List集合去重

List<String> idList = new ArrayList<>()；
idList.add("1");
idList.add("1");
//初始化HashSet对象，并把list对象元素赋值给HashSet对象
HashSet<String> set = new HashSet<>(idList);
//把List集合清空
idList.clear();
//把HashSet对象添加至List集合
idList.addAll(set);