Android Paging RecylerView as ViewPager (Horizontal Swipe of Fragment Pages)

May 4, 2019

Recycler View Paging

Setup

Set RecyclerView to horizontal scrolling
Use PagerSnapHelper to make sure each page/fragment is shown fully (no partial scroll)
Use CirclePagerIndicatorDecoration to display current page indicator
Use LayoutContainer to enable Kotlin Android Extensions ViewBinding for ViewHolder in RecyclerView

class TestPagerActivity : AppCompatActivity() {
    private lateinit var adapter: LocalAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // optional: hide title/actionbar
        supportActionBar?.hide()
        setContentView(R.layout.testpager)

        initUi()
    }

    private fun initUi() {
        adapter = LocalAdapter()
        list.adapter = adapter

        val snapHelper = PagerSnapHelper()
        snapHelper.attachToRecyclerView(list)

        list.addItemDecoration(CirclePagerIndicatorDecoration())
    }

    class LocalAdapter: RecyclerView.Adapter<LocalAdapter.ViewHolder>() {
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocalAdapter.ViewHolder {
            val view = LayoutInflater.from(parent.context)
                .inflate(R.layout.testpager_page, parent, false)
            return ViewHolder(view)
        }

        override fun onBindViewHolder(holder: LocalAdapter.ViewHolder, position: Int) {
            when(position) {
                0 -> {
                    holder.textView.text = "Page #1"
                }
                1 -> {
                    holder.textView.text = "Page #2"
                }
                2 -> {
                    holder.textView.text = "Page #3"
                }
            }
        }

        override fun getItemCount(): Int = 3

        inner class ViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView),
            LayoutContainer
    }
}

Layout

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

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        />
</RelativeLayout>

Modify adapter to support multiple layout.

class LocalAdapter(val viewModel: QuoteSetupViewModel, val fragmentManager: FragmentManager): RecyclerView.Adapter<LocalAdapter.ViewHolder>() {
    override fun getItemViewType(position: Int): Int {
        return when(position) {
            0 -> {
                R.layout.quotesetup_language
            }
            1 -> {
                R.layout.quotesetup_time
            }
            else -> {
                R.layout.testpager_page
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocalAdapter.ViewHolder {
        val view = LayoutInflater.from(parent.context)
            .inflate(viewType, parent, false)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: LocalAdapter.ViewHolder, position: Int) {
        when(position) {
            0 -> {
                // update holder view
            }
            1 -> {
                // update holder view
            }
            3 -> {
                // update holder view
            }
        }
    }

    override fun getItemCount(): Int = 3

    inner class ViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView),
        LayoutContainer
}

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