Encapsulation in Java Flashcards
Encapsulation in Java
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Encapsulation in Java
Encapsulation in Java is a fundamental concept in object-oriented programming (OOP) that refers to the bundling of data and methods that operate on that data within a single unit, which is called a class in Java. Java Encapsulation is a way of hiding the implementation details of a class from outside access and only exposing a public interface that can be used to interact with the class.
In Java, encapsulation is achieved by declaring the instance variables of a class as private, which means they can only be accessed within the class. To allow outside access to the instance variables, public methods called getters and setters are defined, which are used to retrieve and modify the values of the instance variables, respectively. By using getters and setters, the class can enforce its own data validation rules and ensure that its internal state remains consistent.
WHAT IS Encapsulation?
Encapsulationis 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.
How to Achieve Encapsulation
Technically in encapsulation, the variables or data of a class is hidden from any other class and can be accessed only through any member function of its own class in which it is declared.
As in encapsulation, the data in a class is hidden from other classes using the data hiding concept which is achieved by making the members or methods of a class private, and the class is exposed to the end-user or the world without providing any details behind implementation using the abstraction concept, so it is also known as acombination of data-hiding and abstraction.
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.
It is more defined with the setter and getter method.
Advantages of Encapsulation
Data Hiding:it is a way of restricting the access of our data members by hiding the implementation details. Encapsulation also provides a way for data hiding. The user will have no idea about the inner implementation of the class. It will not be visible to the user how the class is storing values in the variables. The user will only know that we are passing the values to a setter method and variables are getting initialized with that value.
Increased Flexibility:We can make the variables of the class read-only or write-only depending on our requirements. If we wish to make the variables read-only then we have to omit the setter methods like setName(), setAge(), etc. from the above program or if we wish to make the variables write-only then we have to omit the get methods like getName(), getAge(), etc. from the above program
Reusability:Encapsulation also improves the re-usability and is easy to change with new requirements.
Testing code is easy:Encapsulated code is easy to test for unit testing.
Freedom to programmer in implementing the details of the system:This is one of the major advantage of encapsulation that it gives the programmer freedom in implementing the details of a system. The only constraint on the programmer is to maintain the abstract interface that outsiders see.
Examples Showing Data Encapulation in Java
Below is the implementation of the above topic:
Java
// Java Program to demonstrate
// Java Encapsulation
// fields to calculate area
class Area {
int length;
int breadth;
// constructor to initialize values
Area(int length, int breadth)
{
this.length = length;
this.breadth = breadth;
}
// method to calculate area
public void getArea()
{
int area = length * breadth;
System.out.println(“Area: “ + area);
}
}
class Main {
public static void main(String[] args)
{
Area rectangle = new Area(2, 16);
rectangle.getArea();
}
}
OutputArea: 32
Example 2:
The program to access variables of the class EncapsulateDemo is shown below:
Java
// Java program to demonstrate
// Java 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; }
}
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);
}
}
OutputGeek’s name: Harsh Geek’s age: 19 Geek’s roll: 51
Example 3:
In the above program, the class Encapsulate is encapsulated as the variables are declared private. The get methods like getAge(), getName(), and getRoll() are set as public, these methods are used to access these variables. The setter methods like setName(), setAge(), setRoll() are also declared as public and are used to set the values of the variables.
Below is the implementation of the defined example:
Java
// Java Program to demonstrate
// Java Encapsulation
class Name {
// Private is using to hide the data
private int age;
// getter
public int getAge() { return age; }
// setter
public void setAge(int age) { this.age = age; }
}
// Driver Class
class GFG {
// main function
public static void main(String[] args)
{
Name n1 = new Name();
n1.setAge(19);
System.out.println(“The age of the person is: “
+ n1.getAge());
}
}
OutputThe age of the person is: 19
