What types of executables can be decompiled?

Question

I think that java executables (jar files) are trivial to decompile and get the source code.

What about other languages? .net and all?

Which all languages can

Answer 1

VB6 if compiled to pcode is also possible to decompile to almost full source using P32Dasm, Flash (or actionscript) is also possible to decompile to full source using something like Flare