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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4. import java.time.*;
  5.  
  6. /* Name of the class has to be "Main" only if the class is public. */
  7. class Ideone {
  8.  
  9. 	public static void main (String[] args) throws java.lang.Exception {
  10.  
  11. 		Person youngest;
  12.  
  13. 		// you could do string comparison if you know the timezones are consistent:
  14.  
  15. 		youngest = listOfPersons.stream()
  16. 		    .max(Comparator.comparing(p -> p.dateOfBirth)).get();
  17.  
  18. 		System.out.println("youngest is: " + youngest.name + " " + youngest.dateOfBirth);
  19.  
  20.         // or you could just parse the date, a safer option:
  21.  
  22. 		youngest = listOfPersons.stream()
  23. 		    .max(Comparator.comparing(p -> LocalDateTime.parse(p.dateOfBirth))).get();
  24.  
  25. 		System.out.println("youngest is: " + youngest.name + " " + youngest.dateOfBirth);
  26.  
  27. 	}
  28.  
  29.  
  30. 	//------------------------------------
  31. 	// types from OP:
  32.  
  33. 	static class Person{
  34. 		String name;
  35. 		String id;
  36. 		String dateOfBirth;
  37. 		int salary;
  38. 	}
  39.  
  40. 	static List <Person> listOfPersons;
  41.  
  42.  
  43. 	//------------------------------------
  44. 	// boring example data initialization:
  45.  
  46. 	// make an iso birthdate string given an age (for initializing data)
  47. 	static String fromAge (int years) {
  48. 		return LocalDateTime.now().minusYears(years).toString(); // ISO8601
  49. 	}
  50.  
  51. 	// make up some data
  52. 	static {
  53. 		listOfPersons = List.of(
  54. 			// fine for example, but i wouldn't init like this in production
  55. 			new Person() {{ name="helga"; dateOfBirth=fromAge(22); }},
  56. 			new Person() {{ name="mortimer"; dateOfBirth=fromAge(48); }},
  57. 			new Person() {{ name="gertrude"; dateOfBirth=fromAge(6); }},
  58. 			new Person() {{ name="jebediah"; dateOfBirth=fromAge(39); }}
  59. 		);
  60. 		listOfPersons.forEach(p -> System.out.println(p.name + ' ' + p.dateOfBirth));
  61. 	}
  62.  
  63.  
  64. }
Success #stdin #stdout 0.2s 55648KB
comments (?)
stdin 
Standard input is empty
stdout 
helga 2000-06-22T14:56:39.329972
mortimer 1974-06-22T14:56:39.330483
gertrude 2016-06-22T14:56:39.331082
jebediah 1983-06-22T14:56:39.331653
youngest is: gertrude 2016-06-22T14:56:39.331082
youngest is: gertrude 2016-06-22T14:56:39.331082
https://ideone.com/viqg7f
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
public

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