How to create a 2 way communication between Java and Python

Question

I am pretty new to both Java and Python, although I have some experience in programming. For an assignement, I need to create a program which uses Java in some way. My project would use Java as an UX, and Python for signal processing and feature extraction, since it has some good tools for that. However, my question is how to establish communication between both programse. Maybe this question has been asked before, but since I do not know the best terms, I could not find answers.

In my Java Program, I can get the file path to a .csv file, send it to Python, and Python returns the original signals and processed signals. For that, I wrote:

private static void sendPython(String path, JTextField console)
    {
        String pathPython = "C:\\Users\\gonca\\Desktop\\untitled0.py";
        String [] cmd = new String[3];
        cmd[0] = "python";
        cmd[1] = pathPython;
        cmd[2] = path;
        Runtime r = Runtime.getRuntime();
        try
        {
            Process p = r.exec(cmd);
            BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String s = "";
            while((s = in.readLine()) != null)
            {
                console.setText(s);
            }
        }
        catch (IOException e)
        {
            console.setText("Unable to run python script");
        }
        
    }

I was thinking of having the py script output the signals in separated lines, with values separated by "," or ";", and using the BufferedRead to read each line, separate the values and create a new ArrayList from the separated values. However, before starting working harder to do that, I would like to know if that is the best way to proceed, or is there a more efficient way to do it.

*General advice*: file-based communication is often slow because files are usually stored on the storage drive (HDD or SSD). You can use **sockets** to enable a fairly-fast and portable **inter-process communications**. If you want even faster performance you could use **shared-memory** but sockets are generally fast enough for most workloads. — Jérôme Richard, Apr 05 '21 at 11:40
@JérômeRichard this advise is valid if the results of the processing need not be persisted out of the single session of the user. An obvious alternative for persistent storage would also be a more robust data base, but this will bring in complexity and is a necessary only if relations exist between the different facets you process. — Boris Strandjev, Apr 05 '21 at 11:55

score 0 · Answer 1 · edited Apr 06 '21 at 21:02

0

There are more ways to do that:

Solution 1:

Use the python library from java with System.loadLibrary, and call the python method. (here is an example using C/C++: Calling a python method from C/C++, and extracting its return value)

Solution 2:

Launch python as another process, and use D-Bus (or something similar) to communicate with it.

edited Apr 06 '21 at 21:02

OneCricketeer

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answered Apr 05 '21 at 13:08

ddd ddd111111

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Then shown code is already calling the Python process fine. I don't see how trying to load native library code will help here, or how a C/C++ example is helpful – OneCricketeer Apr 06 '21 at 21:01

score 0 · Answer 2 · answered Apr 07 '21 at 02:03

Since you have not mentioned how robust your application is I can think of a solution which can be used if you are planning for a higher level architecture.

Create a python based web application (HTTP server) with all logic to process your files.
Create a java app which can communicate via HTTP python server to get the CSV processed information.

Try to avoid Runtime execution of commands with in your codes that faces user as if it not is properly managed there is always a chance for security breach

How to create a 2 way communication between Java and Python

2 Answers2