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How to pass an hour, minute and second in a calendar object in android java

I made an application in which I need to perform a date conversion. Here is my code.

GregorianCalendar c = new GregorianCalendar(Locale.GERMANY); c.set(2011, 04, 29,0,0,0); String cdate = (String) DateFormat.format("yyyy-MM-dd HH:mm:ss", c.getTime()); Log.i(tag,cdate);

Now when I check my LOG, this is the result:

04-22 12: 44: 15.956: INFO / GridCellAdapter (30248): 2011-04-29 HH: 00: 00

why the hour field is not set. I explicitly passed 0 when I created the calendar object, but still it displays HH in LOG. what could be the problem?

thank you in advance.

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3 answers

use lower case hh:

 String cdate = (String) DateFormat.format("yyyy-MM-dd hh:mm:ss", c.getTime());
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set c.set(Calendar.HOUR_OF_DAY,0) and it should work. Have you tried like this?

 c.set(Calendar.YEAR, 2009); c.set(Calendar.MONTH,11); c.set(Calendar.DAY_OF_MONTH,4); c.set(Calendar.HOUR_OF_DAY,0); c.set(Calendar.MINUTE,0); c.set(Calendar.SECOND,0)
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TL; DR

 LocalDate.of( 2011 , 4 , 29 ) // Represent April 29, 2011. .atStartOfDay( ZoneId.of( "America/Montreal" ) ) // Determine the first moment of the day. Often 00:00:00 but not always. .format( DateTimeFormatter.ISO_LOCAL_DATE_TIME ) // Generate a String representing the value of this date, using standard ISO 8601 format. .replace( "T" , " " ) // Replace the `T` in the middle of standard ISO 8601 format with a space for readability.

Using java.time

The modern way is java.time classes.

If you are trying to get the first moment of the day, do not take the time 00:00:00. Anomalies in some time zones mean that the day can start at other times of the day, for example, 01:00:00.

The LocalDate class represents a date value only without time and without a time zone.

The time zone is critical for determining the date. At any given moment, the date changes around the world by zone. For example, a few minutes after midnight in Paris, France is a new day, still "yesterday" in Montreal Quebec .

Specify the time zone name in continent/region format, such as America/Montreal , Africa/Casablanca or Pacific/Auckland . Never use the abbreviation 3-4 letters, for example, EST or IST , since they are not real time zones, and are not standardized or even unique (!).

 ZoneId z = ZoneId.of( "America/Montreal" ); LocalDate today = LocalDate.now( z );

You want to indicate a specific date in your Question.

 LocalDate localDate = LocalDate.of( 2011 , 4 , 29 ) ;

Apply time zone when determining the first moment of the day.

 ZonedDateTime zdt = localDate.atStartOfDay( z ); // Determine the first moment of the day on this date for this zone.

I recommend always including a timezone pointer or offset-from-UTC with your date strings. But if you insist, you can use DateTimeFormatter predefined in java.time, which does not include zone / offset: DateTimeFormatter.ISO_LOCAL_DATE_TIME . Just remove T from the middle.

 String output = zdt.format( DateTimeFormatter.ISO_LOCAL_DATE_TIME ) .replace( "T" , " " ) ;

About java.time

The java.time framework is built into Java 8 and later. These classes supersede the nasty old legacy datetime classes such as java.util.Date , Calendar and SimpleDateFormat .

The Joda-Time project, now in maintenance mode , we recommend switching to the java.time classes.

To learn more, see the Oracle Tutorial . And search for qaru for many examples and explanations. JSR 310 specification .

Where to get java.time classes?

  • Java SE 8 , Java SE 9 , and then
    • Built in.
    • Part of the standard Java API with integrated implementation.
    • Java 9 adds some minor features and fixes.
  • Java SE 6 and Java SE 7
  • Android
    • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) specifically for Android.
    • See How to use ThreeTenABP ....
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