The Observer Pattern is an appropriate design pattern to apply in any situation where you have several objects which are dependent on another object and are required to perform an action when the state of that object changes, or an object needs to notify others without knowing who they are or how many there are.

What is the purpose of the iterator pattern?

Iterator pattern is very commonly used design pattern in Java and . Net programming environment. This pattern is used to get a way to access the elements of a collection object in sequential manner without any need to know its underlying representation.

Which are the consequences of Observer pattern?

Consequences. The Observer pattern lets you vary subjects and observers independently. You can reuse subjects without reusing their observers, and vice versa. It lets you add observers without modifying the subject or other observers.