Can't scroll on standard ListView widget; always over-renders by 150px

Question

ListView won't scroll at all. Error says the issue is in the main.dart file and not in the module I'm working on, but it's the module that's overflowing.

Tried multiple things:

primary: false, physics: const AlwaysScrollableScrollPhysics(), controller: _controller
Flutter dev docs on making a list view
Medium posts on making list views
Countless stack overflow Qs

Here's my code as it stands:

import 'package:flutter/material.dart';

class Listicle extends StatefulWidget {
  @override
  ListicleState createState() => ListicleState();
}

class ListicleState extends State<Listicle> {
  final List<String> entries = <String>['A', 'B', 'C', 'D', 'E', 'F'];
  final List<int> colorCodes = <int>[600, 500, 100, 600, 500, 100];

  ScrollController _controller = new ScrollController();

  @override
  Widget build(BuildContext context) {
    return Container(
      child: ListView.builder(
        primary: false,
        physics: const AlwaysScrollableScrollPhysics(),
        controller: _controller,
        shrinkWrap: true,
        padding: const EdgeInsets.all(8),
        itemCount: entries.length,
        itemBuilder: (BuildContext context, int index) {
          return Container(
            height: 100,
            color: Colors.amber[colorCodes[index]],
            child: Center(child: Text('Entry ${entries[index]}')),
          );
        }
      )
    );
  }
}

Here's the error:

════════ Exception caught by rendering library ═════════════════════════════════════════════════════
The following assertion was thrown during layout:
A RenderFlex overflowed by 150 pixels on the bottom.

The relevant error-causing widget was: 
  Column file:///Users/christopher/AndroidStudioProjects/test_app/lib/main.dart:76:13
The overflowing RenderFlex has an orientation of Axis.vertical.
The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and black striped pattern. This is usually caused by the contents being too big for the RenderFlex.

Consider applying a flex factor (e.g. using an Expanded widget) to force the children of the RenderFlex to fit within the available space instead of being sized to their natural size.
This is considered an error condition because it indicates that there is content that cannot be seen. If the content is legitimately bigger than the available space, consider clipping it with a ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex, like a ListView.

The specific RenderFlex in question is: RenderFlex#c9341 relayoutBoundary=up1 OVERFLOWING
...  needs compositing
...  parentData: offset=Offset(0.0, 80.0); id=_ScaffoldSlot.body (can use size)
...  constraints: BoxConstraints(0.0<=w<=392.7, 0.0<=h<=679.3)
...  size: Size(392.7, 679.3)
...  direction: vertical
...  mainAxisAlignment: start
...  mainAxisSize: max
...  crossAxisAlignment: center
...  verticalDirection: down
◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤
════════════════════════════════════════════════════════════════════════════════════════════════════

I'm very new to flutter/dart (literally started yesterday) and this has me stumped already.

Here's a snapshot: https://i.stack.imgur.com/qlDMZ.png

Can you post the main.dart here? For a quick answer, try wrap `Container` with a `Scaffold` widget — Rocigno Medeiros, Jun 04 '20 at 14:34

score 1 · Accepted Answer · answered Jun 04 '20 at 15:14

This works:

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: Listicle(),
        ),
      ),
    );
  }
}

class Listicle extends StatefulWidget {
  @override
  ListicleState createState() => ListicleState();
}

class ListicleState extends State<Listicle> {
  final List<String> entries = <String>['A', 'B', 'C', 'D', 'E', 'F','G','H'];
  final List<int> colorCodes = <int>[600, 500, 100, 600, 500, 100,100,100];

 @override
  Widget build(BuildContext context) {
    return Container(
      child: ListView.builder(
        primary: false,
        shrinkWrap: true,
        padding: const EdgeInsets.all(8),
        itemCount: entries.length,
        itemBuilder: (BuildContext context, int index) {
          return Container(
            height: 100,
            color: Colors.amber[colorCodes[index]],
            child: Center(child: Text('Entry ${entries[index]}')),
          );
        }
      )
    );
  }
}

score 0 · Answer 2 · answered Jun 04 '20 at 15:15

The error happens because the ListView expands to the max size in main axis direction.

Solution:

As @rocigno-medeiros rightly said in the comment

By wrapping your code in Scaffold makes it work because Scaffold constraints the height of ListView.

class Listicle extends StatefulWidget {
  @override
  ListicleState createState() => ListicleState();
}

class ListicleState extends State<Listicle> {
  final List<String> entries = <String>['A', 'B', 'C', 'D', 'E', 'F'];
  final List<int> colorCodes = <int>[600, 500, 100, 600, 500, 100];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: ListView.builder(
          primary: false,
          physics: AlwaysScrollableScrollPhysics(),
          shrinkWrap: true,
          padding: const EdgeInsets.all(8),
          itemCount: entries.length,
          itemBuilder: (BuildContext context, int index) {
            return Container(
              height: 100,
              color: Colors.amber[colorCodes[index]],
              child: Center(child: Text('Entry ${entries[index]}')),
            );
          },
        ),
      ),
    );
  }
}

Also there's no need for a additional scroll controller if you want default scroll behavior.

Can't scroll on standard ListView widget; always over-renders by 150px

2 Answers2