// Define the bank

public class Bank {
  // Perform a transaction
  public void doTransaction(Transaction transaction, int clerkID) {
    synchronized(transaction.getAccount()) {
      int balance = 0;
      switch(transaction.getTransactionType()) {
        case CREDIT:
          System.out.println("Clerk " + clerkID + ": Start credit of " +
                  transaction.getAccount() + " amount: " +
                  transaction.getAmount());

          // Get current balance
          balance = transaction.getAccount().getBalance();

          // Credits require a lot of checks...
          try {
            Thread.sleep(200);

          } catch(InterruptedException e) {
            System.out.println(e);
          }
          balance += transaction.getAmount();                          // Increment the balance
          transaction.getAccount().setBalance(balance);                // Restore account balance
          System.out.println("  End credit of " +
                  transaction.getAccount() + " amount: " +
                  transaction.getAmount());
          break;

        case DEBIT:
          System.out.println("Clerk " + clerkID + ": Start debit of " +
                  transaction.getAccount() + " amount: " +
                  transaction.getAmount());

          // Get current balance
          balance = transaction.getAccount().getBalance();

          // Debits require even more checks...
          try {
            Thread.sleep(500);
          } catch(InterruptedException e) {
            System.out.println(e);
          }
          balance -= transaction.getAmount();                          // Increment the balance...
          transaction.getAccount().setBalance(balance);                // Restore account balance

          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);
      }
    }
  }
}