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Abstract Class & Interface

Abstract Class & Interface


Abstract Class:   Abstract class is same as other class except that it can not be instantiated .
It is generally to write the common functionality in the parent class.
It can have abstract and non-abstract method.
Abstract class can have final, non-final, static and non-static variables.
It can also implement interface and define the methods of interface, but it can not be instantiated.

Interface:  An interface in java is a blueprint of a class. It has static constants and abstract methods only. Interface basically defines the contract for a class to implement.
It is a mechanism to achieve fully abstraction. There can be only abstract methods in the java interface not method body.
It cannot be instantiated like abstract class.
A class can extend multiple Interfaces. An interface can extend multiple Interfaces.
Abstract classInterface
1) Abstract class can have abstract and non-abstract methods.Interface can have only abstract methods.
2) Abstract class doesn't support multiple inheritance.Interface supports multiple inheritance.
3) Abstract class can have final, non-final, static and non-static variables.Interface has only static and final variables.
4) Abstract class can have static methods, main method and constructor.Interface can't have static methods, main method or constructor.
5) Abstract class can provide the implementation of interface.Interface can't provide the implementation of abstract class.





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