Java Android日历的星期几问题

我试图列出本周从周一到周日的所有工作日。例如，今天（发布此帖子的日期）是2011年9月4日，是周日

我正在启动日历并将一周的第一天设置为周一：

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

当我检查月日时，我得到了正确的结果：

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

但当我将工作日设置为周一时，它会跳到下一周，而不是返回本周的周一：

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)

即使将工作日设为周日，也会在下周日返回，而不是今天

---

有人能解释一下为什么会这样，解决这个问题的最佳方法是什么吗？

事实上，当我检查自己的测试时，它似乎像预期的那样工作，除非日期没有再次设置：

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);

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);

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);

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

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);

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);

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);

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

显示5-5：

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);

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);

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);

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

显示14-12：

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);

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);

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);

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

所以，这不起作用：

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

而这是有效的：

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);

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);

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);

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

而且这也有效：

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

但这一条没有：

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

---

人类不能使用安卓人的语言，只是开玩笑，输入日期，是爪哇棺材上的又一颗钉子。 这个误解问题的核心是错误的文档和两个事实，月从0开始，年从1900开始，但不在日历和他的后代中。 还有一个事实，在日期中，星期日是0，但在日历中，星期日是1

//THIS WORKS CORRECTLY
Date my = new Date(1986 - 1900, 04 - 1, 26);
System.out.println(my);
System.out.println(my.getDay());

Calendar cal = Calendar.getInstance(TimeZone.getDefault());
cal.set(1986, 04 - 1, 26);
System.out.println(cal.getTime());
System.out.println(cal.get(Calendar.DAY_OF_WEEK)-Calendar.SUNDAY);

另一种更方便的方式

//ONE AND ONLY, HUMAN FRIENDLY WAY TO ENTER DATE INTO JAVA
String date = "1986-04-26:01:23:47";
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd:HH:mm:SS");
Date convertedDate = (Date) formatter.parse(date);
System.out.println(convertedDate);

很简单，不是吗？

tl；博士 使用

LocalDate

，不要使用

Calendar

LocalDate.now( ZoneId.of( "Africa/Tunis" ) )
    .with( TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) )
    .plusDays( i ) )

java.time 避免麻烦的旧遗留类

Calendar

，因为它现在是遗留类，被java.time类（特别是）取代

对于没有时间的仅日期值，请使用

LocalDate

而不是日期+时间类型，如

Calendar

或。该类表示一个仅限日期的值，不包含一天中的时间和时区

时区对于确定日期至关重要。在任何一个特定的时刻，世界各地的日期都因地区而异。例如，中午夜后几分钟是新的一天，而中仍然是“昨天”

如果未指定时区，则隐式应用其当前默认值。该默认值可能随时更改，因此您的结果可能会有所不同。最好将所需/预期时区明确指定为参数

以

大陆/地区

的格式指定，例如，或

太平洋/奥克兰

。切勿使用3-4个字母的缩写，如

EST

或

IST

，因为它们不是真正的时区，也不是标准化的，甚至不是唯一的（！）

如果要使用JVM的当前默认时区，请请求它并将其作为参数传递。如果省略，则隐式应用JVM的当前默认值。最好是显式的，因为JVM中任何应用程序的任何线程中的任何代码都可能在运行时的任何时刻更改默认值

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

或者指定一个日期。你可以用一个数字来设置月份，1-12月的数字为1-12

LocalDate ld = LocalDate.of( 1986 , 2 , 23 ) ;  // Years use sane direct numbering (1986 means year 1986). Months use sane numbering, 1-12 for January-December.

或者，最好使用预定义的枚举对象，一年中每个月一个。提示：在整个代码库中使用这些

Month

对象，而不仅仅是一个整数，这样可以使代码更加自我记录，确保有效值，并提供更高的可用性

DayOfWeek

对于星期几，使用

DayOfWeek

enum类。它提供了七个实例，一周中的每一天一个，周一周日

DayOfWeek dow = ld.getDayOfWeek() ;  // Get an enum representing the day-of-week of this date, such as `DayOfWeek.MONDAY`.

调整日期 我们需要找到前一个星期一，如果已经是星期一，就坚持今天的日期。要移动到这些日期，请使用

TemporalAdjuster

的

TemporalAdjuster.previousorname

实现

TemporalAdjuster ta = TemporalAdjusters.previousOrSame( DayOfWeek.MONDAY ) ;
LocalDate previousOrSameMonday = ld.with( ta ) ;

通过调用以递增的方式收集所需的日期。注意java.time是如何使用的。我们根据原始对象的值得到一个新对象，而不是改变原始对象

// Hard-coded `7` is the seven days in a week.
List< LocalDate > dates = new ArrayList<>( 7 ) ;
for( int i = 0 , i < 7 , i ++ ) {
    LocalDate localDate = previousOrSameMonday.plusDays( i ) ;
    dates.add( localDate ) ;
}

当运行时

someDateOfWeek:2011-08-29《太阳报》：伦迪
星期几：2011年8月30日星期日
本周某时：2011年8月31日
星期几：2011-09-01星期日：朱迪
本周某时：2011-09-02星期日：文德雷迪
星期几：2011-09-03星期三
本周某时：2011-09-04塞曼日：迪曼奇

周数 额外提示：如果您想要ISO 8601标准定义的周数，请调用该方法。像这样：

int weekNumber = firstDateOfWeek.getWeekOfWeekyear();

---

您的日期是在第35周。

在设置期间，可能有一些操作在直接使用实例时遗漏了。谢谢您，我正要手动编写设置日期，一切正常，干杯！请你再帮我一个忙，运行你的测试而不使用

int test=cal.get（日历.月日）？如果我这样做-代码在第二次
cal.get（Calendar.DAY\u OF u MONTH）
时再次中断。这没什么大不了的，但我不明白为什么会发生这种事。谢谢，很高兴知道我不是唯一一个。我将尝试进一步研究这一点。仅供参考，像、
java.text.SimpleDateFormat
这样麻烦的旧日期时间类现在被内置在java 8和java 9中的类所取代。看见