How to get all dates of sundays in a particular year in Java?

Question

I am seriously looking for this code...I am new programmer.

Actually I want to make all dates with flag, which all are sunday in a particular year.

Please, I am eagerly waiting for your response....

Answer 1

java.time

Java 8 and later comes with the new java.time package. Inspired by Joda-Time, defined by JSR 310, extended by the ThreeTen-Extra project. These new classes supplant the notoriously troublesome java.util.Date/.Calendar & java.text.SimpleDateFormat and such.

Note that we specify a time zone, crucial for determining a date. For example, a new day dawns earlier in Paris than in Montréal.

ZoneId zoneId = ZoneId.of( "America/Montreal" );  // Time zone is crucial in determining the date. A new day dawns earlier in Paris than In Montréal, for example.

You would write this code to use only LocalDate without any time-of-day. But in business, the full date-time is often more useful. So my example here uses ZonedDateTime.

To be neat, I want the time-of-day set to first moment of the day. You might assume that means 00:00:00.0 but not always because of anomalies such as Daylight Saving Time. To soft-code this first-moment, we want to call the atStartOfDay method found on LocalDate. So we start with LocalDate, then use that method to get a ZonedDateTime object.

Again, note that we specify a time zone when getting today’s date. A very common mistake is to omit time zone. When omitted, the JVM’s current default time zone will be implicitly applied. That means your results can vary by machine or by admin’s settings. Even worse, any code in any thread of any app within this JVM can make a call to change that default time zone at any moment during runtime while your app executes! So always specify rather than rely implicitly on current default.

LocalDate today = LocalDate.now( zoneId );  // We want a ZonedDateTime, but starting with a LocalDate in order to get first moment of the day (see next line).
ZonedDateTime todayStart = today.atStartOfDay( zoneId );  // Set time-of-day to first moment of this date, just to be neat. Usually that time is '00:00:00.0' but not always.

The java.time framework includes some handy TemporalAdjustors to get first day of year, and from there, the first Sunday of that month.

ZonedDateTime firstOfThisYear = todayStart.with( TemporalAdjusters.firstDayOfYear( ) );
ZonedDateTime zdtFirstOfNextYear = firstOfThisYear.with( TemporalAdjusters.firstDayOfNextYear( ) );
ZonedDateTime firstSundayOfThisYear = firstOfThisYear.with( TemporalAdjusters.dayOfWeekInMonth( 1, DayOfWeek.SUNDAY ) );

Now we are set to loop through all the weeks of the year. We increment a week at a time until we find ourselves in the next year. We collect each Sunday in a List.

ZonedDateTime zdt = firstSundayOfThisYear; // Var changing throughout loop.
List< ZonedDateTime > sundays = new ArrayList<>( 53 );  // Set initial capacity to maximum number of values.
while ( zdt.isBefore( zdtFirstOfNextYear ) ) {
    // Handle this iteration.
    sundays.add( zdt );
    System.out.println( "Sunday # " + sundays.size( ) + " : " + zdt );
    // Prepare next iteration.
    zdt = zdt.plusWeeks( 1 );
}

When run.

Sunday # 1 : 2015-01-04T00:00-05:00[America/Montreal]
Sunday # 2 : 2015-01-11T00:00-05:00[America/Montreal]
…
Sunday # 51 : 2015-12-20T00:00-05:00[America/Montreal]
Sunday # 52 : 2015-12-27T00:00-05:00[America/Montreal]

Answer 2

List arrList = new ArrayList();
SimpleDateFormat format1 = new SimpleDateFormat("dd-M-yyyy");
Date date = null;
Calendar cal = Calendar.getInstance();

for (int i = 0; i <= 51; i++) 
{
    try 
    {
        cal.add(Calendar.WEEK_OF_YEAR, +1);
        cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
        String formatted = format1.format(cal.getTime());
        date = format1.parse(formatted);
        arrList.add(date);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Answer 3

