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

Managed languages can be easily decompiled because executable must contain a lot of metadata to support reflection.
Languages like C++ can be compiled to native code. Program structure can be totally changed during compilation\translation processes.
Compiler can easily replace\merge\delete parts of your code. There is no 1 to 1 relationship between original and compiled (native) code.