java - 星期几的Android日历问题

Question

我正在尝试列出本周从周一到周日的所有日期。例如，今天(发布此帖子的日期)是 2011 年 9 月 4 日，是星期日。

我正在启动日历并将一周的第一天设置为星期一:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);

当我检查一个月中的第几天时，我得到了正确的结果:

int check = cal.get(Calendar.DAY_OF_MONTH);
// check is equal to 4

但是当我将工作日设置为星期一时，它会跳转到下一周，而不是返回本周的星期一:

cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
// mon is equal to 5, when expected to be 29 (last Monday of August)

即使将工作日设置为星期日，也会在下星期日而不是今天返回。

谁能解释为什么它会这样工作以及解决这个问题的最佳方法是什么？

Answer 1

事实上，当我检查自己的测试时，它似乎按预期工作，除非再次设置日期:

显示 4-29:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);
cal.set(2011, 8, 4);
int test = cal.get(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + test + "-" + mon);

显示 5-5:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);
cal.set(2011, 8, 5);
int test = cal.get(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + test + "-" + mon);

显示 14-12:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);
cal.set(2011, 8, 14);
int test = cal.get(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + test + "-" + mon);

所以，这是行不通的:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);
//cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH));
int test = cal.get(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + test + "-" + mon); // Display 4-5

并且这行得通:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);

// Workaround
cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH));

int test = cal.get(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + test + "-" + mon); // Display 4-29

并且这也有效:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);

// Workaround
cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH));
cal.get(Calendar.DAY_OF_MONTH);

cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + mon); // Display 29

但这个不是:

Calendar cal = Calendar.getInstance();
cal.setFirstDayOfWeek(Calendar.MONDAY);
cal.setMinimalDaysInFirstWeek(4);

// Workaround
cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH));
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
int mon = cal.get(Calendar.DAY_OF_MONTH);
bTest.setText("" + mon); // Display 5