Java如何将若干时间区间进行合并的方法步骤

  public static List mergePeriod(List periodList) {
    List result = new ArrayList();

    if (periodList == null || periodList.size() <1) {
      return result;
    }

    // 对区间进行排序
    Collections.sort(periodList, new Comparator() {
      @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 list = new ArrayList();
    list.add(date1);
    list.add(date2);
    list.add(date3);
    list.add(date4);
    
    List result = mergePeriod(list);
    
    System.out.println(JSONObject.toJSONStringWithDateFormat(result, JSONObject.DEFFAULT_DATE_FORMAT));
  }

import java.io.*;
import java.util.*;

public class Main {

  static List 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(){
      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);
  }
}