This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
"Object locking" and "class locking" aren't established, meaningful terms with specialized, subtle depths of meaning. They just refer to synchronizing on an instance of a class ("object locking") or synchronizing on the java.lang.Class instance that represents a class ("class locking,") Nothing special or mysterious at all about "class locking"; it's just what static methods (aka "class methods") do for synchronization.