Learn How To Create Tabs With ViewPager2

Learn How To Create Tabs With ViewPager2

If you are here that means you already know what you want. So, in this post we are going to learn about how to create tabs using the new ViewPager2 library. Let’s begin

First you have to create a simple project, and I hope you have it set-up at this point. Let me show you the example project structure which we will follow.

NOTE: I have intentionally left out the view mapping part in this post.

As you can see in the image below you can see four classes in total,but what are they ? There are exactly 2 fragments viz. SimpleItemFragment and Vp2Fragment and we have an adapter Vp2Adapter with a MainActivity.

our example project structure

Next up, we are going to prepare our layouts, which right here is nothing fancy. It is just painfully minimal for the sake of mere demonstration.

The layout of our MainActivity is

<?xml version="1.0" encoding="utf-8"?> <LinearLayout 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" android:orientation="vertical" tools:context=".MainActivity"> <FrameLayout android:id="@+id/container" android:layout_width="match_parent" android:layout_height="match_parent" /> </LinearLayout>

And SimpleItemFragment‘s layout as

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".vp2.SimpleItemFragment"> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_centerInParent="true" android:text="@string/app_name" android:textAlignment="center" /> </RelativeLayout>

Finally, the layout for Vp2Fragment is

<?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" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".vp2.Vp2Fragment"> <com.google.android.material.tabs.TabLayout android:id="@+id/tab_layout" android:layout_width="match_parent" android:layout_height="wrap_content" /> <androidx.viewpager2.widget.ViewPager2 android:id="@+id/view_pager" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_below="@id/tab_layout" /> </RelativeLayout>

Here in the code above we have TabLayout which belongs to com.google.android.material.tabs which you might have not already in your project. Let us see how we can include our dependencies.

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TECHENUM

INCLUDING THE ViewPager2 DEPENDENCY

There is not really much to do when it comes to including the dependency. Just add the code below in dependencies { } block of app > build.gradle and you’re all set after a gradle sync.

implementation 'androidx.viewpager2:viewpager2:1.0.0' implementation 'com.google.android.material:material:1.2.0'

Now we are are en route to learn how to create tabs with ViewPager2.

SETTING UP THE ADAPTER FOR ViewPager2

Now here lies the groundbreaking change in the new library. Before we used to use the FragmentStatePagerAdapter or something similar for ViewPager.

But for ViewPager2 we will be using FragmentStateAdapter which itself is a child of RecyclerView.Adapter.

Look at the code below first

class Vp2Adapter(fragment: Fragment) : FragmentStateAdapter(fragment) { override fun getItemCount(): Int { return 5 } override fun createFragment(position: Int): Fragment { return SimpleItemFragment.newInstance() } }

We will creating a new instance of the fragment for each tabs on createFragment() here modify it as you like.

And, we must return the total number of tabs in getItemCount().

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TECHENUM

COMBINING EVERYTHING

First, we have to map the views to our fragment Vp2Fragment. After that, we have to instantiate the adapter. And then we have to link the Vp2Adapter with TabLayout.

Let use look at the adapter setup part before we see our final code.

TabLayoutMediator( mTabLayout, mViewPager ) { tab, position -> // let us just name it Tab 1 to 5 ; modify it as your need tab.text = "Tab #${position + 1}" }.attach()

The TabLayoutMediator takes in three parameters TabLayout, ViewPager2 and the Behaviour. The code outside object in braces is the final parameter. It’s just cleaner way of passing things around.

Let us look at our full code:

class Vp2Fragment : Fragment() { companion object { fun newInstance() = Vp2Fragment() } private lateinit var mViewPager: ViewPager2 private lateinit var mTabLayout: TabLayout private lateinit var mAdapter: Vp2Adapter override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle? ): View? { return inflater.inflate(R.layout.vp2_fragment, container, false) } override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) mAdapter = Vp2Adapter(this) mTabLayout = view.findViewById(R.id.tab_layout) mViewPager = view.findViewById(R.id.view_pager) mViewPager.adapter = mAdapter TabLayoutMediator( mTabLayout, mViewPager ) { tab, position -> tab.text = "Tab #${position + 1}" }.attach() } }

Now all we have to do in our MainActivity is add the fragment:

class MainActivity : FragmentActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) supportFragmentManager.beginTransaction() .replace(R.id.container, Vp2Fragment.newInstance()) .commit() } }

In the code above the R.id.container is the name of the container where the fragment will be put. And it is located in activity_main.xml

That’s it folks we have successfully learn to create tabs with ViewPager2. Feel free to comment if I have missed anything.

For reference you can check out Android Documentation.

Naveen Niraula

An Android developer with passion for latest technologies. Likes to learn and share the findings and techniques. Also shows keen interest in networking.

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