Per Henrik Lausten

The return value of the Java method getItemValueString has been changed in Lotus Domino 6.5.5, Lotus Domino 7.0 and later releases. Before 6.5.5 the method getItemValueString returns null if the item is empty or if the item does not exist. In 6.5.5, 7.0 and later releases getItemValueString returns the empty string (“”) instead.
I upgraded three [...]

Google Web Toolkit has been released. From the overview: “Google Web Toolkit (GWT) is a Java development framework that lets you escape the matrix of technologies that make writing AJAX applications so difficult and error prone. With GWT, you can develop and debug AJAX applications in the Java language using the Java development tools [...]

Be sure to have a look at the “Java in Notes/Domino Explained” series by Mikkel Heisterberg. Great introdocution to using Java in the Domino environment.