Object-Oriented programming (OOP) is a computer science term used to characterize a programming language that began development in the 1960�s. The term �object-oriented programming� was originally coined by Xerox PARC to designate a computer application that describes the methodology of using objects as the foundation for computation. By the 1980�s, OOP rose to prominence as the programming language of choice, exemplified by the success of C++. Currently, OOPs such as Java, J2EE, C++, C#, Visual Basic.NET, Python and JavaScript are popular OOP programming languages that any career-oriented Software Engineer or developer should be familiar with.
OOP is widely accepted as being far more flexible than other computer programming languages. OOPs use three basic concepts as the fundamentals for the programming language: classes, objects and methods. Additionally, Inheritance, Abstraction, Polymorphism, Event Handling and Encapsulation are also significant concepts within object-oriented programming languages that are explained in online tutorials describing the functionality of each concept in detail.
Class
A Class is a user defined datatype which contains the variables, properties and methods in it. 'A class defines' the abstract characteristics of a thing (object), including its characteristics and the thing's behaviors . One might say that a class is a blueprint or factory that describes the nature of something. For example, the class Dog would consist of traits shared by all dogs, such as breed and fur color (characteristics), and the ability to bark and sit (behaviors). Collectively, the properties and methods defined by a class are called members.
Method
Method is a set of procedural statements for achieving the desired result. It performs different kinds of operations on different data types. In a programming language, methods (sometimes referred to as "functions") are verbs.
Inheritance
Inheritance is a process in which a class inherits all the state and behavior of another class. this type of relationship is called child-Parent or is-a relationship. "Subclasses" are more specialized versions of a class, which inherit attributes and behaviors from their parent classes, and can introduce their own.
Abstraction
Abstraction is simplifying complex reality by modeling classes appropriate to the problem, and working at the most appropriate level of inheritance for a given aspect of the problem.
Encapsulation
Encapsulation conceals the functional details of a class from objects that send messages to it.
Encapsulation is achieved by specifying which classes may use the members of an object. The result is that each object exposes to any class a certain inteface � those members accessible to that class. The reason for encapsulation is to prevent clients of an interface from depending on those parts of the implementation that are likely to change in the future, thereby allowing those changes to be made more easily, that is, without changes to clients. For example, an interface can ensure that puppies can only be added to an object of the class Dog by code in that class. Members are often specified as public, protected or private, determining whether they are available to all classes, sub-classes or only the defining class. Some languages go further: Java uses the default access modifier to restrict access also to classes in the same package,C# and VB.Net reserve some members to classes in the same assembly using keywords internal (C#) or Friend (VB.NET), and Eiffel and C++ allow one to specify which classes may access any member.
polymorphism
Polymorphism allows the programmer to treat derived class members just like their parent class's members. More precisely, Polymorphism in OOP is the ability of objects belonging to different data types to respond to calls of methods of the same name, each one according to an appropriate type-specific behavior. One method, or an operator such as +, -, or *, can be abstractly applied in many different situations.