setState() or markNeedsBuild called during build

问题:

class MyHome extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => new MyHomePage2();
}

class MyHomePage2 extends State<MyHome> {
  List items = new List();

  buildlist(String s) {
    setState(() {
      print("entered buildlist" + s);
      List refresh = new List();
      if (s == 'button0') {
        refresh = [
          new Refreshments("Watermelon", 250),
          new Refreshments("Orange", 275),
          new Refreshments("Pine", 300),
          new Refreshments("Papaya", 225),
          new Refreshments("Apple", 250),
        ];
      } else if (s == 'button1') {
        refresh = [
          new Refreshments("Pina Colada", 250),
          new Refreshments("Bloody Mary", 275),
          new Refreshments("Long Island Ice tea", 300),
          new Refreshments("Screwdriver", 225),
          new Refreshments("Fusion Cocktail", 250),
        ];
      } else if (s == 'button2') {
        refresh = [
          new Refreshments("Virgin Pina Colada", 250),
          new Refreshments("Virgin Mary", 275),
          new Refreshments("Strawberry Flush", 300),
          new Refreshments("Mango Diver", 225),
          new Refreshments("Peach Delight", 250),
        ];
      } else {
        refresh = [
          new Refreshments("Absolute", 250),
          new Refreshments("Smirnoff", 275),
          new Refreshments("White Mischief", 300),
          new Refreshments("Romanov", 225),
          new Refreshments("Blender's Pride", 250),
        ];
      }

      for (var item in refresh) {
        items.add(new ItemsList(item));
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    var abc = MediaQuery.of(context).size;

    print(abc.width);

    var width = abc.width / 4;

    Text text = new Text("Dev");
    Text text2 = new Text("Sneha");
    Text text3 = new Text("Prashant");
    Text text4 = new Text("Vikesh");

    var pad = const EdgeInsets.all(10.0);

    Padding pad1 = new Padding(child: text, padding: pad);
    Padding pad2 = new Padding(child: text2, padding: pad);
    Padding pad3 = new Padding(child: text3, padding: pad);
    Padding pad4 = new Padding(child: text4, padding: pad);

    ListView listView = new ListView(children: <Widget>[
      new Image.asset('images/party.jpg'),
      pad1,
      pad2,
      pad3,
      pad4
    ]);

    Drawer drawer = new Drawer(child: listView);

    return new Scaffold(
      drawer: drawer,

      appBar: new AppBar(
        title: new Text('Booze Up'),
      ),
      body: new Column(children: <Widget>[
        new ListView.builder(
          scrollDirection: Axis.horizontal,
          itemCount: 4,
          itemBuilder: (BuildContext context, int index) {
            return new Column(children: <Widget>[
              new Container(
                child: new Flexible(
                    child: new FlatButton(
                  child: new Image.asset('images/party.jpg',
                      width: width, height: width),
                  onPressed: buildlist('button' + index.toString()),
                )),
                width: width,
                height: width,
              )
            ]);
          },
        ),
        new Expanded(
            child: new ListView(
          padding: new EdgeInsets.fromLTRB(10.0, 10.0, 0.0, 10.0),
          children: items,
          scrollDirection: Axis.vertical,
        )),
      ]),

      floatingActionButton: new FloatingActionButton(
        onPressed: null,
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

class Refreshments {
  String name;
  int price;

  Refreshments(this.name, this.price);
}

class ItemsList extends StatelessWidget {
  final Refreshments refreshments;

  ItemsList(this.refreshments);

  @override
  Widget build(BuildContext context) {
    return new ListTile(
      onTap: null,
      title: new Text(refreshments.name),
    );
  }
}

Formatted by DartPad ;-)

I am having two errors:

1] Horizontal viewport was given unbounded height . A horizontal viewport was given an unlimited amount of vertical space in which to expand.

2] setState() or markNeedsBuild called during build A vertical renderflex overflowed by 99488 pixels.

Please help me with it . I am creating this app where on each image click a list should be shown below . The images will be in a row and the list should be shown below the row.

Thank you.

回答1:

I have recreated what you are trying to do, with only two of your Refreshment items, you probably want to refactor things and handle the layout in a better way, but just for the sake of simplicity try to follow this example and compare it to what you are trying to achieve:

import "package:flutter/material.dart";

class LetsParty extends StatefulWidget {
  @override
  _LetsPartyState createState() => new _LetsPartyState();
}

class _LetsPartyState extends State<LetsParty> {
  Image _partyImage = new Image.network(
      "http://www.freshcardsgifts.co.uk/images/_lib/animal-party-greetings-card-3003237-0-1344698261000.jpg");

  final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();

  List<List> list = [
    ["Pina Colada",
    "Bloody Mary",
    "Strawberry Flush",
    "Mango Diver",
    "Peach Delight"
    ],
    [
      "Absolute",
      "Smirnoff",
      "White Mischief",
      "Romanov",
      "Blender's Pride"
    ]
  ];

  List<String> visibleList = null;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      key: scaffoldKey,
      appBar: new AppBar(title: new Text("Let's Party"),),
      body: new ListView(
        // shrinkWrap: true,
        children: <Widget>[


          new Container (
              height: 150.0,
              child: new ListView.builder(
                  shrinkWrap: true,
                  scrollDirection: Axis.horizontal,
                  itemCount: 2, //add the length of your list here
                  itemBuilder: (BuildContext context, int index) {
                    return new Column(
                      children: <Widget>[

                        ///Flexible let's your widget flex in  the given space, dealing with the overflow you have
                        //  new Flexible(child: new FlatButton(onPressed: ()=>print("You pressed Image No.$index"), child: _partyImage)),
                        new Flexible (child: new Container(
                            child: new FlatButton(onPressed: () {
                              scaffoldKey.currentState.showSnackBar(
                                  new SnackBar(
                                      content: new Text(
                                          "You pressed Image No.$index")));

                              setState(() {
                                visibleList = list[index];
                              });
                            },
                                child: _partyImage),
                            width: 100.0,
                            height: 100.0
                        ),),
                        //Exact width and height, consider adding Flexible as a parent to the Container
                        new Text("Text$index"),
                      ],
                    );
                  })),

          new Column(children: visibleList==null?new List():new List.generate(5, (int i) {
            new ListTile(title: new Text(visibleList[i]),
              onTap: () =>
                  scaffoldKey.currentState.showSnackBar(new SnackBar(
                    content: new Text("Your choise is ${visibleList[i]}"),)),
            );
          }))
        ],),);
  }
}

回答2:

Your code

onPressed: buildlist('button'+index.toString()),

executes buildlist() and passes the result to onPressed, but that is not the desired behavior.

It should be

onPressed: () => buildlist('button'+index.toString()),

This way a function (closure) is passed to onPressed, that when executed, calls buildlist()