Encapsulation is one of the fundamental principles of object-oriented programming that allows objects to hide their internal representation and behavior from other objects. It involves restricting access to components of a class, and allowing access to the class only through public methods. This allows for more secure and maintainable code by preventing accidental or malicious changes to internal data. Getters and setters are commonly used to access private fields in a controlled manner and can include additional logic. Encapsulation provides benefits like making fields read-only or write-only, and allowing classes to control their internal data representation without affecting other code.

2. Disclaimer: This presentation is prepared by trainees of baabtra as a part of
mentoring program. This is not official document of baabtra – Mentoring
Partner
baabtra – Mentoring Partner is the mentoring division of baabte System Technologies Pvt. Ltd

3. ENCAPSULATION
FREDDY P.V
f4freddy@gmail.com

4. OOP

5. Encapsulation
Encapsulation
describes the ability of an object
hide its data and methods from the
rest of the world - one of the
fundamental principles of OOP
(Object Oriented Programming).

6. Data hiding and encapsulation
• Data-hiding or encapsulation is an important
part of the OO paradigm.
• Classes should carefully control access to their
data and methods in order to
– Hide the irrelevant implementation-level details so
they can be easily changed
– Protect the class against accidental or malicious
damage.
– Keep the externally visible class simple and easy to
document
• Java has a simple access control mechanism to
help with encapsulation
– Modifiers: public, protected, private, and package
(default)
6

7. Derived class can restrict visibility
• Private
– Protected and public members of base class are private in derived
class.
• Protected
– Protected and public members of base class are protected in derived
class.
• Public
– Protected and public members of base class are protected and public
in derived class.
• Private members of base class aren’t visible in derived class.
7

8. Access control
• Access to packages
– Java offers no control mechanisms for packages.
– If you can find and read the package you can access it
• Access to classes
– All top level classes in package P are accessible
anywhere in P
– All public top-level classes in P are accessible anywhere
• Access to class members (in class C in package P)
– Public: accessible anywhere C is accessible
– Protected: accessible in P and to any of C’s subclasses
– Private: only accessible within class C
– Package: only accessible in P (the default)
8

9. Getters and setters
• A getter is a method that extracts information from an instance.
– One benefit: you can include additional computation in a getter.
• A setter is a method that inserts information into an instance (also
known as mutators).
– A setter method can check the validity of the new value (e.g., between 1
and 7) or trigger a side effect (e.g., update a display)
• Getters and setters can be used even without underlying matching
variables
• Considered good OO practice
• Essential to javabeans
• Convention: for variable fooBar of type fbtype, define
– getBaabtraBar()
– setBaabraBar(type x)
9

10. /* File name : baabtraTest.java
*/
public class baabtraTest{
private String name;
private String idNum; public String getIdNum(){
return idNum;
private int age; }
public void setAge( int newAge){
public int getAge(){ age = newAge;
}
return age;
public void setName(String
} newName){
public String getName(){ name = newName;
return name; }
public void setIdNum( String newId){ I
}
dNum = newId;
}
}

11. /* File name : RunEncap.java */
public class RunEncap{
public static void main(String args[]){
baabtraTest encap = new baabtraTest();
encap.setName("James");
encap.setAge(20);
encap.setIdNum("12343ms");
System.out.print("Name : " + encap.getName()+ " Age :
"+ encap.getAge());
}
}

12. Benefits of Encapsulation:
• The fields of a class can be made read-only or
write-only.
• A class can have total control over what is
stored in its fields.
• The users of a class do not know how the class
stores its data. A class can change the data
type of a field, and users of the class do not
need to change any of their code.

13. Contact Us