Scrollcontroller in flutter error Exception has occurred - dart

Question

I have two screen , first one fetch all post from wordpress
last one fetch all videos and i use ScollController with ListView to scroll data
look to my code :
ScrollController _scrollController;
#override
void initState() {
_scrollController = new ScrollController();
_scrollController.addListener(() {
print(_scrollController.position.pixels);
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent - 10) {
// if we are the bottom of the page
fetchPosts();
//millisecs += 1500;
//super.initState();
}
super.initState();
});
}
#override
void dispose() {
_scrollController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) { ....
when i tab between screen one to two or screen two to one
i get this error:
Exception has occurred.
FlutterError (A ScrollController was used after being disposed.
Once you have called dispose() on a ScrollController, it can no longer be used.)
trace code:
image error
Launching lib\main.dart on Android SDK built for x86 in debug mode...
Built build\app\outputs\apk\debug\app-debug.apk.
D/EGL_emulation( 8157): eglMakeCurrent: 0xeeebd340: ver 3 1 (tinfo 0xeee9b1d0)
E/eglCodecCommon( 8157): glUtilsParamSize: unknow param 0x000082da
E/eglCodecCommon( 8157): glUtilsParamSize: unknow param 0x000082da
I/Choreographer( 8157): Skipped 49 frames! The application may be doing too much work on its main thread.
D/EGL_emulation( 8157): eglMakeCurrent: 0xeef21ce0: ver 3 1 (tinfo 0xe6f286b0)
D/ ( 8157): HostConnection::get() New Host Connection established 0xe7123880, tid 8184
D/EGL_emulation( 8157): eglMakeCurrent: 0xeeebd340: ver 3 1 (tinfo 0xe7103370)
I/flutter ( 8157): _morePages: false
I/flutter ( 8157): statusCode: 200
I/flutter ( 8157): ══╡ EXCEPTION CAUGHT BY FOUNDATION LIBRARY ╞════════════════════════════════════════════════════════
I/flutter ( 8157): The following assertion was thrown while dispatching notifications for ScrollController:
I/flutter ( 8157): 'package:flutter/src/widgets/framework.dart': Failed assertion: line 1003 pos 12:
I/flutter ( 8157): '_debugLifecycleState == _StateLifecycle.created': is not true.
I/flutter ( 8157):
I/flutter ( 8157): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter ( 8157): more information in this error message to help you determine and fix the underlying cause.
I/flutter ( 8157): In either case, please report this assertion by filing a bug on GitHub:
I/flutter ( 8157): https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter ( 8157):
I/flutter ( 8157): When the exception was thrown, this was the stack:
I/flutter ( 8157): #2 State.initState (package:flutter/src/widgets/framework.dart:1003:12)
I/flutter ( 8157): #3 _PostsPage.initState. (package:flutter_wp2019/ui/PostsLatest.dart:42:13)
I/flutter ( 8157): #4 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:208:21)
I/flutter ( 8157): #5 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:208:21)
I/flutter ( 8157): #6 ScrollPosition.notifyListeners (package:flutter/src/widgets/scroll_position.dart:692:11)
I/flutter ( 8157): #7 ScrollPosition.setPixels (package:flutter/src/widgets/scroll_position.dart:218:9)
I/flutter ( 8157): #8 ScrollPositionWithSingleContext.setPixels
(package:flutter/src/widgets/scroll_position_with_single_context.dart:84:18)
I/flutter ( 8157): #9 ScrollPositionWithSingleContext.applyUserOffset
(package:flutter/src/widgets/scroll_position_with_single_context.dart:127:5)
I/flutter ( 8157): #10 ScrollDragController.update (package:flutter/src/widgets/scroll_activity.dart:373:14)
I/flutter ( 8157): #11 ScrollableState._handleDragUpdate (package:flutter/src/widgets/scrollable.dart:470:12)
I/flutter ( 8157): #12 DragGestureRecognizer.acceptGesture.
(package:flutter/src/gestures/monodrag.dart:176:48)
I/flutter ( 8157): #13 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
I/flutter ( 8157): #14 DragGestureRecognizer.acceptGesture (package:flutter/src/gestures/monodrag.dart:176:9)
I/flutter ( 8157): #15 GestureArenaManager._resolveInFavorOf (package:flutter/src/gestures/arena.dart:263:12)
I/flutter ( 8157): #16 GestureArenaManager._resolve (package:flutter/src/gestures/arena.dart:222:9)
I/flutter ( 8157): #17 GestureArenaEntry.resolve (package:flutter/src/gestures/arena.dart:52:12)
I/flutter ( 8157): #18 OneSequenceGestureRecognizer.resolve (package:flutter/src/gestures/recognizer.dart:166:13)
I/flutter ( 8157): #19 DragGestureRecognizer.handleEvent (package:flutter/src/gestures/monodrag.dart:154:11)
I/flutter ( 8157): #20 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
I/flutter ( 8157): #21 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
I/flutter ( 8157): #22 _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:180:19)
I/flutter ( 8157): #23 _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
I/flutter ( 8157): #24 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
I/flutter ( 8157): #25 _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue
