This page summarizes the differences between the 1.2 and 1.3 releases
of the Collections Framework, along with a brief rationale for each change.
Added singletonList and singletonMap.
Previously, there was a convenience implementation for singleton Set, but no
corresponding implementation for List and Map.
Previously, there were constants for the empty Set and List, but no
corresponding constant for Map.
constuctor for WeakHashMap. The
Map interface dictates that most
Map implementations should have a "copy constructor" that takes a Map
argument. WeakHashMap lacked such a constructor in the 1.2 release.