The Java GIS community is already host to several open-souce toolkits of great capabilitiy. These toolkits provide a great number of services, and allow you the software developer to communicate with a wide varity of spatial information.

The UDIG framework goes the extra mile, providing a well structured application for you to extend. As a software developer you can focus on your tasks needed for your problem. The finding, connecting and display of spatial information can be someone elses problem.