Executing Java JAR With Popen: Couldn't Find or Load Main Class JAR

Question

My Java JAR executes fine in linux command line, and I would like to have it executed through a python script.

I get the following error when trying Popen:

Error: Could not find or load main class jar

Any ideas?

What I've tried thus far:

1. Command line execution of JAR file. Checked.
2. Popen with simple java and -version. checked.
3. Update cwd. Checked.

Working Java call:

>>> javaCall = subprocess.Popen(['java', '-version'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

Failed command:

>>> javaCall = subprocess.Popen(['java', 'jar' , 
'abs/path/to/jar/abc.jar', 
'arg 1', 'arg 2', 'arg 3'], cwd = 
'/abs/path/where/jar and python files live', stdin=subprocess.PIPE, 
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
>>> output, err = javaCall.communicate()
>>> print err
Error: Could not find or load main class jar

Any pointers I'm missing?

• drelliot: Add a - in front of jar ['java', '-jar' ]
• Simply_me: @drelliot. Lol, good catch. it did the trick. Please put it in an answer and I'll mark it.
• drelliot: No worries! happy to help

Answer 1

Missing a - in front of jar

javaCall = subprocess.Popen(['java', 'jar' , 
'abs/path/to/jar/abc.jar', 
'arg 1', 'arg 2', 'arg 3'], cwd = 
'/abs/path/where/jar and python files live', stdin=subprocess.PIPE, 
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
>>> output, err = javaCall.communicate()
>>> print err
Error: Could not find or load main class jar

Change to: javaCall = subprocess.Popen(['java', '-jar' , ~~~