CircularViewPager

A circular ViewPager example using the new ViewPager2

In this example, will be building a single activity app with ViewPager2 and a FragmentPagerAdapter supporting circular navigation between 3 pages or more.

I'm using an beta version(1.0.0-beta05) of the library androidx.viewpager2:viewpager2.

1. Add the ViewPager2 library to the dependencies in your build.gradle

dependencies {
    implementation 'androidx.viewpager2:viewpager2:1.0.0-beta05'
}

2. Add the ViewPager2 view to your project:

<androidx.viewpager2.widget.ViewPager2 xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/vwpHome"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

3. Create the FragmentStateAdapter adapter:

getItemCount() needs to returns a huuuuge number. (2147483647)

getCenterPage() returns the central page based on the huuuuge number. This method is used to get the position of the initial page to set in the ViewPager2, in this case the user needs to swipe ˜1073741823 time to reach the end of the ViewPager2.

class CircularPagerAdapter(fragmentManager: FragmentManager, lifecycle: Lifecycle) : FragmentStateAdapter(fragmentManager, lifecycle) {

    override fun getItemCount() = Integer.MAX_VALUE

    /**
     * Create the fragment based on the position
     */
    override fun createFragment(position: Int) = HomePagerScreens.values()[position % HomePagerScreens.values().size].fragment.java.newInstance()

    /**
     * Returns the same id for the same Fragment.
     */
    override fun getItemId(position: Int): Long = (position % HomePagerScreens.values().size).toLong()

    fun getCenterPage(position: Int = 0) = Integer.MAX_VALUE / 2 + position
}

4. Set the adapter to the ViewPager

val circularAdapter = CircularPagerAdapter(supportFragmentManager, lifecycle)
vwpHome.apply {
    adapter = circularAdapter
    setCurrentItem(circularAdapter.getCenterPage(), false)
}