Android list1去除list2中的元素

public static void main(String[] args) {
        List<String> firList = new ArrayList<String>();
        firList.add("");
        List<String> twoList = new ArrayList<String>();
        twoList.add("");
        twoList.add("");
        firList.removeAll(twoList);
        System.out.println(firList.toString());
    }