[Java] Java如何将若干时间区间进行合并的方法步骤

public static List<PeriodDto> mergePeriod(List<PeriodDto> periodList) {
  List<PeriodDto> result = new ArrayList<PeriodDto>();
 
  if (periodList == null || periodList.size() < 1) {
  return result;
  }
 
  // 对区间进行排序
  Collections.sort(periodList, new Comparator<PeriodDto>() {
  @Override
  public int compare(PeriodDto o1, PeriodDto o2) {
    if ((o1.getFrom().getTime() - o2.getFrom().getTime()) > 0) {
    return 1;
    } else if ((o1.getFrom().getTime() - o2.getFrom().getTime()) == 0) {
    return 0;
    } else {
    return -1;
    }
  }
  });
  PeriodDto prev = null;
  for (PeriodDto item : periodList) {
  if (prev == null || prev.getTo().before(item.getFrom())) {
    result.add(item);
    prev = item;
  } else if (prev.getTo().before(item.getTo())) {
    prev.setTo(item.getTo());
  }
  }
 
  return result;
}

public static void main(String[] args) throws ParseException {
 
   PeriodDto date1 = new PeriodDto();
   date1.setFrom(DateUtils.fmtDate("2020-01-01 12:00:00"));
   date1.setTo(DateUtils.fmtDate("2021-01-01 12:00:00"));
   
   PeriodDto date2 = new PeriodDto();
   date2.setFrom(DateUtils.fmtDate("2019-05-01 12:00:00"));
   date2.setTo(DateUtils.fmtDate("2020-04-29 12:00:00"));
   
   PeriodDto date3 = new PeriodDto();
   date3.setFrom(DateUtils.fmtDate("2018-01-01 12:00:00"));
   date3.setTo(DateUtils.fmtDate("2019-01-01 12:00:00"));
   
   PeriodDto date4 = new PeriodDto();
   date4.setFrom(DateUtils.fmtDate("2012-01-01 12:00:00"));
   date4.setTo(DateUtils.fmtDate("2023-01-01 12:00:00"));
   
   List<PeriodDto> list = new ArrayList<PeriodDto>();
   list.add(date1);
   list.add(date2);
   list.add(date3);
   list.add(date4);
   
   List<PeriodDto> result = mergePeriod(list);
   
   System.out.println(JSONObject.toJSONStringWithDateFormat(result, JSONObject.DEFFAULT_DATE_FORMAT));
 }

[{"from":"2018-01-01 12:00:00","to":"2019-01-01 12:00:00"},{"from":"2019-05-01 12:00:00","to":"2021-01-01 12:00:00"},{"from":"2022-01-01 12:00:00","to":"2023-01-01 12:00:00"}]

import java.io.*;
import java.util.*;
 
public class Main {
 
  static List<int[]> f = new ArrayList<>();
 
  public static void main(String[] args) throws IOException{
  BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
  int n = Integer.parseInt(read.readLine());
  for(int i = 1; i <= n; i++) {
    String[] str = read.readLine().split(" ");
    int[] t = {Integer.parseInt(str[0]),Integer.parseInt(str[1])};
    f.add(t);
  }
  f.sort(new Comparator<int[]>(){
    public int compare(int[] o1, int[] o2){
    return o1[0] - o2[0];
    }
  });
  int ed = Integer.MIN_VALUE, res = 0;
  for (int[] t : f) {
    if(t[0] > ed) res ++;
    ed = Math.max(ed, t[1]);
  }
  System.out.println(res);
  }
}