String input through constructor

[brittney_2]

I need to write a class that stores a user-input date as a String in the format mmddyyyy. The constructor validates the input, but it accepts a String input and it tokenizes it into three parts, all int variables and in order to do that I have to tokenize the String input. I am having trouble setting the constructor part of it. I get constructors, but I have never used one where there was input passed through it, so I'm confused on how to go about it. any help would be greatly appreciated!

[brittney_2]

This is what I have so far, but I am getting stuck

import java.util.StringTokenizer;
import java.util.Scanner;

public class CheckDate
{
 public int validMonth;
 public int validDay;
 public int validYear;

 Scanner input = new Scanner(System.in);

 public CheckDate(input.nextLine())
 {

[JamesCherrill]

You declare the parameter(s) of a constructor just like an ordinary method eg

public CheckDate(String mmddyyyyString) { ...

then call them passing parameters also like an ordinary method, eg

CheckDate cd = new CheckDate(input.nextLine));

[brittney_2]

Ok, now what if I want to tokenize them into three parts so it becomes mm/dd/yyyy? I've looked online for some examples and this is what I saw, but I don't know if she wants us to use the split method. She hasn't gone over this with us yet and our assignment i due before next class, so I am extremely lost and the book doesn't go into to much detail. This is what I have so far:

/**Lab 08
 * Class CheckDate that stores a user-input date as a String in the format mmddyyyy
 */

import java.util.StringTokenizer;
import java.util.Date;
import java.text.SimpleDateFormat;

public class CheckDate
{
 public int validMonth;
 public int validDay;
 public int validYear;



 public CheckDate(String date)throws InvalidDateException 
 {

 StringTokenizer dateToken = new StringTokenizer(date, "/");

         int validMonth = Integer.parseInt (dateToken.nextToken().trim());
         int validDay = Integer.parseInt (dateToken.nextToken().trim());
         int validYear = Integer.parseInt (dateToken.nextToken().trim());



       if ((validMonth == 4 || validMonth == 6 || validMonth == 9 || validMonth == 11) &&(validDay > 30))
          {
             throw new InvalidDateException("Day value must be greater than 0 and less than 30");
           }
              else
               {
                      setValidDate(validDay, validMonth, validYear);
                }

        if (validMonth == 2 && validDay > 28)
           {
            throw new InvalidDateException ("Day value must be greater than 0 and less than 28");
        }
         else if(validMonth > 31)
         {
           throw new InvalidDateException ("Day value must be greater than 0 and less than 31");
         }
         else
         {

            setValidDate(validDay, validMonth, validYear);
         }

       if(validMonth < 1 || validMonth > 12)
         {
            throw new InvalidDateException("Month value must be greater than 0 and less than 12");
          }
             else
             {
                  setValidDate(validDay, validMonth, validYear);
             }


       if(validYear < 2010)
       {
           throw new InvalidDateException("Year must be greater than 2010");
        }
            else
           {
               setValidDate(validDay, validMonth, validYear);
           }
 }//end constructor

  public void setValidDate(int day, int month, int year) 
    {

     validDay = day;
     validMonth = month;
     validYear = year; 
    }

    public String getValidDate()
    {
      return (validMonth + "/" + validDay + "/" + validYear + "/");
    }

    public String getLongDate()
    {

    }

 }

She also wants us to use Stringbuilder to conver mm/dd/yyyy to a long date format.

[JamesCherrill]

You can't tokenise an mmddyyyy string by using "/" as a delimiter, becuase the string doesn't contain any "/" characters!
Because the format is fixed, you can simply use String's substring method to pick out each of the three parts, then parse each of those into int values.

[brittney_2]

The user is asked to input a date with "/", so that is why I used it that way.

[JamesCherrill]

OK,I was confused when you said " a user-input date as a String in the format mmddyyyy"
If the user input is mm/dd/yyyy then you can just use String's split method to separate the three parts.

[brittney_2]

When I tried to use the split method it would only grab the 0 from lets say 06/12/2011, and then throws an excption, instead of grabbing the 6.

[JamesCherrill]

Obviously an error in your (undisclosed) code. There's nothing wrong with split.

"06/12/2011".split("/") splits correctly - try executing

System.out.println(Arrays.toString("06/12/2011".split("/")));

[brittney_2]

Well the test harness didn't have a print out to the arrays though. One of the reasons I am confused by the split methods.

[JamesCherrill]

I just showed you the print so you could see how the split method returns its results (and see that it is working), that's all.

[brittney_2]

Ok, I see now ha! Thank you.