Java OCA OCP Practice Question 13

Question

Which of the following are true about Observer and Observable?

  • A. Observer is an interface and Observable is a class?
  • B. When an Observable object is updated it invokes the update() method of its observers.
  • C. Observable objects must be GUI components.
  • D. They are in the Collections API.


A and B.

Note

Observer and Observable are not part of the Collections API.

They do not have any relationship to GUI components.




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