How to Convert an ArrayList to a HashSet?

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class ArrayListToHashSet {

  public static void main(String[] args) {
    List<String> list = new ArrayList<String>();
    list.add(null);
    list.add("A"); 
    list.add("B");
    Set<String> hashset = new HashSet<String>(list);
    list = new ArrayList<String>(hashset);
    System.out.println(list.toString());
  }
}

The above code example also can be used to remove duplicate items from an ArrayList.

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class ArrayListToHashSet {

    public static void main(String[] args) {
        List list = new ArrayList();
        list.add(null);
        list.add("A");
        list.add("A");
        list.add("A");
        list.add("A");
        list.add("B");
        list.add("B");
        list.add("B");
        list.add("C");
        Set hashset = new HashSet(list);
        list = new ArrayList(hashset);
        System.out.println(list.toString());
    }

}