Question

我知道一年中的周数，一周从星期日开始，然后是星期一，星期二......星期六。

由于我知道周数，使用Java代码获取特定周的日期的有效方法是什么？

Answer 1

如果您不想使用外部库，只需使用日历。

SimpleDateFormat sdf = new SimpleDateFormat("MM dd yyyy");
Calendar cal = Calendar.getInstance();
cal.set(Calendar.WEEK_OF_YEAR, 23);        
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
System.out.println(sdf.format(cal.getTime()));

Answer 2

纯Java 8 / java.time解决方案

基于this：

final long calendarWeek = 34;
LocalDate desiredDate = LocalDate.now()
            .with(IsoFields.WEEK_OF_WEEK_BASED_YEAR, calendarWeek)
            .with(TemporalAdjusters.previousOrSame(DayOfWeek.MONDAY));

Answer 3

您可以使用joda time库

int weekNumber = 10;
DateTime weekStartDate = new DateTime().withWeekOfWeekyear(weekNumber);
DateTime weekEndDate = new DateTime().withWeekOfWeekyear(weekNumber + 1);

Answer 4

您没有提到您确切需要的返回类型，但此代码应该对您有用。 sysouts和formatter只是为了显示结果。

Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
cal.set(Calendar.WEEK_OF_YEAR, 30);
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
cal.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
System.out.println(formatter.format(cal.getTime()));
cal.add(Calendar.DAY_OF_WEEK, 6);
System.out.println(formatter.format(cal.getTime()));

Answer 5

此答案与其他答案几乎相同。但是，事情就这样了：

int year = 2018;
int week = 27;
int day = 1; //assuming week starts from sunday
Calendar calendar = Calendar.getInstance();
calendar.setWeekDate(year, week, day);
System.out.println(calendar.getTime());

Answer 6

for(int i=1; i<=7; i++) {
            if(i <= 3) {
                LocalDate desiredDate = LocalDate.now()
                        .with(IsoFields.WEEK_OF_WEEK_BASED_YEAR, 26)
                        .with(TemporalAdjusters.previousOrSame(DayOfWeek.of(i)));
                System.out.println(desiredDate.format(DateTimeFormatter.ofPattern("dd/MM/yyyy")));
            } else {
                LocalDate desiredDate = LocalDate.now()
                        .with(IsoFields.WEEK_OF_WEEK_BASED_YEAR, 26)
                        .with(TemporalAdjusters.nextOrSame(DayOfWeek.of(i)));
                System.out.println(desiredDate.format(DateTimeFormatter.ofPattern("dd/MM/yyyy")));
            }
        }

此代码段根据给定的周数提供从星期一到星期日的日期输出：

28/06/2021
29/06/2021
30/06/2021
01/07/2021
02/07/2021
03/07/2021
04/07/2021

验证支票https://www.epochconverter.com/weeks/2021

如何获得一周的日期（我知道周数）？

6 个答案:

纯Java 8 / java.time解决方案