使用Java8对LocalDateTime对象进行间隔分组

import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class DateTimeGroupingExample {
    public static void main(String[] args) {
        // 假设这是我们的LocalDateTime对象列表
        List<LocalDateTime> dateTimes = List.of(
            LocalDateTime.of(2023, 1, 1, 12, 0),
            LocalDateTime.of(2023, 1, 1, 13, 30),
            LocalDateTime.of(2023, 1, 1, 12, 45),
            LocalDateTime.of(2023, 1, 1, 14, 15)
        );

        // 根据小时分组
        Map<Integer, List<LocalDateTime>> groupedByHour = dateTimes.stream()
            .collect(Collectors.groupingBy(dateTime -> dateTime.getHour()));

        // 打印分组结果
        groupedByHour.forEach((hour, times) -> 
            System.out.println("Hour " + hour + ": " + times));
    }
}

Map<Integer, List<LocalDateTime>> groupedByHalfHour = dateTimes.stream()
    .collect(Collectors.groupingBy(dateTime -> dateTime.truncatedTo(ChronoUnit.HALF_HOURS).getHour()));