Parsing different date formats in a string in Java

Question

I have a string which can possibly contain a date in any of the following formats:

2001-01-05 (yyyy-mm-dd)
2001/01/05 (yyyy/mm/dd)
01/05/2001 (dd/mm/yyyy)
01-05-2001 (dd-mm-yyyy)
2001 january 5
2001 5 january
january 5 2001
5 january 2001
january 5
5 january

I want to be able to parse the particular string and extract the Date object from it.

My approach was as follows:

String[] date_formats = {
                            "yyyy-MM-dd",
                            "yyyyy/MM/dd", 
                            "dd/MM/yyyyy",
                            "dd-MM-yyyy",
                            "yyyy MMM dd",
                            "yyyy dd MMM",
                            "dd MMM yyyy",
                            "dd MMM",
                            "MMM dd",
                            "dd MMM yyyy"};

String output_date = null;
for (String formatString : date_formats)
{
     try
     {    
         Date mydate = new SimpleDateFormat(formatString).parse(token);
         SimpleDateFormat outdate = new SimpleDateFormat("yyyyMMdd");
         output_date = outdate.format(mydate);
         break;
     }
     catch (ParseException e) {
         System.out.println("Next!");
     }
 }

This doesn't seem to work as expected. Especially for dates like 5 January 2001 etc. How do I go about doing this?

Answer 1

Use SimpleDateFormat.setLenient(false). This way it will not attempt to parse dates that aren't the exact format it wants.

Answer 2

You need to have all formats in the date_formats array for the type of format you anticipate would be coming in.

Have a look at the SimpleDateFormat javadocs.

Have a look at the examples in the javadocs.

2001-01-05      - yyyy-MM-dd 
2001/01/05      - yyyy/MM/dd
01/05/2001      - dd/MM/yyyy 
01-05-2001      - dd-MM-yyyy 
2001 january 5  - yyyy MMMMM d
2001 5 january  - yyyy d MMMMM
january 5 2001  - MMMMM d yyyy 
5 january 2001  - d MMMMM yyyy
january 5       - MMMMM d
5 january       - d MMMMM