The ABCs of Synchronization for Intermediate Readers

Java threads, especially synchronization, are among my favorite things
to read about. Jeff Friesen's Java Tech: The ABCs of Synchronization, Part 2 makes the trickier problems understandable without assuming you already know the subject inside out.

The article introduces wait and notify, walks through a producer-consumer example, outlines the problem with local copies of values, and throws in a brief look at the new classes in java.util.concurrent (J2SE 5.0). There's also a particularly interesting exercise at the end to see what you've learned.