Question

我有以下代码：

class _StandardCardState extends State<StandardCard> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Card(
        margin: EdgeInsets.fromLTRB(16.0, 16.0, 16.0, 0.0),
        child: Padding(
          padding: const EdgeInsets.all(12.0),
          child: Row(
            children: <Widget>[
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: <Widget>[
                    Row(
                      children: <Widget>[
                        Text(
                          'L*: ',
                          style: TextStyle(
                              fontSize: 18.0, color: Colors.grey[600]),
                        ),
                        Text(
                          widget.standard.L.toString(),
                          style: TextStyle(
                              fontSize: 18.0, color: Colors.grey[600]),
                        ),
                      ],
                    ),
                    SizedBox(height: 6.0),
                    Row(
                      children: <Widget>[
                        //some children
                      ],
                    ),
                    SizedBox(height: 6.0),
                    Row(
                      children: <Widget>[
                        //some children
                      ],
                    ),
                  ],
                ),
              ),
              PopupMenuButton<WhyFarther>(
                onSelected: (WhyFarther result) {
                  setState(() {
                    var _selection = result;
                  });
                },
                itemBuilder: (BuildContext context) =>
                    <PopupMenuEntry<WhyFarther>>[
                  const PopupMenuItem<WhyFarther>(
                    value: WhyFarther.harder,
                    child: Text(
                      'Working a lot harder',
                      style: TextStyle(fontSize: 18.0, color: Colors.grey[600]),
                    ),
                  ),
                  const PopupMenuItem<WhyFarther>(
                    value: WhyFarther.smarter,
                    child: Text(
                      'Being a lot smarter',
                      style: TextStyle(fontSize: 18.0, color: Colors.grey[600]),
                    ),
                  ),
                  const PopupMenuItem<WhyFarther>(
                    value: WhyFarther.selfStarter,
                    child: Text(
                      'Being a self-starter',
                      style: TextStyle(fontSize: 18.0, color: Colors.grey[600]),
                    ),
                  ),
                  const PopupMenuItem<WhyFarther>(
                    value: WhyFarther.tradingCharter,
                    child: Text(
                      'Placed in charge of trading charter',
                      style: TextStyle(fontSize: 18.0, color: Colors.grey[600]),
                    ),
                  ),
                ],
              )
            ],
          ),
        ),
      ),
    );
  }
}

，然后ListView.builder仍通过另一个函数调用

。当我尝试使用色板更改popupMenuItem中的文本样式时，出现错误“无效的常量值”。

为什么上面的文本小部件没有抛出此错误？以及如何避免这种情况，然后如何在PopupMenuButtons中使用色板？

Answer 1

我只需要在PopupMenuItem之前删除“ const” ...有时在复制编码有很大帮助的情况下阅读。

在PopupMenuItem中使用颜色样本时出现抖动错误

1 个答案: