In this tutorial, we will learn about basics of OOPs. Object Oriented Programming is a paradigm that provides many concepts such as inheritance, data binding, polymorphism etc.
Simula is considered as the first object-oriented programming language. The programming paradigm where everything is represented as an object, is known as truly object-oriented programming language.
Smalltalk is considered as the first truly object-oriented programming language
Object means a real word entity such as pen, chair, table etc.
Object-Oriented Programming is a methodology or paradigm to design a program using classes and objects.
It simplifies the software development and maintenance by providing some concepts:
Any entity that has state and behavior is known as an object. For example: chair, pen, table, keyboard, bike etc. It can be physical and logical.
Collection of objects is called class. It is a logical entity.
When one object acquires all the properties and behaviors of parent object i.e. known as inheritance. It provides code re-usability. It is used to achieve runtime polymorphism.
When one task is performed by different ways i.e. known as polymorphism. For example: to convense the customer differently, to draw something e.g. shape or rectangle etc.
In java, we use method overloading and method overriding to achieve polymorphism.
Another example can be to speak something e.g. cat speaks meaw, dog barks woof etc.
class Calculation {
void sum(int a,int b){System.out.println(a+b);}
void sum(int a,int b,int c){System.out.println(a+b+c);}
public static void main(String args[]){
Calculation obj = new Calculation();
obj.sum(10,10,10);
obj.sum(20,20);
}
}
Hiding internal details and showing functionality is known as abstraction. For example: phone call, we don't know the internal processing.
In java, we use abstract class and interface to achieve abstraction.
Binding (or wrapping) code and data together into a single unit is known as encapsulation. For example: capsule, it is wrapped with different medicines.
A java class is the example of encapsulation. Java bean is the fully encapsulated class because all the data members are private here.
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