Write a program to solve the following expression by taking user input of 3.14*r^2

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Hello guys, welcome to lingarajtechhub.com . Today we are going to discuss the given expression by taking user input of 3.14*r^2.


package com.mul.java;
import java.util.Scanner;
public class Mul {
public static void main(String[] args) {
          double r;
          Scanner sc=new Scanner(System.in);
          System.out.println("Enter the value of r:");
          r=sc.nextDouble( );           
          double p=3.14*r*r;


  • package com.mul.java

 It is a java package , this package is created in a java project and it contains classes inside the package.


  • import java.util.Scanner

In java, Scanner is a class. util package used for obtaining the input of the data  types like int, double, float , char  and strings.


  • public class Mul

 “Mul” is the class-name , class is a template used to create objects & class-name first letters must be capital. It is public means we can use this outside of the package.


  • public static void main(String[] args)

 It is a main method in which we can execute a program.

  •  public : It is an access modifier. The main() is public because we can access main() outside of the class , if main() can’t be public then JVM(Java Virtual Machine) can’t be called main() & code can’t be executed. 
  •  Static : static is a keyword in which the main method has to be static in which JVM can load the class into memory and call the main method without creating an instance.
  •  Void : Void is a data type. It means no return type. 
  •  main(): Main is a function. 
  •  String [] args : string means collection of characters ,String[] args represents a collection of Strings that are separated by a space and can be typed into the program on the terminal directly. 


  • double r

Here r  is the variable and double is a data type of the variable.


  • Scanner sc=new Scanner(System.in)

Scanner is a class and sc is the instance of the object which is the new Scanner . System.in is an argument.


  • System.out.println(“Enter the value of r:”)

System is a class name and out is the instance of the system. Println is to print the new line & print the value of r.


  • r=sc.nextDouble( )

“r”  is a variable that we take and sc is our instance name which is created for an object and nextInt() is a method of a Scanner object that reads in a string of digits or char and converts them into a double type.


  • double p=3.14*r*r

Here “p” is a variable where a given question output will be stored and double is the data type.


  • System.out.println(“Result=”+p)

System is a predefined class. Out is a static variable of type printstream present in the system class. Println shows the result.

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Myself Sonalin Shaoo. I am quite happy to contribute here some java programming content and my friends Lipsa Mohanty ,Sushil Puhan, Aswin Kumar Nayak also help me to contribute their Opinion on this .

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