Replace uses of Enumeration, Vector, etc, in Swing APIs
For example, the JList constructor can take a Vector, but not any other type of collection. There are several problems with this, starting with the fact that no one I know uses Vectors anymore. Secondly, JList should not care what data structure is used to hold the elements that it gets. If anything, JList should take a Collection, and iterate over that to get the list elements.
Also, some methods, such as getExpandedDescendants() and getDescendantToggledPaths() in JTree return Enumerations rather than Iterators.
It would be relatively easy to add these, I think. Please consider it. The introduction of Swing coincided with the introduction of the Collection framework, so it is understandable why Swing doesn't make use of them. That said, it's been years, and for those of us who are used to using Collections classes, they're annoyances that harken back to the days of JDK 1.1