java：如何获取一周、一月、一年的第一天和最后一天

天和最后一天"/>

java：如何获取一周、一月、一年的第一天和最后一天

先说一年。

public static Calendar getFirstDayOfYear(Calendar c)
{c.set(Calendar.DAY_OF_YEAR,1);return c;
}public static Calendar getLastDayOfYear(Calendar c)
{c.set(Calendar.DAY_OF_YEAR,1);c.add(Calendar.DAY_OF_YEAR,-1);c.add(Calendar.YEAR,1);return c;
}

一月的第一天和最后一天

public static Calendar getFirstDayOfMonth(Calendar c)
{c.set(Calendar.DAY_OF_MONTH, 1);return c;
}public static Calendar getLastDayOfMonth(Calendar c)
{c.set(Calendar.DAY_OF_MONTH, 1);c.add(Calendar.MONTH, 1);c.add(Calendar.DAY_OF_YEAR, -1);return c;
}

一周的第一天和最后一天。需要注意的一个问题是一周的开始和结束在不同的地区是不一样的。

	public static Calendar getFirstDayOfWeek(Calendar c){c.set(Calendar.DAY_OF_WEEK, 1);return c;}public static Calendar getLastDayOfWeek(Calendar c){c.set(Calendar.DAY_OF_WEEK, 1);c.add(Calendar.DAY_OF_YEAR, 6);return c;}

如果一周的开始时间是固定的，那么，要用下面的方法来获取一周的第一天和最后一天：

	public static Calendar getFirstDayOfWeek(Calendar x){boolean isFirstSunday = (x.getFirstDayOfWeek() == Calendar.SUNDAY);int weekDay = x.get(Calendar.DAY_OF_WEEK);if (isFirstSunday){weekDay = weekDay - 1;if (weekDay == 0){weekDay = 7;}}x.add(Calendar.DAY_OF_YEAR, (-1) * (weekDay - 1));return x;}public static Calendar getLastDayOfWeek(Calendar x){boolean isFirstSunday = (x.getFirstDayOfWeek() == Calendar.SUNDAY);int weekDay = x.get(Calendar.DAY_OF_WEEK);if (isFirstSunday){weekDay = weekDay - 1;if (weekDay == 0){weekDay = 7;}}x.add(Calendar.DAY_OF_YEAR, 7 - weekDay);return x;}