Recycleview in coordinatorlayout

Question

I am trying to create RelativeLayout that has CoordinatorLayout and LinearLayout at bottom and found some strange behavior that I can't resolve. This is my layout

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/sender"
        android:background="@android:color/white"
        android:fitsSystemWindows="true">

        <android.support.design.widget.AppBarLayout
            android:id="@+id/appbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?actionBarSize"
                android:background="?colorPrimary"
                app:layout_scrollFlags="scroll|enterAlways" />

        </android.support.design.widget.AppBarLayout>

        <android.support.v7.widget.RecyclerView
            android:id="@+id/messages_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    </android.support.design.widget.CoordinatorLayout>

    <LinearLayout
        android:id="@+id/sender"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:gravity="center_vertical"
        android:background="@android:color/white">

        <EditText
            android:id="@+id/inputText"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:inputType="text" />

        <Button
            android:fontFamily="sans-serif"
            style="?android:attr/borderlessButtonStyle"
            android:textAppearance="?android:textAppearanceButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/send"
            android:textColor="?colorPrimary"
            android:id="@+id/send"/>

    </LinearLayout>

</RelativeLayout>

After changing data in adapter I trying to scroll to last element ( for example by recyclerView.smoothScrollToPosition(size); )and all I see is part of last view (not full size). If recycleview not nest to CoordinatorLayout - all works as expecting - I see full sized last element view. How can I change layout to works it all correctly ?

Answer 1

Issue seems to be that smoothScrollToPosition() will silently scroll RecyclerView without letting CoordinatorLayout about the scroll being happening. This is what I came up with. Nice thing about it is that it should only scroll AppBarLayout if you have enough items in Adapter.

    final AppBarLayout layout = (AppBarLayout) findViewById(R.id.appbar);
    layout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
        @Override
        public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
            lastVerticalOffset = verticalOffset;
        }
    });
    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            if (tryCollapseAppbarOnNextScroll && lastVerticalOffset != -layout.getTotalScrollRange()) {
                layout.setExpanded(false);
                tryCollapseAppbarOnNextScroll = false;
            }
        }
    });

Now whenever you send a message, do this:

tryCollapseAppbarOnNextScroll = true;
recyclerView.smoothScrollToPosition(adapter.getItemCount()-1);