1. import java.time.Instant;
  2. import java.time.LocalDateTime;
  3. import java.time.ZoneId;
  4. import java.time.ZonedDateTime;
  5. import java.time.format.DateTimeFormatter;
  6. import java.util.ArrayList;
  7. import java.util.List;
  9. public class TimestampSplitter {
  11. /**
  12. * Splits a list of timestamps into lists based on different levels of precision.
  13. *
  14. * @param timestamps A list of timestamps (represented as milliseconds since epoch).
  15. * @return A map where keys are precision levels (e.g., "year", "month", "day")
  16. * and values are lists of timestamps at that precision. Returns an empty map if input is null or empty.
  17. */
  18. public static List<List<Long>> splitTimestamps(List<Long> timestamps) {
  19. if (timestamps == null || timestamps.isEmpty()) {
  20. return new ArrayList<>();
  21. }
  23. List<List<Long>> result = new ArrayList<>();
  25. // Split by year
  26. List<Long> yearlyTimestamps = new ArrayList<>();
  27. for (Long timestamp : timestamps) {
  28. Instant instant = Instant.ofEpochMilli(timestamp);
  29. ZonedDateTime zonedDateTime = instant.atZone(ZoneId.systemDefault());
  30. yearlyTimestamps.add(zonedDateTime.toLocalDateTime().toInstant().toEpochMilli());
  31. }
  32. result.add(yearlyTimestamps);
  35. // Split by month
  36. List<Long> monthlyTimestamps = new ArrayList<>();
  37. for (Long timestamp : timestamps) {
  38. Instant instant = Instant.ofEpochMilli(timestamp);
  39. ZonedDateTime zonedDateTime = instant.atZone(ZoneId.systemDefault());
  40. monthlyTimestamps.add(zonedDateTime.toLocalDate().toInstant().toEpochMilli());
  41. }
  42. result.add(monthlyTimestamps);
  44. // Split by day
  45. List<Long> dailyTimestamps = new ArrayList<>();
  46. for (Long timestamp : timestamps) {
  47. Instant instant = Instant.ofEpochMilli(timestamp);
  48. ZonedDateTime zonedDateTime = instant.atZone(ZoneId.systemDefault());
  49. dailyTimestamps.add(zonedDateTime.toLocalDate().toInstant().toEpochMilli());
  50. }
  51. result.add(dailyTimestamps);
  53. return result;
  54. }
  57. public static void main(String[] args) {
  58. //Example Usage
  59. List<Long> timestamps = List.of(
  60. 1678886400000L, // March 15, 2023
  61. 1678972800000L, // March 16, 2023
  62. 1679059200000L, // March 17, 2023
  63. 1704000000000L, // January 1, 2024
  64. 1704006000000L //January 2, 2024
  65. );
  67. List<List<Long>> splitData = splitTimestamps(timestamps);
  69. for (int i = 0; i < splitData.size(); i++) {
  70. System.out.println("Timestamps for " + getPrecision(i) + ": " + splitData.get(i));
  71. }
  72. }
  74. private static String getPrecision(int index) {
  75. switch (index) {
  76. case 0: return "Year";
  77. case 1: return "Month";
  78. case 2: return "Day";
  79. default: return "Unknown";
  80. }
  81. }
  82. }

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