What is abstraction in oops?

Answer 1

Abstraction means to describe with a term or a brief sentence that the audience can understand the entirety.

In OOPS context, the program unit is an abstraction by itself. When we use the term "program", we sort of know what it is, yet don't know anything of the detail what it can and will do.

Hence, any software element may be thought of as an abstraction in OOPS if you do not know the detail implementation!! The element may be small as a method, a property, a class, an interface, and up to the entire application/program itself.

Answer 2

Abstraction is simplifying complex reality by modelling classes appropriate to the problem, and working at the most appropriate level of inheritance for a given aspect of the problem.

For example, Lassie the Dog may be treated as a Dog much of the time, a Collie when necessary to access Collie-specific attributes or behaviors, and as an Animal (perhaps the parent class of Dog) when counting Timmy's pets.

Abstraction is also achieved through Composition. For example, a class Car would be made up of an Engine, Gearbox, Steering objects, and many more components. To build the Car class, one does not need to know how the different components work internally, but only how to interface with them, i.e., send messages to them, receive messages from them, and perhaps make the different objects composing the class interact with each other.

Answer 3

The keyword abstract can be used with both classes and methods in Java.

An abstract class can never be instantiated. Its sole purpose or rather mission in life is to be extended (subclassed).

An abstract method is a method that's been declared as abstract but not implemented. In other words, the method contains no code. You mark a method abstract when you want to force subclasses to provide the implementation.