(Android) Get first day of week

Question

How to get first day of week, when we know one of the date in the week?

I know the current month , the current year and the current date of week. Then, are there some way to know the first day of the current week.

Thank you.

Answer 1

hello if you need to get the first day of the current week "monday"

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH,  Calendar.MONDAY-calendar.get(Calendar.DAY_OF_WEEK));
  Log.w(TAG, "first day of week" + calendar.getTime());

2 if you need the first day of the week for 20-12-2016

Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH, 20);
        calendar.set(Calendar.MONTH,Calendar.DECEMBER);
        calendar.set(Calendar.YEAR,2016);
        calendar.add(Calendar.DAY_OF_MONTH,Calendar.MONDAY - calendar.get(Calendar.DAY_OF_WEEK));
    Log.w(TAG,"first day of week:"+calendar.getTime());

i hope this will help you

Answer 2

Try this:

// get today and clear time of day

Calendar cal = Calendar.getInstance();
cal.set(Calendar.HOUR_OF_DAY, 0); // ! clear would not reset the hour of day !
cal.clear(Calendar.MINUTE);
cal.clear(Calendar.SECOND);
cal.clear(Calendar.MILLISECOND);

// get start of this week in milliseconds

cal.set(Calendar.DAY_OF_WEEK, cal.getFirstDayOfWeek());
System.out.println("Start of this week:       " + cal.getTime());
System.out.println("... in milliseconds:      " + cal.getTimeInMillis());

Reference : How to get the first day of the current week and month?

Hope this may help you!

Answer 3

hello if you need to get the first day of the current week "monday"

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH,  Calendar.MONDAY-calendar.get(Calendar.DAY_OF_WEEK));
Log.w(TAG, "first day of week" + calendar.getTime());

2 if you need the first day of the week for 20-12-2016

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DAY_OF_MONTH, 20);
calendar.set(Calendar.MONTH,Calendar.DECEMBER);
calendar.set(Calendar.YEAR,2016);
calendar.add(Calendar.DAY_OF_MONTH,Calendar.MONDAY - calendar.get(Calendar.DAY_OF_WEEK));
Log.w(TAG,"first day of week:"+calendar.getTime());

i hope this will help you

Answer 4

tl;dr

The modern approach uses the java.time classes rather than the troublesome old Calendar & Date classes.

LocalDate.of( 2017 , Month.MARCH , 23 )
         .with( TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) )

LocalDate

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

LocalDate someDate = LocalDate.of( 2017 , Month.MARCH , 23 ) ;

TemporalAdjuster

To get the first day of the week, (a) decide what is the first day of the week for you, (b) use a TemporalAdjuster implementation defined in TemporalAdjusters to get the date for a specific DayOfWeek enum object.

LocalDate ld = someDate.with( TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) ) ;

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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?

• Java SE 8 , Java SE 9 , and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport .
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP… .