Theia said:
Thank you both of you! ^^ I think I understand Java's popularity a little better now. :D I haven't thought python being "a glue", thought - I've used sh scripts to put different programs together. But well, why not. As for Java and Android, no, I didn't know.
C# is another big hole in my knowledge. Several years ago I made some short programs in pure C, but as far as I understand, C# is something completely different.
Maybe I then keep coding Fortran for now. But I need to consider more carefully what language to use for some bigger programs I'm planning... Thank you again!
Let me give some more background then. ;)
Yes, sh scripting is used to put different programs together. Both perl and python evolved from sh scripting, based on the need for more elaborate programming constructions and performance while maintaining the power of sh scripting.
All of them are interpreted languages, meaning they are powerful but slow.
Once upon a time C and Fortran were created. The definitions of those languages, including their libraries, fit on a couple dozen sheets of paper.
Then C evolved into C++, in which object orientation, templates, and a much larger library was added. Those take up hundreds of sheets of paper.
Then, inspired by C++, java and C# were created, improving the syntax, object orientation, and again adding a much larger library, although they run significantly slower (but not as slow as scripting languages).
C# was created by Microsoft, meaning it will only work with Microsoft products, and it does it well.
Java was created by Sun and has been released to the general public.
C, Fortran, and C++ are compiled languages, meaning they are fast, but after compilation can only run on the target platform.
Java and C# are compilation-just-in-time languages, meaning the actual compilation only happens just before it is needed on the target platform. As such they can run on any platform and still have (some of) the power of compiled languages.