How to convert the date value "26th May 2017" to "26/05/2017"?

Question

Is there any java library available to parse language specific ordinal indicator/suffix?

I have a date value like the following: 26th May 2017. I want to convert this to 26/05/2017. Could anyone please guide me how to do?

Answer 1

You can parse this format directly to a Java 8 LocalDate using a custom date format:

static final Map<Long, String> ORDINAL_DAYS = new HashMap<>();
static
 {
   ORDINAL_DAYS.put(1, "1st");
   .... more ....
   ORDINAL_DAYS.put(26, "26th");
   .... more ....
   ORDINAL_DAYS.put(31, "31st");
 }

static final DateTimeFormatter FORMAT_DAY_MONTH_YEAR = new DateTimeFormatterBuilder()
  .appendText(ChronoField.DAY_OF_MONTH, ORDINAL_DAYS)
  .appendLiteral(' ')
  .appendText(ChronoField.MONTH_OF_YEAR)
  .appendLiteral(' ')
  .appendText(ChronoField.YEAR)
  .toFormatter();


 String dateInString = "26th May 2017";

 LocalDate date = LocalDate.parse(dateInString, FORMAT_DAY_MONTH_YEAR);

This is using the version of DateTimeFormatter.appendText which accepts a map that is used to map the day string.

You will need to fill in all the missing entries in ORDINAL_DAYS that I have left out for brevity.

Answer 2

Assuming you don’t need very strict input validation, since you are converting from the format with th on the number (or st or nd in 31st, 2nd and more), I suggest you simply remove those two letters first. A regex may do that:

    // remove st, nd, rd or th after day of month
    dateInString 
            = dateInString.replaceFirst("^(\\d+)(st|nd|rd|th)( \\w+ \\d+)$", "$1$3");
    String dateOutString = LocalDate.parse(dateInString, 
                    DateTimeFormatter.ofPattern("d MMM uuuu", Locale.ENGLISH))
            .format(DateTimeFormatter.ofPattern("dd/MM/uuuu"));

The result is

26/05/2017

This works if your input contains a three letter abbreviation for the month, like Apr, May or Jun. To accept a full month name instead (April, May, June), you need 4 Ms instead of 3 in the format pattern: d MMMM uuuu.

Answer 3

As stated by @OleV.V. in this comment, you can use a pattern with optional sections (to parse the different suffixes st, nd, rd and th).

You must also use a java.util.Locale to force month names to English. The code will be like this:

String input = "26th May 2017";
DateTimeFormatter parser = DateTimeFormatter
    // parse the day followed by st, nd, rd or th (using optional patterns delimited by [])
    .ofPattern("dd['st']['nd']['rd']['th'] MMM yyyy")
    // force English locale to parse month names
    .withLocale(Locale.ENGLISH);
// formatter for dd/MM/yyyy output
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy").withLocale(Locale.ENGLISH);
System.out.println(formatter.format(parser.parse(input))); // 26/05/2017

---

The code above will work for month names with 3 letters (like May or Aug). If you want to parse the full names (like August or March), just change MMM to MMMM:

DateTimeFormatter parser = DateTimeFormatter
    // using MMMM to parse full month name (like "August")
    .ofPattern("dd['st']['nd']['rd']['th'] MMMM yyyy")
    .withLocale(Locale.ENGLISH);

---

PS: If you want to parse both cases (3-letter or full month names) using the same parser, you can do this:

DateTimeFormatter parser = DateTimeFormatter
    // can parse "March" or "Mar" (MMMM or MMM)
    .ofPattern("dd['st']['nd']['rd']['th'][ MMMM][ MMM] yyyy")
    .withLocale(Locale.ENGLISH);

Answer 4

Assuming you are asking about Java, this link: https://www.mkyong.com/java/how-to-convert-string-to-date-java/ May help you.

The overall gist is:

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

public class TestDateExample3 {

    public static void main(String[] argv) {



        SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");

        String dateInString = "26th May 2017"; // Remove your 'th', 'nd', etc. from the input string.

        String withoutEnding = dateInString;
        //Something like this
        if(dateInString.contains("th") withoutEnding = dateInString.replace("th", "");
        if(dateInString.contains("nd") withoutEnding = dateInString.replace("nd", "");
        if(dateInString.contains("st") withoutEnding = dateInString.replace("st", "");
        if(dateInString.contains("rd") withoutEnding = dateInString.replace("rd", "");

        try {

            Date date = formatter.parse(withoutEnding);
            System.out.println(date);
            System.out.println(formatter.format(date));

        } catch (ParseException e) {
            e.printStackTrace();
        }

    }

}

Where dd/MM/yyyy is a date formatter that would give you 26/05/2017.

Hope this helps!

EDIT: Also see http://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html for a full list of the different pattern letters for SimpleDateFormat.