java date 时间最大连续天数

java localdate 时间最大连续天数

  public class DateUtils {

  public static Date addDays(Date time, Integer day) {
    try {
      SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
      Calendar cd = Calendar.getInstance();
      cd.setTime(time);
      cd.add(Calendar.DATE, day);
      return getDateByPattern(sdf.format(cd.getTime()), DAY_FORMAT);
    } catch (Exception ex) {
      log.error("日期增加自然天出错：{}", ex);
      return null;
    }
  }


 public static int continuousDayDate(List<Date> dateList) {
    if (CollectionUtils.isEmpty(dateList) ) {
      log.error("参数有误,连续天数为0  dayList{}" , dateList);
      return 0;
    }
    
    List<LocalDate> datetimeList = dateList.stream()
      .map(e-> LocalDateTime.ofInstant(e.toInstant(), ZoneId.systemDefault()))
      .sorted(LocalDateTime::compareTo)
      .map(LocalDateTime::toLocalDate)
      .collect(Collectors.toList());
    return continuousDayLocalDate(datetimeList);
  }
  
  public static int continuousDayLocalDate(List<LocalDate> dateList){
    if (dateList == null || dateList.size() ==0) {
      return 0;
    }
    dateList = dateList.stream().sorted(LocalDate::compareTo).collect(Collectors.toList());
    int maxContinuousDay = 1;
    int continuousDay = 1;
    for (int i = 0; i < dateList.size(); i++) {
      if (i == dateList.size() -1){
        break;
      }
      LocalDate date = dateList.get(i);
      LocalDate secondDate = dateList.get(i + 1);
      if (date.plusDays(1).equals(secondDate)){
        continuousDay ++;
        if (continuousDay > maxContinuousDay){
          maxContinuousDay = continuousDay;
        }
      }else {
        continuousDay = 1;
      }
    }
    return maxContinuousDay;
  }
  
  public static void main(String[] args) {
    List<Date> dates = new ArrayList<>();
    Date date = new Date();
    dates.add(addDays(date, 1));
    dates.add(addDays(date, 2));
    dates.add(addDays(date, 5));
    dates.add(addDays(date, 7));
    dates.add(addDays(date, 8));
    dates.add(addDays(date, 9));
    
    System.out.println(continuousDayDate(dates));
  
  
    List<LocalDate> list = new ArrayList<>();
  
    list.add(LocalDate.now());
    list.add(LocalDate.now().plusDays(1));
    list.add(LocalDate.now().plusDays(2));
  
    System.out.println(DateUtil.continuousDayLocalDate(list));
  }
  }
 }