Reading Java system.out.print via Python subprocess [duplicate]

Question

I am running a Python script that runs a Java class that requires nondeterministic user input:

import sys
import subprocess
from subprocess import Popen, PIPE

p = Popen("java myclass", shell=True, stdout=subprocess.PIPE)

while True:
    inline = p.stdout.readline()
    if not inline:
        break

sys.stdout.write(inline)
sys.stdout.flush()

When output is displayed using System.out.print(), the output is displayed properly. However, when a prompt for user input is printed with System.out.print(), the output is not displayed. I tried switching p.stdout.readline() to p.stdout.read(), but then no output is displayed. Is there a way to display an input prompt that does not have a carriage return?

EDIT

For example, if the Java class contains the following:

System.out.println("Message 1);
System.out.println("Message 2);
System.out.print("Enter a number:")

Running the pure Java code would display all 3 lines.

The code running through Python would only display the following:

Message 1
Message 2

You can use strip to remove the carriage return : inline = p.stdout.readline().strip() — Ashwini Chaudhary
– Ashwini Chaudhary, Commented Apr 25, 2013 at 20:26
I am confused. All System.out prints are done to STDOUT, so reading it should be no different. However, a System.in is reading from STDIN, so you would have to write out the "user input" with the appropriate combination of keys to indicate the input had stopped. — CodeChimp
– CodeChimp, Commented Apr 25, 2013 at 20:28

constantlearner · Accepted Answer · 2013-04-25 20:47:30Z

2

p1 = subprocess.Popen(["/usr/bin/java", "MyClass"], stdout=subprocess.PIPE)
print p1.stdout.read()

answered Apr 25, 2013 at 20:47

constantlearner

5,2477 gold badges47 silver badges65 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Joe Devilla Over a year ago

Thanks, I was able to get the prompt using this:

Collectives™ on Stack Overflow

Reading Java system.out.print via Python subprocess [duplicate]

1 Answer 1

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Linked

Related