如何基于字符串内的日期时间段对List<String>进行排序？

问题分析 #

你的需求是对包含文件路径的List<String>进行排序，排序依据是路径末尾的日期时间字符串（格式如2023-09-11-19-30-10-00445）。观察该格式可知，字符串的字典序与时间先后顺序完全一致，因此可以直接提取该子串后进行比较，无需额外转换为日期对象（若需更严谨的日期校验，也可转换为日期类）。

解决方案 #

方法1：自定义Comparator排序

通过提取每个路径中的目标日期子串，基于子串的字典序实现排序：

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

public class PathSorter {
    public static void main(String[] args) {
        List<String> pathList = new ArrayList<>();
        // 初始化待排序列表
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0057c620ea6040849da9bceb977e7332-2023-09-11-19-30-10-00445.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_00e1cd4e425243bda8e09ee2b7b2334f-2023-09-11-19-30-02-00554.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_021b63466ff6406d8b30b25bda63b49f-2023-09-11-19-30-21-00218.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_049a681a00214155b7dab7c94c871341-2023-09-11-19-30-15-00036.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_068e490f3b78453293e84bdfb49112ad-2023-09-11-19-30-14-00288.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0694fca541d0486689c6591b16cb1fbc-2023-09-11-19-30-14-00405.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0a8d4975741e4b088ead2bfd1edee1ad-2023-09-11-19-30-07-00188.txt");

        // 按提取的日期子串排序
        pathList.sort(Comparator.comparing(PathSorter::extractDateTimeString));

        // 输出排序结果
        pathList.forEach(System.out::println);
    }

    // 提取路径中的日期时间子串
    private static String extractDateTimeString(String path) {
        // 去掉末尾的.txt后缀
        String withoutExtension = path.substring(0, path.lastIndexOf(".txt"));
        // 提取最后一个'-'之后的日期时间字符串
        return withoutExtension.substring(withoutExtension.lastIndexOf('-') + 1);
    }
}

方法2：Stream API排序（简洁风格）

如果偏好函数式编程，可通过Stream实现排序：

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class PathSorterStream {
    public static void main(String[] args) {
        List<String> pathList = new ArrayList<>();
        // 初始化待排序列表（同方法1）
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0057c620ea6040849da9bceb977e7332-2023-09-11-19-30-10-00445.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_00e1cd4e425243bda8e09ee2b7b2334f-2023-09-11-19-30-02-00554.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_021b63466ff6406d8b30b25bda63b49f-2023-09-11-19-30-21-00218.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_049a681a00214155b7dab7c94c871341-2023-09-11-19-30-15-00036.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_068e490f3b78453293e84bdfb49112ad-2023-09-11-19-30-14-00288.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0694fca541d0486689c6591b16cb1fbc-2023-09-11-19-30-14-00405.txt");
        pathList.add("datareplay/upstream/20230911/2023-09-11/WIRE_ISSN.WIRE_CRTD_0a8d4975741e4b088ead2bfd1edee1ad-2023-09-11-19-30-07-00188.txt");

        // 排序并收集结果
        List<String> sortedList = pathList.stream()
                .sorted(Comparator.comparing(path -> {
                    String withoutExt = path.substring(0, path.lastIndexOf(".txt"));
                    return withoutExt.substring(withoutExt.lastIndexOf('-') + 1);
                }))
                .collect(Collectors.toList());

        // 输出结果
        sortedList.forEach(System.out::println);
    }
}

补充说明 #

• 若需要降序排序，只需在Comparator.comparing()后添加.reversed()即可。
• 如果要确保日期格式合法，可将提取的子串转换为LocalDateTime处理毫秒部分，示例如下：

  private static LocalDateTime parseDateTime(String dateStr) {
      String[] parts = dateStr.split("-");
      String dateTimePart = String.join("-", Arrays.copyOfRange(parts, 0, 6));
      int nano = Integer.parseInt(parts[6]) * 1000000; // 五位毫秒转纳秒
      return LocalDateTime.parse(dateTimePart, DateTimeFormatter.ofPattern("yyyy-MM-dd-HH-mm-ss"))
              .plusNanos(nano);
  }
  

  排序时使用Comparator.comparing(PathSorter::parseDateTime)即可。

内容的提问来源于stack exchange，提问作者NoobCoder