What is abstraction ?
Abstraction in Java or Object oriented programming is a way to segregate implementation from interface and one of the five fundamentals along with Encapsulation, Inheritance, Polymorphism, Class and Object. Abstraction in Java is achieved by using interface and abstract class in Java. An interface or abstract class is something which is not concrete , something which is incomplete. In order to use interface or abstract class we need to extend and implement abstract method with concrete behavior. One example of Abstraction is creating interface to denote common behavior without specifying any details about how that behavior works e.g. You create an interface called Server which has start() and stop() method. This is called abstraction of Server because every server should have way to start and stop and details may differ. As I said earlier Abstraction in Java is implemented using abstract class and interface as discussed in next section. In fact What is abstraction in Java, Difference between Abstraction and Encapsulation is also a very popular core Java interview because strong OOPS skill is one of the primary requirement for Java developers.
