Which of these methods is used to notify observer the change in observed object?
A. update()
B. notify()
C. check()
D. observed()
Answer: Option A
This Question Belongs to Java Program >> Interfaces And Abstract Classes
A. A contract specifying a set of methods that a class must implement
B. A class that cannot be instantiated
C. A class that contains only static methods
D. A subclass of the Object class
In Java, can a class implement multiple interfaces?
A. Interfaces cannot be implemented by classes
B. Only abstract classes can implement interfaces
C. No, a class can only implement one interface
D. Yes, a class can implement multiple interfaces
What is the purpose of an abstract class in Java?
A. To declare abstract methods
B. To provide a base class with common methods and fields
C. To make a class final
D. To declare abstract methods
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