(package:flutter/src/gestures/binding.dart:101:7)
I/flutter ( 8157): #26 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket
(package:flutter/src/gestures/binding.dart:85:7)
I/flutter ( 8157): #27 _invoke1 (dart:ui/hooks.dart:168:13)
I/flutter ( 8157): #28 _dispatchPointerDataPacket (dart:ui/hooks.dart:122:5)
I/flutter ( 8157): (elided 2 frames from class _AssertionError)
I/flutter ( 8157):
I/flutter ( 8157): The ScrollController sending notification was:
I/flutter ( 8157): ScrollController#bcc47(one client, offset 21.4)
I/flutter ( 8157): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/chatty ( 8157): uid=10083(com.example.flutterwp2019) 1.ui identical 16 lines
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/zygote ( 8157): Do partial code cache collection, code=29KB, data=23KB
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/chatty ( 8157): uid=10083(com.example.flutterwp2019) 1.ui identical 1 line
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/zygote ( 8157): After code cache collection, code=29KB, data=23KB
I/zygote ( 8157): Increasing code cache capacity to 128KB
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/chatty ( 8157): uid=10083(com.example.flutterwp2019) 1.ui identical 11 lines
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/zygote ( 8157): Do partial code cache collection, code=59KB, data=40KB
I/zygote ( 8157): After code cache collection, code=59KB, data=40KB
I/zygote ( 8157): Increasing code cache capacity to 256KB
I/flutter ( 8157): 30.00837053571422
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 42.86551339285711
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 55.72265625
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 71.41741071428567
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 88.56863839285711
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 105.71986607142856
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 120.24285714285713
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 117.38013392857141
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 110.24843749999997
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 93.09720982142858
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 63.0888392857143
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 23.11116071428569
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 0.0
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 1.4313616071428896
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 8.58816964285711
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 24.006696428571445
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 41.15792410714289
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 64.00948660714289
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 85.4296875
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 108.28125
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 120.24285714285713
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 2.8376116071428896
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 7.131696428571445
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 11.42578125
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 18.557477678571445
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 24.28292410714289
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 39.977678571428555
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 57.12890625
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 77.14285714285717
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 97.13169642857144
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 115.71428571428572
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): 120.24285714285713
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): _morePages: false
I/flutter ( 8157): statusCode: 200
I/flutter ( 8157): _morePages: false
I/flutter ( 8157): statusCode: 400
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/chatty ( 8157): uid=10083(com.example.flutterwp2019) 1.ui identical 22 lines
I/flutter ( 8157): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line
1003 pos 12: '_debugLifecycleState == _StateLifecycle.created': is not
true.
I/flutter ( 8157): _morePages: false
I/flutter ( 8157): statusCode: 200
image error
Thanks Advance

Answer 1

super.initState() is on the wrong location
#override
void initState() {
super.initState(); // <<< added
_scrollController = new ScrollController();
_scrollController.addListener(() {
print(_scrollController.position.pixels);
if (_scrollController.position.pixels ==
_scrollController.position.maxScrollExtent - 10) {
// if we are the bottom of the page
fetchPosts();
//millisecs += 1500;
//super.initState();
}
// super.initState(); // <<< removed
});
}

Answer 2

Add this into the widget where you are initializing the scroll controller:
#override
void dispose() {
_controller.dispose();
super.dispose();
}
and move the super.init() above the intialization