Observer and Observable are a pair of interface and class in the java.util package to implement a general purpose Observer pattern. something similar to the event delegation model. Observable is any Object on which Observers may be registered and which notifies the registered Observers about the changes taking place in the state of the Observable. Observer is an interface which is used for implementing the action to be taken when the update is taking place on the Observable.
The Zen of Java Programming.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com