// Define the bank

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

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

            // Credits require a lot of checks...
            try {
              Thread.sleep(100);

            } 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("Start debit of " +
                    transaction.getAccount() + " amount: " +
                    transaction.getAmount());

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

            // Debits require even more checks...
            try {
              Thread.sleep(150);

            } catch(InterruptedException e) {
              System.out.println(e);
            }
            balance -= transaction.getAmount();                        // Decrement 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);
      }
    }
  }
}