修改下面代码，定义一个静态变量的String型变量output，用以储存书输出结果，并且在消息对话框中实现，我想问 的就是怎样在消息对话框中实现它，求大神指教，有点急
import java.util.Scanner;
//import javax.swing.*;

public class PrintCalendar {
  public static void main(String[] args){
      Scanner input = new Scanner(System.in);
     // Calender calender = new Calender();
       //String  output =" ";
      
      System.out.print("Enter full year (e.g.,2001): ");
      int year = input.nextInt();
      
      System.out.print("Enter month in number between 1 and 12: ");
      int month = input.nextInt();
      
      printMonth(year,month);
      
              
      }

 
  public static void printMonth(int year,int month){
      printMonthTitle(year,month);
      printMonthBody(year,month);
      
  }
  public static void printMonthTitle(int year,int month){
      System.out.println("        "+getMonthName(month)+" "+year);
      System.out.println("---------------------------");
      System.out.println("Sun Mon Tue Wed Thu Fri Set");
      
  }
  public static String getMonthName(int month){
      String monthName = " ";
      switch(month){
      case(1):monthName = "January";break;
      case(2):monthName = "February";break;
      case(3):monthName = "Match";break;
      case(4):monthName = "April";break;
      case(5):monthName = "May";break;
      case(6):monthName = "June";break;
      case(7):monthName = "July";break;
      case(8):monthName = "August";break;
      case(9):monthName = "September";break;
      case(10):monthName = "October";break;
      case(11):monthName = "November";break;
      case(12):monthName = "December";break;
      }
      return monthName;
  }
  public static void printMonthBody(int year,int month){
      int startDay = getStartDay(year,month);
      int numberOfDaysInMonth = getNumberOfDaysInMonth(year,month);
      int i=0;
       for(i=0;i<startDay;i++)
          System.out.print("    ");
      for(i=1;i<=numberOfDaysInMonth;i++){
          System.out.printf("%4d",i);
         
      if ((i+startDay)%7==0)
          System.out.println();
      }
      System.out.println();
  }
  public static int getStartDay(int year,int month){
      final int START_DAY_FOR_JAN_1_1800 = 3;
      int totalNumberOfDays = getTotalNumberOfDays(year,month);
      return (totalNumberOfDays+START_DAY_FOR_JAN_1_1800)%7;
  }
  public static int getTotalNumberOfDays(int year,int month){
      int total = 0;
      for (int i= 1800;i<year;i++)
          if(isLeapYear(i))
              total +=366;
          else
              total+=365;
      for(int i=1;i<month;i++)
          total=total+getNumberOfDaysInMonth(year,i);
      return total;
  }
  public static int getNumberOfDaysInMonth(int year,int month){
      if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
          return 31;
      if(month==4||month==6||month==9||month==11)
          return 30;
      if(month==2)
          return isLeapYear(year)?29:28;
      return 0;
      }
  public static boolean isLeapYear(int year){
      return (year %400==0||(year%4==0 && year%100!=0));
  }
 
}