bundled executable jar file - couldnot find main class

Question

I am trying to execute a jar file StartupUtil.jar but it's giving an error of Couldnot find and load main class. I looked at other similar question and tried but couldnot figure out what is wrong.

My structure for created StartupUtil.jar is

->com.ihc.startup.util.StartupService

->META-INF/MANIFEST.MF

The content of MANIFEST is:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.2
Created-By: 1.7.0_79-b15 (Oracle Corporation)
Main-Class: com.ihc.startup.util.StartupService
Class-Path: C:\Users\tgupta12\workspace_new\IHC_Startup\lib\bson-3.0.1
 .jar C:\Users\tgupta12\workspace_new\IHC_Startup\lib\mongodb-driver-3
 .0.1.jar C:\Users\tgupta12\workspace_new\IHC_Startup\lib\mongodb-driv
 er-core-3.0.1.jar C:\Users\tgupta12\workspace_new\IHC_Startup\classes

Here is my build.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="Startup" default="build" basedir=".">
    <property file="./build.properties" />

    <path id="lib-classpath">
        <fileset dir="${libApp.dir}">
            <include name="*.jar"/>
        </fileset>
        <pathelement path="${bin.dir}"/>
    </path>

    <target name="build" description="Compile main source tree java files">
        <echo message="  Build Startup Utility" />
        <mkdir dir="${bin.dir}"/>

        <echo message="  Compiling source files" />
        <javac destdir="${bin.dir}" source="${versionJDK}" target="${versionTarget}" debug="true"
             deprecation="false" optimize="false" failonerror="true" includeantruntime="false">
            <src path="${src.dir}"/>
            <classpath refid="lib-classpath"/>
        </javac>
        <echo message="  ...Compilation of source files OK" />

        <echo message="  Generating JAR for Startup - StartupUtility.jar" />
        <delete file="${out.dir}/${startup-util-name}" />
        <!-- convert classpath to a flat list/string -->
        <pathconvert property="lib.classpath" pathsep=" ">
            <path refid="lib-classpath" />
            <!--<flattenmapper />-->
        </pathconvert>

        <jar destfile = "${out.dir}/${startup-util-name}" basedir = "${bin.dir}" includes = "**/*">
            <manifest >
                <attribute name="Class-Path" value="${lib.classpath}" />
                <attribute name="Main-Class" value="com.ihc.startup.util.StartupService"/>
            </manifest>
        </jar>
        <echo message="  ...JAR Created for Startup" />

    </target>

<target name="run" depends="build">
    <java jar="${out.dir}/${startup-util-name}" fork="true"/>
</target>

Below is my build.properties file:

#Directories
build.dir=build
src.dir=src
libApp.dir=lib
out.dir=out
web.dir=WebContent/WEB-INF
bin.dir=classes
webcontent.dir=WebContent

#File Name
war-file-name=StartupService.war
startup-util-name=StartupUtil.jar

#Target Properties
versionJDK=1.7
versionTarget=1.7

When it tries to execute the target run it gives

Error: Could not find or load main class com.ihc.startup.util.StartupService

Answer 1

I strongly suspect that the problem is it can't find the dependencies, which means it can't properly load the main class. I've never seen absolute filenames given in a manifest before, nor am I convinced about how you're breaking the lines (although that may be valid). Given how unportable it is to use the absolute filenames, I strongly suggest you just use relative ones.

Change your manifest to just:

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.2
Created-By: 1.7.0_79-b15 (Oracle Corporation)
Main-Class: com.ihc.startup.util.StartupService
Class-Path: bson-3.0.1.jar mongodb-driver-3.0.1.jar mongodb-driver-core-3.0.1.jar

Then put those jar files in the same directory as StartupUtil.jar .