Question

我需要Java中当前月份的开始日期和结束日期。当JSP页面加载当前月份时，它应该自动计算该月份的开始和结束日期。它应该与年份和月份无关。那是一个月有31天或30天或28天。这也应该满足闰年。你可以帮帮我吗？

例如，如果我在列表框中选择月份，我需要开始日期为1，结束日期为31。

Answer 1

你去了：

public Pair<Date, Date> getDateRange() {
    Date begining, end;

    {
        Calendar calendar = getCalendarForNow();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
        setTimeToBeginningOfDay(calendar);
        begining = calendar.getTime();
    }

    {
        Calendar calendar = getCalendarForNow();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        setTimeToEndofDay(calendar);
        end = calendar.getTime();
    }

    return Pair.of(begining, end);
}

private static Calendar getCalendarForNow() {
    Calendar calendar = GregorianCalendar.getInstance();
    calendar.setTime(new Date());
    return calendar;
}

private static void setTimeToBeginningOfDay(Calendar calendar) {
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);
}

private static void setTimeToEndofDay(Calendar calendar) {
    calendar.set(Calendar.HOUR_OF_DAY, 23);
    calendar.set(Calendar.MINUTE, 59);
    calendar.set(Calendar.SECOND, 59);
    calendar.set(Calendar.MILLISECOND, 999);
}

PS：Pair类只是一对两个值。

Answer 2

如果你有选项，你最好避免使用可怕的Java Date API，而是使用Jodatime。这是一个例子：

LocalDate monthBegin = new LocalDate().withDayOfMonth(1);
LocalDate monthEnd = new LocalDate().plusMonths(1).withDayOfMonth(1).minusDays(1);

Answer 3

尝试使用Java 8中的LocalDate：

LocalDate today = LocalDate.now();
System.out.println("First day: " + today.withDayOfMonth(1));
System.out.println("Last day: " + today.withDayOfMonth(today.lengthOfMonth()));

Answer 4

使用date4j库：

dt.getStartOfMonth();
dt.getEndOfMonth();

Answer 5

Date begining, ending;
Calendar calendar_start =BusinessUnitUtility.getCalendarForNow();
  calendar_start.set(Calendar.DAY_OF_MONTH,calendar_start.getActualMinimum(Calendar.DAY_OF_MONTH));
  begining = calendar_start.getTime();
  String start= DateDifference.dateToString(begining,"dd-MMM-yyyy");//sdf.format(begining);


   //            for End Date of month
  Calendar calendar_end = BusinessUnitUtility.getCalendarForNow();
  calendar_end.set(Calendar.DAY_OF_MONTH,calendar_end.getActualMaximum(Calendar.DAY_OF_MONTH));
      ending = calendar_end.getTime();
      String end=DateDifference.dateToString(ending,"dd-MMM-yyyy");//or sdf.format(end);

enter code here



public static Calendar getCalendarForNow() {
        Calendar calendar = GregorianCalendar.getInstance();
        calendar.setTime(new Date());
        return calendar;
    }

Answer 6

Calendar c = Calendar.getInstance();
    int year = c.get(Calendar.YEAR);
    int month = c.get(Calendar.MONTH);
    int day = 1;
    c.set(year, month, day);
    int numOfDaysInMonth = c.getActualMaximum(Calendar.DAY_OF_MONTH);
    System.out.println("First Day of month: " + c.getTime());
    c.add(Calendar.DAY_OF_MONTH, numOfDaysInMonth-1);
    System.out.println("Last Day of month: " + c.getTime());

Answer 7

试用此代码

Calendar calendar = Calendar.getInstance();
int yearpart = 2010;
int monthPart = 11;
int dateDay = 1;
calendar.set(yearpart, monthPart, dateDay);
int numOfDaysInMonth = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
System.out.println("Number of Days: " + numOfDaysInMonth);
System.out.println("First Day of month: " + calendar.getTime());
calendar.add(Calendar.DAY_OF_MONTH, numOfDaysInMonth-1);
System.out.println("Last Day of month: " + calendar.getTime());

