设置DAY_OF_WEEK会返回意外结果

我想将给定的日历实例的时间戳设置为一周的开头(星期一),而是返回一个看似完全不相关的时间戳 - 除非我在这之前访问任何日历的字段.我在下面提供了一个示例,请在Ideone中看到这个可运行的示例.

这是预期的行为吗？这背后的逻辑是什么？是的,我听说过Joda Time.

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;
import java.util.TimeZone;


class MyTest {

private static Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("CET"), Locale.FRANCE);
private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");

public static void main(String[] args) {

    // Set to any date.
    calendar.set(2013, 10, 3);
    System.out.println(dateFormat.format(calendar.getTime()));

    // Set to another day.
    calendar.set(2014, 0, 15);
    // --- THE WTF STARTS HERE ---
    // Uncommenting the line below returns the correct date in the end.
    // calendar.getTime();

    // Set to monday of current week.
    calendar.set(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());

    // Expected outdate is 20140113
    System.out.println(dateFormat.format(calendar.getTime()));

}

}

akaya.. 5

文档中的Field Manipulation章节清楚地解释了它.它虽然有点怪异.

http://docs.oracle.com/javase/6/docs/api/java/util/Calendar.html

示例:考虑最初设置为1999年8月31日的GregorianCalendar.调用集(Calendar.MONTH,Calendar.SEPTEMBER)将日期设置为1999年9月31日.这是一个临时内部表示,如果getTime(),则解析为1999年10月1日然后被叫.但是,在调用getTime()之前调用set(Calendar.DAY_OF_MONTH,30)会将日期设置为1999年9月30日,因为在set()之后没有重新计算.

编辑

从日历字段解决方案部分相同的文档

If there is any conflict in calendar field values, Calendar gives priorities to 
calendar fields that have been set more recently. The following are the default 
combinations of the calendar fields. The most recent combination, as determined 
by the most recently set single field, will be used.

For the date fields:

 YEAR + MONTH + DAY_OF_MONTH
 YEAR + MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
 YEAR + MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
 YEAR + DAY_OF_YEAR
 YEAR + DAY_OF_WEEK + WEEK_OF_YEAR

我认为MONTH和DAY_OF_WEEK之间的差异就是这个.如果在最后一个语句中设置MONTH,则它与YEAR + MONTH + DAY_OF_MONTH匹配并覆盖所有这些语句.如果您设置DAY_OF_WEEK,则它与YEAR + DAY_OF_WEEK + WEEK_OF_YEAR匹配,因此不会覆盖月份值.或类似的东西.说实话,我看起来越多,看起来就越破碎.它完全没有意义.最好继续使用JodaTime