Compiling java from python

Question

I'm writing a script to compile a .java file from within python But the error

import subprocess
def compile_java(java_file):
    cmd = 'javac ' + java_file 
    proc = subprocess.Popen(cmd, shell=True)

compile_java("Test.java")

Error:

javac is not recognized as an internal or external command windows 7

I know how to fix the problem for CMD on windows. But how do I solve it for python? What I mean is: how do i set the path?

Are you sure javac is actually on your Windows PATH? That's likely what it's using — Chris Thompson
– Chris Thompson, Commented Aug 10, 2011 at 19:02
Instead of setting the PATH, why not simply provide the absolute path of javac (or javac.exe in your case)? — Bart Kiers
– Bart Kiers, Commented Aug 10, 2011 at 19:18
You can try os.environ['PATH'] = PathToJava and see if that works. It works on Linux but I've never tried on Windows. — bschaffer13
– bschaffer13, Commented Aug 10, 2011 at 19:23

agf · Accepted Answer · 2011-08-10 19:23:36Z

10

proc = subprocess.Popen(cmd, shell=True, env = {'PATH': '/path/to/javac'})

or

cmd = '/path/to/javac/javac ' + java_file 
proc = subprocess.Popen(cmd, shell=True)

answered Aug 10, 2011 at 19:23

agf

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2 Comments

Jean-François Fabre Over a year ago

you really don't need shell=True, just pass the arguments as a list

agf Over a year ago

@Jean-FrançoisFabre He may need that for other env setup we don't know about; it was in the question so I left it in the answer.

3ck · Accepted Answer · 2011-08-12 21:01:20Z

1

You can also send arguments as well:

            variableNamePython = subprocess.Popen(["java", "-jar", "lib/JavaTest.jar", variable1, variable2, variable3], stdout=subprocess.PIPE)
            JavaVariableReturned = variableNamePython.stdout.read()
            print "The Variable Returned by Java is: " + JavaVariableReturned

The Java code to receive these variables will look like:

public class JavaTest {
    public static void main(String[] args) throws Exception {
        String variable1 = args[0];
        String variable2 = args[1];
        String variable3 = args[2];

edited Aug 12, 2011 at 21:01

answered Aug 12, 2011 at 18:48

3ck

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1 Comment

Paŭlo Ebermann Over a year ago

Welcome to Stack Overflow! Could you change your example so it applies to the problem at hand, i.e. invoking javac Test.java instead of java -jar lib/JavaMail.jar?

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