Flutter TextField input only decimal numbers

Question

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),       
),

Answer 1

try this:

inputFormatters: [
  FilteringTextInputFormatter.allow(RegExp(r"[0-9.]")),
  TextInputFormatter.withFunction((oldValue, newValue) {
    final text = newValue.text;
    return text.isEmpty
        ? newValue
        : double.tryParse(text) == null
            ? oldValue
            : newValue;
  }),
],

demo:

TextFormField(
  keyboardType: TextInputType.numberWithOptions(
    decimal: true,
    signed: false,
  ),
  onChanged: _yourOnChange,
  inputFormatters: [
    FilteringTextInputFormatter.allow(RegExp(r"[0-9.]")),
    TextInputFormatter.withFunction((oldValue, newValue) {
      final text = newValue.text;
      return text.isEmpty
          ? newValue
          : double.tryParse(text) == null
              ? oldValue
              : newValue;
    }),
  ],
)

Answer 2

You can use TextInputFormatter for this case.

Here is an example for the same,

Subclass 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;
    }
  }
}

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,
   ),
 )

Answer 3

I am using this code and it's giving different results , on some phones it shows only numbers and on others it shows dashes and other chars , so it depends on the launcher or something like that i guess, in iPhone i guess it will show the correct keyboard ( i have tried on iPhone 7s plus).

the inputFormatters will allow only numbers so you will get what you want.

   TextField(
     textAlign: TextAlign.start,
     keyboardType: TextInputType.numberWithOptions(decimal: true),
     inputFormatters: <TextInputFormatter>[
                          FilteringTextInputFormatter.digitsOnly
                       ],
   ),

Answer 4

I've been looking the answer to this problem too and found it after many attempts and hard work.

you can use this regex for decimal.

inputFormatters: [
        FilteringTextInputFormatter.allow(RegExp(r'^[0-9]+\.?[0-9]*'))
      ],

Answer 5

Add the inputFormatters line:

 TextField(
     inputFormatters: <TextInputFormatter>[FilteringTextInputFormatter.allow(RegExp(r'^\d+\.?\d{0,2}'))],
          ...)

Answer 6

I have used this code in one of my Project and its working fine. I hope it will helps you.

TextField(
         decoration: InputDecoration(
         border: InputBorder.none,
         hintText: "Amount",
         hintStyle:
         TextStyle(color: Colors.grey, fontSize: 12.0),
         ),
         style: TextStyle(color: Colors.black, fontSize: 12.0),
         controller: _amountController[index],
         textInputAction: TextInputAction.done,
         keyboardType: TextInputType.numberWithOptions(decimal: true),)

Answer 7

try this one for decimal

import 'package:flutter/services.dart';
...
keyboardType: TextInputType.numberWithOptions(decimal: true),
inputFormatters: [FilteringTextInputFormatter.allow(RegExp('[0-9.,]+')),],
onChanged: (value) => doubleVar = double.parse(value),

Also

RegExp('([0-9]+(.[0-9]+)?)') For allow digits and only one dot