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  1. import java.util.*;
  2.  
  3. class Item {
  4.     @Override
  5.     public boolean equals(Object obj) {
  6.         return false;   // not even equal to itself.
  7.     }
  8. }
  9.  
  10. public class Main {
  11.     public static void main(String[] args) {
  12.         Collection<Item> items = new HashSet<Item>();
  13.         Item i = new Item();
  14.         items.add(i);
  15.         System.out.println(items.contains(i));   // Prints true!
  16.     }
  17. }
Success #stdin #stdout 0.11s 320576KB
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true
https://ideone.com/VBZ7dN
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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