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Is multiple interface possible?
Yes, a class can implement multiple interfaces. Each interface provides contract for some sort of behavior.
Do you have to use every method in an interface?
Yes, it is mandatory to implement all the methods in a class that implements an interface until and unless that class is declared as an abstract class. Implement every method defined by the interface.
Is it possible to declare an interface as final?
Making an interface final. If you make a method final you cannot override it and, if you make a variable final you cannot modify it. If you make an interface final, you cannot implement its methods which defies the very purpose of the interfaces. Therefore, you cannot make an interface final in Java.
When do you need to register multiple implementations of the same interface?
One of those cases is when you need to register multiple implementations of the same interface. Not as bad as it seems, there are several ways to overcome this limitation and here are some of them which may or may not work for your specific case, but definitely some ideas how to solve your problem.
Can a class implement multiple interfaces in Java?
Yes, multiple (any number of) classes can implement one interface. Multiple inheritance using classes is not supported in Java & leads to a very famous problem known as Diamond problem where as it is supported using interfaces. , Oops ! Yes multiple classes can implement one interface irrespective of being in the same program or different.
When do you do not need to implement an interface?
The Reset method is provided for COM interoperability. It does not necessarily need to be implemented; instead, the implementer can simply throw a NotSupportedException. By a mistake of the design of the interface, it should have been more than one interface in the first place.
Can a class extend more than one interface?
One class can extend only one class at a time. One class can implement ‘n’ number of interfaces at a time. One interface can extends more than one interface simultaneously. Interface cannot implements or extends a class. Since defined things cannot be made as undefined things.