记录一下flutter的小细节，setState()

setState 只能更新当前widget的状态，当前widget下面还有别的widget情况下，是不会生效子widget

List<String> items = List.generate(10, (index) => "item$index");

class ChatList extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Expanded(
            child: ListView.builder(
              itemCount: items.length,
              itemBuilder: (context, index) {
                return ChatItem(chat: items[index]);
              },
            )
            )]);
  }
}


class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return ChatList();
  }

  void changeChatList(){
    setState(){
      items.add("new data")
    }
  }
}

这样在Hone Page调用chagngeChatList方法，ChatList中的视图没有变化，可以将items移动到HomePage，并将值通过构造传入，这种做法可以给变量提权

修改后

class ChatList extends StatelessWidget {

  final List<String> items;

  const ChatList({this.items})

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Expanded(
            child: ListView.builder(
              itemCount: items.length,
              itemBuilder: (context, index) {
                return ChatItem(chat: items[index]);
              },
            )
            )]);
  }
}


class HomePage extends StatelessWidget {
  List<String> items = List.generate(10, (index) => "item$index");
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return ChatList(items);
  }

  void changeChatList(){
    setState(){
      items.add("new data")
    }
  }
}