Tutorial 0 - Hello, world!¶
In this tutorial, you’ll take a really simple “Hello, world!” program written in Python, convert it into a classfile, and run it on the Java Virtual Machine.
This tutorial assumes you’ve read and followed the instructions in Installation. If you’ve done this, you should have:
- Java 7 (or higher) installed and available on your path,
envdirectory for your virtualenv
tutorialdirectory with a VOC checkout,
- An activated Python 3.4+ virtual environment,
- VOC installed in that virtual environment,
- A compiled VOC support library.
Start a new project¶
Let’s start by creating a
tutorial0 directory in the tutorial directory alongside the
voc directory you just cloned into:
$ mkdir tutorial0 $ cd tutorial0
So that your directory structure looks like:
tutorial ├── env ├── ouroboros ├── tutorial0 └── voc
Then create a file called
example.py in this
Add the following Python code to
Save the file. Run VOC over this file, compiling the Python code into a Java class file:
$ voc -v example.py
This runs the VOC compiler over the
example.py source file. The
asks VOC to use verbose output so you can see what is going on.
You will see output like the following:
Compiling example.py ... Writing python/example.class ...
This will produce an
example.class in the
This classfile can run on any Java 6 (or higher) VM. To run the project, type:
- On Linux / OS X
$ java -classpath ../voc/dist/python-java-support.jar:. python.example Hello World!
- On Windows
> java -classpath ../voc/dist/python-java-support.jar;. python.example Hello World!
Congratulations! You’ve just run your first Python program under Java using VOC! Now you’re ready to get a little more adventurous.