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, 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.
encapsulation in java programming |
Example:
//
Java program to demonstrate encapsulation
public
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;
}
}
The program to access variables of the class
EncapsulateDemo is shown below:
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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);
}
}
|
Output:
Geek's name:Harsh
Geek's age:19
Geek's roll:51
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 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.
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