There is all manner of good stuff in here - GeoTools really makes use of the collections API and these classes help along the way:
- DisjointSet - two disjoint sets will keep each other in sync (as content is added to one set it will be removed from the other and vice versa)
- DerivedSet - abstract class for when you want to make a sub set
- DerivedMap - abstract class for when you want to make a sub map
Deprecate Collections
A few of our collection implementations were deprecated when we upgraded to Java 1.4:
- Singleton - please use Collections.singleton( obj )