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));

  }

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);

   }

}