Expanded/ Multi-Level List in Flutter for Android and iOS

By | July 14, 2019

Here is a simple example for creating expanded list in flutter.

Watch Video Tutorial


We will create a new class named “Entry” which will be the data on each row of the list.

class Entry {
  final String title;
  final List<Entry>
      children; // Since this is an expansion list ...children can be another list of entries
  Entry(this.title, [this.children = const <Entry>[]]);
}

Data Source

Let’s create the array to be shown in the expanded list.

// This is the entire multi-level list displayed by this app
final List<Entry> data = <Entry>[
  Entry(
    'Chapter A',
    <Entry>[
      Entry(
        'Section A0',
        <Entry>[
          Entry('Item A0.1'),
          Entry('Item A0.2'),
          Entry('Item A0.3'),
        ],
      ),
      Entry('Section A1'),
      Entry('Section A2'),
    ],
  ),
  // Second Row
  Entry('Chapter B', <Entry>[
    Entry('Section B0'),
    Entry('Section B1'),
  ]),
  Entry(
    'Chapter C',
    <Entry>[
      Entry('Section C0'),
      Entry('Section C1'),
      Entry(
        'Section C2',
        <Entry>[
          Entry('Item C2.0'),
          Entry('Item C2.1'),
          Entry('Item C2.2'),
          Entry('Item C2.3'),
        ],
      )
    ],
  ),
];

Create Row Widget

// Create the Widget for the row
class EntryItem extends StatelessWidget {
  const EntryItem(this.entry);
  final Entry entry;

  // This function recursively creates the multi-level list rows.
  Widget _buildTiles(Entry root) {
    if (root.children.isEmpty) {
      return ListTile(
        title: Text(root.title),
      );
    }
    return ExpansionTile(
      key: PageStorageKey<Entry>(root),
      title: Text(root.title),
      children: root.children.map<Widget>(_buildTiles).toList(),
    );
  }

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

Create the List

ListView.builder(
    itemCount: data.length,
    itemBuilder: (BuildContext context, int index) => EntryItem(
        data[index],
        ),
),

That’s it.


Complete code

import 'package:flutter/material.dart';

class ExpansionTileDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Expansion List'),
        ),
        body: ListView.builder(
          itemCount: data.length,
          itemBuilder: (BuildContext context, int index) => EntryItem(
                data[index],
              ),
        ),
      ),
    );
  }
}

// Welcome to another flutter tutorial
// In this video we will see how to create a multi-level Expansion List
// First Let's create a class for each row in the Expansion List

class Entry {
  final String title;
  final List<Entry>
      children; // Since this is an expansion list ...children can be another list of entries
  Entry(this.title, [this.children = const <Entry>[]]);
}

// This is the entire multi-level list displayed by this app
final List<Entry> data = <Entry>[
  Entry(
    'Chapter A',
    <Entry>[
      Entry(
        'Section A0',
        <Entry>[
          Entry('Item A0.1'),
          Entry('Item A0.2'),
          Entry('Item A0.3'),
        ],
      ),
      Entry('Section A1'),
      Entry('Section A2'),
    ],
  ),
  // Second Row
  Entry('Chapter B', <Entry>[
    Entry('Section B0'),
    Entry('Section B1'),
  ]),
  Entry(
    'Chapter C',
    <Entry>[
      Entry('Section C0'),
      Entry('Section C1'),
      Entry(
        'Section C2',
        <Entry>[
          Entry('Item C2.0'),
          Entry('Item C2.1'),
          Entry('Item C2.2'),
          Entry('Item C2.3'),
        ],
      )
    ],
  ),
];

// Create the Widget for the row
class EntryItem extends StatelessWidget {
  const EntryItem(this.entry);
  final Entry entry;

  // This function recursively creates the multi-level list rows.
  Widget _buildTiles(Entry root) {
    if (root.children.isEmpty) {
      return ListTile(
        title: Text(root.title),
      );
    }
    return ExpansionTile(
      key: PageStorageKey<Entry>(root),
      title: Text(root.title),
      children: root.children.map<Widget>(_buildTiles).toList(),
    );
  }

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

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