Textformfield在下一个按钮上为空。扑

Question

点击下一个按钮时，Textfield的值变为空。 仅对于输入数字类型的textformfiels会发生这种情况。 文本类型字段没有问题。 字段代码如下：

                                  TextFormField(
                                    textAlignVertical: TextAlignVertical.top,
                                    style:
                                        TextStyle(fontFamily: 'BalooThambi2'),

                                    textCapitalization:
                                        TextCapitalization.words,
                                    //controller: _vehicleNameController,
                                    //initialValue: userData.VName,
                                    autocorrect: true,
                                    focusNode: focus2,
                                    textInputAction: TextInputAction.next,
                                    autofocus: true,
                                    onFieldSubmitted: (v) {
                                      FocusScope.of(context)
                                          .requestFocus(focus3);
                                    },
                                    decoration: dateTimeInputDecoration(),
                                    validator: (val) {
                                      if (val.isEmpty) {
                                        return 'This field is required!';
                                      }
                                      return null;
                                    },

                                    keyboardType: TextInputType.number,
                                  ),

InputDecoration dateTimeInputDecoration() {
    return InputDecoration(
      contentPadding: EdgeInsets.all(8),
      errorStyle: TextStyle(color: Colors.white),
      filled: true,
      fillColor: Colors.white,
      enabledBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(10.0)),
        borderSide: BorderSide(color: Colors.transparent, width: 2),
      ),
      focusedBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(10.0)),
        borderSide: BorderSide(color: Colors.transparent, width: 2),
      ),
    );
  }