[Android] RecyclerView animated transition between Grid and List layouts.

If you have a RecyclerView that can display data both in a grid and a list you may think about making transition between them animated. And this article shows how to achieve this easily 🙂.

Sample example. You can find link to whole project on GitHub at the end of the article.

1. Assuming that you already have RecyclerView your layout should look something like this:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
    tools:context=".MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

2. First of all we need to initialise GridLayoutManager for our RecyclerView. I have initialisation code in onCreate() function of my activity.

class MainActivity : AppCompatActivity() {

    private var layoutManager: GridLayoutManager? = null
    ...

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        layoutManager = GridLayoutManager(this, 3)
        recyclerView.layoutManager = layoutManager
        ...
    }

    ...
}

3. The next step is to create adapter. I’ve written `SimpleAdapter` class that has link to layoutManager of our recycler view.

class SimpleAdapter(
        private val layoutManager: GridLayoutManager? = null
) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    ...
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return ...
    }

    override fun onBindViewHolder(p0: RecyclerView.ViewHolder, p1: Int) {
    }

    override fun getItemCount() = 5

    override fun getItemViewType(position: Int): Int {
        ...
    }
}

And attach it to RecyclerView in onCreate() of activity. Now it should look like this:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    layoutManager = GridLayoutManager(this, 3)
    recyclerView.layoutManager = layoutManager
    adapter = SimpleAdapter(layoutManager)
    recyclerView.adapter = adapter
}

4. The last but not the least step — create 2 view holders for different modes.

and

Layout for simple_item.xml :

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="110dp"
    android:layout_height="144dp"
    android:layout_margin="8dp"
    android:background="@color/colorPrimaryDark" />

Layout for detailed_item.xml :

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="144dp"
    android:layout_margin="8dp"
    android:background="@color/colorPrimaryDark" />

We’ve finished with the preparatory work and now the magic begins✨

To make recycler view animated we need to change the spanCount in our layout manager and call adapter.notifyItemRangeChanged() for all adapter items. I have button in menu so my code to handle layout changes looks like this:

override fun onOptionsItemSelected(item: MenuItem?): Boolean {
    when (item?.itemId) {
        R.id.change_layout -> {
            if (layoutManager?.spanCount == 1) {
                layoutManager?.spanCount = 3
                item.title = "list"
            } else {
                layoutManager?.spanCount = 1
                item.title = "grid"
            }
            adapter?.notifyItemRangeChanged(0, adapter?.itemCount ?: 0)
        }
    }
    return super.onOptionsItemSelected(item)
}

And in adapter create the different view holders depending on mode:

Voila! You have animated transition between grid and list modes in recycler view 😀.

The whole project can be found here — https://github.com/alla-dubovska/animation-example