颤振更新文字 [英] Flutter update countertext

问题描述

在Flutter中，当用户在 TextFormField 中键入内容时， inputDecoration的计数器文本属性不会更改.在用户键入文字时，可以减少原语吗?

In Flutter, inputDecoration's countertext property does not change as the user is typing in the TextFormField. Is it possible to decrement the countertext as the user is typing?

TextFormField(
 keyboardType: TextInputType.number,
 decoration: new InputDecoration(
   counterText: "9",
   hintText: "Enter exact order number",
  ),
)

推荐答案

我对此 answer 处理您的问题

class StackEditText extends StatefulWidget {
  @override
  _StackEditTextState createState() => _StackEditTextState();
}

class _StackEditTextState extends State<StackEditText> {

  TextEditingController _controller = new TextEditingController();

  void onValueChange() {
      setState(() {
        _controller.text;
      });
  }

  @override
  void initState() {
    super.initState();
    _controller.addListener(onValueChange);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Container(
        child: TextFormField(
          controller: _controller,
          maxLength: 9,
          decoration: InputDecoration(
            counterText: "${9 - _controller.text.length}",
            hintText: 'Enter exact order number',
          ),
        ),
      ),
    );
  }
}

这篇关于颤振更新文字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！