The use of Object Oriented (OO) design and Object Oriented Programming (OOP) are becoming increasingly
popular. Thus, it is useful to have an introductory understanding of OOP and some of the
programming features of OO languages. You can develop OO software in any high level language, like
C or Pascal. However, newer languages such as Ada, C++, and F90 have enhanced features that make
OOP much more natural, practical, and maintainable. C++ appeared before F90 and currently, is probably
the most popular OOP language, yet F90 was clearly designed to have almost all of the abilities of
C++ . However, rather than study the new standards many authors simply refer to the two decades old
F77 standard and declare that Fortran can not be used for OOP. Here we will overcome that misinformed
point of view.
Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface.
The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code.
4 Key concepts of OOP
Inheritance
Encapsulation
Polymorphism
AbstractionEncapsulation
Polymorphism
Inheritance
In object-oriented programming (OOP), inheritance is when an object or class is based on another object (prototypal inheritance) or class (class-based inheritance), using the same implementation (inheriting from an object or class) specifying implementation to maintain the same behavior (realizing an interface; inheriting behavior). It is a mechanism for code reuse and to allow independent extensions of the original software via public classes and interfaces. The relationships of objects or classes through inheritance give rise to a hierarchy. Inheritance was invented in 1967 for Simula.
Encapsulation
Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding.
Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface.
The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code.
Benefits of Encapsulation
- The fields of a class can be made read-only or write-only.
- A class can have total control over what is stored in its fields.
Polymorphism
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.Any Java object that can pass more than one IS-A test is considered to be polymorphic. In Java, all Java objects are polymorphic since any object will pass the IS-A test for their own type and for the class Object.
It is important to know that the only possible way to access an object is through a reference variable. A reference variable can be of only one type. Once declared, the type of a reference variable cannot be changed
A reference variable can refer to any object of its declared type or any subtype of its declared type. A reference variable can be declared as a class or interface type.
Abstraction
In object-oriented programming, abstraction is one of 4 central principles (along with encapsulation and inheritance). Through the process of abstraction, a programmer hides all but the relevant data about an object in order to reduce complexity and increase efficiency.
