Question

How to find the dates of the last Sunday of each month of a given year in Scala

Answer 1

import java.time.{LocalDate, DayOfWeek}
import java.time.format.DateTimeFormatter

// Return all last Sundays of each month in a given year
def lastSundaysOfYear(year: Int): Iterator[LocalDate] = new Iterator[LocalDate] {
  private var month: Int = 1

  override def hasNext: Boolean = month <= 12

  override def next(): LocalDate = {
    // Last day of the month
    var date: LocalDate =
      LocalDate.of(year, month, 1)
        .plusMonths(1)
        .minusDays(1)

    // Walk backward to Sunday
    while (date.getDayOfWeek != DayOfWeek.SUNDAY) {
      date = date.minusDays(1)
    }

    month += 1
    date
  }
}

@main def lastSundaysMain(args: String*): Unit = {
  val year: Int =
    if (args.nonEmpty)
      args.head.toInt
    else
      2026

  val fmt: DateTimeFormatter = DateTimeFormatter.ofPattern("MM/dd/yyyy")

  for (date <- lastSundaysOfYear(year)) {
    println(date.format(fmt))
  }
}



/*
run:

01/25/2026
02/22/2026
03/29/2026
04/26/2026
05/31/2026
06/28/2026
07/26/2026
08/30/2026
09/27/2026
10/25/2026
11/29/2026
12/27/2026

*/

 

70+ SQL courses for beginners and professionals