获取给定日期范围内的字符串日期列表-Scala [英] Get list of string dates between a given date range - Scala

问题描述

我正在尝试获取Scala中给定范围的字符串日期列表.是否有直接/简短的方法来实现这一目标?

I am trying to get a list of string dates in Scala for a given range. Is there a direct/shorter way to achieve this?

val format = "yyyMMdd"
val startDate = "20200101"
val endDate = "20200131"

预期产量=列表(2020101,20200102，.....，20200131)

Expected Output = List(2020101,20200102, ....., 20200131)

推荐答案

您可以执行以下操作:

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

public class Main {
    public static void main(String[] args) {
        // Tests
        System.out.println(getDateList("20200101", "20200110"));
        System.out.println(getDateList("20200101", "20200131"));
    }

    static List<String> getDateList(String strStartDate, String strEndDate) {
        // List to be populated with the desired strings
        List<String> result = new ArrayList<>();

        // Formatter for the desired pattern
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");

        // Parse strings to LocalDate instances
        LocalDate startDate = LocalDate.parse(strStartDate, formatter);
        LocalDate endDate = LocalDate.parse(strEndDate, formatter);

        // Loop starting with start date until end date with a step of one day
        for (LocalDate date = startDate; !date.isAfter(endDate); date = date.plusDays(1)) {
            result.add(date.format(formatter));
        }

        // Return the populated list
        return result;
    }
}

输出:

[20200101, 20200102, 20200103,..., 20200110]
[20200101, 20200102, 20200103,..., 20200131]

使用Java Stream API的解决方案:

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        // Tests
        System.out.println(getDateList("20200101", "20200110"));
        System.out.println(getDateList("20200101", "20200131"));
    }

    static List<String> getDateList(String strStartDate, String strEndDate) {
        // Formatter for the input and desired pattern
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");

        // Parse strings to LocalDate instances
        LocalDate startDate = LocalDate.parse(strStartDate, formatter);
        LocalDate endDate = LocalDate.parse(strEndDate, formatter);

        return Stream.iterate(startDate, date -> date.plusDays(1))
                .limit(ChronoUnit.DAYS.between(startDate, endDate.plusDays(1)))
                .map(date -> date.format(formatter))
                .collect(Collectors.toList());
    }
}

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