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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.util.stream.*;
  5. import java.lang.*;
  6. import java.io.*;
  7.  
  8. /* Name of the class has to be "Main" only if the class is public. */
  9. class Ideone
  10. {
  11. 	public static void main (String[] args) throws java.lang.Exception
  12. 	{
  13. 		HashSet<A> ha1 = new HashSet<A>();
  14. 		ha1.add(new A(1));
  15. 		ha1.add(new A(2));
  16. 		ha1.add(new A(3));
  17. 		HashSet<A> ha2 = new HashSet<A>();
  18. 		ha2.add(new A(2));
  19. 		ha2.add(new A(3));
  20. 		ha2.add(new A(4));
  21. 		HashSet<B> hb =
  22. 			Stream
  23. 			.concat(ha1.stream(), ha2.stream())
  24. 			.map(a -> new B(a.x))
  25. 			.collect(Collectors.toCollection(HashSet::new));
  26. 	    System.out.println(hb.size());
  27. 	}
  28. }
  29.  
  30.  
  31.  
  32. class A
  33. {
  34.  int x;
  35.  String y;
  36.  A(int x) {this.x=x;}
  37. }
  38.  
  39. class B
  40. {
  41.  int x;
  42.  B(int x) {this.x=x;}
  43.  public int hashCode() {return x;}
  44.  public boolean equals(Object other) {
  45.  	if (other == null) return false;
  46.  	B b = (B)other;
  47.  	return b.x == x;
  48.  }
  49. }
Success #stdin #stdout 0.09s 711680KB
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https://ideone.com/QJ012x
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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