JAVA计算圆的面积

public class Helloworld {
public static void main(String[] args) {
System.out.println("请输入半径:");
Scanner sc = new Scanner(System.in);
int r = sc.nextInt();		
double area = 0;  
area = r*r*3.14;//面积			
System.out.println("该圆的面积为:"+area);
}