2 import java.io.BufferedReader;
3 import java.io.FileReader;
4 import java.io.PrintWriter;
5 import java.time.LocalDate;
6 import java.time.LocalTime;
7 import java.time.format.DateTimeFormatter;
8 import java.io.IOException;
10 public class DateWriter {
12 public static void main(String[] args) throws IOException {
13 if (args.length < 3) {
14 System.out.println("Usage: java " + DateWriter.class.getSimpleName() + " /path/to/file/with/timestamps /path/to/new/timestamp/file/with/dates initial_date_in_MM/dd/uuuu_format");
17 String pathOriginal = args[0];
18 String pathModified = args[1];
19 String initialDateStr = args[2];
20 DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("MM/dd/uuuu");
21 LocalDate date = LocalDate.parse(initialDateStr, dateFormatter);
22 File originalFile = new File(pathOriginal);
24 File modifiedFile = new File(pathModified);
25 modifiedFile.createNewFile();
26 BufferedReader reader = new BufferedReader(new FileReader(originalFile));
27 PrintWriter writer = new PrintWriter(modifiedFile);
29 String prevLine = null;
30 while ((line = reader.readLine()) != null) {
31 if (isNewDay(line, prevLine)) {
33 date = date.plusDays(1);
35 writer.println(String.format("%s %s", date.format(dateFormatter), line));
43 private static boolean isNewDay(String line, String prevLine) {
44 if (prevLine == null) {
47 // First part handles case where we pass midnight and the following timestamp is an AM timestamp
48 // Second case handles case where we pass midnight, but the following timestamp is a PM timestamp
49 return line.endsWith("AM") && prevLine.endsWith("PM") || toLocalTime(line).isBefore(toLocalTime(prevLine));
52 private static LocalTime toLocalTime(String timeString) {
53 return LocalTime.parse(timeString, DateTimeFormatter.ofPattern("h:mm:ss a"));