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Tabs and scrolling demo can crash - null.scrollTo() #4193

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Tabs and scrolling demo can crash - null.scrollTo()#4193
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HansMuller
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c: crashStack traces logged to the consolec: regressionIt was better in the past than it is nowcustomer: galleryRelating to flutter/gallery repository. Please transfer non-framework issues there.f: scrollingViewports, list views, slivers, etc.frameworkflutter/packages/flutter repository. See also f: labels.p: material_uimaterial_ui package in flutter/packages

Description

@HansMuller
HansMuller
opened on May 25, 2016

This occurred while swiping repeatedly and rapidly in one direction.

Running lib/main.dart on Nexus 5...
--------- beginning of main
Observatory listening on http://127.0.0.1:48446
Diagnostic server listening on http://127.0.0.1:57845
Application running.
Type "h" or F1 for help, "r" or F5 to restart the app, and "q", F10, or ctrl-c to quit.
W/ActivityManager: Unable to start service Intent { cmp=com.google.android.gms/.phenotype.service.PhenotypeCommitChimeraService (has extras) } U=0: not found
E/flutter : [ERROR:dart_error.cc(17)] Unhandled exception:
E/flutter : The null object does not have a method 'scrollTo'.
E/flutter : 
E/flutter : NoSuchMethodError: method not found: 'scrollTo'
E/flutter : Receiver: null
E/flutter : Arguments: [0.0]
E/flutter : #0      Object._noSuchMethod (dart:core-patch/object_patch.dart:42)
E/flutter : #1      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
E/flutter : #2      TabsDemoState.build.<anonymous closure>.<anonymous closure> (/builds/dev/flutter/examples/flutter_gallery/lib/demo/tabs_demo.dart:46)
E/flutter : #3      State.setState (package:flutter/src/widgets/framework.dart:419)
E/flutter : #4      TabsDemoState.build.<anonymous closure> (/builds/dev/flutter/examples/flutter_gallery/lib/demo/tabs_demo.dart:44)
E/flutter : #5      TabBarSelectionState.value=.<anonymous closure> (package:flutter/src/material/tabs.dart:599)
E/flutter : #6      _RootZone.runUnary (dart:async/zone.dart:1204)
E/flutter : #7      _FutureListener.handleValue (dart:async/future_impl.dart:131)
E/flutter : #8      _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:637)
E/flutter : #9      _Future._propagateToListeners (dart:async/future_impl.dart:667)
E/flutter : #10     _Future._completeWithValue (dart:async/future_impl.dart:477)
E/flutter : #11     _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:528)
E/flutter : #12     _microtaskLoop (dart:async/schedule_microtask.dart:41)
E/flutter : #13     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)

Activity

  1. HansMuller
    added
    c: regressionIt was better in the past than it is now
    p: material_uimaterial_ui package in flutter/packages
    customer: galleryRelating to flutter/gallery repository. Please transfer non-framework issues there.
    customer: leafy
    on May 25, 2016

  2. HansMuller commented on May 26, 2016

    @HansMuller
    HansMuller
    on May 26, 2016
    ContributorAuthor

    In this case, when the app is notified that the selected tab has changed the Scrollable that corresponded to the newly selected TabBarView has been discarded. So its GlobalKey's currentState is null.

    The source of this problem appears to be that the TabBarSelection onChanged() only callback runs when the animation between TabBarView's (between the old and newly selected tab) has completed, and the TabBarViews are materialized and discarded as needed. The TabBarViews are implemented with a PageableList and only two tab pages (for taps on a tab) or three tab pages (for TabBarView left/right drags) are materialized by the PageableList at any time. It looks like it's posisble for the PageableList to be rebuilt more than once before the onChanged callback runs.

  3. eseidelGoogle
    removed
    customer: leafy
    on Jun 17, 2016

  4. eseidelGoogle commented on Jun 17, 2016

    @eseidelGoogle
    eseidelGoogle
    on Jun 17, 2016
    Contributor

    Similar to #4195, customer leafy worked around by skipping the test.

  5. Hixie
    modified the milestone: on Aug 1, 2016
  6. Hixie
    added
    frameworkflutter/packages/flutter repository. See also f: labels.
    on Sep 12, 2016
  7. Hixie
    modified the milestones: , on Jan 30, 2017
  8. Hixie
    added
    f: scrollingViewports, list views, slivers, etc.
    on Oct 17, 2017
  9. Hixie
    modified the milestones: 3: Current Milestone, on Dec 20, 2017
  10. Hixie
    added
    c: crashStack traces logged to the console
    on Dec 20, 2017
  11. cdotstout
    added a commit that references this issue on Apr 3, 2018

    Revert "Set ui, io, and gpu thread names. (flutter#4182)" (flutter#4193)

    3af233d

  12. zoechi commented on Jan 9, 2019

    @zoechi
    zoechi
    on Jan 9, 2019
    Contributor

    I can't reproduce #4195 Do you think this is still an issue?

  13. HansMuller
    self-assigned this
    on Mar 20, 2019

  14. HansMuller commented on Mar 26, 2019

    @HansMuller
    HansMuller
    on Mar 26, 2019
    ContributorAuthor

    Unfortunately this bug corresponds to versions of the tabs implementation and the tabs demo that no longer exist. I can no longer reproduce the crash and code path that was failing is gone. I'm going to close this issue. It's a shame that it has taken so long!

  15. HansMuller
    closed this as completedon Mar 26, 2019

  16. github-actions commented on Aug 17, 2021

    @github-actions
    github-actionsbot
    on Aug 17, 2021

    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

  17. github-actions
    locked as resolved and limited conversation to collaborators on Aug 17, 2021
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c: crashStack traces logged to the consolec: regressionIt was better in the past than it is nowcustomer: galleryRelating to flutter/gallery repository. Please transfer non-framework issues there.f: scrollingViewports, list views, slivers, etc.frameworkflutter/packages/flutter repository. See also f: labels.p: material_uimaterial_ui package in flutter/packages

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