1. import java.util.ArrayList;
  2. import java.util.HashMap;
  3. import java.util.List;
  4. import java.util.Map;
  6. public class LogFlattener {
  8. /**
  9. * Flattens a nested log entry structure into a single-level map.
  10. *
  11. * @param logEntries A list of log entry maps.
  12. * @return A list of flattened maps, one for each log entry.
  13. */
  14. public static List<Map<String, String>> flattenLogs(List<Map<String, Object>> logEntries) {
  15. List<Map<String, String>> flattenedLogs = new ArrayList<>();
  17. for (Map<String, Object> logEntry : logEntries) {
  18. Map<String, String> flattenedEntry = new HashMap<>();
  19. flattenHelper(logEntry, flattenedEntry);
  20. flattenedLogs.add(flattenedEntry);
  21. }
  23. return flattenedLogs;
  24. }
  26. private static void flattenHelper(Map<String, Object> logEntry, Map<String, String> flattenedEntry) {
  27. for (Map.Entry<String, Object> entry : logEntry.entrySet()) {
  28. String key = entry.getKey();
  29. Object value = entry.getValue();
  31. if (value instanceof Map) {
  32. // Recursively flatten nested maps
  33. Map<String, Object> nestedMap = (Map<String, Object>) value;
  34. flattenHelper(nestedMap, flattenedEntry);
  35. } else if (value != null) {
  36. // Convert non-map values to strings
  37. flattenedEntry.put(key, String.valueOf(value));
  38. }
  39. }
  40. }
  42. public static void main(String[] args) {
  43. // Example Usage
  44. List<Map<String, Object>> logEntries = new ArrayList<>();
  46. Map<String, Object> log1 = new HashMap<>();
  47. log1.put("timestamp", "2023-10-27T10:00:00");
  48. log1.put("level", "INFO");
  49. Map<String, Object> details1 = new HashMap<>();
  50. details1.put("user", "john.doe");
  51. details1.put("message", "User logged in.");
  52. log1.put("details", details1);
  53. logEntries.add(log1);
  55. Map<String, Object> log2 = new HashMap<>();
  56. log2.put("timestamp", "2023-10-27T10:05:00");
  57. log2.put("level", "ERROR");
  58. Map<String, Object> details2 = new HashMap<>();
  59. details2.put("user", "jane.doe");
  60. details2.put("message", "Failed to process request.");
  61. log2.put("details", details2);
  62. logEntries.add(log2);
  65. List<Map<String, String>> flattenedLogs = flattenLogs(logEntries);
  67. for (Map<String, String> flattenedLog : flattenedLogs) {
  68. System.out.println(flattenedLog);
  69. }
  70. }
  71. }

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