I'm trying to use ProcessBuilder in Java to run some python code. print is causing errors but print() works fine.
The java code is:
List<String> list = Arrays.asList("python", "C:/.../test.py");
ProcessBuilder pb = new ProcessBuilder(list);
Process process = pb.start();
It generates a file if test.py is this
open('C:/.../outputtest2.txt', 'a')
print(5)
but it doesnt't work if test.py is this
open('C:/.../outputtest2.txt', 'a')
print 5
Both work fine if I run the script from the command line. I've tried changing and even removing Python 3 from the PATH but still getting the error. I can't find any similar errors online.
This is a python syntax error. As you know in python 3 you have to put parentheses for print function. for some reasons ( e.g. system cache) your ProcessBuilder use python 3 for running your python code.
This problem should solve by restarting the computer but if it doesn't work, you can run it manually with python 2.x
For example :
List<String> list = Arrays.asList("C:/python27/python.exe", "C:/.../test.py");
ProcessBuilder pb = new ProcessBuilder(list);
Related
I'm trying to train a neural network to play Halite 3. The provided interface is a bash script which:
1. compiles my bot
2. calls the binary file with a string to run the bot java myBot
I'm trying to run this script from Java to train the network.
I've tried using a ProcessBuilder to run the script as well as the binary in the script. Running the script produces no output, and using echo I've determined that the program terminates when javac is called in the script. Removing that call, it terminates when the program is run.
I've tried calling the program directly as well using ProcessBuilder, and this does indeed produce output. The issue is it doesn't run the bots properly saying it can't find the file. I've tried changing the path to be relative to different directory levels as well as the absolute path (the java command doesn't seem to like absolute paths?).
Calling the binary directly:
List<String> cmd = new ArrayList<>();
cmd.add(dir+ "/src/halite");
// Replay
cmd.add("--replay-directory");
cmd.add(dir+"/replays/");
// Options
cmd.add("--results-as-json");
cmd.add("--no-logs");
// Dimensions
cmd.add("--width");
cmd.add("16");
cmd.add("--height");
cmd.add("16");
// Players
cmd.add("\"java -cp . myBot\"");
cmd.add("\"java -cp . myBot\"");
Process proc = new ProcessBuilder(cmd).start();
InputStream is = proc.getInputStream();
Scanner s = new Scanner(is);
while (s.hasNext()){
System.out.println((String) s.next());
}
This code does produce a JSON, however, I get an error in my logs saying that the bots do not run.
In my java program I am trying to run a different program through CMD with its output appearing in a command window in the foreground and then analyze the exit code of the child program (foo) in the main java program. Unfortunately, all I seem to be able to access is the exit code of the CMD window, which is always 0.
The following is a snippet of what I'm doing:
ProcessBuilder pb = new ProcessBuilder();
pb.directory(new File(dir));
pb.command("cmd","/c","start","/wait","foo.exe",arg);
process = pb.start();
exitVal = process.waitFor();
but exitVal is always 0 regardless of how foo exits. How can I get just the exit code of foo?
I'm also pretty new to java so if there's a more elegant way of doing this, I'm open to suggestions.
I found a solution by modifying one of the things I had tried before to account for windows batch being finicky. The solution was to send another command to cmd to tell it to exit with the most recent error code. Earlier I had tried this by appending & exit %errorlevel% to the command but cmd variables are only updated at the end of each command line, not at the end of each command.
To force update, I used %^errorlevel% instead.
I made a new process, but it never finishes.
I was trying with ProcessBuilder and Runtime but none of it worked, both got stuck.
Builder code:
ProcessBuilder a = new ProcessBuilder(
"java",
"-classpath",
"D:\\TAP",
"AnalizadorLexico",
"<",
"D:\\TAP\\Lol1.txt");
Process process=a.start();
Runtime code:
Process process=cmd.exec(
"java -classpath D:\\TAP AnalizadorLexico < D:\\TAP\\Lol1.txt ");
The command works in Windows CMD.
