import java.text.NumberFormat;
import java.util.Scanner;
public class CircleTest {
double r=scanner.nextDouble();
double per=2*Math.PI*r;
double area=Math.PI*r*r;
NumberFormat nf = NumberFormat.getNumberInstance();//NumberFormat及保存小数的方法
nf.setMaximumFractionDigits(2);
System.out.println("周长为:"+(nf.format(per)));
System.out.println("面积为:"+(nf.format(area)));
}
}
import java.util.Scanner;
public class CircleTest {
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);//控制台(用户)输入double r=scanner.nextDouble();
double per=2*Math.PI*r;
double area=Math.PI*r*r;
NumberFormat nf = NumberFormat.getNumberInstance();//NumberFormat及保存小数的方法
nf.setMaximumFractionDigits(2);
System.out.println("周长为:"+(nf.format(per)));
System.out.println("面积为:"+(nf.format(area)));
}
}