Observer Pattern Pros & Cons


  • 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.


  • 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

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