It it existed, I have not seen it. May I asked why do
you want venturing into this borderline between 2
steaming camps?

i wanna work with both java  and c# but i wanna learn one of them very good and
have an idea about the other
so i need this convertor to convert  my code  from the one i know well to the one
i not very good in it

if(language.equals("C#"){
System.out.println("EVIL");
return Java;
}

Once again my keyboard klicks

I'v been a bit outa touch of .NET but I remember Microsoft talking
about JUMP = java  User Migration Program, obviously java to .net

for that go to Microsoft site and search

still not sure about the way bak from .NET to java
but
the following paragraph will also help


Introduction

Two paths are available for migrating Java applications to .Net:
upgrade them to Visual J# .Net or convert  them to Visual C# .Net.
Upgrading Java applications to J# is the quickest and easiest way to
port Java applications to the .Net Framework. Java developers are
instantly productive on Visual J# .Net because they are already
familiar with the syntax and set of class libraries.

Java applications can convert to C# using the Microsoft Java
Language Conversion Assistant (JLCA). code  that calls Java APIs can
convert to comparable C# code that uses the .Net Framework. The JLCA
converts 90% of JDK-level 1.1.4 calls and emits issues in code for
the other 10%. Each issue is linked to a topic with guidelines for
modifications needed to finish the conversion.

Though converting to C# is slower than upgrading to J#, it offers
more opportunities because converted applications use native .Net
Framework APIs.