I built an executable jar using an ant script, the only external jar I used was joda-time 2.0. The ant build script \"seemed\" to work as I did not recieve any compile error
Unless you're using a custom classloader or something like JarJar, then you cannot bundle external JARs inside your executable JAR. Your manifest file will need to list a classpath, but the JVM will look for the JARs you list in the same directory as your executable JAR, not inside your executable JAR.