The method getOutputStream() on the Process class returns a stream you can write to in Java that connects to the stdin stream of the process. You should be able to read this as you would normally read stdin for each language (e.g., cin for C++, scanf for C, STDIN.read for Ruby, don't know Python!)
If this is what you're doing and it isn't working (your question sounds like it might be but it's hard to tell) could you post some code to make it easier to see what you might be doing wrong?
Answer from Jonathan on Stack OverflowGetting Java to talk to Python, C, C++, and Ruby - Stack Overflow
What's the quickest way for a Ruby programmer to pick up Python? - Stack Overflow
Benefits of moving from Python to Ruby?
When it comes to scripting languages, the objective differences are very nuanced. Largely, it depends on what you want to do. Python, for example, is extremely popular in the data sciences. A complementary example for Ruby would be rapid application development with Ruby on Rails, a web framework that allows you to build web applications very quickly. Another example would be building an API using Ruby's Sinatra library. Python also has web frameworks, so it's not as if Ruby has an exclusive claim to this benefit, but many developers find tools like Ruby on Rails and Sinatra very satisfying and beneficial to work with.
My recommendation would be to give Ruby an honest shot. Don't make the mistake of simply trying to write Python code using Ruby. Really dig in to what makes Ruby, Ruby. If you enjoy it, then you've added another language to your tool belt. If you don't, you might walk away with some ideas about development that you can apply to Python.
More on reddit.comWhat makes Python is so popular and Ruby died ?
Videos
The method getOutputStream() on the Process class returns a stream you can write to in Java that connects to the stdin stream of the process. You should be able to read this as you would normally read stdin for each language (e.g., cin for C++, scanf for C, STDIN.read for Ruby, don't know Python!)
If this is what you're doing and it isn't working (your question sounds like it might be but it's hard to tell) could you post some code to make it easier to see what you might be doing wrong?
You should probably use a standard interprocess mechanism like a pipe or socket.
All of these languages have libraries available for both, and this strategy allows communication between any 2 of your processes (Java/Ruby, Ruby/Python, Java/C, etc)
A safe bet is to just dive into python (skim through some tutorials that explain the syntax), and then get coding. The best way to learn any new language is to write code, lots of it. Your experience in Ruby will make it easy to pick up python's dynamic concepts (which might be harder to get used to for say a Java programmer).
Try a python tutorial or book on learning python.
After running through some tutorials on-line (the ones posted so far look pretty good), find a current Ruby project you've done (or are working on) and re-write it in Python. I've used this technique to transition from various languages, and it's helped enormously.