问题
I'm going to achieve this UI in my App:
Well, Some ways that I tried before:
1. Using CollapsingToolbarLayout
I put my CardView insid of CollapsingToolbarLayout and put them all in AppBarLAyout.
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_scrollFlags="scroll|exitUntilCollapsed" >
<CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<!-- My Views Goes there -->
</CardView
<android.support.v7.widget.Toolbar
android:id="@+id/flexible.example.toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@null"
app:layout_collapseMode="pin"
style="@style/ToolBarWithNavigationBack"
/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<RecyclerView
app:layout_behavior="@string/appbar_scrolling_view_behavior"
></RecyclerView>
</android.support.design.widget.CoordinatorLayout>
P.S: I removed unrelated codes, don't mention me
This Way works correctly but!!! When CardView height goes taller than screen height, it's content igonered by AppBarLayout and does not show to user
2. Using NestedScrollView
I put CardView and RecyclerView inside NestedScrollView. But the problem is When User Reached To end of RecyclerView and then scroll back to top, fling goes laggy and buggy and stop some where ans user have to scroll more and more to get to top!
<android.support.v4.widget.NestedScrollView
android:id="@+id/nested_scrollbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="fill_vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
android:scrollbars="none" >
<LinearLayout
android:id="@+id/nested_scrollbar_linear"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<android.support.v7.widget.CardView
android:id="@+id/flexible.example.cardview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardBackgroundColor="@color/post_card_backgroind"
app:cardCornerRadius="0dp"
app:cardElevation="0dp">
</android.support.v7.widget.CardView>
<android.support.v7.widget.RecyclerView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="@dimen/four"
android:layout_marginEnd="@dimen/four"
android:layout_marginLeft="@dimen/four"
android:layout_marginRight="@dimen/four"
android:layout_marginStart="@dimen/four"
android:layout_marginTop="@dimen/four"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
How can fix this issue?! I don't want use adapters that make header for recyclerview, I got performance related issue from some of them.
Answer
Put RecyclerView inside NestedScrollView as you can see in 2 and apply .setNestedScrollingEnabled and set it to false
回答1:
You should use getItemViewType. It is easy and won't create any performance overhead. Change the code in your Adapter like this:
public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
class CardViewHolder extends RecyclerView.ViewHolder {
...
}
class ItemViewHolder extends RecyclerView.ViewHolder {
...
}
@Override
public int getItemViewType(int position) {
if (position == 0) {
return 0; // Card Type
} else {
return 1; // Item Type
};
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
switch (viewType) {
case 0:
// Card Type
return new CardViewHolder(...);
case 1:
// Item Type
return new ItemViewHolder(...);
}
}
// Optional
// If your data list does not contain CardView data
// You may need to add extra count in adapter
@Override
public final int getItemCount() {
// Add one count for CardView data
return list.size() + 1;
}
@Override
public T getItem(int position) {
// As the position is change because of CardView at position 0
// So you may have to decrement the corresponding index
return list.get(position - 1);
}
}
UPDATE 1
If you don't want to update the adapter, you can use
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<CardView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!-- Views Goes there -->
</CardView>
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
// This is the key
android:nestedScrollingEnabled="false"/>
</LinearLayout>
</android.support.v4.widget.NestedScrollView>
android:nestedScrollingEnabled is available in API Level 21 through xml.
For lower APIs use java method i.e. recyclerView.setNestedScrollingEnabled(false); or ViewCompat.setNestedScrollingEnabled(recyclerView, false);
NOTE (12-12-2016)
When using nested scroll. Be aware of the known issue of RecyclerView not recycling views as asked here and here (apparent reason answered by Arpit Ratan and me respectively). So I'll suggest to go with the first solution i.e. using getItemViewType. For more details, see complete and better answers like this or this.
UPDATE 2
You can use setFullSpan. If the orientation of your StaggeredGridLayoutManager is vertical, you can use the following code to span it's width to full screen:
public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
if (position == 0) {
StaggeredGridLayoutManager.LayoutParams layoutParams = (StaggeredGridLayoutManager.LayoutParams) viewHolder.itemView.getLayoutParams();
layoutParams.setFullSpan(true);
}
}
回答2:
the problem in 2.using
But the problem is When User Reached To end of RecyclerView and then scroll back to top
it can be deal by add android:descendantFocusability="blocksDescendants in the first layout under the NestedScrollView like this:
<android.support.v4.widget.NestedScrollView
android:id="@+id/nested_scrollbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="fill_vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
android:scrollbars="none" >
<LinearLayout
android:id="@+id/nested_scrollbar_linear"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:descendantFocusability="blocksDescendants" >
it work for me. NestedScrollView scrolls to top on Recyclerview resized
来源：https://stackoverflow.com/questions/37437161/dealing-with-recyclerview-nestedscrollview-and-cardview