Why the Common Language Runtime Cannot Support Java [closed]

Question

Today the Common Language Run Time Supports Many Languages including Iron Python and Iron Ruby. We can similarly can use J Ruby and J Python in Java Run Time environments . If so why the .net frame work common language run time cannot support for Java? Um just curious to know though u may see this as a dumb question .

Answer 1

The CLR was actually designed so that it could do everything required to run Java. (Indeed, there are some warts in the way IL is defined which are there specifically for compatibility with Java.) You just need a way of converting bytecode to IL, or compiling from Java source code to IL. J# was one way of doing this, but the limitation of using Java 1.1.4 was a pretty huge one.

I suspect the reason for not going further wasn't an issue with running Java as a language, but the fact that system libraries would need porting. If you were willing to write Java-like source code but target .NET framework libraries (and only .NET framework libraries), with a version of the JLS which switched java.lang.String to System.String etc, it would be doable. I don't think there'd be much benefit though, when C# is simply a nicer language in almost all ways.

You may be interested in looking at IKVM.NET though - an implementation of Java running on the CLI.

Answer 2

First of all, Java may only be called Java if it compiles to JVM bytecode and runs on a certified JVM (iirc), those were the reasons behind Microsoft's efforts being named J++ and J#.

Then there is still J#, which is something close to Java, running on the CLR.

Then there is IKVM which is an implementation of a JVM and the class library on top of the CLR.

Actually, the class library might be the most annoying thing in this case. J# comes with an own library containing the Java core classes just for that purpose and the language closely ties in with that class library (just as it does in .NET).

The final thing though is probably: Why bother at all? Java itself would be a sub-par language on the CLR, where careful effort is needed to recreate things like its not-actual generics. Due to this interoperability with other CLR languages will likely be limited, too. There are powerful translators from Java to C# if you have a large Java codebase and want to use .NET, but a CLR-native Java, compatible with SuOracle's would be a lot of effort for something that you'd only want to touch for compatibility purposes and which poorly interfaces with the CLR or other .NET languages.