Putting your own type in a LinkedHashSet : LinkedHashSet « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. LinkedHashSet

import java.util.LinkedHashSet;
import java.util.Set;

public class MainClass {

  public static Set fill(Set a, int size) {
    for (int i = 0; i < size; i++)
      a.add(new MyType(i));
    return a;
  }

  public static void test(Set a) {
    fill(a, 10);
    fill(a, 10); // Try to add duplicates
    fill(a, 10);
    System.out.println(a);
  }

  public static void main(String[] args) {
    test(new LinkedHashSet());
  }
}

class MyType implements Comparable {
  private int i;

  public MyType(int n) {
    i = n;
  }

  public boolean equals(Object o) {
    return (o instanceof MyType) && (i == ((MyType) o).i);
  }

  public int hashCode() {
    return i;
  }

  public String toString() {
    return i + " ";
  }

  public int compareTo(Object o) {
    int i2 = ((MyType) o).i;
    return (i2 < i ? -1 : (i2 == i ? 0 : 1));
  }
}
//

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