Convert date with ordinal numbers (11th, 22nd, etc.)

Question

How to convert a date having the following format

September 22nd 2015, 10:39:42 am

to

09/22/2015 10:39:42

Answer 1

Here a shorter Java-8-only solution without an external library:

DateTimeFormatter formatter = 
  DateTimeFormatter.ofPattern(
    "MMMM d['st']['nd']['rd']['th'] yyyy, hh:mm:ss a", Locale.ENGLISH);
formatter = 
  new DateTimeFormatterBuilder().parseCaseInsensitive().append(formatter).toFormatter();
LocalDateTime dateTime = 
  formatter.parse("September 22nd 2015, 10:39:42 am", LocalDateTime::from);
String text = DateTimeFormatter.ofPattern("MM/dd/yyyy HH:mm:ss").format(dateTime);
System.out.println(text); // 09/22/2015 10:39:42

There is only one caveat: The suggested parser might also accept funny inputs like "...22ndst..." etc. but I think this can be neglected here.