Flutter :- 如何对自定义列表进行排序。

Question

在这里，我希望我已经列出了一些项目，我想根据它的id或评级来排序。当我点击侧面的抽屉按钮时，它将需要重新排列列表视图和排序的项目，希望你能理解我的问题。

我试过这个方法 畅通的排序 包来进行排序，但对我来说是行不通的，因为它会根据索引进行排序，而我想根据自己的值进行排序。

以下是输出图像

以下是我的代码

class _MapAddressListingScreenState extends State<MapAddressListingScreen>
    with AfterLayoutMixin<MapAddressListingScreen> {
  final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
  List addressData;

  @override
  void afterFirstLayout(BuildContext context) {
    _getAddress();
  }

  _getAddress() {
    List requestedLatlong = ModalRoute.of(context).settings.arguments;

    print("============================Address Data");
    print(requestedLatlong);
    setState(() {
      addressData = requestedLatlong;
    });
  }

  List<Widget> _addressData() {
    List<Widget> _address = [];
    for (int i = 0; i < addressData.length; i++) {
      _address.add(
        GestureDetector(
          onTap: () {
            print('address list taped');
            AddWalkinModel model = widget.addWalkinModel;
            print("After model");
            model.fromMap = false;
            model.fromMapListing = true;
            model.autoAssign = addressData[i]['autoAssign'];
            model.branchId = addressData[i]['branchId'];
            model.branchServiceId = addressData[i]['branchServiceId'];
            print("After Model Model");
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) => DynamicScreen(
                  addWalkinModel: model,
                ),
              ),
            );
          },
          child: AddressListingTile(listingTileData: addressData[i]),
        ),
      );
    }
    return _address;
  }

  Widget itemCard() {
    return Container(
      child: Column(
        children: _addressData(),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    var colorStyles = Theming.colorstyle(context);
    return Scaffold(
      key: _scaffoldKey,
      backgroundColor: colorStyles['primary'],
      appBar: AppBar(
        title: Text("BSP Listview "),
        centerTitle: true,
        elevation: 0,
        leading: IconButton(
          icon: Icon(Icons.arrow_back_ios),
          onPressed: () {
            Navigator.pop(context);
          },
        ),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.sort),
            onPressed: () {
              _scaffoldKey.currentState.openEndDrawer();
            },
          ),
        ],
      ),
      endDrawer: Drawer(
    child: Column(
      children: <Widget>[
        SizedBox(
          height: 100,
        ),
        FlatButton(
            onPressed: () {
              ratingSort.shuffle();
            },
            child: Text("sort")),
      ],
    ),
  ),
      body: Stack(
        children: <Widget>[
          Container(
            child: ClipRRect(
              borderRadius: new BorderRadius.only(
                  topLeft: const Radius.circular(30.0),
                  topRight: const Radius.circular(30.0)),
              child: Stack(
                children: <Widget>[
                  SingleChildScrollView(
                    child: Container(
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.start,
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: <Widget>[
                          itemCard(),
                        ],
                      ),
                    ),
                  )
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

Answer 1

你可以使用 sort 的方法 list 用于对列表进行排序，具体格式如下。

@override
  void initState() {
    super.initState();

    for(int i=0;i<fields.length;i++) {
      print("BEFORE==>>> ${fields[i].rating}");
    }

    fields.sort((a, b) => a.rating.compareTo(b.rating));  ///FROM THIS LINE YOU CAN PERFORM SHORTING ACCORDING TO THE RATING BASES

    for(int i=0;i<fields.length;i++) {
      print("AFTER==>>> ${fields[i].rating}");
    }

  }

我已经使用我的演示自定义列表为它

List<Fields> fields = [
  new Fields(
    'DEFAULT CATEGORY',
    2,
  ),
  new Fields(
    'DEFAULT CATEGORY',
    1,
  ),
  new Fields(
    'DEFAULT CATEGORY',
    5,
  ),
  new Fields(
    'DEFAULT CATEGORY',
    3,
  ),
  new Fields(
    'DEFAULT CATEGORY',
    4,
  ),
];

而输出将遵循

请查看完整的代码来源

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutterlearningapp/colors.dart';

class HomeScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _HomeScreen();
  }
}

class _HomeScreen extends State<HomeScreen> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Material(
        child: Scaffold(
      appBar: AppBar(
        title: Text("Demo Scroll"),
      ),
      body: Container(
        height: double.infinity,
        width: double.infinity,
        color: Colors.white,
        child: Column(
          children: <Widget>[
            RaisedButton(
              child: Text("Shoring"),
              onPressed: (){
                setState(() {
                  fields.sort((a, b) => a.rating.compareTo(b.rating));

                });

              },


            ),
            Expanded(
              child:  ListView.builder
                (
                  itemCount: fields.length,
                  itemBuilder: (BuildContext ctxt, int index) {
                    return ListTile(
                      title: new Text("Rating #${fields[index].rating}"),
                      subtitle: new Text(fields[index].title),
                    );
                  }
              ) ,
            )


          ],

        ),
      ),
    ));
  }
}

class Fields {
  final String title;
  final int rating;

  Fields(this.title, this.rating);
}

List<Fields> fields = [
  new Fields(
    'Two',
    2,
  ),
  new Fields(
    'One',
    1,
  ),
  new Fields(
    'DEFAULT CATEGORY',
    5,
  ),
  new Fields(
    'Three',
    3,
  ),
  new Fields(
    'Four',
    4,
  ),
];

而上面的程序输出如下