Question

我遇到错误，尝试编辑TextField一段时间，它显示红色屏幕，然后一切恢复正常：

I / flutter（30508）：引发了另一个异常：构建函数返回null。

我的代码像这样：

  void _showDialog(BuildContext context, result, int decision) {
    // flutter defined function
    showDialog(
        context: context,
        builder: (BuildContext context) {
          // return object of type Dialog
          return AlertDialog(
            title: Text("Tutar Giriniz"),
            content: TextField(
              controller: _textFieldController,
              keyboardType: TextInputType.number,
            ),
            actions: <Widget>[
              // usually buttons at the bottom of the dialog
              new FlatButton(
                child: new Text("Kapat"),
                onPressed: () {
                  result["amount"] = _textFieldController.text;
                  result['decision'] = decision;
                  Navigator.of(context).pop();
                },
              ),
            ],
          );
        });
  }```

Answer 1

我找到了解决方案。关于类的构建功能。我那里有一个if条件，我用空容器写了else条件。

if (snapshot.connectionState == ConnectionState.done) {
                return FittedBox(
                    fit: BoxFit.fitWidth,
                    child: DataTable(
                      columns: [
                        DataColumn(label: Text('Maç')),
                        DataColumn(label: Text('Ev Sahibi')),
                        DataColumn(label: Text('Beraberlik')),
                        DataColumn(label: Text('Deplasman')),
                      ],
                      rows: List.generate(matches.length,
                          (index) => _getDataRow(matches[index], context)),
                    ));
              } else {
                return Container();
              }```

生成函数返回null

1 个答案: