我试图找出有多少个星期一,例如,特定年份的特定月份。 是否有一个库可以在特定年份的日历中导入java?
答案 0 :(得分:2)
使用Java 8及更高版本中内置的java.time类。
YearMonth month = YearMonth.of(2017, 1);
LocalDate start = month.atDay(1).with(TemporalAdjusters.nextOrSame(DayOfWeek.MONDAY));
int count = (int) ChronoUnit.WEEKS.between(start, month.atEndOfMonth()) + 1;
System.out.println(count);
答案 1 :(得分:0)
Java 7 + JodaTime
import org.joda.time.DateTimeConstants;
import org.joda.time.Days;
import org.joda.time.LocalDate;
import java.util.Date;
public class Test {
public static int getNumberOfMondays(Date start, Date end) {
LocalDate startDate = LocalDate.fromDateFields(start);
LocalDate endDate = LocalDate.fromDateFields(end);
int days = Days.daysBetween(startDate, endDate).getDays();
int mondayCount = 0;
//Get number of full weeks: 1 week = 1 Monday
mondayCount += days / 7;
int remainder = days % 7;
if (startDate.dayOfWeek().get() == DateTimeConstants.MONDAY || startDate.dayOfWeek().get() > (startDate.dayOfWeek().get() + remainder) % 8) {
mondayCount++;
}
return mondayCount;
}
}
答案 2 :(得分:0)
即使是具有所有缺点的旧`Calendar'-API也能实现解决方案:
int year = 2017;
int month = Calendar.JANUARY;
int dow = Calendar.MONDAY;
GregorianCalendar gcal = new GregorianCalendar(year, month, 1);
while (gcal.get(Calendar.DAY_OF_WEEK) != dow) {
gcal.add(Calendar.DAY_OF_MONTH, 1);
}
System.out.println(gcal.getActualMaximum(Calendar.DAY_OF_WEEK_IN_MONTH)); // 5
新的Java-8-API没有DAY_OF_WEEK_IN_MONTH字段(严格意义上),但您可以这样做:
int year = 2017;
int month = 1;
LocalDate ld1 =
LocalDate.of(year, month, 1).with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
LocalDate ld2 =
LocalDate.of(year, month, 1).with(TemporalAdjusters.lastInMonth(DayOfWeek.MONDAY));
System.out.println(ChronoUnit.WEEKS.between(ld1, ld2) + 1); // 5