利用set排序数组并且去掉重复的数组元素

 public class testList {
     public static void main(String[] args){
         java.util.List<String> ls = new java.util.ArrayList<>();
         ls.add("A");
         ls.add("B");
         ls.add("C");
         String[] str = {"A","B","C","D"};
         for(int i=0;i<str.length;i++){
             ls.add(str[i]);
         }
         java.util.Set<String> set = new java.util.TreeSet<>(ls);
         java.util.List<String> lsr = new java.util.ArrayList<>();
         lsr.addAll(set);
         System.out.println(lsr.toString());
     }
 }

打印结果：[A, B, C, D]