Dates.java

// ****************************************************************
// Congminh Tran
// 10/23/19
//
// Dates.java
//
// Determine whether a 2nd-millenium date entered by the user
// is valid
//
// ****************************************************************
import java.util.Scanner;  //Import packages and methods from Scanner class

public class Dates
{
   public static void main (String[] args)
   {
      int month, day, year;   //date read in from user
      int daysInMonth;        //number of days in month read in
      boolean monthValid, yearValid, dayValid;  //true if input from user is valid
      boolean leapYear;  //true if user's year is a leap year

      Scanner scan = new Scanner(System.in);

      //Get integer month, day, and year from user
      System.out.print("Enter month: ");
      month = scan.nextInt();

      System.out.print("Enter day: ");
      day = scan.nextInt();

      System.out.print("Enter year: ");
      year = scan.nextInt();

      //Check to see if month is valid, set monthValid accordingly
      if (month <= 12 && month >= 1)
         monthValid = true;

      //Check to see if year is valid, set yearValid accordingly
      if (year <= 1999 && year >= 1000)
         yearValid = true;

      //Determine whether it's a leap year, set leapYear accordingly
      if ((year % 400) == 0 || ((year % 4) == 0 && (year % 100) != 0))
         leapYear = true;

      //Set daysInMonth based on what month user entered.
      if ((month % 2) == 1 || month == 8 || month == 10 || month == 12)
         daysInMonth = 31;
      else if ((month % 2) == 0 && month != 2 || month == 9 || month == 11)
         daysInMonth = 30;
      else
      {
         if (leapYear = true)
            daysInMonth = 29;
         else
            daysInMonth = 28;
      }

      //Determine whether day entered is valid, based on value set in daysInMonth.
      if (day <= daysInMonth && day >= 1)
         dayValid = true;

      //Determine whether ENTIRE date is valid and print appropriate message
      if (dayValid == true && monthValid == true && yearValid == true)
         System.out.println(month + "/" + day + "/" + year +"is a valid date.");


      //If date is valid only: Print if date is a leap year. DO NOT PRINT LEAP YEAR STATUS IF DATE IS INVALID
   }
}