flutter - 用户单击按钮时如何在列表中添加 TextField？

Question

我添加项目的按钮没有显示。

我要求用户填写玩家姓名。如果用户想添加一个播放器，则单击一个按钮以添加一个新字段

List<Widget> _playerList = new List(); //_playerList is my List name

ListView.builder(
    itemBuilder: (context,index){
      _playerList.add(new TextField());
      Widget widget = _playerList.elementAt(index);
    return widget;
    }),

    new FlatButton.icon(
                        color: Colors.black,
                        icon: Icon(
                          Icons.add,
                          color: Colors.white,
                          size: 18,
                        ),
                        label: Text('Add player',
                            style: TextStyle(fontSize: 12, color: Colors.white)),
                        onPressed: () {
                          _playerList.add(new Text("ggg"));
                        },


                    ),

添加按钮不显示

Answer 1

在您的代码中，下面的部分产生了问题-

ListView.builder(
    itemBuilder: (context,index){
      _playerList.add(new TextField());
      Widget widget = _playerList.elementAt(index);
    return widget;
    }),

删除'_playerList.add(new TextField());'线。 它应该喜欢-

 class Items extends StatefulWidget {
      @override
      State<StatefulWidget> createState() {
        return _ItemsState();
      }
    }

    class _ItemsState extends State<Items> {
       List<Widget> _playerList = new List(); //_playerList is my List name

      @override
      Widget build(BuildContext context) {
        // TODO: implement build
        return Scaffold(
            body: Column(
              children: <Widget>[
                new FlatButton.icon(
                  color: Colors.black,
                  icon: Icon(
                    Icons.add,
                    color: Colors.white,
                    size: 18,
                  ),
                  label: Text('Add player',
                      style: TextStyle(fontSize: 12, color: Colors.white)),
                  onPressed: () {
                    setState(() {

                      _playerList.add(new Text("ggg"));
                      print(_playerList);
                    });
                  },
                ),
                Expanded(
                    child: ListView.builder(
                      itemCount:_playerList.length ,
                        itemBuilder: (context,index){
                          Widget widget = _playerList.elementAt(index);
                          return widget;
                        })
                )
              ],
            ));
      }
    }