Pass two separate arguments to ProcessBuilder instead of concatenating --arg1 and argumentValue:

ProcessBuilder builder = new ProcessBuilder("C:\\Python33\\python.exe",
                                            "-u",
                                            "C:\\...\\script.py,
                                            "--arg1",
                                            "argumentValue");

Otherwise the program to be executed will see a single argument --arg1 argumentValue that it does not recognise.

Usually when executing commands using ProcessBuilder, PATH variable is not taken into consideration. Your python C:/Machine_Learning/Text_Analysis/Ontology_based.py is directly working in your CMD shell because it can locate the python executable using the PATH variable. Please provide the absolute path to python command in your Java code. In below code replace <Absolute Path to Python> with the path to python command and its libraries. Usually it will something like C:\Python27\python in Windows by default

package text_clustering;

import java.io.*;

public class Similarity {

    /**
     * 
     * @param args
     * 
     */
    public static void main(String[] args){
        try{
            String pythonPath = "C:/Machine_Learning/Text_Analysis/Ontology_based.py";
            //String pythonExe = "C:/Users/AppData/Local/Continuum/Anaconda/python.exe";
            ProcessBuilder pb = new ProcessBuilder(Arrays.asList("<Absolute Path to Python>/python", pythonPath));
            Process p = pb.start();

            BufferedReader bfr = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line = "";
            System.out.println("Running Python starts: " + line);
            int exitCode = p.waitFor();
            System.out.println("Exit Code : "+exitCode);
            line = bfr.readLine();
            System.out.println("First Line: " + line);
            while ((line = bfr.readLine()) != null){
                System.out.println("Python Output: " + line);


            }

        }catch(Exception e){System.out.println(e);}
    }

}

This May Be Helpful !

You can use Java Runtime.exec() to run python script, As an example first create a python script file using shebang and then set it executable.

#!/usr/bin/python
import sys
print 'Number of Arguments:', len(sys.argv), 'arguments.'
print 'Argument List:', str(sys.arv)
print('This is Python Code')
print('Executing Python')
print('From Java')

if you save the above file as script_python and then set the execution permissions using

chmod 777 script_python

Then you can call this script from Java Runtime.exec() like below

import java.io.*;
import java.nio.charset.StandardCharsets;

public class ScriptPython {
       Process mProcess;

public void runScript(){
       Process process;
       try{
             process = Runtime.getRuntime().exec(new String[]{"script_python","arg1","arg2"});
             mProcess = process;
       }catch(Exception e) {
          System.out.println("Exception Raised" + e.toString());
       }
       InputStream stdout = mProcess.getInputStream();
       BufferedReader reader = new BufferedReader(new InputStreamReader(stdout,StandardCharsets.UTF_8));
       String line;
       try{
          while((line = reader.readLine()) != null){
               System.out.println("stdout: "+ line);
          }
       }catch(IOException e){
             System.out.println("Exception in reading output"+ e.toString());
       }
}
}

class Solution {
      public static void main(String[] args){
          ScriptPython scriptPython = new ScriptPython();
          scriptPython.runScript();
      }

}

Just give them as separate strings in the array, instead of combining the last two into "val_31 val_32":

String[] command = {"script.py", "run",
                    "-arg1", "val1", 
                    "-arg2", "val2" ,          
                    "-arg3" , "val_31", "val_32",
       };

Otherwise it will escape the space in between val_31 and val_32 because you are telling it that they're a single parameter. Incidentally, you can also use the varargs constructor and skip having to create an array, if you want:

ProcessBuilder probuilder = new ProcessBuilder( "script.py", "run",
                    "-arg1", "val1", 
                    "-arg2", "val2" ,          
                    "-arg3" , "val_31", "val_32");

just use some sort of medium where python or java reads/writes to say a .json file. To run things on your machine using java you can use https://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html#exec(java.lang.String) Runtime.exec(String); where the String is some system dependent command (like a command line for windows, if you can start a python script from cmd you can use Runtime.exec to run the script) You can get the Process object https://docs.oracle.com/javase/7/docs/api/java/lang/Process.html from that Runtime.exec call it returns a Process object. I've not gone this deep into the Process class but according to the docs: By default, the created subprocess does not have its own terminal or console. All its standard I/O (i.e. stdin, stdout, stderr) operations will be redirected to the parent process, where they can be accessed via the streams obtained using the methods getOutputStream(), getInputStream(), and getErrorStream(). The parent process uses these streams to feed input to and get output from the subprocess. Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, or even deadlock. Where desired, subprocess I/O can also be redirected using methods of the ProcessBuilder class.

