Date Parsing in Java

[stephendfrancis]

Date parsing seems to be a difficult area in most languages. I'm looking for a reliable way of doing it using standard Java libraries. My current approach is:

...
public static SimpleDateFormat sdf = new SimpleDateFormat( "dd/MM/yyyy" );

...
java.util.Date dDate = sdf.parse( strValue );

where strValue is a String input from the user.

I have two specific questions:

1. if strValue is an invalid date e.g. "29/2/2001", instead of throwing an Exception (which I would prefer) dDate is set to the next appropriate date (i.e. "1/3/2001" in this case). How do I get an Exception if the date is invalid?

2. if strValue has a 2-digit date e.g. &quot;4/4/01&quot;, dDate is set to &quot;04/04/0001&quot; - 1 A.D. is really outside the relevant date range for this software...! I know my date format specifies 4 digits, so Java is doing something logical. But is there a way of both allowing 4-digit input (if given), but also determining that a 2-digit year should be of a given century (e.g. 1900s if year >50 and 2000s if year <50) - or in these enlightened post-Y2K days is such a thing frowned upon?

Many thanks...
Stephen.

 

[Vepo]

Hi,

You should implement your own logic for that kinds of cases.
Here is one example (far from complete) which may give you an idea.
_____________________________________________
import java.text.*;
import java.util.*;

public class SimpleDF extends SimpleDateFormat
{
public void applyPattern(String pattern_)
{
super.applyPattern(pattern_);

dayStart = pattern_.indexOf(&quot;d&quot;
monthStart = pattern_.indexOf(&quot;M&quot;
}

public Date parse(String txt_) throws ParseException
{
Date date = super.parse(txt_);

int dLen = txt_.indexOf(&quot;/&quot;, dayStart);

int days = new Integer(txt_.substring(dayStart, dLen)).intValue();

int mLen = txt_.indexOf(&quot;/&quot;, monthStart);
int m = new Integer(txt_.substring(monthStart, mLen)).intValue()-1;

if(DAYS_IN_MONTH[m] < days)
{
throw new ParseException(&quot;Illegal number of days!!!&quot;, monthStart);
}

return date;
}

private static final int[] DAYS_IN_MONTH = {31,28,31,30,31,30,31,31,30,31,30,31};
private int dayStart;
private int monthStart;
}

__________________________________________________________

previous example works only with separator &quot;/&quot; and the parsed date string must be at form of &quot;dd/mm/yyyy&quot; and much more
...But I think that's the way, override the parse method and handle the string to be parsed....