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Object-Oriented Programming Concepts

Updated on 15 February 2020
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Java Object oriented programmi
7 min read 2 views
Updated on 15 February 2020

OOP is a very important concept of programming languages like C++, Java, and Python. Before Object-Oriented Programming programs were treated as procedures. In Object-Oriented Programming, objects are the most important part of your program. Accessing and changing these objects to get results is the main point of Object-Oriented Programming. As the name suggests OOPs Programming language means a language that uses the OOPs concept. 

The main key concepts in OOPs are: 




Class




Modifiers- It defines the scope of a class. In Java Public and Default modifier is used before class.

Private and Protected modifiers can not be used with the class names

Example 1- 

//Default Modifier

class Test{ ... }


Example 2- 

//Public Modifier

public class Test{ ... }


Class Name- The class name should begin with capital letters (But it is not mandatory).


Example - 

class DemoClass { 

}


Body- In java, the class body should be surrounded with {}. 


Object




Behavior- It is basically represented by the method of an object. 


Entity- It is basically used to provide a unique name to an object and it enables one object to talk with other objects. 


Example:


public class Example_Object_Java { 

public static void main(String args[]) { 


//Object Creation(Here obj is a reference variable) Example_Object_Java obj=new Example_Object_Java(); 


}

}


Polymorphism- 




Types of Polymorphism in Java: 




Inheritance- 




Types of Inheritance in Java-




Encapsulation




Example:

class Encaps_Exa{ 

private int enc_var1;

private int enc_var2;


public void setA(int enc_var1) { 


this.enc_var1=enc_var1;

}

public void setB(int enc_var2

this.enc_var2=enc_var2;

}

public int getA(){ 

return enc_var1;

}

public int getB(){ 

return enc_var2;

}

}

public class Example

public static void main(String args[])

Encaps_Exa obj=new Encaps_Exa();

obj.setA(10); 

System.out.println(obj.getA());

obj.setB(20);

System.out.println(obj.getB()); 


}

}


Abstraction




In java, abstraction can be achieved in two ways- 



Example-

package Java_Test; 

abstract class Abs_Exm{

abstract void A1();

}

public class Abstract_Class_Imp extends Abs_Exm { 

void A1()

System.out.println("Abstract method implemented");

}

public static void main(String[] args) { 

// TODO Auto-generated method stub Abs_Exm abs=new Abstract_Class_Imp (); abs.A1(); 




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