You need to specify your python path:

run in your terminal: "which python3"

ProcessBuilder builder = new ProcessBuilder("your/python/path/python3","main.py","-rd ",selectedFile.getAbsolutePath());

You can use Java Runtime.exec() to run python script, As an example first create a python script file using shebang and then set it executable.#!/usr/bin/python import sys print ('Number of Arguments:', len(sys.argv), 'arguments.') print ('Argument List:', str(sys.argv)) print('This is Python Code') print('Executing Python') print('From Java')if you save the above file as script_python and then set the execution permissions usingchmod 777 script_pythonThen you can call this script from Java Runtime.exec() like belowimport java.io.*; import java.nio.charset.StandardCharsets; public class ScriptPython { Process mProcess; public void runScript(){ Process process; try{ process = Runtime.getRuntime().exec(new String[]{"script_python","arg1","arg2"}); mProcess = process; }catch(Exception e) { System.out.println("Exception Raised" + e.toString()); } InputStream stdout = mProcess.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(stdout,StandardCharsets.UTF_8)); String line; try{ while((line = reader.readLine()) != null){ System.out.println("stdout: "+ line); } }catch(IOException e){ System.out.println("Exception in reading output"+ e.toString()); } } } class Solution { public static void main(String[] args){ ScriptPython scriptPython = new ScriptPython(); scriptPython.runScript(); } }Hope this helps and if not then its recommended to join our Java training class and learn about Java in detail.

You can check the ProcessBuilder documentation over at Sunoracle, but basically, you can run the interpreter for the scripting language and pass the script you want to run to it.

For example, let's say you have a script in /home/myuser/py_script.py, and python is in /usr/bin/

class ProcessRunner
{
    public static void main(String [] args)
    {
        ProcessBuilder pb = new ProcessBuilder("/usr/bin/python", "/home/myuser/py_script.py");
        Process p = pb.start();
    }
}

An extremely basic example, you can get fancier with changing the working directory and change the environment.

You can also construct ProcessBuilder with a String array or a subtype of List<String>. The first item in the list should be the program/executable you want to run, and all the following items are arguments to the program.

String pbCommand[] = { "/usr/bin/python", "/home/myuser/py_script.py" };
ProcessBuilder pb = new ProcessBuilder(pbCommand);
Process p = pb.start();

When you spawn a process from another process, they can only (mostly rather) communicate through their input and output streams. Thus you cannot expect the return value from main33() in python to reach Java, it will end its life within Python runtime environment only. In case you need to send something back to Java process you need to write that to print().

Modified both of your python and java code snippets.

import sys
def main33():
    print("This is what I am looking for")

if __name__ == '__main__':
    globals()[sys.argv[1]]()
    #should be 0 for successful exit
    #however just to demostrate that this value will reach Java in exit code
    sys.exit(220)

public static void main(String[] args) throws Exception {       
        String filePath = "D:\\test\\test.py";      
        ProcessBuilder pb = new ProcessBuilder()
            .command("python", "-u", filePath, "main33");        
        Process p = pb.start(); 
        BufferedReader in = new BufferedReader(
            new InputStreamReader(p.getInputStream()));
        StringBuilder buffer = new StringBuilder();     
        String line = null;
        while ((line = in.readLine()) != null){           
            buffer.append(line);
        }
        int exitCode = p.waitFor();
        System.out.println("Value is: "+buffer.toString());                
        System.out.println("Process exit value:"+exitCode);        
        in.close();
    }