Observer Pattern Pros & Cons

Pros:

• Supports the principle to strive for loosley coupled designs between objects that interact.
• Allows you to send data to many other objects in a very efficient mannor.
• No modification is need to be done to the subject to add new observers.
• You can add and remove observers at anytime.

Cons

• Java’s built in class Observable forces the use of inheritance vs programming to an interface
• Observable protects crucial methods which means you can’t even create an instance of the Observable class and compose it with your own objects, you have to subclass.
• If not used carefully the observer pattern can add unecessary complexity
• The order of Observer notifications is undependable