Why is Java Observer deprecated?

Ans: The Observable class and the Observer interface have been deprecated in Java 9 because the event model supported by Observer and Observable is quite limited, the order of notifications delivered by Observable is unspecified, and state changes are not in one-for-one correspondence with notifications.

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What is a concrete Observer?

The ConcreteObservers are classes that contain information specific to the current instance . The update function is called by the subject’s notify() operation. The observers update independently based on their current state. The Observer is the parent class of the concrete observers.

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What is Observer pattern in C++?

Observer in C++ Observer is a behavioral design pattern that allows some objects to notify other objects about changes in their state . The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface.

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