Question

I have a java programming assignment where you have to input a date on a single line and it gives you a numerology (horoscope-like) report based on the date. It is assumed that the user will enter a formatted date, separated with spaces.

I can retrieve the month, day, and year of the input by using in.nextInt(). However, I also have to check that the user used a correct separating character for each part of the date, which means I just have to check whether the user used forward slashes.

When looking at my code below, I currently use charAt() to find the separating characters. The problem is that the date won’t always be 14 characters long. So a date in the form of 10 / 17 / 2004 is 14 characters long, but a date of 4 / 7 / 1992 is only 12 characters long, meaning that “slash1” won’t always be in.charAt(3), in the latter situation it would be in.charAt(2).

Does java have a method that allows something like in.nextChar()? I know that it doesn’t, but how could I just find a next character in the date?

EDIT: I forgot to reflect this originally, but my professor said that we are NOT allowed to use the String.split() method, for some reason. The thing is, I get the month, day, and year perfectly fine. I just need to check that the person used a forward slash to separate the date. If a dash is entered, the date is invalid.

public void getDate()
{
    char slash1, slash2;

    do
    {
        System.out.print("Please enter your birth date (mm / dd / yyyy): ");
        Scanner in = new Scanner(System.in);
        String date = in.nextLine();

        month = in.nextInt();
        day = in.nextInt();
        year = in.nextInt();

        slash1 = date.charAt(3);
        slash2 = date.charAt(8);
    } while (validDate(slash1, slash2) == false);

    calcNum();
}

Answer 1

I would use Scanner just to get a line. Then split() the line on whitespace and check the fields:

import java.util.Scanner;
import java.util.regex.Pattern;

public class GetDate {

   int month, day, year;

   public static void main(String[] args)
   {
      GetDate theApp = new GetDate();
      theApp.getDate();

   }

   public void getDate()
   {
      String date;
      do
      {
         System.out.print("Please enter your birth date (mm / dd / yyyy): ");
         Scanner in = new Scanner(System.in);
         date = in.nextLine();
      } while (validDate(date) == false);


      calcNum();
   }

   boolean validDate(String date)
   {
      // split the string based on white space
      String [] fields = date.split("\\s");

      // must have five fields
      if ( fields.length != 5 )
      {
         return false;
      }

      // must have '/' separators
      if ( ! ( fields[1].equals("/") && fields[3].equals("/") ) )
         return false;

      // must have integer strings
      if ( ! ( Pattern.matches("^\\d*$", fields[0]) && 
               Pattern.matches("^\\d*$", fields[2]) &&
               Pattern.matches("^\\d*$", fields[4]) ) )
         return false;

      // data was good, convert strings to integer 
      // should also check for integer within range at this point
      month = Integer.parseInt(fields[0]);
      day = Integer.parseInt(fields[2]);
      year = Integer.parseInt(fields[4]);

      return true;
   }

   void calcNum() {}
}