how to remove widget from list builder in flutter code example

Example 1: how to remove listview in flutter

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Slidable Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Slidable Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final List<_HomeItem> items = List.generate(
    5,
    (i) => _HomeItem(
      i,
      'Tile n°$i',
    ),
  );

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: _buildList(context),
      ),
    );
  }

  Widget _buildList(BuildContext context) {
    return ListView.builder(
      itemBuilder: (context, index) {
        return Tile(items[index], _deleteItem);
      },
      itemCount: items.length,
    );
  }

  void _deleteItem(_HomeItem item) {
    setState(() {
      print(context);
      print("remove: $item");
      print("Number of items before: ${items.length}");
      items.remove(item);
      print("Number of items after delete: ${items.length}");
    });
  }
}

class Tile extends StatefulWidget {
  final _HomeItem item;
  final Function delete;

  Tile(this.item, this.delete);

  @override
  State<StatefulWidget> createState() => _TileState(item, delete);
}

class _TileState extends State<Tile> {
  final _HomeItem item;
  final Function delete;

  _TileState(this.item, this.delete);

  @override
  Widget build(BuildContext context) {
    return ListTile(
      key: ValueKey(item.index),
      title: Text("${item.title}"),
      subtitle: Text("${item.index}"),
      onTap: () => delete(item),
    );
  }
}

class _HomeItem {
  const _HomeItem(
    this.index,
    this.title,
  );

  final int index;
  final String title;
}

Example 2: how to remove listview in flutter

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

void main() => runApp(new MyApp());

// create a global saved set
Set<WordPair> savedGlobal = new Set<WordPair>();

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Startup Name Generator',
      home: new RandomWords(),
    );
  }
}

class RandomWords extends StatefulWidget {
  @override
  RandomWordsState createState() => new RandomWordsState();
}

class RandomWordsState extends State<RandomWords> {
  final List<WordPair> _suggestions = <WordPair>[];
  final TextStyle _biggerFont = const TextStyle(fontSize: 18.0);

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: const Text('Startup Name Generator'),
        actions: <Widget>[
          // change the onPressed function
          new IconButton(icon: const Icon(Icons.list), onPressed: () {
            Navigator.push(
              context,
              MaterialPageRoute(
                builder: (context) => DetailPage()
              )
            );
          }),
        ],
      ),
      body: _buildSuggestions(),
    );
  }

  Widget _buildSuggestions() {
    return new ListView.builder(
      padding: const EdgeInsets.all(16.0),
      itemBuilder: (BuildContext _context, int i) {
        if (i.isOdd) {
          return const Divider();
        }
        final int index = i ~/ 2;
        if (index >= _suggestions.length) {
          _suggestions.addAll(generateWordPairs().take(10));
        }
        return _buildRow(_suggestions[index]);
      });
  }

  Widget _buildRow(WordPair pair) {
    final bool alreadySaved = savedGlobal.contains(pair);

    return new ListTile(
      title: new Text(
        pair.asPascalCase,
        style: _biggerFont,
      ),
      trailing: new Icon(
        alreadySaved ? Icons.favorite : Icons.favorite_border,
        color: alreadySaved ? Colors.red : null,
      ),
      onTap: () {
        setState(() {
          if (alreadySaved) {
            savedGlobal.remove(pair);
          } else {
            savedGlobal.add(pair);
          }
        });
      },
    );
  }
}

// add a new stateful page
class DetailPage extends StatefulWidget {
  @override
  _DetailPageState createState() => _DetailPageState();
}

class _DetailPageState extends State<DetailPage> {
  final TextStyle _biggerFont = const TextStyle(fontSize: 18.0);

  @override
  Widget build(BuildContext context) {

    Iterable<ListTile> tiles = savedGlobal.map((WordPair pair) {
      return new ListTile(
        onLongPress: () {
          setState(() {
            savedGlobal.remove(pair);
          });
        },
        title: new Text(
          pair.asPascalCase,
          style: _biggerFont,
        ),
      );
    });

    final List<Widget> divided = ListTile.divideTiles(
      context: context,
      tiles: tiles,
    ).toList();

    return new Scaffold(
      appBar: new AppBar(
        title: const Text('Saved Suggestions'),
      ),
      body: new ListView(children: divided),
    );
  }
}