I was looking for a Java library to manipulate files using the PDF (Portable Document File) format. The two obvious possibilities seemed to be:
BTW This isn't a detailed comparison but a general impression of the two products (a gut feeling)...Hmm decisions, decisions....
I downloaded both JARs and checked out the documentation. I soon realised that there was a big difference in the quantity of documentation available (iText has a lot more). Which makes sense since Bruno Lowagie (iText creator) has been working on the library since about 1999 while PDF Clown is relatively new.
I started out by installing the Jar files in Eclipse and trying out a simple example. Unfortunately I seemed to have a small problem with the PDF Clown example (SerializationModeEnum.Compact mentioned in the UserGuide didn't seem to exist) while the iText example worked fine.
I also then read the following note about PDF Clown: "This project is young, so that it's to be considered UNSTABLE. Feel free to experiment with it, but DO NOT use it in a production environment (so: beware!)" at: http://www.stefanochizzolini.it/en/projects/clown/downloads.html#License Needless to say it didn't really fill me with confidence for PDF Clown ;-)
On the other hand iText has been used successfully by numerous commercial and open source applications: Macromedia ColdFusion (now belongs to Adobe), Jasper-Reports, Eclipse/BIRT, Google Calendar, etc.
For these reasons I decided to go with iText.
The main inconvenient with iText is that it doesn't properly implement the MVC (Model-View-Controller) pattern, meaning that it doesn't give the possibility to properly separate content and presentation.
The fact that I chose iText does not mean that PDF Clown is without merit: I like the object-oriented approach Stefano Chizzolini has taken. I simply feel that the library needs a bit more time before truly becoming mature.
If following this article people are interested in using iText I would advise to get Bruno Lowagie's book "iText in Action": http://www.1t3xt.com/docs/book.php which is pretty much a definite guide.