Encapsulation in Java

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.

• Other 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 own class in which they are 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 class as 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 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.

  

Example of Encapsulation in Java

How to implement encapsulation in java:
1) Make the instance variables private so that they cannot be accessed directly from outside the class. You can only set and get values of these variables through the methods of the class.
2) Have getter and setter methods in the class to set and get the values of the fields.

class EncapsulationDemo{
    private int ssn;
    private String empName;
    private int empAge;

    //Getter and Setter methods

 
    public int getEmpSSN()

    {
        return ssn;
    }

    public String getEmpName()

    {
        return empName;
    }

    public int getEmpAge()

    {
        return empAge;
    }

    public void setEmpAge(int newValue)

    {
        empAge = newValue;
    }

    public void setEmpName(String newValue)

    {
        empName = newValue;
    }

    public void setEmpSSN(int newValue)

    {
        ssn = newValue;
    }
}
public class EncapsTest 

   {
    public static void main(String args[])

       {
         EncapsulationDemo obj = new EncapsulationDemo();
         obj.setEmpName("Mario");
         obj.setEmpAge(32);
         obj.setEmpSSN(112233);
         System.out.println("Employee Name: " + obj.getEmpName());
         System.out.println("Employee SSN: " + obj.getEmpSSN());
         System.out.println("Employee Age: " + obj.getEmpAge());
      } 
}

Output:

Employee Name: Mario
Employee SSN: 112233
Employee Age: 32

Benefits 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 that how the class is storing values in the variables. He only knows 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-only depending on our requirement. If we wish to make the variables as 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.