Java程序利用switch语句输出对应的月份的天数

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

public class test{
       public static void main(String[] args) throws IOException

       {
              System.out.println("请输入月份:");
              BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
                   int i=Integer.parseInt(br.readLine());
                   while (i>12 || i<1){
                            System.out.println("请重新输入！");
                            br = new BufferedReader(new InputStreamReader(System.in));
                            a=Integer.parseInt(br.readLine());
                   }
                   System.in.close();
                   br.close();
                

                   switch (i){

                   case 1:
                       System.out.println("本月共 "+31+" 天");
                       break;

                   case 2:
                         System.out.println("本月共 "+28+"或"+29+" 天");
                       break;

                   case 3:
                           System.out.println("本月共 "+31+" 天");
                            break;

                   case 4:
                           System.out.println("本月共 "+30+" 天");
                           break;

                   case 5:
                            System.out.println("本月共 "+31+" 天");
                            break;

                   case 6:
                            System.out.println("本月共 "+30+" 天");
                            break;

                   case 7:
                            System.out.println("本月共 "+31+" 天");
                            break;

                   case 8:
                            System.out.println("本月共 "+31+" 天");
                            break;

                   case 9:
                            System.out.println("本月共 "+30+" 天");
                            break;

                   case 10:
                            System.out.println("本月共 "+31+"天");
                            break;

                   case 11:
                            System.out.println("本月共 "+30+" 天");
                            break;

                   case 12:
                            System.out.println("本月共 "+31+" 天");
                            break;

                   default:
                            System.out.println("请重新输入！");
                   }
            }
}