Getting started with Jython
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A student in my Python Fundamentals class asked me to demonstrate how to get started with Jython.
I've never used Jython and I'm not a Java programmer (processing doesn't count!) but I agreed to see if I could install it and demonstrate using a Java standard library class for him.
I didn't use my package manager to install but went the manual route, downloading the latest stable version from jython.org. This got me a file called jython_installer-2.5.2.jar. Did I mention I'm not a Java programmer? Still some vague memory prompted me to try:
$ java -jar jython_installer-2.5.2.jar
Aha! This popped up a graphical installer window! I selected my language, accepted the license, accepted the default installation components and chose an installation location of ~/bin/jython2.5.2. Then I was asked to pick a java home directory with the default being the current directory. I had no idea what this meant but noticed a second option of '/usr/lib/jvm/java-6-openjdk/jre' which existed and seemed a plausible choice.
The installer finished and I was off to see what new stuff I had in my install directory.
$ cd ~/bin/jython2.5.2 $ ./jython Jython 2.5.2 (Release_2_5_2:7206, Mar 2 2011, 23:12:06) [OpenJDK Server VM (Sun Microsystems Inc.)] on java1.6.0_20 Type "help", "copyright", "credits" or "license" for more information. >>>
Of course now I have no idea what I can do with the Java standard library. I googled for "Java standard libary" and found myself at the official docs for Java. Oh yeah - I guess Oracle owns Java now... Let's see: Java.math.BigInteger looks interesting. Can I import it?
>>> from java.math import BigInteger >>> x = BigInteger("10000000000000000000000") >>> y = BigInteger("10000000000000000000000") >>> x + y Traceback (most recent call last): File "", line 1, in TypeError: unsupported operand type(s) for +: 'java.math.BigInteger' and 'java.math.BigInteger' >>> dir(BigInteger) ['ONE', 'TEN', 'ZERO', '__class__', '__copy__', '__deepcopy__', ... snip... 'abs', 'add', 'and', 'andNot', 'bit', ...] >>> x.add(y) 20000000000000000000000
Yes, that is a big integer!
I also poked around in the demos a bit - Demo/awt/Colors.py is an 18 line Python program that looks pretty simple and running it:
$ jython Demos/awt/colors.py
reveals that it uses the AWT toolkit to put a bunch of labels with color names and the corresponding color in a gui window. Jython seems to do what it says on the label - lets me talk to Java classes but with the Python runtime - and it seems simple enough to get started on. Good luck!
Published at DZone with permission of Simeon Franklin, DZone MVB. See the original article here.
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