Date converter in JAVA

Question

I have date like Tue Mar 19 00:41:00 GMT 2013, how to convert it to 2013-03-19 06:13:00?

final DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
final Date date = bdate; 
Date ndate = formatter.parse(formatter.format(date)); 
System.out.println(ndate);

gives the same date.

You start by searching StackOverflow for one of the millionth posts about date conversions in Java. — pcalcao, Mar 19 '13 at 20:07
@evening: Well why not fix the question so that the times are right? You're asking for people's help here - the least you can do is make sure you ask a sensible question. — Jon Skeet, Mar 19 '13 at 20:10
@evening: Okay, that's better. Now why would you *expect* a formatter with a format of "yyyy-MM-dd HH:mm:ss" to be able to parse a value of "Tue Mar 19 00:41:00 GMT 2013"? — Jon Skeet, Mar 19 '13 at 20:21
The format "E M d hh:mm:ss z yyyy" will parse that format I think. Not "yyyy-MM-dd HH:mm:ss" format. — Sten Roger Sandvik, Mar 19 '13 at 20:23
@JonSkeet: I don't know... It outprints the correct date if I don't use the formatter.parse, but i need to convert it to date. Please help or I'll die. You can really save my life. Please. — good_evening, Mar 19 '13 at 20:23
@evening: Hyperbole will get you nothing. You've got perfectly good answers already. — Jon Skeet, Mar 19 '13 at 20:27

score 4 · Answer 1 · answered Mar 19 '13 at 20:04

4

Use two SimpleDateFormat objects with appropriate formats and use the first to parse the string into a date and the second to format the date into a string again.

answered Mar 19 '13 at 20:04

Ridcully

23,362
7
71
86

score 2 · Answer 2 · answered Mar 19 '13 at 20:13

2

As the first answer says. First parse your date with SimpleDateFormat like this:

Date from = new SimpleDateFormat("E M d hh:mm:ss z yyyy").parse("Tue Mar 19 00:41:00 GMT 2013");

Then use that to format the resulting date object with another instance of SimpleDateFormat like this:

String to = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(from);

See the javadoc of SimpleDateFormat here. Hope that helps.

answered Mar 19 '13 at 20:13

Sten Roger Sandvik

2,526
2
19
16

JUst one thing left, how to convert string to date? thanks – good_evening Mar 19 '13 at 20:15
String to date is the first line. Just use parse on SimpleDateFormat. – Sten Roger Sandvik Mar 19 '13 at 20:18
oplease check thread again, thank you veyr muich – good_evening Mar 19 '13 at 20:21

score 2 · Answer 3 · answered Mar 19 '13 at 20:56

One major thing that the others have left out is dealing with the timezone (TZ). Anytime you use a SimpleDateFormat to go to/from a string representation of the date, you really need to be aware of what TZ you're dealing with. Unless you explicitly set the TZ on the SimpleDateFormat, it will use the default TZ when formatting/parsing. Unless you only deal with date strings in the default timezone, you'll run into problems.

Your input date is representing a date in GMT. Assuming that you also want the output to be formatted as GMT, you need to make sure to set the TZ on the SimpleDateFormat:

public static void main(String[] args) throws Exception
{
    String inputDate = "Tue Mar 19 00:41:00 GMT 2013";
    // Initialize with format of input
    SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
    // Configure the TZ on the date formatter. Not sure why it doesn't get set
    // automatically when parsing the date since the input includes the TZ name,
    // but it doesn't. One of many reasons to use Joda instead
    sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
    Date date = sdf.parse(inputDate);
    // re-initialize the pattern with format of desired output. Alternatively,
    // you could use a new SimpleDateFormat instance as long as you set the TZ
    // correctly
    sdf.applyPattern("yyyy-MM-dd HH:mm:ss");
    System.out.println(sdf.format(date));
}

score 1 · Accepted Answer · answered Mar 19 '13 at 20:10

1

Use SimpleDateFormat in this way:

final DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
final Date date = new Date();
System.out.println(formatter.format(date));

answered Mar 19 '13 at 20:10

Igor Rodriguez

1,196
11
16

How to convert formatter.format(date) to date? – good_evening Mar 19 '13 at 20:14
@evening: with formatter.parse(String), giving it a string in the same format. – Igor Rodriguez Mar 19 '13 at 20:17
final DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); final Date date = bdate; Date ndate = formatter.parse(formatter.format(date)); System.out.println(ndate); – good_evening Mar 19 '13 at 20:18
@evening: Yes, they are inverse operations. – Igor Rodriguez Mar 19 '13 at 20:23
@evening: The date you are printing in your last comment is not formatted, that's the reason you get the default output for date: "Tue Mar 19 00:41:00 GMT 2013". For displaying it in other way, you need to format, as posted. – Igor Rodriguez Mar 19 '13 at 20:25
1

@evening: Date class stores the date as a long value, but when you print it, it displays it in a readable format, that is: "Tue Mar 19 00:41:00 GMT 2013". You don't need to do anything with that format until you decide to display it to the user. In that moment need to format that date to the way you would like to display it, and you do it with the SimpleDateFormat, that returns a String in the format you specified, in your case "2013-03-19 06:13:00" (using the posted pattern). – Igor Rodriguez Mar 19 '13 at 20:29

score 0 · Answer 5 · answered Mar 19 '13 at 20:13

0

If you do any calculations or parsing with dates please use JodaTime because the standard JAVA date support is really buggy

answered Mar 19 '13 at 20:13

emd

740
4
12

Buggy? Is an awful implementation, but I don't know those bugs. – Igor Rodriguez Mar 19 '13 at 20:19
Yes, JodaTime or any JSR 310 implementations is a must when doing date/time calcluations. – Sten Roger Sandvik Mar 19 '13 at 20:21
@stenrs: JSR310 is still in development as i know and it will replace the data api in JAVA 8. Stephen Colebourne created JodaTime and is developing JSR310 – emd Mar 19 '13 at 20:24
@emd: Also, it's this one: https://github.com/ThreeTen/threeten. – Sten Roger Sandvik Mar 19 '13 at 22:21
@stenrs - you're right – emd Mar 19 '13 at 22:22

Date converter in JAVA

5 Answers5