如何使用Flutter检查和检索空双值

Question

我正在使用Flatter desktop项目，我想检索一些双值，但当继续将某些字段作为空字段并尝试检索数据时，我遇到了一个错误，无法填充所有文本字段。如何将这些TextField检查为空字段并检索空值。

错误：-════════ 用手势捕捉异常═══════════════════════════════════════════ 处理手势时引发以下FormatException:无效的double

抛出异常时，这是堆栈#0double.parse（dart： core-patch/double_patch.dart:111： 28）#1_HomePageState.build.。包：urban_laundry/page/home_page.dart:992#2 State.set状态包：flutter/.../小部件/framework.dart:1088#3_HomePageState.build.包：urban_laundry/页面/home_page.dart:975#4_InkResponseState_handleTap包：flutter/.../材质/ink_well.dart:989#5 GestureRecognizer.invoke回调包：flutter/.../手势/recognizer.dart:193#6TapGestureRecognizer.handleTapUp软件包：flutter/.../手势/tap.dart:608#7 BaseTapGesture认可器。_checkUp软件包：flutter/.../手势/tap.dart:296#8 BaseTapGestureRecognizer.handlePrimaryPointer软件包：flutter/.../手势/tap.dart:230#9 PrimaryPointerGestureRecognizer.handle事件包：flutter/.../手势/recognizer.dart:558#10指针路由器。_dispatch包：flutter/.../手势/pointer_router.dart:94#11指针路由器。_dispatchEventToRoutes包：flutter/.../手势/pointer_router.dart:139#12_LinkedHashMapMixin。.../手势/pointer_router. dart： 137#14 PointerRouter.路由包： flutter/.../手势/pointer_router. dart： 123#15 GestureBinding. handle活动包： flutter/.../手势/binding. dart： 440#16 GestureBinding.调度事件包： flutter/.../手势/binding. dart： 420#17 RendererBinding.调度事件包： flutter/.../渲染/binding. dart： 278

代码：-

  final price1 = TextEditingController();
  final price2 = TextEditingController();
  final price3 = TextEditingController();

  final deliveryCharge = TextEditingController();

  double? p1;
  double? p2;
  double? p3;
  double? delivery;
  double total = 0.0;

  void priceTotal() {
    double p1 = double.parse(price1.text);
    double p2 = double.parse(price2.text);
    double p3 = double.parse(price3.text);

    double delivery = double.parse(deliveryCharge.text);

    print(total.toString());
    setState(() {
      total = (p1 + p2 + p3 + delivery);
    });
  }

文本字段：-

Padding(
  padding: const EdgeInsets.only(
      top: 10.0, left: 10.0),
  child: SizedBox(
    width: 200.0,
    child: TextField(
      controller: price3,
      decoration: const InputDecoration(
        border: OutlineInputBorder(
          borderRadius: BorderRadius.all(
              Radius.circular(10.0)),
        ),
        prefixIcon: Padding(
          padding: EdgeInsets.all(8.0),
          child: FaIcon(
            FontAwesomeIcons.rupeeSign,
            size: 20.0,
          ),
        ),
        hintText: 'Price',
      ),
    ),
  ),
),

新闻界：-

  onPressed: () {
    setState(() {
      delivery = double.parse(deliveryCharge.text);
      p1 = double.parse(price1.text);
      p2 = double.parse(price2.text);
      p3 = double.parse(price3.text);
      priceTotal();
    });
  },

Answer 1

如果数据为空，则可以将其替换为零。让我们试试看。

      delivery = double.parse(deliveryCharge.text??"0");
      p1 = double.parse(price1.text??"0");
      p2 = double.parse(price2.text??"0");
      p3 = double.parse(price3.text??"0");