Variable in Java - What is a variable in java with example

Variable in Java - What is a variable in java with example

Variable in Java

Java Variable

What is a variable?

Ans. It is nothing but a placeholder of data. It is a memory location. Example int a, b; Here a and b is are variable of data type int.

How many types of variables are there in Java?

It has three types. A local variable, an Instance variable, and a Class variable.
  • Local Variable: It is defined within the method and constructor. These variables' visibility remains within the method and constructor.
  • Instance Variables: Define inside a class. It is available for every object of the class.
  • Class variable: when a variable defines with the keyword static inside a class is known as the class variable.
  • All objects of the class share static variables because of only a single copy of these available in the memory.

java variable naming conventions camelcase

Java variable is written as firstName. This is a camel case, as we write any variable or method, we use all small characters of the first word of the variable and the second first letter will start with a capital letter.

State the difference between token and identifier, variable.

Ans. The smallest individual unit of the program is called Token. e.g:  Identifiers, keywords, Literals, etc. whereas an identifier is a name given to different parts of a program, it is also known as variables. e.g. variable, functions, classes, etc.
Variable: A memory location that stores value is known as a variable. It is like a box in memory where we keep or store values. E.g. int a;

Explain the Instance Variable. Give an example.

Ans. Variables associated with the instance of a class are called instance variables. E.g. 
class ABC
int a,b,c;    // Instance variable
void sum()
a = 20;
b = 30;
c = a + b;

Another example


public class TaxCalculator
     // Instance Variables
    int pan;
    String name;
    double taxableincome;
    double tax;            
    void input()throws IOException
        InputStreamReader in=new InputStreamReader(;
        BufferedReader br=new BufferedReader(in);
        System.out.println("Enter name and taxable income:");
    void computeData()
         tax = 0;
        else if(taxableincome>60000 && taxableincome<=150000)
         tax = taxableincome*0.05;
        else if(taxableincome>150000 && taxableincome<=500000)
         tax = taxableincome*0.1;
    void displayData()
        System.out.println("Name=" + name);
        System.out.println("Taxable Income=" + taxableincome);
        System.out.println("Tax Paid=" + tax);
    public static void main(String args[])throws IOException
        TaxCalculator ob=new TaxCalculator();


Q. What is the final variable?

When a variable defines with the final keyword then its value can be changed throughout the whole program.
class Circle{ 
 final double pi=3.14;//final variable cannot be change 
 double a, r;                
 void area(){
  r = 3.5;            
  a = r*r*pi; 
  System.out.println("Area=" + a)
 public static void main(String args[]){ 
 Circle obj=new  Circle(); 
}//end of class 

Q. Can the‘ main’ method be declared final?

Yes, the main method can declare as final.
public class Example
    public static final void main(String args[])
        int a=6;

Q. What is a static variable?

A static variable is shared by all instances of a class. It is also known as a class variable and it is declared with the keyword ‘static’.  Instances (objects) of the same class share a single copy of static variables.
class School
    int rollno; 
    String section;
    String name; 
    static String schoolName ="InspireSkills Edu";  // Static variable
    // constructor 
    School(int r, String s, String n){ 
        rollno = r; 
        section = s;
        name = n; 
    void display ()
        System.out.println(rollno + " " + section + "   " + name + " " + schoolName);
    public static void main(String args[])
        School ob1 = new School(1, "A", "Mukesh"); 
        School ob2 = new School(2, "B", "Aryan"); 


 * A shop will give a discount of 10% if the cost of the purchased quantity is more than 1000.
 *  Ask the user for quantity, Suppose, one unit will cost 100. Judge and print total cost for the user.
import java.util.*;
public class Discount
    public static void main(String args[])
        double qty, cost=0.0, tqty,dis;
        Scanner sc=new Scanner(;
        System.out.println("Enter Quantity:");
            dis=tqty*10/100.0; // Percentage

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