this will explain it to you
http://en.wikipedia.org/wiki/J_Sharp
quote taken from article:
"While J# provides a Java syntax on top of .NET's framework, IKVM is effectively a Java framework running on top of .NET's framework. J# is generally not considered to be a language on par with C# or VB.NET, and does not have the same level of support, samples, or updates as the other languages do. This fact notwithstanding, J# is a usable .Net language and has access to all the CLR features."
but we see it also has its uses:
"J# can work with java bytecode as well as source so it can be used to transition applications that use third party libraries even if their original source is unavailable."