Scrollable Recycler view and view pager

Question

I have a screen where i need to display a toolbar at the top, a slideshow below the toolbar and a recyclerview below the slideshow. For displaying the slideshow I am using a viewPager which slides images horizontally.

The problem I am currently facing is that when the recyclerview is scrolled the viewPager needs to scroll with it and the toolbar should stay pinned.

I tried putting the viewPager and the recyclerview inside a nested Scroll but since a nested scroll requires a single child i had to put both the viewpager and recyclerview inside a linear layout because of which the scrolling behaviour of the recyclerview went for a toss ( i am monitoring the recyclerview scroll so i can load more results when it reaches the bottom ).

Answer 1

You can solve this problem by using CoordinatorLayout, AppBarLayout, and CollapsingToolbarLayout. You put your Toolbar and ViewPager in the CollapsingToolbarLayout, and you use the RecyclerView as the scrolling sibling to the AppBarLayout so that it can correctly collapse the ViewPager.

Here's some example XML I used to achieve what I think you described:

<android.support.design.widget.CoordinatorLayout
    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.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <android.support.v4.view.ViewPager
                android:layout_width="match_parent"
                android:layout_height="200dp"
                android:layout_marginTop="?attr/actionBarSize"/>

            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_collapseMode="pin"/>

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

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

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

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

The only tricky bit is that the <Toolbar> tag has to come after the <ViewPager> tag, since they're both inside a view that derives from FrameLayout. Normally, this would mean that the toolbar obscures the top portion of the viewpager, but the viewpager's marginTop attribute stops that from happening.