格里高利历法返回奇怪的值？

Question

public class MyCalendar { 

    GregorianCalendar greg = new GregorianCalendar(); 
    String[] month = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}; 
    String[] day = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}; 

    public void printMonth(int d, int m, int y) { 
    GregorianCalendar greg= new GregorianCalendar(greg.get(Calendar.YEAR), 
       greg.get(Calendar.MONTH), 1); 

      System.out.println(month[greg.get(Calendar.MONTH)]); 
      System.out.println(greg.get(Calendar.FRIDAY)); 
      System.out.println(greg.get(Calendar.SATURDAY)); 
    } 

我无法弄清楚为什么greg.get（Calendar ._____）给了我意想不到的值。

YEAR, MONTH, DATE all give me correct values: 2015, 9, 6 

FRIDAY returns 279 

SATURDAY returns 3 

SUNDAY returns 2015 

TUESDAY returns 41 

有人可以向我解释为什么我得到这些数字吗？我试图找出如何在本月的所有星期六的日期，并认为greg.get(Calendar.SATURDAY)可能是有用的这样做。

Answer 1

所以，Calendar#get可以让你得到Calendar对象的paritcular领域，如DAY_OF_WEEK，然后可以映射回Calendar.MONDAY通过Calendar.SUNDAY，使其更容易理解的返回结果。

所以，要计算的SATURDAY S IN一个月的数字，你需要先找到第一SATURDAY（是的，我尝试设置DATE后使用cal.set(Calendar.DAY_OF_WEEK, Calendar.SATUDAY)，但它给了不一致的结果）

Calendar cal = Calendar.getInstance(); 
cal.set(Calendar.DATE, 1); 

while (cal.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY) { 
    cal.add(Calendar.DATE, 1); 
} 

，然后简单地算进7天，直到我们离开当月

int count = 0; 
int month = cal.get(Calendar.MONTH); 
while (cal.get(Calendar.MONTH) == month) { 
    count++; 
    cal.add(Calendar.DATE, 7); 
} 

System.out.println("This month has " + count + " saturdays"); 

的Java 8

LocalDate date = LocalDate.now(); 
LocalDate endOfMonth = date.withDayOfMonth(date.lengthOfMonth()); 

date = date.withDayOfMonth(1); 
System.out.println(date); 
date = date.with(ChronoField.DAY_OF_WEEK, DayOfWeek.SATURDAY.getValue()); 

int count = 0; 
while (date.isEqual(endOfMonth) || date.isBefore(endOfMonth)) { 
    count++; 
    date = date.plusDays(7); 
} 

System.out.println("You have " + count + " Saturdays");