Observer Pattern (4) Step By Step

From step 3, we can see that the BankAccount class is still subject to change, so in this step, we will abstract the BankAccount a bit more, code change in bold:

public class BankAccount

{

ArrayList<IAccountObserver> observerList = new ArrayList<IAccountObserver>();

public void Withdraw(int data)

{

//...

}

public void Notify(UserAccountArgs args)

{

foreach (IAccountObserver observer in observerList)

{

observer.Update(args);

}

}

public void AddObserver(IAccountObserver observer)

{

observerList.Add(observer);

}

public void RemoveObserver(IAccountObserver observer)

{

observerList.Remove(observer);

}

}