In this tutorial, we will discuss Encapsulation in Java programming language.
Encapsulation is one of the most important OOP concepts in Java similar C++ and Python.
Other Oop concepts are inheritance, Polymorphism and Abstraction
Encapsulation is used for security purpose. It binds data members and methods into a single unit with data security. Encapsulation helps to hide the implementation details from the user. This is because data values are private.
Private data member (Variable ) cannot be accessed from outside of class. It is known as data hiding in encapsulation.
To use encapsulation in Java, data member in the class must be declared as private(for security.
It improves maintainability, flexibility, and re-usability
Users would not know about what is going on behind on the scenes:
Encapsulation makes data hiding in Java because other class will not be able to access the private data members inside the class
The following shows a simple example of encapsulation of Java:
Program 1
class stu_name{
private String name;
//global variable declaration as private
//this variable access only public methods of class
void set_name(String name)
{//set method with argument
this.name=name;//this method can access private variale
//assign local variable to global variable
}
String get_name(){//get method
return name;//this method can access private variale
}
}
class stu_det1{
public static void main(String args[]){
stu_name st=new stu_name();
//create object for class stu_name
st.set_name("kannan");
//call set method
System.out.println(st.get_name());
}//call get method
}
//save this file as stu_det1.java
When the above program is compiled and executed, it produces the following result
kannan
In the above program, we demonstrate about encapsulation in Java. The variable set as private. The get method(get_Name()) and set method (set_Name())set as public. These two methods are used to access these variables(name) for arguments.
Program 2
class time{
private int hour; //the global variable declared as private
private int minute;
private int second; // hour, minute, second are private variables
public void displayTime() // method is declared for calculate time
{
System.out.println("The time is:"+hour+":"+minute+":"+second);
}
public void setHour(int h){ //set method for hour to access
hour=h;
}
public int getHour(){ //get method for hour to access
return hour;
}
public void setMinute(int m){ //set method for minute to access
minute=m;
}
public int getMinute(){ //get method for second to access
return minute;
}
public void setSecond(int s){ //set method for second to access
second=s;
}
public int getSecond(){ //get method for second to access
return second;
}
}
public class clock{
public static void main(String args[]){
time t=new time();
//setting values of the variables
t.setHour(3);
t.setMinute(05);
t.setSecond(45);
//call method to calculate display time
t.displayTime();
}
}
When the above program is compiled and executed, it produces the following result.
The time is:3:5:45
Program 3
class studentdetails{ //this class save as studentdetails.java
String name;
int id;
int m1;
int m2;
int m3;
int tot;
int avg;
void set_Name(String name,int id){
this.name=name;
this.id=id;
}
void get_Name(){
System.out.println("student name is:"+name);
System.out.println("student id is:"+id);
}
void set_Marks(int m1,int marks2,int marks3){
this.m1=m1;
m2=marks2;
m3=marks3;
}
void get_Marks(){
System.out.println("student marks1 is:"+m1);
System.out.println("student marks2 is:"+m2);
System.out.println("student marks3 is:"+m3);
System.out.println("student total is:"+tot);
System.out.println("student average is:"+avg);
System.out.println(".......");
}
void calculate()
{
tot=m1+m2+m3;
avg=tot/3;
}
}
class calctot{//this class save as clactot.java
public static void main(String args[]){
studentdetails st = new studentdetails();
st.set_Name("Kanthavel",34);
st.set_Marks(67,78,89);
st.get_Name();
st.calculate();
st.get_Marks();
}
}
When the above program is compiled and executed, it produces the following result:
student name is:kanthavel student id is:34 student marks1 is:67 student marks2 is:78 student marks3 is:89 student total is:234 student average:78 .............
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