Java tutorial
import java.time.LocalDate; import java.time.Month; import java.time.temporal.TemporalAdjusters; public class Main { public static void main(String[] args) { LocalDate date = LocalDate.of(2014, Month.FEBRUARY, 25); // 2014-02-25 // first day of February 2014 (2014-02-01) LocalDate firstDayOfMonth = date.with(TemporalAdjusters.firstDayOfMonth()); System.out.println(firstDayOfMonth); } }