Encapsulation in Java

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, 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 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 a combination 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

The program to access variables of the class EncapsulateDemo is shown below:

Java

// Java program to demonstrate encapsulation
class Encapsulate {
// private variables declared
// these can only be accessed by
// public methods of class
private String prutorName;
private int prutorRoll;
private int prutorAge;

// get method for age to access
// private variable prutorAge
public int getAge() { return prutorAge; }

// get method for name to access
// private variable prutorName
public String getName() { return prutorName; }

// get method for roll to access
// private variable prutorRoll
public int getRoll() { return prutorRoll; }

// set method for age to access
// private variable prutorage
public void setAge(int newAge) { prutorAge = newAge; }

// set method for name to access
// private variable prutorName
public void setName(String newName)
{
prutorName = newName;
}

// set method for roll to access
// private variable prutorRoll
public void setRoll(int newRoll) { prutorRoll = newRoll; }
}

public class TestEncapsulation {
public static void main(String[] args)
{
Encapsulate obj = new Encapsulate();

// setting values of the variables
obj.setName("salman");
obj.setAge(20);
obj.setRoll(51);

// Displaying values of the variables
// Displaying values of the variables
System.out.println("Prutor's name: " + obj.getName());
System.out.println("Prutor's age: " + obj.getAge());
System.out.println("Prutor's roll: " + obj.getRoll());

// Direct access of prutorRoll is not possible
// due to encapsulation
// System.out.println("Prutor's roll: " +
// obj.prutorName);
}
}
Output
Prutor's name: salman
Prutor's age: 20
Prutor's roll: 51

In the above program, the class EncapsulateDemo is encapsulated as the variables are declared as private. The get methods like getAge() , getName() , 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.

Advantages of Encapsulation:

• 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 as read-only or write-know that only depending on our requirement. 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 as 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 easy to change with new requirements.
  Testing code is easy: Encapsulated code is easy to test for unit testing.