how to set time to 0 if date is invalid in java (mm/dd both = 0 if month or day is invalid)

Question

I have to write a program that checks the date of an invoice to make sure that the date is correct. So far, the code is set up so that if the month entered is >= 1 or <= 12 the month is valid. If the month is > 12 or < 1, the month is automatically set to 0. The day is set up similarly, If the day >= 1 or <= 31, the day is valid. If not, the day = 0. What I need to do now is make the limit for days to be dependent on the month, so that a date like 04/31/2015 can't be valid. Furthermore, the day needs to be set to 0 when the month = 0. I was wondering what the most effective way to improve my code so I can make this happen might be? Do I need to implement the Gregorian Calendar in any way? Anyway, here is my code so far:

     if((day <=31) && (day >= 1))
        dayDue = day;
    else
        day = 0;

    if((month >= 1) && (month <= 12))
        monthDue = month;
    else 
        month = 0;  

    if((year >= 2011) && (year <= 2017))
        yearDue = year;
    else
        year = 0;

[Checking validity of date](http://stackoverflow.com/questions/4528047/checking-the-validity-of-a-date) might help — sam, Oct 15 '15 at 22:12
your comment put me on the right track. I will answer my own question with the code I used to solve this problem, but I'm sure there is an easier way. — Roberson Terry, Oct 15 '15 at 22:53

Roberson Terry · Answer 1 · 2015-10-16T00:58:23.157

what I used to fix this problem (there might be a simpler way to do this, but this is what I did):

    if((day <= 31) && (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12))
        dayDue = day;
    else if((day > 31) && (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12))
        dayDue = 31;
    else if((day <= 30) && (month == 4 || month == 6 || month == 9 || month == 11))
        dayDue = day;
    else if((day > 30) && (month == 4 || month == 6 || month == 9 || month == 11))
        dayDue = 30;
    else if((day <= 28) && (month ==2))
        dayDue = day;
    else if((day > 28) && (month ==2))
        dayDue = 28;
   //accounting for leap years
    if ((day == 29) && (month == 2) && (year == 2012 || year == 2016))
        dayDue = day;
    else if((day > 29) && (month == 2) && (year == 2012 || year == 2016))
        dayDue = 29;

    if((month >= 1) && (month <= 12))
        monthDue = month;
    else if(month == 0)
        day = 0;
    else 
        month = 0;

the scope of my program was between 2011 and 2017, so an exception was made for days on or exceeding the 29th of February on 2012 or 2016. Thanks for the response — Roberson Terry, Oct 16 '15 at 00:48

score 0 · Accepted Answer · edited Jun 20 '20 at 09:12

Instead of using multiple if, try this.

//02/29/2016 is the next leap year, other are invalid dates
String[] stringDate = {"04/31/2015", "02/29/2016", "06/40/2015"};
SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
dateFormat.setLenient(false);
    
for (String str: stringDate) {
    try {
        if(dateFormat.parse(str, new ParsePosition(0)) != null) {
            System.out.println(str + ": valid");
        } else {
            System.out.println(str + ": Invalid date");
        }
    } catch (Exception e) {
      e.printStackTrace();
    }
}

Output:

04/31/2015: Invalid date

02/29/2016: valid

06/40/2015: Invalid date

We are using SimpleDateFormat for parsing and validating date. It uses parsing operation uses the calendar to produce a Date and returns Null if no date is found.

Demo

Thanks for the response! I was able to apply all of your comments to write an acceptable program for what I'm trying to do. I appreciate your help. — Roberson Terry, Oct 16 '15 at 00:45

how to set time to 0 if date is invalid in java (mm/dd both = 0 if month or day is invalid)

2 Answers2