public class DropRepetition {

    public static void main(String[] args) {

        Vector<String> v = new Vector<String>();

        v.add("1");

        v.add("1");

        v.add("2");

        v.add("2");

        v.add("3");

        v.add("3");

        dropRepetition1(v);

        dropRepetition2(v);

    }

    private static Vector<String> dropRepetition1(Vector<String> v) {

        //创建新的Vector对象

        Vector<String> newV = new Vector<String>();

        for (String str : newV) {

            if(!newV.contains(str))

                newV.add(str);

        }

        return newV;

    }

    private static HashSet<String> dropRepetition2(Vector<String> v) {

        //构造新的HashSet

        HashSet<String> set = new HashSet<String>(v);

        return set;

    }

}