使用Java计算圆面积

/*NowJava.com - 时代Java*/

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;


public class Main {


  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) {/** 来自 nowjava - 时代Java**/

      System.out.println("Invalid radius value" + ne);

      System.exit(0);

    } catch (IOException ioe) {

      System.out.println("IO Error :" + ioe);