使用threeten,LocalDate获取每月的第一天和最后一天

Question

我有一个LocalDate需要获得该月的第一天和最后一天.我怎么做？

例如.13/2/2014我需要以LocalDate格式获得1/2/2014和28/2/2014.

使用threeten LocalDate类.

Answer 1

只需使用withDayOfMonth,并lengthOfMonth():

LocalDate initial = LocalDate.of(2014, 2, 13);
LocalDate start = initial.withDayOfMonth(1);
LocalDate end = initial.withDayOfMonth(initial.lengthOfMonth());

Answer 2

API旨在支持与业务需求紧密匹配的解决方案

import static java.time.temporal.TemporalAdjusters.*;

LocalDate initial = LocalDate.of(2014, 2, 13);
LocalDate start = initial.with(firstDayOfMonth());
LocalDate end = initial.with(lastDayOfMonth());

但是,Jon的解决方案也很好.

Answer 3

YearMonth

为了完整性,在我看来更优雅,请看这个YearMonth类的使用.

YearMonth month = YearMonth.from(date);
LocalDate start = month.atDay(1);
LocalDate end   = month.atEndOfMonth();

Answer 4

Jon Skeets的答案是正确的,并且值得我的upvote,只需添加这个略有不同的完整性解决方案:

import static java.time.temporal.TemporalAdjusters.lastDayOfMonth;

LocalDate initial = LocalDate.of(2014, 2, 13);
LocalDate start = initial.withDayOfMonth(1);
LocalDate end = initial.with(lastDayOfMonth());

Answer 5

LocalDate endDate = startDate.withDayOfMonth(1).plusMonths(1).minusDays(1);

或者

    LocalDate startDate = LocalDate.now();
    System.out.println("startDate: "+startDate);
    
    LocalDate firstDayOfMonth_of_startDate = startDate.withDayOfMonth(1); 
    System.out.println("firstDayOfMonth_of_startDate: "+firstDayOfMonth_of_startDate);
    
    LocalDate firstDayOfNextMonth_of_startDate = firstDayOfMonth_of_startDate.plusMonths(1); 
    System.out.println("firstDayOfNextMonth_of_startDate: "+firstDayOfNextMonth_of_startDate);
    
    LocalDate lastDayOfTheMonth_of_startDate = firstDayOfNextMonth_of_startDate.minusDays(1); 
    System.out.println("lastDayOfTheMonth_of_startDate: "+lastDayOfTheMonth_of_startDate);

    // or everything in one line
    LocalDate endDate = startDate.withDayOfMonth(1).plusMonths(1).minusDays(1);
    System.out.println("endDate: "+endDate);

和打印输出

startDate: 2021-11-05
firstDayOfMonth_of_startDate: 2021-11-01
firstDayOfNextMonth_of_startDate: 2021-12-01
lastDayOfTheMonth_of_startDate: 2021-11-30
endDate: 2021-11-30

Answer 6

 LocalDate monthstart = LocalDate.of(year,month,1);
 LocalDate monthend = monthstart.plusDays(monthstart.lengthOfMonth()-1);

Answer 7

如果有人来寻找前一个月的第一天，和上月的最后一天：

public static LocalDate firstDayOfPreviousMonth(LocalDate date) {
        return date.minusMonths(1).withDayOfMonth(1);
    }


public static LocalDate lastDayOfPreviousMonth(LocalDate date) {
        return date.withDayOfMonth(1).minusDays(1);
    }