java如何查找startDate和endDate之间的每周日期传递字符串，如“Wed，Thu”，它是动态传递的

Question

当我通过startDate和endDate传递一周中的某一天时，比如字符串“Mon，Tue，Wed，Thu，Fri，Sat，Sun”，那么我希望每周的日期基于startDate和endDate之间通过的一周中的某一天

天可以是从传入方法的整周或自定义日

一,。我的试用码

public List<LocalDate> getWeeklyDateByStringofDays(String DaysofWeek, LocalDate startDate, LocalDate endDate) {
    List<String> daysOfWeekList = Arrays.asList(DaysofWeek.split(","));
    // How can do it no idea
}

Answer 1

您可以按如下方式操作：

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        // Test
        System.out.println(getWeeklyDateByStringofDays("Mon, Tue, Wed", LocalDate.parse("2020-09-14"),
                LocalDate.parse("2020-12-14")));
    }

    static List<LocalDate> getWeeklyDateByStringofDays(String daysOfWeek, LocalDate startDate, LocalDate endDate) {
        // Split the string on optional whitespace followed by comma which in turn may
        // be followed by optional whitespace
        String[] daysOfWeekList = daysOfWeek.split("\\s*,\\s*");

        // The list to be populated with desired dates and returned
        List<LocalDate> result = new ArrayList<>();

        // Formatter to get only day name e.g. Mon from the date
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("EEE", Locale.ENGLISH);

        for (String day : daysOfWeekList) {
            // Loop starting with the startDate until the endDate with a step of one day
            for (LocalDate date = startDate; !date.isAfter(endDate); date = date.plusDays(1)) {
                if (date.format(dtf).equals(day)) {
                    result.add(date);
                }
            }
        }

        // Sort the list
        Collections.sort(result);

        return result;
    }
}

输出：

[2020-09-14, 2020-09-15, 2020-09-16, 2020-09-21, 2020-09-22, 2020-09-23, 2020-09-28, 2020-09-29, 2020-09-30, 2020-10-05, 2020-10-06, 2020-10-07, 2020-10-12, 2020-10-13, 2020-10-14, 2020-10-19, 2020-10-20, 2020-10-21, 2020-10-26, 2020-10-27, 2020-10-28, 2020-11-02, 2020-11-03, 2020-11-04, 2020-11-09, 2020-11-10, 2020-11-11, 2020-11-16, 2020-11-17, 2020-11-18, 2020-11-23, 2020-11-24, 2020-11-25, 2020-11-30, 2020-12-01, 2020-12-02, 2020-12-07, 2020-12-08, 2020-12-09, 2020-12-14]

注意：如果参数中的日期名称在任何情况下都可以是，请在上面给出的代码中将date.format(dtf).equals(day)替换为date.format(dtf).equalsIgnoreCase(day)

Answer 2

1. 将DaysOfWeek输入字符串解析为List<DayOfWeek>对象。例如，首先调用.split("\\s*,\\s*")以获取包含Mon、Tue等内容的字符串数组

2. 将字符串"Mon"变成DayOfWeek.MONDAY。见下文

3. 创建一个for循环，循环开始和结束之间的每个日期：for (LocalDate d = start; d.isBefore(end); d = d.plusDays(1))。每个日期，获取它代表的星期几，并检查它是否在您的列表中

我如何将“Mon”转换为DOW。星期一

您可以制作自己的hashmap，将字符串映射到DayOfWeek值。或者，您可以依赖java的日期解析，但这有点棘手：

Locale where = Locale.forLanguageTag("en"); 
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("EEEE", where);
TemporalAccessor accessor = formatter.parse("monday");
DayOfWeek dow = DayOfWeek.from(accessor);

当然，请注意您必须如何指定语言。毕竟，在整个地球上，有很多方式可以说“星期一”：

Answer 3

你可以从LocalDate中以三个字母的格式（例如Mon）获取DayOfWeek，并在daysOfWeek中检查包含内容

localdate.getDayOfWeek().getDisplayName(TextStyle.SHORT, Locale.US))

并使用Stream.iterate在范围内迭代，如果LocalDate中的DayOfWeek包含在daysOfWeek中，则过滤，然后在列表中收集localdates

  public List<LocalDate> getWeeklyDateByStringofDays(String daysOfWeek, LocalDate startDate,
      LocalDate endDate) {
    final int days = (int) startDate.until(endDate, ChronoUnit.DAYS);
    return Stream.iterate(startDate, d -> d.plusDays(1))
        .limit(days)
        .filter(d -> daysOfWeek.contains(d.getDayOfWeek()
                                          .getDisplayName(TextStyle.SHORT, Locale.US)))
        .collect(Collectors.toList());
  }