Change String to date using LocalDate in Java

Question

I need to change String date="20160101" to "January 1,2016" by using LocalDate. Right now, my code looks like this:

DateTimeFormatter formatter = DateTimeFormatter.BASIC_ISO_DATE;
LocalDate date = LocalDate.parse("20120403", formatter);
System.out.println(date);

The output is: 2016-01-01

Do I need to use a DateTimeFormatterBuilder to do that, or is there an easier way? Thank you!

https://docs.oracle.com/javase/tutorial/datetime/iso/format.html — shmosel, Feb 13 '17 at 00:24

score 2 · Answer 1 · answered Feb 13 '17 at 00:58

2

LocalDate#toString method prints the date in ISO-8601 format uuuu-MM-dd. That's why your output is coming as 2016-01-01. If you need the output in "January 1,2016" format instead, you need to again format the date to MMM d, yyyy format.

DateTimeFormatter formatter = DateTimeFormatter.BASIC_ISO_DATE;
LocalDate date = LocalDate.parse("20120403", formatter);
String strDate = date.format(DateTimeFormatter.ofPattern("MMM d, yyyy"));
System.out.println(strDate);

answered Feb 13 '17 at 00:58

VHS

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Thank you very much for your help guys! – Ahab Feb 13 '17 at 01:20
I can't have it returned as a String. It needs to be returned as LocalDate. The only reason why i printed it was because I wanted to test it. – Ahab Feb 13 '17 at 01:22
If that is the case, you already have the LocalDate object. The `date` object is actually a LocalDate object. What's wrong with it> – VHS Feb 13 '17 at 01:23
2

@Ahab Date objects don't have formats. The format is added when you convert them to strings. – Sotirios Delimanolis Feb 13 '17 at 01:23
I get it now. Thank you very much for The help! – Ahab Feb 13 '17 at 01:29

score 1 · Answer 2 · answered Feb 13 '17 at 00:26

1

You dont have to use a builder. DateTimeFormatter can be created directly from a string here

answered Feb 13 '17 at 00:26

Fermat's Little Student

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score 0 · Answer 3 · edited May 23 '17 at 11:45

Date-time objects have no format

Your comments indicate that you are conflating date-time objects with strings representing their values.

Date-time objects have no format. The objects can generate strings to represent their values, but such strings are distinct and separate. Likewise, a date-time object can be instantiated by parsing a string, but the new date-object will be distinct and separate.

Localizing

You can generate a string as shown in the Answer by VHS where you specify a certain formatting pattern. But generally a better route is to let java.time localize automatically for you.

To localize, specify:

FormatStyle to determine how long or abbreviated should the string be.
Locale to determine (a) the human language for translation of name of day, name of month, and such, and (b) the cultural norms deciding issues of abbreviation, capitalization, punctuation, separators, and such.

Example:

Locale l = Locale.CANADA_FRENCH ; // Or Locale.US, Locale.ITALY, etc.
DateTimeFormatter f = DateTimeFormatter.ofLocalizedDate( FormatStyle.FULL ).withLocale( l );
String output = myLocalDate.format( f );

The DateTimeFormatterBuilder class is for special needs. Generally all you need is the DateTimeFormatter class.

See this example code run live at IdeOne.com. But beware of limitation with that IdeOne.com web site’s implementation of Java: Alternate locales are ignored, hard-coded to a single English locale (perhaps Locale.US).

DateTimeFormatter formatter = DateTimeFormatter.BASIC_ISO_DATE;
LocalDate localDate = LocalDate.parse("20120403", formatter);

String outputStandard = localDate.toString();

DateTimeFormatter fCanadaFrench = 
    DateTimeFormatter.ofLocalizedDate( FormatStyle.LONG )
                     .withLocale( Locale.CANADA_FRENCH ) ;
String outputCanadaFrench = localDate.format( fCanadaFrench ) ;

DateTimeFormatter fUS = 
    DateTimeFormatter.ofLocalizedDate( FormatStyle.LONG )
                     .withLocale( Locale.US ) ;
String outputUS = localDate.format( fUS ) ;

localDate.toString(): 2012-04-03

outputCanadaFrench: 3 avril 2012

outputUS: April 3, 2012

Change String to date using LocalDate in Java

3 Answers3

Date-time objects have no format

Localizing