Java List remove duplicate elements

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

public class Main {
  public static void main(String[] argv) {
    List<String> arrayList1 = new ArrayList<String>();

    arrayList1.add("CSS");
    arrayList1.add("CSS");
    arrayList1.add("HTML");
    arrayList1.add("HTML");
    arrayList1.add("HTML");
    arrayList1.add("Java");

    System.out.println(arrayList1);
    //from   w  w  w .j a  va2 s . c o  m
    Set<String> hashSet = new HashSet<String>(arrayList1);

    List<String> arrayList2 = new ArrayList<String>(hashSet);

    System.out.println(arrayList2);
  }
}