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  1. import java.util.*;
  2. import java.lang.*;
  3.  
  4. class Main
  5. {
  6. 	static class Person {
  7. 		private String first;
  8. 		private String last;
  9. 		public String getFirst() {return first;}
  10. 		public String getLast() {return last;}
  11. 		public Person(String f, String l) {
  12. 			first = f;
  13. 			last = l;
  14. 		}
  15. 		public String toString() {
  16. 			return first+" "+last;
  17. 		}
  18. 	}
  19. 	public static void main (String[] args) throws java.lang.Exception
  20. 	{
  21. 		List<Person> people = new ArrayList<Person>();
  22. 		people.add(new Person("John", "Smith"));
  23. 		people.add(new Person("John", "Scott"));
  24. 		people.add(new Person("Jack", "First"));
  25. 		people.add(new Person("John", "Walker"));
  26. 		people.add(new Person("Jack", "Black"));
  27. 		Set<Object> seen = new HashSet<Object>();
  28. 		for (Person p : people) {
  29. 			final Person thisPerson = p;
  30. 			class Wrap {
  31. 				public int hashCode() { return thisPerson.getFirst().hashCode(); }
  32. 				public boolean equals(Object o) {
  33. 					Wrap other = (Wrap)o;
  34. 					return other.wrapped().getFirst().equals(thisPerson.getFirst());
  35. 				}
  36. 				public Person wrapped() { return thisPerson; }
  37. 			};
  38. 			Wrap wrap = new Wrap();
  39. 			if (seen.add(wrap)) {
  40. 				System.out.println(p + " is new");
  41. 			} else {
  42. 				System.out.println(p + " is a duplicate");
  43. 			}
  44. 		}
  45. 	}
  46. }
Success #stdin #stdout 0.03s 245632KB
comments (?)
stdin 
Standard input is empty
stdout 
John Smith is new
John Scott is a duplicate
Jack First is new
John Walker is a duplicate
Jack Black is a duplicate
https://ideone.com/moP94
language:
Java (HotSpot 12)
created:
12 years ago
visibility:
public

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