The JLCA is a tool that converts Java source codes into C# codes automatically. I suppose writing such a tool is much easier than writing a C# to Java code conversion tool because Java was designed to be platform independent, so there are no operating system-specific codes in the Java core API classes.
I can't write much about this tool until it goes final and its feature set solidifies. [4]
[4] At time of writing, the final version of J# has just been released while JLCA is still in beta.
3.137.181.20