From comments:
The "<" works with cmd(or other shells). Java program does not interpret it as input. You can use "cmd /c java progr < input ", but that makes it windows specific.
A better way will be to use real Java APIs for it: See ProcessBuilder
Once you get past this , please check another FAQ item on this
I have been looking for an answer for how to execute a java jar file through python and after looking at:
Execute .jar from Python
How can I get my python (version 2.5) script to run a jar file inside a folder instead of from command line?
How to run Python egg files directly without installing them?
I tried to do the following (both my jar and python file are in the same directory):
import os
if __name__ == "__main__":
os.system("java -jar Blender.jar")
and
import subprocess
subprocess.call(['(path)Blender.jar'])
Neither have worked. So, I was thinking that I should use Jython instead, but I think there must a be an easier way to execute jar files through python.
Do you have any idea what I may do wrong? Or, is there any other site that I study more about my problem?
I would use subprocess this way:
import subprocess
subprocess.call(['java', '-jar', 'Blender.jar'])
But, if you have a properly configured /proc/sys/fs/binfmt_misc/jar you should be able to run the jar directly, as you wrote.
So, which is exactly the error you are getting?
Please post somewhere all the output you are getting from the failed execution.
This always works for me:
from subprocess import *
def jarWrapper(*args):
process = Popen(['java', '-jar']+list(args), stdout=PIPE, stderr=PIPE)
ret = []
while process.poll() is None:
line = process.stdout.readline()
if line != '' and line.endswith('\n'):
ret.append(line[:-1])
stdout, stderr = process.communicate()
ret += stdout.split('\n')
if stderr != '':
ret += stderr.split('\n')
ret.remove('')
return ret
args = ['myJarFile.jar', 'arg1', 'arg2', 'argN'] # Any number of args to be passed to the jar file
result = jarWrapper(*args)
print result
I used the following way to execute tika jar to extract the content of a word document. It worked and I got the output also. The command I'm trying to run is "java -jar tika-app-1.24.1.jar -t 42250_EN_Upload.docx"
from subprocess import PIPE, Popen
process = Popen(['java', '-jar', 'tika-app-1.24.1.jar', '-t', '42250_EN_Upload.docx'], stdout=PIPE, stderr=PIPE)
result = process.communicate()
print(result[0].decode('utf-8'))
Here I got result as tuple, hence "result[0]". Also the string was in binary format (b-string). To convert it into normal string we need to decode with 'utf-8'.
With args: concrete example using Closure Compiler (https://developers.google.com/closure/) from python
import os
import re
src = test.js
os.execlp("java", 'blablabla', "-jar", './closure_compiler.jar', '--js', src, '--js_output_file', '{}'.format(re.sub('.js$', '.comp.js', src)))
(also see here When using os.execlp, why `python` needs `python` as argv[0])
How about using os.system() like:
os.system('java -jar blabla...')
os.system(command)
Execute the command (a string) in a subshell. This is implemented by calling the Standard C function system(), and has the same limitations. Changes to sys.stdin, etc. are not reflected in the environment of the executed command.
I'm trying to run Python, Ruby, C, C++, and Java scripts from a java program, and Processbuilder was suggested to me as a good way to run the scripts. From what I understand, Processbuilder mostly runs native files (.exe on windows, etc.). However, I have heard a few things about running scripts (nonnative) files using Processbuilder. Unfortunately, everything I find on the subject is incredibly vague.
If someone could clarify a way to run nonnative scripts such as Python, Ruby, etc. I would be most grateful!
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();
To avoid having to manually enter the entire location of the script, which may also result in portability issues, here's what I did:
String pwd = System.getProperty("user.dir");
ProcessBuilder pb = new ProcessBuilder("/usr/bin/python", pwd+'/'+scriptName, arg1, arg2);
Process p = pb.start();