java to c# and c# to java

Microsoft has the Java Language Conversion Assistant (JLCA) that enables
developers to migrate their existing Java code to C# on the .NET Framework.
It can be found at:


http://msdn2.microsoft.com/en-us/vstudio/aa718346.aspx

However, the reverse, a C# to Java is more difficlut to achieve

http://jsc.sourceforge.net/