You can download the source code for the examples in the book and the solutions to the following exercises from http://www.wrox.com.
Modify the last example in the chapter so that each transaction is a debit or a credit at random.
Modify the result of the previous exercise to incorporate an array of clerks, each running in their own thread and each able to handle both debits and credits.
Extend the result of the previous exercise to incorporate two supervisors for two teams of clerks, where the supervisors each run in their own thread. The supervisor threads should originate transactions and pass them to the clerks they supervise.