The Sun Certified Java Developer Exam with J2SE 5: paper version from Amazon, PDF from Apress, Online reference: Books 24x7 Personal blog
On the other hand, from the assignment specification, lock/unlock should NOT be used for lock/unlock since only ONE client is assumed to use the system, as far as lock/unlock overhead is concerned for non-netowked mode.
The Sun Certified Java Developer Exam with J2SE 5: paper version from Amazon, PDF from Apress, Online reference: Books 24x7 Personal blog
The Sun Certified Java Developer Exam with J2SE 5: paper version from Amazon, PDF from Apress, Online reference: Books 24x7 Personal blog