How to pass some data from python3 to java

Here is my problem: I need to create a discord bot that uses speech recognition to recognize voice commands and send the recognized strings to a Java program (a Spigot Minecraft plugin in this case) from that bot/python program. I've scanned all over and I couldn't find any suitable methods to do this. The only thing that I can think of is creating a file with the necessary data inside it or its name and use that as a "bridge" between the bot and the plugin, but I don't think it's a very orthodox or suitable method. (I tried jython, but it's stuck to python2.7 as far as I know).

I assume we are talking about separate Python and Java processes since you found Jython to be not useful for your case. I think there are really two questions in this: (a) how to get data from Python to Java and (b) what format to use.

For (a) you could use a named pipe or domain sockets (I believe they now also exist on Windows). For the differences between these two inter-process communication abstractions see here. Another option would be TCP but unless there is a possible scenario where the processes reside on different machines this is not likely to be the best.

The answer to (b) depends a bit on the nature of the data. JSON could be an option but you might also want to look at alternatives that might be faster. The ones that come to my mind are Apache Thrift and Google's Protocol Buffers.