Adding Another Collection with the addAll() method: public boolean addAll(Collection c) : HashSet « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. HashSet

Each element in the collection passed in will be added to the set via the equivalent of calling the add() method on each element.

If the underlying set changes, true is returned.

If no elements are added, false is returned.

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public class MainClass {

  public static void main(String[] a) {
    String elements[] = { "A", "B", "C", "D", "E" };
    Set set = new HashSet(Arrays.asList(elements));

    elements = new String[] { "E", "F" };

    set.addAll(Arrays.asList(elements));

    System.out.println(set);
  }
}

[D, A, F, C, B, E]