Flutter TextField仅输入十进制数字

问题描述

我只想在Flutter的TextField中输入小数.我尝试了下面的代码，但是没有用.它允许使用字母(a-z)和特殊字符.

I want to input only decimal number in TextField in Flutter. I tried below code but that's not working. It allows alpha (a-z) and special characters.

TextField(
  controller:
      new TextEditingController(text: listDisplay[position].getBlockQty(),
  ),
  textAlign: TextAlign.center,
  maxLines: 1,
  keyboardType: TextInputType.numberWithOptions(
      decimal: true,
      signed: false),
),

推荐答案

在这种情况下，您可以使用TextInputFormatter.

You can use TextInputFormatter for this case.

这里是一个例子，

子类TextInputFormatter

import 'package:flutter/services.dart';

class RegExInputFormatter implements TextInputFormatter {
  final RegExp _regExp;

  RegExInputFormatter._(this._regExp);

  factory RegExInputFormatter.withRegex(String regexString) {
    try {
      final regex = RegExp(regexString);
      return RegExInputFormatter._(regex);
    } catch (e) {
      // Something not right with regex string.
      assert(false, e.toString());
      return null;
    }
  }

  @override
  TextEditingValue formatEditUpdate(
      TextEditingValue oldValue, TextEditingValue newValue) {
    final oldValueValid = _isValid(oldValue.text);
    final newValueValid = _isValid(newValue.text);
    if (oldValueValid && !newValueValid) {
      return oldValue;
    }
    return newValue;
  }

  bool _isValid(String value) {
    try {
      final matches = _regExp.allMatches(value);
      for (Match match in matches) {
        if (match.start == 0 && match.end == value.length) {
          return true;
        }
      }
      return false;
    } catch (e) {
      // Invalid regex
      assert(false, e.toString());
      return true;
    }
  }
}

与您的文本字段一起使用

Use it in with your textfield

final _amountValidator = RegExInputFormatter.withRegex('^\$|^(0|([1-9][0-9]{0,}))(\\.[0-9]{0,})?\$');
...
TextField(
  inputFormatters: [_amountValidator],
  keyboardType: TextInputType.numberWithOptions(
    decimal: true,
     signed: false,
   ),
 )

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