Flutter TextField input only decimal numbers

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),
),

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),)

[![enter image description here][1]][1]
[1]:

You can use `TextInputFormatter` for this case.

Here is an example for the same,

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

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.

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

Add the inputFormatters line:




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

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]*'))
],
```

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

try this:
```dart
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:

```dart
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;
}),
],
)
```