[Android 8.0] com.facebook.react.uimanager.NativeViewHierarchyManager.dropView (NativeViewHierarchyManager.java:536)

[7772]

🐛 Bug Report

This bug occurs unpredictably but continuously in Android 8.0. There is #20288 related this bug but it is not perfect solution, So we have still faced this issue.

Since the issue is merged on react-native, dropView method is like below.

  protected synchronized void dropView(View view) {
    UiThreadUtil.assertOnUiThread();
    if (mTagsToViewManagers.get(view.getId()) == null) {
      // This view has already been dropped (likely due to a threading issue caused by async js
      // execution). Ignore this drop operation.
      return;
    }
    if (!mRootTags.get(view.getId())) {
      // For non-root views we notify viewmanager with {@link ViewManager#onDropInstance}
      resolveViewManager(view.getId()).onDropViewInstance(view);
    }
    ViewManager viewManager = mTagsToViewManagers.get(view.getId());
    if (view instanceof ViewGroup && viewManager instanceof ViewGroupManager) {
      ViewGroup viewGroup = (ViewGroup) view;
      ViewGroupManager viewGroupManager = (ViewGroupManager) viewManager;
      for (int i = viewGroupManager.getChildCount(viewGroup) - 1; i >= 0; i--) {
        View child = viewGroupManager.getChildAt(viewGroup, i);
        if (child == null) {
            FLog.e(TAG, "Unable to drop null child view");
        } else if (mTagsToViews.get(child.getId()) != null) {
          dropView(child);
        }
      }
      viewGroupManager.removeAllViews(viewGroup);
    }
    mTagsToViews.remove(view.getId());
    mTagsToViewManagers.remove(view.getId());
  }

The parameter, View view is passed on dropView method and it may be sometimes null. So view object can not invoke getId method.

Simply add this codes below in the top of dropView method.

if (view == null) return;

To Reproduce

I have tried to reproduce this bug, but It is difficult to make the circumstance that the bug occurs.

Expected Behavior

The bug do not occur when view is null.

Code Example

Environment

[skip envinfo]

I used this environment but this issue will occur on all versions.

  OS: macOS 10.14.4
  Node: 8.12.0
  Yarn: Not Found
  npm: 6.4.1
  Watchman: 4.9.0
  Xcode: Xcode 10.1 Build version 10B61
  Android Studio: 3.2 AI-181.5540.7.32.5014246

  react: 16.3.0-alpha.1 => 16.3.0-alpha.1
  react-native: 0.55.4 => 0.55.4

[react-native-bot]

Can you run react-native info and edit your issue to include these results under the Environment section?

If you believe this information is irrelevant to the reported issue, you may write `[skip envinfo]` alongside an explanation in your Environment: section.