1 public class testList {
 2     public static void main(String[] args){
 3         java.util.List<String> ls = new java.util.ArrayList<>();
 4         ls.add("A");
 5         ls.add("B");
 6         ls.add("C");
 7         String[] str = {"A","B","C","D"};
 8         for(int i=0;i<str.length;i++){
 9             ls.add(str[i]);
10         }
11         java.util.Set<String> set = new java.util.TreeSet<>(ls);
12         java.util.List<String> lsr = new java.util.ArrayList<>();
13         lsr.addAll(set);
14         System.out.println(lsr.toString());
15     }
16 }