Difference between Abstraction and Encapsulation in Java with Examples
Abstraction and Encapsulation are two of the 4 pillars that build the foundation of Object-Oriented-Programming. Basic characteristics involve code-reusability, overriding, security purpose, data hiding, and implementation hiding. However, for a beginner, it can be quite confusing to understand the difference between the two as both of them offer data hiding on their own. In this article, we’ll learn about the differences along with code.
Encapsulation is defined as the wrapping up of data under a single unit. It is the mechanism that binds together code and the data it manipulates. Another way to think about encapsulation is, that it is a protective shield that prevents the data from being accessed by the code outside this shield. Technically in encapsulation, the variables or data of a class are hidden from any other class and can be accessed only through any member function of its class in which they are declared. As in encapsulation, the data in a class is hidden from other classes, so it is also known as data hiding. Encapsulation can be achieved by Declaring all the variables in the class as private and writing public methods in the class to set and get the values of variables.
// Java program to demonstrate encapsulation
class Encapsulate {
// private variables declared
// these can only be accessed by
// public methods of class
private String geekName;
private int geekRoll;
private int geekAge;
// get method for age to access
// private variable geekAge
public int getAge() { return geekAge; }
// get method for name to access
// private variable geekName
public String getName() { return geekName; }
// get method for roll to access
// private variable geekRoll
public int getRoll() { return geekRoll; }
// set method for age to access
// private variable geekage
public void setAge(int newAge) { geekAge = newAge; }
// set method for name to access
// private variable geekName
public void setName(String newName)
{
geekName = newName;
}
// set method for roll to access
// private variable geekRoll
public void setRoll(int newRoll) { geekRoll = newRoll; }
}
// Class to access variables
// of the class Encapsulate
public class TestEncapsulation {
public static void main(String[] args)
{
Encapsulate obj = new Encapsulate();
// setting values of the variables
obj.setName("Harsh");
obj.setAge(19);
obj.setRoll(51);
// Displaying values of the variables
System.out.println("Geek's name: " + obj.getName());
System.out.println("Geek's age: " + obj.getAge());
System.out.println("Geek's roll: " + obj.getRoll());
// Direct access of geekRoll is not possible
// due to encapsulation
// System.out.println("Geek's roll: " +
// obj.geekName);
}
}
Data Abstraction is the property by virtue of which only the essential details are displayed to the user. The trivial or the non-essential units are not displayed to the user. Ex: A car is viewed as a car rather than its individual components. Data Abstraction may also be defined as the process of identifying only the required characteristics of an object ignoring the irrelevant details. The properties and behaviors of an object differentiate it from other objects of similar type and also help in classifying/grouping the objects.
// Java program to illustrate the concept of Abstraction
abstract class Shape {
String color;
// these are abstract methods
abstract double area();
public abstract String toString();
// abstract class can have a constructor
public Shape(String color)
{
System.out.println("Shape constructor called");
this.color = color;
}
// this is a concrete method
public String getColor() { return color; }
}
class Circle extends Shape {
double radius;
public Circle(String color, double radius)
{
// calling Shape constructor
super(color);
System.out.println("Circle constructor called");
this.radius = radius;
}
@Override double area()
{
return Math.PI * Math.pow(radius, 2);
}
@Override public String toString()
{
return "Circle color is " + super.color
+ " and area is : " + area();
}
}
class Rectangle extends Shape {
double length;
double width;
public Rectangle(String color, double length,
double width)
{
// calling Shape constructor
super(color);
System.out.println("Rectangle constructor called");
this.length = length;
this.width = width;
}
@Override double area() { return length * width; }
@Override public String toString()
{
return "Rectangle color is " + super.color
+ " and area is : " + area();
}
}
public class Test {
public static void main(String[] args)
{
Shape s1 = new Circle("Red", 2.2);
Shape s2 = new Rectangle("Yellow", 2, 4);
System.out.println(s1.toString());
System.out.println(s2.toString());
}
}