List集合数据去重

List集合数据去重

1.借助Set的特性进行去重

    public static List list distinct(List list) {
        final boolean sta = null != list && list.size() > 0;
        List doubleList= new ArrayList();
        if (sta) {
            Set set = new HashSet();
            set.addAll(list);
            doubleList.addAll(set);
        }
        return doubleList;
    }

2.利用set集合特性保持顺序一致去重

// Set去重并保持原先顺序的两种方法
   public static void delRepeat(List list) {
   	   //方法一
       List listNew = new ArrayList(new TreeSet(list));
       //方法二
       List listNew2 = new ArrayList(new linkedHashSet(list));
   }

3.set形式删除

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