Background
We have quite a complex layout that has CollapsingToolbarLayout in it, together with a RecyclerView at the bottom.
In certain cases, we temporarily disable the expanding/collapsing of the CollapsingToolbarLayout, by calling setNestedScrollingEnabled(boolean) on the RecyclerView.
The problem
This usually works fine.
However, on some (bit rare) cases, slow scrolling on the RecyclerView gets semi-blocked, meaning it tries to scroll back when scrolling down. It's as if it has 2 scrolling that fight each other (scroll up and scroll down):
The code to trigger this is as such:
res/layout/activity_scrolling.xml
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.example.user.myapplication.ScrollingActivity">
<android.support.design.widget.AppBarLayout
android:id="@+id/app_bar"
android:layout_width="match_parent"
android:layout_height="@dimen/app_bar_height"
android:fitsSystemWindows="true"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:popupTheme="@style/AppTheme.PopupOverlay"/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:id="@+id/nestedView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_anchor="@id/app_bar"
app:layout_anchorGravity="bottom|end">
<Button
android:id="@+id/disableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="disable"/>
<Button
android:id="@+id/enableNestedScrollingButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="enable"
/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>
ScrollingActivity.java
public class ScrollingActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scrolling);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
final RecyclerView nestedView = (RecyclerView) findViewById(R.id.nestedView);
findViewById(R.id.disableNestedScrollingButton).setOnClickListener(new OnClickListener() {
@Override
public void onClick(final View v) {
nestedView.setNestedScrollingEnabled(false);
}
});
findViewById(R.id.enableNestedScrollingButton).setOnClickListener(new OnClickListener() {
@Override
public void onClick(final View v) {
nestedView.setNestedScrollingEnabled(true);
}
});
nestedView.setLayoutManager(new LinearLayoutManager(this));
nestedView.setAdapter(new Adapter() {
@Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
return new ViewHolder(LayoutInflater.from(parent.getContext()).inflate(
android.R.layout.simple_list_item_1,
parent,
false)) {
};
}
@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
((TextView) holder.itemView.findViewById(android.R.id.text1)).setText("item " + position);
}
@Override
public int getItemCount() {
return 100;
}
});
}
}
What I've tried
At first I thought it's because of something else (I thought it's a weird combination with DrawerLayout), but then I've found a minimal sample to show it, and it's just as I thought: it's all because of the setNestedScrollingEnabled.
I tried to report about this on Google's website (here), hoping it will get fixed if it's a real bug. If you wish to try it out, or watch the videos of the issue, go there, as I can't upload them all here (too large and too many files).
I've also tried to use special flags as instructed on other posts (examples: here, here, here, here and here) , but none helped. In fact each of them had an issue, whether it's staying in expanded mode, or scrolling in a different way than what I do.
The questions
Is this a known issue? Why does it happen?
Is there a way to overcome this?
Is there perhaps an alternative to calling this function of setNestedScrollingEnabled ? One without any issues of scrolling or locking the state of the CollapsingToolbarLayout ?
