Document Interface Library is an API implementing MDI, SDI and TDI for Java.
Using this document interface library, you can switch your application between MDI, SDI and TDI changing only one line of code. You can also write a simple routine that lets the user choose which document interface model he or she wants to use.
The library is released under GNU LGPL.
Library is from here only available in source code form since it as standalone is aimed at developers. Use the javadoc tool the generate documentation. For better understanding and an example, check out the Notepad-like demo (zipped source code, GNU GPL).