Null check operator used on a null value

[abhimanyu95]

When onChanged is not passed then this error is thrown .After passing onChanged it works fine.

Null check operator used on a null value

This is the stack

When the exception was thrown, this was the stack:
#0 _OTPTextFieldState.buildTextField. (package:otp_text_field/otp_field.dart:156:27)
#1 EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:2276:27)
#2 EditableTextState.textEditingValue= (package:flutter/src/widgets/editable_text.dart:2474:5)
#3 RenderEditable._handleDelete (package:flutter/src/rendering/editable.dart:877:27)
#4 RenderEditable._handleKeyEvent (package:flutter/src/rendering/editable.dart:550:7)

[xscotophilic]

══╡ EXCEPTION CAUGHT BY WIDGETS ╞═══════════════════════════════════════════════════════════════════
The following _CastError was thrown while calling onChanged:
Null check operator used on a null value

When the exception was thrown, this was the stack:
#0      _OTPTextFieldState.buildTextField.<anonymous closure> (package:otp_text_field/otp_field.dart:183:27)
#1      EditableTextState._formatAndSetValue (package:flutter/src/widgets/editable_text.dart:2298:27)
#2      EditableTextState.userUpdateTextEditingValue (package:flutter/src/widgets/editable_text.dart:2505:5)
#3      RenderEditable._setTextEditingValue (package:flutter/src/rendering/editable.dart:563:27)
#4      RenderEditable._handleDelete (package:flutter/src/rendering/editable.dart:1851:5)
#5      RenderEditable._handleKeyEvent (package:flutter/src/rendering/editable.dart:676:7)
#6      RawKeyboard._handleKeyEvent (package:flutter/src/services/raw_keyboard.dart:675:17)
#7      BasicMessageChannel.setMessageHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:73:49)
#8      BasicMessageChannel.setMessageHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:72:47)
#9      _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binding.dart:284:33)
#10     _invoke3.<anonymous closure> (dart:ui/hooks.dart:223:15)
#14     _invoke3 (dart:ui/hooks.dart:222:10)
#15     PlatformDispatcher._dispatchPlatformMessage (dart:ui/platform_dispatcher.dart:520:7)
#16     _dispatchPlatformMessage (dart:ui/hooks.dart:90:31)
(elided 3 frames from dart:async)
════════════════════════════════════════════════════════════════════════════════════════════════════

[xscotophilic]

Even when erasing OTP gives error

Another exception was thrown: Null check operator used on a null value

Another exception was thrown: Null check operator used on a null value

[calinvasileandrei]

Same problem with onCompleted and it throws this error on every pin input!

[tajirhas9]

I have opened a pull request (#14) regarding the solution to this problem.
You can change the file according to the comment of the pull request until author merges the pull request.

[Nitish-29]

I'm also facing the same issue , throws the error on every pin input. is there any update on this

[mohamed97alsaee]

this error cuz onChange method will work even if you didn't use it so just you can put it without any functionality just as fast solve like this :

onChanged: (s) {},

i wish if that's help you .

[xscotophilic]

I think @mohamed97alsaee is right!

[sabikrahat]

This solution works for me properly.

OTPTextField(
length: 4,
otpFieldStyle: OtpFieldStyle(
backgroundColor: Colors.grey[200]!,
borderColor: Colors.white,
),
width: ScreenSize.width,
fieldWidth: 55,
style: const TextStyle(
fontSize: 18,
fontWeight: FontWeight.w700,
),
textFieldAlignment: MainAxisAlignment.spaceAround,
fieldStyle: FieldStyle.box,
onChanged: (val) {
setState(() {
pin = val;
});
print(pin);
},
onCompleted: (_) {},
),

[JulianBissekkou]

Also fixed in #27