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

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

Code:

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;
          System.out.println("Result="+p);
	}
}

Line-1:

package com.mul.java

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

Line-2:

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.

Line-3:

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.

Line-4:

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.

Line-5:

double r

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

Line-6:

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.

Line-7:

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.

Line-8:

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.

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