I\'ve heard that the advantage of java is that people can write code, compile it for the JVM, and run it anywhere. Each person just needs a JVM app for their platform.
The main advantage, to me, is the library portability. Libraries might have version dependencies between themselves, but, other than that, a JAR just works.
There is the so-called classloader hell, but that's not nearly as common.
In most other languages, you either have to find the correct library binary, or you have to download the sources to install it.