if we hv abstract class then why we use interface?
An Abstract class is similar to an interface. You cannot instantiate them, but you can extend them. Any class that extends the abstract class has to provide the implementation to the abstract methods. Hence these classes can be used as a skeleton to similar classes where some common functionality may be required. Such functionality can also be embedded into these classes. Unlike interfaces, abstract classes can have method code also. So they are very useful.
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