flutter - 在屏幕之间传递数据

Question

我是 Flutter 的新手，我想在屏幕之间传递一些数据。

我知道这里有人问了一个类似的问题，但我尝试了那个解决方案，但我的代码不起作用。

我尝试:“在 Flutter 中的屏幕之间传递数据”

搜索条码:

import 'package:flutter/material.dart';
import 'Screen_4.dart';

class SearchList extends StatefulWidget {
  SearchList({Key key}) : super(key: key);
  @override
  _SearchListState createState() => _SearchListState();
}

class _SearchListState extends State<SearchList> {
  Widget appBarTitle = Text(
    "Search ",
    style: TextStyle(color: Colors.white),
  );
  Icon actionIcon = Icon(
    Icons.search,
    color: Colors.white,
  );
  final key = GlobalKey<ScaffoldState>();
  final TextEditingController _searchQuery = TextEditingController();

  List<String> _list;
  bool _IsSearching;
  String _searchText = "";

  _SearchListState() {
    _searchQuery.addListener(() {
      if (_searchQuery.text.isEmpty) {
        setState(() {
          _IsSearching = false;
          _searchText = "";
        });
      } else {
        setState(() {
          _IsSearching = true;
          _searchText = _searchQuery.text;
        });
      }
    });
  }

  @override
  void initState() {
    super.initState();
    _IsSearching = false;
    init();
  }

  void init() {
    _list = List();
    _list.add("Google");
    _list.add("IOS");
    _list.add("Andorid");
    _list.add("Dart");
    _list.add("Flutter");
    _list.add("Python");
    _list.add("React");
    _list.add("Xamarin");
    _list.add("Kotlin");
    _list.add("Java");
    _list.add("RxAndroid");
    _list.add('Lenovo');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: key,
      appBar: buildBar(context),
      body: ListView(
        padding: EdgeInsets.symmetric(vertical: 8.0),
        children: _IsSearching ? _buildSearchList() : _buildList(),
      ),
    );
  }

  List<ChildItem> _buildList() {
    return _list.map((contact) => ChildItem(contact)).toList();
  }

  List<ChildItem> _buildSearchList() {
    if (_searchText.isEmpty) {
      return _list.map((contact) => ChildItem(contact)).toList();
    } else {
      List<String> _searchList = List();
      for (int i = 0; i < _list.length; i++) {
        String name = _list.elementAt(i);
        if (name.toLowerCase().contains(_searchText.toLowerCase())) {
          _searchList.add(name);
        }
      }
      return _searchList.map((contact) => ChildItem(contact)).toList();
    }
  }

  Widget buildBar(BuildContext context) {
    return AppBar(centerTitle: true, title: appBarTitle, actions: <Widget>[
      IconButton(
        icon: actionIcon,
        onPressed: () {
          setState(() {
            if (this.actionIcon.icon == Icons.search) {
              this.actionIcon = Icon(
                Icons.close,
                color: Colors.white,
              );
              this.appBarTitle = TextField(
                controller: _searchQuery,
                style: TextStyle(
                  color: Colors.white,
                ),
                decoration: InputDecoration(
                    prefixIcon: Icon(Icons.search, color: Colors.black),
                    hintText: "Search...",
                    hintStyle: TextStyle(color: Colors.white)),
              );
              _handleSearchStart();
            } else {
              _handleSearchEnd();
            }
          });
        },
      ),
    ]);
  }

  void _handleSearchStart() {
    setState(() {
      _IsSearching = true;
    });
  }

  void _handleSearchEnd() {
    setState(() {
      this.actionIcon = Icon(
        Icons.search,
        color: Colors.white,
      );
      this.appBarTitle = Text(
        "Search Sample",
        style: TextStyle(color: Colors.white),
      );
      _IsSearching = false;
      _searchQuery.clear();
    });
  }
}

class ChildItem extends StatelessWidget {
  final String name;
  ChildItem(this.name);
  @override
  Widget build(BuildContext context) {
    return ListTile(
      title: Text(this.name), //onTap: () => print(name));
      onTap: () {
        Navigator.push(
            context, MaterialPageRoute(builder: (context) => ShowData()));
      },
    );
  }
}

我想要显示结果的屏幕:

import 'search_bar_no_API.dart';

class ShowData extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.blue,
        title: Text('The Name Here'),
      ),

我想要的是:例如:搜索:谷歌按:名称谷歌然后转到应用栏上名称为 Google 的其他页面。

Answer 1

在您的 ChildItem 类中执行此操作:

class ChildItem extends StatelessWidget {
  final String name;
  ChildItem(this.name);
  @override
  Widget build(BuildContext context) {
    return ListTile(
      title: Text(this.name), //onTap: () => print(name));
      onTap: () {
        Navigator.push(
            context, MaterialPageRoute(builder: (context) => ShowData(title: this.name)));
      },
    );
  }
}

你会注意到，我将 this.name 传递给了 Navigator.push 中 ShowData 类的属性 title (...)因此在您的 ShowData 类中，创建一个类型为 String 的 final 变量，例如。 final String title 并创建类 ShowData 的 Constructor，就像这样 ShowData({this.title})。以下是 ShowData 类的完整代码:

class ShowData extends StatelessWidget {
  final String title;
  ShowData({this.title});
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.blue,
        title: Text(title),
      )
    );
  }
}