Removing All Elements: public void clear() : HashSet « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. HashSet

You can still get an UnsupportedOperationException thrown when working with a read-only set.

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);

    set.clear();

    System.out.println(set);
  }
}

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