Deployed jar can't find the main class while using Apache Ant

Question

I built a jar file using the following build.xml below:

<project name="sampleproject">
        <!--Source Directory-->
        <property name="src.dir" value="src" />
        <property name="deploy.name" value="samplejar.jar" />
        <property name="lib.dir" value="./lib" />
        <property name="deploy.dir" value="target" />
        <property name="compile.dir" value="target/classes" />


        <!--Define directory name for third party libraries-->
        <property name="jar-all" location="${lib.dir}" />

        <!--Fileset is a group of files, here **/* matches all jar files across all directory levels-->
        <fileset id="jars" dir="${jar-all}">
        </fileset>

        <!--Setting the classpath-->
        <path id="classpath">
            <fileset refid="jars" />
            <pathelement location="." />
            <pathelement location="${src.dir}" />
            <pathelement location="${compile.dir}" />
        </path>

        <path id="cp">
            <fileset refid="jars" />
        </path>

        <pathconvert property="classpath.path" refid="cp" pathsep=" " dirsep="/">
            <map from="${jar-all}" to="lib" />
        </pathconvert>

        <echo>${classpath}</echo>
        <!--Clean-->
        <target name="clean">
            <delete dir="${deploy.dir}" />
        </target>

        <!--Jar-->
        <target name="jar" depends="compile">
            <jar destfile="${deploy.dir}/${deploy.name}.jar" basedir="${compile.dir}">
                <manifest>
                    <attribute name="Main-Class" value="main.java.Main" />
                    <attribute name="Class-Path" value="${classpath.path}" />
                </manifest>
                <include name="${src.dir}/META-INF/persistence.xml" />
                <restrict>
                    <not>
                        <or>
                            <name name="**/*.RSA" />
                            <name name="**/*.SF" />
                            <name name="**/*.DSA" />
                        </or>
                    </not>
                    <archives>
                        <zips>
                            <fileset dir="lib" includes="**/*.jar" />
                        </zips>
                    </archives>
                </restrict>
            </jar>

        </target>

        <!--Compile-->
        <target name="compile">
            <mkdir dir="${compile.dir}" />
            <javac includeantruntime="false" srcdir="${src.dir}" destdir="${compile.dir}">

                <classpath refid="classpath" />
            </javac>
        </target>
    </project>

My folder structure is like this:

.
./.settings
./bin
./bin/main
./bin/main/java
./bin/META-INF
./lib
./lib/aws
./lib/hibernate
./src
./src/main
./src/main/java
./src/META-INF
./target
./target/classes
./target/classes/main
./target/classes/main/java

My MANIFEST.MF

Created-By: 1.8.0_45-b14 (Oracle Corporation)
Built-Date: ${TODAY}
Main-Class: main.java.Main
Class-Path: lib/activation.jar lib/aws/aws-java-sdk-1.3.2.jar lib/aws/
 httpclient-4.1.1.jar lib/aws/httpcore-4.4.1.jar lib/aws/mail-1.4.3.ja
 r lib/aws/stax-1.2.0.jar lib/aws/stax-api-1.0.1.jar lib/commons-beanu
 tils-1.8.3.jar lib/commons-codec-1.4.jar lib/commons-configuration-1.
 8.jar lib/commons-httpclient-3.0.1.jar lib/commons-io-2.1.jar lib/com
 mons-lang-2.4.jar lib/commons-logging-1.1.1.jar lib/hibernate/antlr-2
 .7.7.jar lib/hibernate/c3p0-0.9.1.jar lib/hibernate/commons-collectio
 ns-3.2.1.jar lib/hibernate/dom4j-1.6.1.jar lib/hibernate/hibernate-c3
 p0-4.0.1.Final.jar lib/hibernate/hibernate-commons-annotations-4.0.1.
 Final.jar lib/hibernate/hibernate-core-4.0.1.Final.jar lib/hibernate/
 hibernate-entitymanager-4.0.1.Final.jar lib/hibernate/hibernate-jpa-2
 .0-api-1.0.1.Final.jar lib/hibernate/javassist-3.15.0-GA.jar lib/hibe
 rnate/jboss-logging-3.1.0.CR2.jar lib/hibernate/jboss-transaction-api
 _1.1_spec-1.0.0.Final.jar lib/jackson-all-1.9.5.jar lib/log4j-1.2.16.
 jar lib/mail.jar lib/mongo-2.8.0.jar lib/morphia-0.99.jar lib/mysql-c
 onnector-java-5.1.12-bin.jar lib/mysql-connector-java-5.1.25-bin.jar 
 lib/org.json.jar lib/ymmi-utilities-2.0.jar

Whenever I run the jar produced it gives me, Error: Could not find or load main class main.java.Main .

Also, I want to include lib folder & it's subfolders as well since it contains the libraries required to run the jar.

Before it gave me, No Persistence provider for EntityManager named but I solved that by using <include name="${src.dir}/META-INF/persistence.xml" /> . Any where I am might wrong?

Answer 1

Your problem is the <include> element in the jar task. I executed your script and the Main.class file is not added to the jar. Replace the

<include

by

<fileset dir="${src.dir}" includes="META-INF/persistence.xml" />

This way it will still add all files located in your ${compile.dir}.

Are you new to java ? Normally you put your source files in src/main/java and resources in src/main/resources. These folders are the root folder of your classpath meaning: If your project classes would be in package org.myproject, than you would put the Main.java file in src/main/java/org/myproject/Main.java In your build script you than set the property "src.dir" to "src/main/java".

With all resources (=files which do not need to be compiled but must be available in the jar) in src/main/resources the fileset element in the jar task could just be:

<fileset dir="scr/main/resources"/>

This way all resource files you plan to add to your project will automatically added to your jar.

Why do I tell you this ? If one day you would think of using maven instead of ant, maven expects the sources to be in src/main/java and resources in src/main/resources. ( https://maven.apache.org/guides/introduction/introduction-to-the-standard-directory-layout.html )

Answer 2

Regarding you other dependant jars: Now you include all jars twice: you add the content of them using the <archives> element within the jar and you define them in the Class-Path attribute of the manifest.mf file.

If you really like to build a single jar containing all dependant files, you don't need to specify the manifest attribute Class-Path.

If you want your jar file containing only your files and deliver the dependant jars separately: remove the <archives> element within the jar task.