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Hi i have some problem with DAY_OF_WEEK. After research but don't know why.

Input date is :

30/01/2016 - SATURDAY

After run :

calendar.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);

Output :

31/01/2016 - SUNDAY(Wrong).

I want it must 30/01/2016 - SATURDAY, Please help me ?

Sanoop Surendran
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Lights
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2 Answers2

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try by passing Date

Calendar calendar = Calendar.getInstance;
calendar.set(2016, Calendar.JANUARY, 30);

or try this too

Calendar c = Calendar.getInstance();
 c.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);
for(int i=0; i<7; i++)
{
   System.out.print("Start Date : " + c.getTime() + ", ");
   c.add(Calendar.DAY_OF_WEEK, 6);
}
brahmy adigopula
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tl;dr

LocalDate.of( 2016 , Month.JANUARY , 30 )
    .with( TemporalAdjusters.next( DayOfWeek.SATURDAY ) ) 

2016-02-06

java.time

The modern approach uses java.time classes rather than the troublesome old Calendar class that is now legacy.

LocalDate

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

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment, so your results may vary. Better to specify your desired/expected time zone explicitly as an argument.

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

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

If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the JVM’s current default is applied implicitly. Better to be explicit, as the default may be changed at any moment during runtime by any code in any thread of any app within the JVM.

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

Or specify a date. You may set the month by a number, with sane numbering 1-12 for January-December.

LocalDate ld = LocalDate.of( 1986 , 2 , 23 ) ;  // Years use sane direct numbering (1986 means year 1986). Months use sane numbering, 1-12 for January-December.

Or, better, use the Month enum objects pre-defined, one for each month of the year. Tip: Use these Month objects throughout your codebase rather than a mere integer number to make your code more self-documenting, ensure valid values, and provide type-safety.

LocalDate ld = LocalDate.of( 1986 , Month.FEBRUARY , 23 ) ;

Adjuster

To move from one date to another, use a TemporalAdjuster implementation found in TemporalAdjusters class. Specify the desired day-of-week using [DayOfWeek][2] enum.

LocalDate previousOrSameMonday = today.with( TemporalAdjusters.previousOrSame( DayOfWeek.SATURDAY ) ) ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

Basil Bourque
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