**this will give u all Sundays of the year **

invented By me and friend Hemant

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;





public class Test {

    public static void main(String[] args) {



        SimpleDateFormat format =new SimpleDateFormat("dd-MMM-yyyy");
        String DATE_FORMAT = "yyyy MM dd";

        SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
        Calendar c1 = Calendar.getInstance(); // today

        String y=sdf.format(c1.getTime());
        String years=y.substring(0,4);
        int year=Integer.parseInt(years);
        //Connection con=null;

        Calendar cal = new GregorianCalendar(year, Calendar.JANUARY, 1);
        for (int i = 0, inc = 1; i <366 && cal.get(Calendar.YEAR) == year; i+=inc) {
            if (cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
                // this is a sunday
                String frm="";
                frm=format.format(cal.getTime());
            //System.out.println("From  :"+frm);

                  System.out.println("the value of the sunday is "+format.format(cal.getTime()));
                cal.add(Calendar.DAY_OF_MONTH, 7);   
            } else {
                cal.add(Calendar.DAY_OF_MONTH, 1);
            }






        }
    }
}

Answer 4

I recently developed [Lamma Date] which is designed to serve this type of use cases.

Following code will print out all Sundays in 2014:

List<Date> sundays2014 = Dates.from(2014, 1, 1).to(2014, 12, 31).byWeek().on(DayOfWeek.SUNDAY).build();

for(Date date: sundays2014) {
    System.out.println(date);
}

Answer 5

A year has approximately 365 days, so the Big-O's n is pretty manageable. I'd say just iterate from the beginning of the year through to the last day of the year, and check if each day is a Sunday or not.

You need at least Calendar.get(), Calendar.DAY_OF_WEEK and Calendar.SUNDAY

Answer 6

This is an example code using java.util.Calendar and java.util.GregorianCalendar that prints out each Sunday of the year 2009. A lot of optimizing can be done in formatting the date, but i'll leave that as an exercise for you.

import java.util.Calendar;
import java.util.GregorianCalendar;

public class Test
{
    public static void main(String[] args)
    {
        int year =2009;
        int dayOfWeek = Calendar.SUNDAY;
        String dayOfWeekString = "Sunday";
        // instantiate Calender and set to first Sunday of 2009
        Calendar cal = new GregorianCalendar();
        cal.set(2009, 0, 1, 0, 0); cal.getTime();
        cal.set(Calendar.DAY_OF_WEEK, dayOfWeek); cal.getTime();
        int i = 1;
        while (cal.get(Calendar.YEAR) == 2009)
        {
            System.out.println(dayOfWeekString + " " + i + ": " + cal);
            cal.add(Calendar.DAY_OF_MONTH, 7);
            i++;
        }
    }
}

As you can see, TiGz's way of using Joda Time is a lot simpler.

Answer 7

Something like this should work.

int year = 2009;
Calendar cal = new GregorianCalendar(year, Calendar.JANUARY, 1);
for (int i = 0, inc = 1; i < 366 && cal.get(Calendar.YEAR) == year; i+=inc) {
    if (cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) {
        // this is a sunday
        cal.add(Calendar.DAY_OF_MONTH, 7); 
        inc = 7;
    } else {
        cal.add(Calendar.DAY_OF_MONTH, 1);
    }
}

Answer 8

If i was doing it I would use Joda Time to find the first Sunday in the year using LocalDate. Create 1st of Jan and then add 1 day until it is a Sunday, then add 7 days until your run out of year.

LocalDate date = new LocalDate(YEAR, 1, 1);
while ( date.dayOfWeek() != 7 )
{
  date = date.addDays(1);
}

while ( date.year() == YEAR )
{
  date = date.addDays(7);
}

Or something like that.

Answer 9

Create a new calendar. Set the time to 1/1/yyyy and some time. Check if the current date is a Sunday and roll forward one day until it is. That's the first Sunday of the year. Roll forward 7 days until the year no longer matches, marking as you go.

Answer 10

Study the the docs of java.util.Calendar carefully.