Function that takes the radius of a circle as an argument and returns its area in java.

import java.util.*;

class Circle

{

    public static double circleArea(double x)

  {

     double ar;

     ar=3.14*x*x;

     return ar;

   }

    public static void main(String[] args) 

{

    Scanner sc =new Scanner(System.in);

    System.out.print("enter the radius=");

   double r=sc.nextDouble();

   double area=circleArea(r);

   System.out.println("the area of circle is =      "+area);

  }

}

■》Output->

enter the radius=10

the area of circle is = 314.0