我在我的Flutter应用程序中创建了一个自定义的Numpad小部件。

class NumPadCheckout extends StatelessWidget {
  final TextEditingController controller;
  final Function delete;
  final Function onSubmit;
  const NumPadCheckout({
    Key? key,
    required this.delete,
    required this.onSubmit,
    required this.controller,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const SizedBox(height: 20),
        Row(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            NumberButtonCheckout(
              number: "1",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "2",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "3",
              controller: controller,
            ),
          ],
        ),
        // const SizedBox(height: 20),
        Row(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            NumberButtonCheckout(
              number: "4",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "5",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "6",
              controller: controller,
            ),
          ],
        ),
        // const SizedBox(height: 20),
        Row(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            NumberButtonCheckout(
              number: "7",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "8",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "9",
              controller: controller,
            ),
          ],
        ),
        // const SizedBox(height: 20),
        Row(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            // this button is used to delete the last number
            NumberButtonCheckout(
              number: "00",
              controller: controller,
            ),
            NumberButtonCheckout(
              number: "0",
              controller: controller,
            ),
            CustomKey(
              iconData: Icons.keyboard_backspace,
              onPressed: () => delete,
            )
          ],
        ),
      ],
    );
  }
}
class NumberButtonCheckout extends StatelessWidget {
  final String number;
  final TextEditingController controller;
  const NumberButtonCheckout({
    Key? key,
    required this.number,
    required this.controller,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: width,
      height: height,
      child: ElevatedButton(
        onPressed: () {
          controller.text += number.toString();
        },
        child: Center(
          child: Text(
            number.toString(),
          ),
        ),
      ),
    );
  }
}
class CustomKey extends StatelessWidget {
  final IconData iconData;
  final VoidCallback? onPressed;
  const CustomKey({
    Key? key,
    required this.iconData,
    required this.onPressed,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: width,
      height: height,
      child: ElevatedButton(
        onPressed: () => onPressed,
        child:  Center(
          child: Icon(
              iconData
          ),
        ),
      ),
    );
  }
}

现在我想在一个屏幕中添加这个，并使用它来输入数字到同一屏幕上的多个TextFormField中。每个TextFormField都应该有自己的TextEditingControllers。当退格键在数字键盘中时，也需要清除数据。如何在Flutter中做到这一点？