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  1. import java.util.ArrayList;
  2. import java.util.List;
  3. import java.util.Objects;
  4. import java.util.TreeSet;
  5.  
  6. class Ideone {
  7.     public static void main(String[] args) {
  8.         Foo fooOne = Foo.of(1);
  9.         Foo fooTwo = Foo.of(2);
  10.         Foo fooThree = Foo.of(3);
  11.         TreeSet<Foo> set = new TreeSet<>();
  12.         set.addAll(List.of(fooOne, fooTwo, fooThree));
  13.         System.out.println(set.contains(fooOne));
  14.         fooOne.setValue(4);
  15.         System.out.println(set.contains(fooOne));
  16.         System.out.println(new ArrayList<>(set).contains(fooOne));
  17.     }
  18. }
  19.  
  20. class Foo implements Comparable<Foo> {
  21.     private int value;
  22.  
  23.     private Foo(int value) {
  24.         this.setValue(value);
  25.     }
  26.  
  27.     public static Foo of(int value) {
  28.         return new Foo(value);
  29.     }
  30.  
  31.     public int getValue() {
  32.         return value;
  33.     }
  34.  
  35.     public Foo setValue(int value) {
  36.         this.value = value;
  37.         return this;
  38.     }
  39.  
  40.     @Override
  41.     public boolean equals(Object o) {
  42.         if (this == o) {
  43.             return true;
  44.         }
  45.         if (o == null || getClass() != o.getClass()) {
  46.             return false;
  47.         }
  48.         Foo foo = (Foo) o;
  49.         return getValue() == foo.getValue();
  50.     }
  51.  
  52.     @Override
  53.     public int hashCode() {
  54.         return Objects.hash(value);
  55.     }
  56.  
  57.     @Override
  58.     public int compareTo(Foo that) {
  59.         return getValue() - that.getValue();
  60.     }
  61. }
Success #stdin #stdout 0.06s 32580KB
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https://ideone.com/rpLwa1
language:
Java (HotSpot 12)
created:
4 years ago
visibility:
public

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