希望它有所帮助。

Answer 8

简单最好，请尝试一下

Calendar calendar = Calendar.getInstance();
            calendar.add(Calendar.MONTH, 0);
            calendar.set(Calendar.DATE, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
            Date monthFirstDay = calendar.getTime();
            calendar.set(Calendar.DATE, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
            Date monthLastDay = calendar.getTime();

        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        String startDateStr = df.format(monthFirstDay);
        String endDateStr = df.format(monthLastDay);

        Log.e("DateFirstLast",startDateStr+" "+endDateStr);

Answer 9

对于Java 8+，以下方法将首先给出当前月份＆amp;最后日期为LocalDate实例。

public static LocalDate getCurrentMonthFirstDate() {
    return LocalDate.ofEpochDay(System.currentTimeMillis() / (24 * 60 * 60 * 1000) ).withDayOfMonth(1);
}

public static LocalDate getCurrentMonthLastDate() {
    return LocalDate.ofEpochDay(System.currentTimeMillis() / (24 * 60 * 60 * 1000) ).plusMonths(1).withDayOfMonth(1).minusDays(1);
}

旁注：使用LocalDate.ofEpochDay(...)代替LocalDate.now()会大大提高性能。此外，使用millis-in-day-expression而不是结束值86400000表现更好。我最初认为后者的表现要好于表达式：P

Answer 10

public static void main(String[] args) 
    {
        LocalDate today = LocalDate.now();
        System.out.println("First day: " + 
today.withDayOfMonth(1));
        System.out.println("Last day: " + today.withDayOfMonth(today.lengthOfMonth()))
    }

Answer 11

您可以按以下方式实现它：

public void FirstAndLastDate() {

    SimpleDateFormat sdf = new SimpleDateFormat("yyy-MM-dd");
    //start date of month
    calendarStart = Calendar.getInstance();
    calendarStart.set(Integer.parseInt((new SimpleDateFormat("yyyy")).format(new Date().getTime()))
            , Integer.parseInt((new SimpleDateFormat("MM")).format(new Date().getTime()))
            , Calendar.getInstance().getActualMinimum(Calendar.DAY_OF_MONTH));

    //End Date of month
    calendarEnd = Calendar.getInstance();
    calendarEnd.set(Integer.parseInt((new SimpleDateFormat("yyyy")).format(new Date().getTime()))
            , Integer.parseInt((new SimpleDateFormat("MM")).format(new Date().getTime()))
            , Calendar.getInstance().getActualMaximum(Calendar.DAY_OF_MONTH));

    Toast.makeText(this, sdf.format(calendarStart.getTime()) + "\n" + sdf.format(calendarEnd.getTime()), Toast.LENGTH_SHORT).show();

}

Answer 12

使其更加模块化，您可以拥有一个计算startDate或EndDate的主要功能，而且您可以拥有getMonthStartDate，getMonthEndDate和getMonthStartEndDate的单独方法。根据您的要求使用方法。

public static String getMonthStartEndDate(){
    String start = getMonthDate("START");
    String end = getMonthDate("END");
    String result = start + " to " + end;
    return result;
}

public static String getMonthStartDate(){
    String start = getMonthDate("START");
    return start;
}

public static String getMonthEndDate(){
    String end = getMonthDate("END");
    return end;
}

/**
 * @param filter 
 * START for start date of month e.g.  Nov 01, 2013
 * END for end date of month e.g.  Nov 30, 2013
 * @return
 */
public static String getMonthDate(String filter){
            String MMM_DD_COMMA_YYYY       = "MMM dd, yyyy";
    SimpleDateFormat sdf = new SimpleDateFormat(MMM_DD_COMMA_YYYY);
    sdf.setTimeZone(TimeZone.getTimeZone("PST"));
    sdf.format(GregorianCalendar.getInstance().getTime());

    Calendar cal =  GregorianCalendar.getInstance();
    int date = cal.getActualMinimum(Calendar.DATE);
    if("END".equalsIgnoreCase(filter)){
        date = cal.getActualMaximum(Calendar.DATE);
    }
    cal.set(Calendar.DATE, date);
    String result =  sdf.format(cal.getTime());
    System.out.println(" " + result  );

    return result;
}

当月的开始和结束日期

12 个答案: