Convert a string into iso date format

Question

So I am trying to convert a string into an iso format for the date. This is the string that I am trying to convert "2016-07-05 02:14:35.0" I would like to have it in this format the iso 8601 "2016-07-05T02:14:35.0"

I have this so far

 DateTimeFormatter format = DateTimeFormat.forPattern("YYYY-MM-DDTHH:mm:sszzz");
     new LocalDate();
    LocalDate newDate = LocalDate.parse(created,format);
     created = newDate.toString();

But it is giving me this exception

ERROR: Illegal pattern component: T; nested exception is java.lang.IllegalArgumentException: Illegal pattern component: T

I followed the examples and I don't know what I am doing wrong here. Any help would be appreciated.

Answer 1

Firstly, that value is a LocalDateTime , not a LocalDate . If you want to get a date out in the end, I'd convert it to a LocalDateTime first, then take the date part of that.

When performing date formatting and parsing, always read the documentation really carefully . It looks like you're using Joda Time (due to using forPattern ; if you can move to Java 8 that would be beneficial). That means you should be reading the DateTimeFormat docs .

Current problems with your pattern:

• You're using 'D' instead of 'd'; that means day-of-year
• You've specified 'T' without quoting it, and it isn't in the pattern anyway
• You've ignored the fraction-of-second part of your value
• You've specified 'zz' when there's no time zone indicator in the value.

Here's a working example:

import org.joda.time.*;
import org.joda.time.format.*;

public class Test {
    public static void main(String[] args) {
        String text = "2016-07-05 02:14:35.0";
        DateTimeFormatter format = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss.S");
        LocalDateTime localDateTime = LocalDateTime.parse(text, format);
        System.out.println(localDateTime);
    }
}

If you actually want to parse values with T in the middle, you'd use a pattern of "yyyy-MM-dd'T'HH:mm:ss.S" - note how then the T is quoted so it's treated literally instead of as a format specifier.

Note that this is just parsing. It's not "converting a string into ISO date format" - it's converting a string into a LocalDateTime . If you then want to format that value in an ISO format, you need to be using DateTimeFormatter.print , with an appropriate format. For example, you might want to convert to a format of yyyy-MM-dd'T'HH:mm:ss.S ':

import org.joda.time.*;
import org.joda.time.format.*;

public class Test {
    public static void main(String[] args) {
        String text = "2016-07-05 02:14:35.0";
        DateTimeFormatter parser = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss.S");
        LocalDateTime localDateTime = LocalDateTime.parse(text, parser);
        DateTimeFormatter printer = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.S");
        String formatted = printer.print(localDateTime);
        System.out.println(formatted); // Output 2016-07-05T02:14:35.0
    }
}

The code above will only handle a single digit fraction-of-second. You could parse using .SSS instead of .S , but you really need to work out what you want the output to be in different cases (eg for 100 milliseconds, do you want .1 or .100?).

Answer 2

You have some errors in your code:

• The pattern should be 'yyyy-MM-dd HH:mm:ss.SSS'. Be aware of upper-
  and lowercase.
• Use LocalDateTime to get date and time. LocalDate only holds the date.

The corrected code:

String created = "2016-07-05 02:14:35.000";
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
LocalDateTime newDate = LocalDateTime.parse(created,format);
created = newDate.toString();
System.out.println(created);

Answer 3

Use the following format to convert

     String format = "yyyy-mm-dd hh:mm:ss"

You are using the wrong format to convert. Using T is only to separate the date from time. Use the format like this

     String = "yyyy-MM-dd'T'HH:mm:ss"