我创建了一个简单的屏幕，该屏幕接受字母列表并将其呈现在网格中。我有一个带随机播放方法的按钮，可以随机播放此列表。在我的构建方法中，我看到状态正在用新列表更新，并且每次按下按钮时都会打印出随机排列的列表，但是屏幕没有变化。

class _LetterContainerState extends State<LetterContainer> {
  List<String> _letters = ['D', 'A', 'B', 'C', 'E', 'F', 'G', 'H'];



  void shuffle() {
    var random = new Random();
    List<String> newLetters = _letters;
    for (var i = newLetters.length - 1; i > 0; i--) {
      var n = random.nextInt(i + 1);
      var temp = newLetters[i];
      newLetters[i] = newLetters[n];
      newLetters[n] = temp;
    }

    setState(() {
      _letters = newLetters;
    });
  }

  @override
  Widget build(BuildContext context)  {
    print('LETTERS');
    print(_letters);
    List<LetterTile> letterTiles =
        _letters.map<LetterTile>((letter) => new LetterTile(letter)).toList();

    return new Column(
      children: <Widget>[
        new FlatButton(onPressed: shuffle, child: new Text("Shuffle")),
        new Container(

            color: Colors.amberAccent,
            constraints: BoxConstraints.expand(height: 200.0),
            child: new GridView.count(
              crossAxisCount: 4,
              mainAxisSpacing: 4.0,
              crossAxisSpacing: 4.0,
              children: letterTiles,
            ))
      ],
    );
  }
}

编辑：

import 'package:flutter/material.dart';

class Vowels {
  static const values = ['A', 'E', 'I', 'O', 'U'];

  static bool isVowel(String letter) {
    return values.contains(letter.toUpperCase());
  }
}

class LetterTile extends StatefulWidget {
  final String value;
  final bool isVowel;

  LetterTile(value)
            : value = value,
              isVowel = Vowels.isVowel(value);

  @override
  _LetterTileState createState() => new _LetterTileState(this.value);

}

class _LetterTileState extends State<LetterTile> {
  _LetterTileState(this.value);

  final String value;

  @override
  Widget build(BuildContext context) {
    Color color = Vowels.isVowel(this.value) ? Colors.green : Colors.deepOrange;
    return new
    Card(
      color: color,
      child: Padding(
        padding: EdgeInsets.all(8.0),
        child: Text(
          this.value,
          style: TextStyle(fontSize: 40.0, color: Colors.white)
        )
      )
    );

  }

}