bank.java

Java Classic Examples是我买的两本书：《JAVA经典实例》和《java入门经典源代码》里边附送光盘里带的源码

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

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

        // Credits require 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 Transaction.DEBIT:
      synchronized(transaction.getAccount())
      {
        System.out.println("Start debit of " +
                 transaction.getAccount() + " amount: " + 
                 transaction.getAmount());


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

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