I know JDK 1.5 pretty well. As we all know, besides new API (such as AtomicInteger, for example), there were major language changes such as providing support for generic, adding enum, prividing auto-boxing and auto-unboxing and so on.
I want to find some resources that have preferably short description of new features in JDK 1.6 and 1.7 (for big new features I prefer to read complete explanations). As far changes of API only major changes is acceptable and short review of new one (if I recall write there is new way to read characters from the console, for example). As far as features goes I want to find complete list (such changes in the allocation of the objects, now JVM can actually creates objects on the stack for optimization purposes, for example, but I don't know the details).
For JDK 1.6 Core Java Technology Features and Java™ SE 6 compatibility with J2SE 5.0. For JDK 1.7 Working with Java SE 7 Exception Changes, but it is incomplete list.
JDK 1.6 Compatibility http://www.oracle.com/technetwork/java/javase/compatibility-137541.html
Core Java Technology Features http://www.oracle.com/technetwork/articles/java/javase6-build39-139826.html http://java.sun.com/developer/technicalArticles/J2SE/Desktop/JavaSE6_build39.html
Java SE 6 Performance White Paper http://www.oracle.com/technetwork/java/6-performance-137236.html
Quick note, implementation of the java.util.ArrayList was changed (due to bug 6260652).
JDK 1.7
Java SE 7 and JDK 7 Compatibility http://www.oracle.com/technetwork/java/javase/compatibility-417013.html (there are some behavioral incompatibilities).
Java SE 7 Features and Enhancements http://www.oracle.com/technetwork/java/javase/jdk7-relnotes-418459.html
A look at Java 7's new features http://radar.oreilly.com/2011/09/java7-features.html (see also http://docs.oracle.com/javase/7/docs/technotes/guides/language/type-inference-generic-instance-creation.html for diamond operator)
(Misc) JDK 7: New Interfaces, Classes, Enums, and Methods http://marxsoftware.blogspot.com/2011/03/jdk-7-new-interfaces-classes-enums-and.html