]

When I use this, then I get an error while "ant compile". At the moment I extract every source-code files of my external jar files and put them into my own "src" directory. Then I can run my project without problems because the dependencies are included when compiling and running my project. But I think that this is not the best use-case. But until now I have not found any other solution that will provide the external jar files in my own jar file. I think I have to focus again on the classpath declaration in the manifest as you told me...

[Mads Hansen]

@Benny Neugebauer - double check your properties file entries to see if there is any trailing whitespace for your path values.