Calling a python script from a Java jar file

Question

I am working on a project using Java and Python using Java for the GUI and Python for the backend. The Java program calls a Python script when a button is pressed using the following code:

Runtime r = Runtime.getRuntime();
String pyScript = "resources/script.py";
String scriptPath = getClass().getResource(pyScript).toExternalForm();
// Strip "file/" from path
scriptPath = scriptPath.substring(scriptPath.indexOf("/") + 1);
Process p = r.exec("python " + scriptPath)

The python script is located in a folder called resources in the src folder of the Java project. This code works when I run my program in my IDE (IntelliJ) however when I create a .jar file and attempt to run the script nothing occurs. I can confirm that the program does still find the script within the .jar file. How can I get the script to run?

Answer 1

In this solution, we run the script if the file exists. The script could be on a full or relative path. The script is not in the jar file.

TestPython.java

import java.lang.*;
import java.io.*;

public class TestPython {
    public static void main(String[] args) {

        System.out.println("I will run a Python script!");
        Runtime r = Runtime.getRuntime();
        String pyScript = "py/test.py";

        File f = new File(pyScript);
        if (f.exists() && !f.isDirectory()) {
            try {
                Process p = r.exec("python " + pyScript);
                BufferedReader in = new BufferedReader(
                    new InputStreamReader(p.getInputStream()));
                String line = null;
                while ((line = in .readLine()) != null) {
                    System.out.println(line);
                }
                System.out.println("Python script ran!!");
            } catch (Exception ex) {
                System.out.println("Something bad happened!!");
                ex.printStackTrace();
            }
        } else {
            System.out.println("Unexistent file!" + pyScript);
        }
    }
}

py/test.py

print("I'm a Python script!!!")

Output:

I will run a Python script!

I'm a Python script!!!

Python script ran!!