Java program to calculate the area of circle using radius

 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class CalculateCircleAreaExample 
{
	public static void main(String[] args) 
	{
		int radius = 0;
		System.out.println("Please enter radius of a circle");

		try
		{
			BufferedReader br = new BufferedReader(new
			InputStreamReader(System.in));
			radius = Integer.parseInt(br.readLine());
		}
		catch(NumberFormatException ne)
		{
			System.out.println("Invalid radius value" + ne);
			System.exit(0);
		}
		catch(IOException ioe)
		{
			System.out.println("IO Error :" + ioe);
			System.exit(0);
		}
		double area = Math.PI * radius * radius;
		System.out.println("Area of a circle is " + area);
	}
}

 
Please enter radius of a circle
5
Area of a circle is 78.53981633974483