Encapsulation in java with example program

What is meant by encapsulation in java?

• Binding the data with its related functionalities known as encapsulation
• Here data means variables and functionalities means methods.
• So keeping the variable and related methods in one place.
• That place is "class". class is the base for encapsulation.
• Lets see example program on encapsulation, how the variables and methods defined in a class

What is encapsulation in object oriented programming?
 
Basic java example program on data encapsulation:

1. package com.instanceofjava;
2.  
3. public class EncapsulationDemo {
4.  
5.   String name;
6.   int rno;
7.   String address;
8.  
9. public String getName() {
10.        return name;
11.  }
12.  
13. public void setName(String name) {
14.         this.name = name;
15. } 
16. 
    
17. public int getRno() {
18.        return rno;
19. }
20.  
21. public void setRno(int rno) {
22.      this.rno = rno;
23. }
24.  
25. public String getAddress() {
26.         return address;
27. }
28.  
29.  public void setAddress(String address) {
30.     this.address = address;
31. }
32.  
33. public void showInfo(){
34.  
35.       System.out.println("Name: "+getName());
36.       System.out.println("R.No: "+getRno());
37.       System.out.println("Name: "+getAddress());
38.  
39.     }
40. }

Class:

• The above example program shows how the variables and methods will be there in a class.
• So class is the base for encapsulation
• class is user defined data type in java means by using class we can structure our own programs.
• Lest see a example program on class.

1. package com.instanceofjava;
2.  
3. public class ClassDemo {
4.  
5.     //variables of a class
6.    String empName;
7.    int empId;
8.    String Designation;
9.  
10.  //getter and setter methods for variables 
11.  //by using these methods we can set the value to the variable and gat the value from the
12.  //variables
13.  
14.  public String getEmpName() {
15.         return empName;
16. }
17.  
18.  public void setEmpName(String empName) {
19.       this.empName = empName;
20. }
21.  
22. public int getEmpId() {
23.        return empId;
24. }
25.  
26. public void setEmpId(int empId) {
27.         this.empId = empId;
28. }
29. 
    
30. public String getDesignation() {
31.         return Designation;
32. }
33.  
34.  public void setDesignation(String designation) {
35.         Designation = designation;
36. }
37. 
    
38. }

Object:

• Instance of class is known as object.
• Instance means dynamic memory allocation. So dynamic memory allocation to class is called object.
• By using "new" keyword the object will be created dynamically.
• Class is a template. By using object we will get memory for all variables so that we can use them.


• We can create number of objects for one class based on our requirements.
• Below an example program on class and object.

1. package com.instanceofjava; 
2.  
3. public class User {
4.  
5.    String Name;
6.     int Id;
7.     String address;
8.  
9.  public String getName() {
10.      return Name;
11. }
12.  
13. public void setName(String name) {
14.         Name = name;
15. }
16.  
17. public int getId() {
18.       return Id;
19. }
20.  
21. public void setId(int id) {
22.        Id = id;
23. }
24.  
25. public String getAddress() {
26.         return address;
27. }
28.  
29. public void setAddress(String address) {
30.         this.address = address;
31. }
32.  
33. public static void main(String [] args){
34.  
35.        User obj= new User();
36.  
37.         obj.setName("sai");
38.         obj.setId(1);
39.         obj.setAddress("xyz");
40.  
41.         System.out.println(obj.getName());
42.         System.out.println(obj.getId());
43.         System.out.println(obj.getAddress());
44.  
45.     }
46. }

Output:

1. sai
2. 1
3. xyz