List多种去重方法&去重后排序

通过HashSet踢除重复元素

public static List removeDuplicate(List list) {   
    HashSet h = new HashSet(list);   
    list.clear();   
    list.addAll(h);   
    return list;   
}

循环List中的所有元素然后删除重复

public  static  List  removeDuplicate(List list)  {       
  for  ( int  i  =   0 ; i  <  list.size()  -   1 ; i ++ )  {       
      for  ( int  j  =  list.size()  -   1 ; j  >  i; j -- )  {       
           if  (list.get(j).equals(list.get(i)))  {       
              list.remove(j);       
            }        
        }        
      }        
    return list;       
}

List去重后排序

 public static void pastLeep5(List<String> list){
        System.out.println("list = [" + list + "]");
        //new TreeSet<String>(list);去重后排序
        List<String> listNew=new ArrayList<>(new TreeSet<String>(list));
        System.out.println("listNew = [" + listNew + "]");
 }