Have you looked at these? They suggest different ways of doing this:

Call Python code from Java by passing parameters and results

How to call a python method from a java class?

In short one solution could be:

public void runPython() 
{ //need to call myscript.py and also pass arg1 as its arguments.
  //and also myscript.py path is in C:\Demo\myscript.py

    String[] cmd = {
      "python",
      "C:/Demo/myscript.py",
      this.arg1,
    };
    Runtime.getRuntime().exec(cmd);
}

edit: just make sure you change the variable name from str to something else, as noted by cdarke

Your python code (change str to something else, e.g. arg and specify a path for file):

def returnvalue(arg) :
    if arg == "hi" :
        return "yes"
    return "no"
print("calling python function with parameters:")
print(sys.argv[1])
arg = sys.argv[1]
res = returnvalue(arg)
print(res)
with open("C:/path/to/where/you/want/file.txt", 'w') as target:  # specify path or else it will be created where you run your java code
    target.write(res)

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();
      }

}

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.

Command line arguments are not stdin. args[0] is a command line argument. You should be able to do it like

cmd = ['java', java_class, 'SomeInputString']

Try using Java ScriptEngine to run the code as Jython.

Sample program:

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class Main {

     /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws ScriptException {
        ScriptEngine engine = new ScriptEngineManager().getEngineByName("python");

        // Using the eval() method on the engine causes a direct
        // interpretataion and execution of the code string passed into it
        engine.eval("import sys");
        engine.eval("print sys");

        // Using the put() method allows one to place values into
        // specified variables within the engine
        engine.put("a", "42");

        // As you can see, once the variable has been set with
        // a value by using the put() method, we an issue eval statements
        // to use it.
        engine.eval("print a");
        engine.eval("x = 2 + 2");

        // Using the get() method allows one to obtain the value
        // of a specified variable from the engine instance
        Object x = engine.get("x");
        System.out.println("x: " + x);
    }

}

You'll need to include the jython engine jar in your classpath. look for it here

Last argument in your below call is for command line arguments:

PythonInterpreter.initialize(System.getProperties(), System.getProperties(), new String[0]);

From PythronInterpreter javadocs:

initialize

public static void initialize(Properties preProperties, Properties postProperties, String[] argv)

Initializes the Jython runtime. This should only be called once, before any other Python objects (including PythonInterpreter) are created. Parameters: preProperties - A set of properties. Typically System.getProperties() is used. preProperties override properties from the registry file. postProperties - Another set of properties. Values like python.home, python.path and all other values from the registry files can be added to this property set. postProperties override system properties and registry properties. argv - Command line arguments, assigned to sys.argv.

You are passing args as the second argument of Runtime.exec(...).

This overrides the default (inherited) environment of the new process to be useless, and hence the Path variable no longer contains the path to python.exe.

You need to use this version of Runtime.exec(...):

public Process exec(String[] cmdarray);

Which you would do so like this:

public static void main(String[] args) {
    ...

    List<String> process_args = new ArrayList<String>(Arrays.asList("cmd", "/c", "python", "ps.py"));
    process_args.addAll(Arrays.asList(args));

    Runtime r = Runtime.getRuntime();
    try {

        Process p = r.exec(process_args.toArray(new String[] {}));
        ...
    } catch (IOException e) {
        ...
    }
}