Das deutsche Python-Forum

Excuse my English, mein Deutsch is nicht gut.

I had a java application which was testing servers. We are migrating to python, and for a start we are making use of the jar from the java application.

I use the jar in my python script, and call the

```
subprocess.call(
['java', '-jar', 'XYZ.jar', '-url', 'opc.tcp://localhost:XXXX', '-check', 'AB', '-specVersion', '2.0', '-test', 'testclient.TestGeneral'])

```
This works perfect!
However, we plan to have a clear structure by using classes(OOP).

So I make some modifications and I write the below

```
class TestClient:

def performTest(self):

subprocess.call(['java', '-jar', 'XYZ.jar', '-url', 'opc.tcp://localhost:XXXX', '-check', 'AB', '-specVersion', '2.0', '-test', 'testclient.TestGeneral'])


if __name__ == "__main__":
client = TestClient()
client.performTest()
```

I get an error saying

```
Error: Unable to access jarfile XYZ.jar
```

How is it that the jar becomes unaccesable? Am i missing something here? Please let me know

Methodes are written in Python all lower case: perform_test.
Use only classes, if you really need them. In contrast to Java, you don't have to put everything in classes.

Besides introducing classes you also changed something in running your program. The file XYZ.jar is not in your current working directory.

Thank you for your reply.
I figured out the error. In pycharm IDE, I had not added the working directory for the run configuration. My silly mistake

https://python-forum.io/thread-34390.html and again

NB: I would use `run()` instead of `call()`. See the documentation for more information. And ``check=True`` so error exit codes are not silently ignored in the Python program.

To second Sirius3: classes are there for a reason, and that reason ist *not* to write simple functions in a more complicated way that they need to be. If you don't use `self` or just have one method besides `__init__()` so `__init__()` basically is just an extra step to get arguments to that one method, there is a good chance you don't really have a use case for a class.

Thanks for the suggestion . I had missed adding the directory path for my new run configuration in pycharm. Got it working through that