Threads and Concurrent Programming

The Clerk Class

The Clerk thread should simulate the behavior of serving the next customer in line, so the Clerk thread will repeatedly access TakeANumber.nextCustomer() and then serve that customer.  For the sake of this simulation, we’ll just print a message to indicate which customer is being served. Because there’s only one clerk in this simulation, the only variable in its internal state will be a reference to the TakeANumber object (Fig. 14.22). In addition to the constructor, all we really need to define for this class is the run() method. This leads to the definition of Clerk shown in Figure 14.23. In this case, the sleep() method is necessary to allow the Customer threads to run. The Clerk will sit in an infinite loop serving the next customer on each iteration.