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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  
  11.  
  12.     public static void main(String[] args){
  13.         Set<Name> s = new HashSet<Name>();
  14.         Name n1 = new Name("Donald", "Duck");
  15.         Name n2 = new Name("Donald", "Duck");
  16.         s.add(n1);
  17.  
  18.         System.out.print("HashCodes equal: ");
  19.         System.out.println( n1.hashCode() == n2.hashCode());
  20.         System.out.print("Objects equal: ");
  21.         System.out.println( n1.equals(n2) );
  22.  
  23.         System.out.print("HashSet contains n1: ");
  24.         System.out.println(s.contains(n1));
  25.  
  26.         System.out.print("HashSet contains n2: ");
  27.         System.out.println(s.contains(n2));
  28.     }
  29. }
  30. class Name {
  31.     private String first, last;
  32.  
  33.     public Name(String first, String last){
  34.         this.first = first; 
  35.         this.last = last;
  36.     }
  37.  
  38. 	@Override
  39.     public boolean equals(Object o){
  40.     	Name n = (Name)o;
  41.         return n.first.equals(first) && n.last.equals(last);
  42.     }
  43.  
  44.     public int hashCode(){
  45.         return 31*first.hashCode()+last.hashCode();
  46.     }
  47.  
  48. }
Success #stdin #stdout 0.07s 381184KB
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stdin
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Standard input is empty
stdout
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HashCodes equal: true
Objects equal: true
HashSet contains n1: true
HashSet contains n2: true
https://ideone.com/XF73gc
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

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