Threads - Beginning Java - page 792

System.out.println(" End debit of " +
transaction.getAccount() + " amount: " +
transaction.getAmount());

break;

default: // We should

never get here
System.out.println("Invalid transaction");
System.exit(1);

}

}

}

}

Directory "UsingExecutors"

The doTransaction() method for the Bank object is executed in a Clerk thread. The code in the
doTransaction() method for the bank is synchronized on the account to which the transaction applies.
This ensures that only one clerk can access any given account at a time. As before, debits take longer
than credits to process. The doTransaction() method includes output for each transaction that is pro-
cessed so you can see all the details of what goes on in the bank before that final accounts are displayed.
Running Banking Operations
The main() method creates and initiates all the threads that operate the bank. Here's the class definition:

import java.util.Vector;
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

public class UsingExecutors {

public static void main(String[] args) {
int[] initialBalance = {500, 800}; // The initial

account balances
int[] totalCredits = new int[initialBalance.length]; // Two cr

totals

int[] totalDebits = new int[initialBalance.length]; // Two db

totals

int transactionCount = 20; // Number of debits and

of credits
int clerkCount = 2;

// Create the account, the bank, and the clerks...