Read Write CSV with LocalDateTime Data

import java.io.Writer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.stream.Collectors;

public class Ranking {
  class Record {
    private LocalDateTime datetime;
    private int data1, data2;

    public LocalDateTime getDatetime() {
      return datetime;
    }

    public void setDatetime(LocalDateTime datetime) {
      this.datetime = datetime;
    }

    public int getData1() {
      return data1;
    }

    public void setData1(int data1) {
      this.data1 = data1;
    }

    public int getData2() {
      return data2;
    }

    public void setData2(int data2) {
      this.data2 = data2;
    }
  }

  private final static Path DATA_DIR = Paths.get("/home/data");
  private final static String CSV_GLOB = "*.csv";
  private final static Path OUT_PATH = Paths.get("/home/ranking/ranking.csv");
  private final LocalDateTime beg;
  private final LocalDateTime end;
  private Map<String, List<Record>> all;
  private Map<String, Integer> rank;

  public Ranking(LocalDateTime beg, LocalDateTime end) {
    this.beg = beg;
    this.end = end;
    all = new TreeMap<>();
    rank = null;
  }

  private void integrate() {
    if (!all.isEmpty()) {
      return;
    }
    DateTimeFormatter dt = DateTimeFormatter.ofPattern("uuuu'/'MM'/'dd'T'HH':'mm':'ss");
    try {
      for (Path csv: Files.newDirectoryStream(DATA_DIR, CSV_GLOB)) {
        String user = csv.getFileName().toString().replace(".csv", "");
        boolean first = true;
        for (Scanner in = new Scanner(csv); in.hasNextLine();) {
          if (first) {
            in.nextLine(); // for header
            first = false;
            continue;
          }
          String[] line = in.nextLine().split(",");
          Record r = new Record();
          r.setDatetime(LocalDateTime.parse(line[0] + "T" + line[1], dt));
          r.setData1(Integer.parseInt(line[2]));
          r.setData2(Integer.parseInt(line[3]));
          if (!all.containsKey(user)) {
            all.put(user, new ArrayList<>());
          }
          all.get(user).add(r);
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    all.forEach((k, v) -> {
      v.sort(new Comparator<Record>() {
        @Override
        public int compare(Record o1, Record o2) {
          return o1.getDatetime().compareTo(o2.getDatetime());
        }
      });
    });
  }

  private void extract() {
    if (rank != null) {
      return;
    }
    rank = new LinkedHashMap<>();
    // filtered with specify time and then summarize(Total)
    all.forEach((k, v) -> {
      rank.put(k,
          v.stream()
              .filter(r -> (r.getDatetime().isAfter(beg) || r.getDatetime().isEqual(beg))
                  && (r.getDatetime().isBefore(end) || r.getDatetime().isEqual(end)))
              .mapToInt(r -> r.getData1() + r.getData2()).sum());
    });
    // reverse sort on rank's value(Total)
    rank = rank.entrySet().stream().sorted(Collections.reverseOrder(Map.Entry.comparingByValue()))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1,
            LinkedHashMap::new));
  }

  public void writeCSV() {
    System.out.println("read data...");
    integrate();
    for (Entry<String, List<Record>> e: all.entrySet()) {
      System.out.println("USER: " + e.getKey() + ", LINES: " + e.getValue().size());
    }
    System.out.println("calc total...");
    extract();
    for (Entry<String, Integer> e: rank.entrySet()) {
      System.out.println(e);
    }
    System.out.println("write csv to " + OUT_PATH);
    try (Writer out = Files.newBufferedWriter(OUT_PATH)) {
      StringBuilder sb = new StringBuilder("RANKING,USER,TOTAL\n");
      int i = 1;
      for (Entry<String, Integer> e: rank.entrySet()) {
        sb.append(i++);
        sb.append(",");
        sb.append(e.getKey());
        sb.append(",");
        sb.append(e.getValue());
        sb.append("\n");
      }
      out.write(sb.toString());
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  public static void main(String[] args) {
    if (args.length != 3) {
      return;
    }
    DateTimeFormatter dt = DateTimeFormatter.ofPattern("uuuu'/'MM'/'dd'T'HH':'mm");
    new Ranking(LocalDateTime.parse(args[0] + "T" + args[1], dt),
        LocalDateTime.parse(args[0] + "T" + args[2], dt)).writeCSV();
  }

}