OOPs concepts

In this article we will learn about OOP ( Object oriented programing ) concepts. If you want to learn further lessons about objects, classes, inheritance, polymorphism, how objects interact with each other then you must read these lesson carefully.

There are total 7 core OOPs concepts.

 1. Abstraction 

Abstraction is the concept of hiding the internal details and describing things in simple terms. For example, a method that adds two integers. The method internal processing is hidden from outer world. There are many ways to achieve abstraction in object oriented programming, such as encapsulation and inheritance.

A java program is also a great example of abstraction. Here java takes care of converting simple statements to machine language and hides the inner implementation details from outer world.

 2. Encapsulation

Encapsulation is the technique used to implement abstraction in object oriented programming. Encapsulation is used for access restriction to a class members and methods.

Access modifier keywords are used for encapsulation in object oriented programming. For example, encapsulation in java is achieved using private, protected and public keywords.

 3.  Inheritance 


Inheritance is the object oriented programming concept where an object is based on another object. Inheritance is the mechanism of code reuse. The object that is getting inherited is called superclass and the object that inherits the superclass is called subclass.

We use extends keyword in java to implement inheritance. 

 4. Polymorphism 


Polymorphism is the concept where an object behaves differently in different situations. There are two types of polymorphism – compile time polymorphism and runtime polymorphism.

Compile time polymorphism is achieved by method overloading.

Runtime polymorphism is implemented when we have “IS-A” relationship between objects. This is also called as method overriding because subclass has to override the superclass method for runtime polymorphism. If we are working in terms of superclass, the actual implementation class is decided at runtime. Compiler is not able to decide which class method will be invoked. This decision is done at runtime, hence the name as runtime polymorphism or dynamic method dispatch.

 5. Association 


Association is the OOPS concept to define the relationship between objects. Association defines the multiplicity between objects. For example Teacher and Student objects. There is one to many relationship between a teacher and students. Similarly a student can have one to many relationship with teacher objects. However both student and teacher objects are independent of each other.

 6. Aggregation 


Aggregation is a special type of association. In aggregation, objects have their own life cycle but there is an ownership. Whenever we have “HAS-A” relationship between objects and ownership then it’s a case of aggregation.

For example consider two classes Student class and Address class. Every student has an address so the relationship between student and address is a Has-A relationship. But if you consider its vice versa then it would not make any sense as an Address doesn’t need to have a Student necessarily. 

 7. Composition 


Composition is a special case of aggregation. Composition is a more restrictive form of aggregation. When the contained object in “HAS-A” relationship can’t exist on it’s own, then it’s a case of composition. For example, House has-a Room. Here room can’t exist without house.

Comments

Post a Comment

Popular posts from this blog

Building blocks of .NET

Image
In this article we view three key (and interrelated) topics that make it all possible: the CLR, CTS, and CLS . Common Language Runtime From a programmer’s point of view, .NET can be understood as a runtime environment and a comprehensive base class library. The runtime layer is properly referred to as the Common Language Runtime , or CLR. The primary role of the CLR is to locate, load, and manage .NET objects on your behalf. The CLR also takes care of a number of low-level details such as memory management, application hosting, coordinating threads, and performing basic security checks (among other low-level details). Common Type System Another building block of the .NET platform is the Common Type System , or CTS. The CTS specification fully describes all possible data types and all programming constructs supported by the runtime, specifies how these entities can interact with each other, and details how they are represented in the .NET metadata format. Common Languag...
Read more

Command line argument

Image
With the first introduction post of C# you can understand the return value of the Main() method, let’s examine the incoming array of string data. Assume that you now want to update your application to process any possible command-line parameters. One way to do so is using a C# for loop. We will see for loop in C# in later article. Accessing command line arguments with for loop Program using System; public class CLA { public static void Main(string[] args) { //this loop prints any number of given command line arguments for(int i=0; i<args.Length; i++) { Console.WriteLine("arg-" + i + " = " + args[i]); } } } Output F:\Code\Algorithm>csc CLA.cs F:\Code\Algorithm>CLA tangled java elaborately arg-0 = tangled arg-1 = java arg-2 = elaborately Explanation Here, you are checking to see whether the array of strings contains some number of items using the Length property of Sys...
Read more

Datatype and keyword

Image
Like any programming language, C# defines keywords for fundamental data types, which are used to represent local variables, class data member variables, method return values, and parameters. Unlike other programming languages, however, these keywords are much more than simple compiler- recognized tokens. Rather, the C# data type keywords are actually shorthand notations for full-blown types in the System namespace. Table lists each system data type, its range, the corresponding C# keyword, and the type’s compliance with the common language specification (CLS). C# keyword System type Range Meaning CLS complaint? bool System.Boolean true or false Represents truth or falsity Yes sbyte System.SByte -128 to 127 signed 8-bit number No byte System.Byte 0 to 255 Unsigned 8-bit ...
Read more