How to create Tab Layout in an Android App using Kotlin?

This example demonstrates how to create Tab Layout in an Android App using Kotlin.

Step 1 − Create a new project in Android Studio, go to File? New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

Example

<?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=".MainActivity">
<com.google.android.material.tabs.TabLayout
   android:id="@+id/tabLayout"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:background="#1db995">
</com.google.android.material.tabs.TabLayout>
<androidx.viewpager.widget.ViewPager
   android:id="@+id/viewPager"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_below="@id/tabLayout"
   android:layout_centerInParent="true"
   android:layout_marginTop="100dp"
   tools:layout_editor_absoluteX="8dp" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.viewpager.widget.ViewPager
import com.google.android.material.tabs.TabLayout
import com.google.android.material.tabs.TabLayout.OnTabSelectedListener
import com.google.android.material.tabs.TabLayout.TabLayoutOnPageChangeListener
class MainActivity : AppCompatActivity() {
   lateinit var tabLayout: TabLayout
   lateinit var viewPager: ViewPager
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      tabLayout = findViewById(R.id.tabLayout)
      viewPager = findViewById(R.id.viewPager)
      tabLayout.addTab(tabLayout.newTab().setText("Football"))
      tabLayout.addTab(tabLayout.newTab().setText("Cricket"))
      tabLayout.addTab(tabLayout.newTab().setText("NBA"))
      tabLayout.tabGravity = TabLayout.GRAVITY_FILL
      val adapter = MyAdapter(this, supportFragmentManager,
      tabLayout.tabCount)
      viewPager.adapter = adapter
      viewPager.addOnPageChangeListener(TabLayoutOnPageChangeListener(tabLayout))
      tabLayout.addOnTabSelectedListener(object : OnTabSelectedListener {
         override fun onTabSelected(tab: TabLayout.Tab) {
            viewPager.currentItem = tab.position
         }
         override fun onTabUnselected(tab: TabLayout.Tab) {}
         override fun onTabReselected(tab: TabLayout.Tab) {}
      })
   }
}

Step 4 − Create a new Adapter kotlin class (MyAdapter.kt) and add the following code −

import android.content.Context
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentManager
import androidx.fragment.app.FragmentPagerAdapter
@Suppress("DEPRECATION")
internal class MyAdapter(
   var context: Context,
   fm: FragmentManager,
   var totalTabs: Int
) :
FragmentPagerAdapter(fm) {
   override fun getItem(position: Int): Fragment {
      return when (position) {
         0 -> {
            Football()
         }
         1 -> {
            Cricket()
         }
         2 -> {
            NBA()
         }
         else -> getItem(position)
      }
   }
   override fun getCount(): Int {
      return totalTabs
   }
}

Step 5 − Create 3 Fragment activities (Cricket, Football, NBA - You can have your name) and the following code −

Cricket.kt

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
class Cricket : Fragment() {
   override fun onCreateView(
   inflater: LayoutInflater, container: ViewGroup?,
   savedInstanceState: Bundle?
   ): View? {
      // Inflate the layout for this fragment
      return inflater.inflate(R.layout.fragment_cricket, container, false)
   }
}

fragment_cricket.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".Cricket">
<!-- TODO: Update blank fragment layout -->
<TextView
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:text="Cricket Fragment"
   android:textAlignment="center"
   android:textSize="16sp"
   android:textStyle="bold" />
</FrameLayout>

Football.kt

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
class Football : Fragment() {
   override fun onCreateView(
   inflater: LayoutInflater, container: ViewGroup?,
   savedInstanceState: Bundle?
   ): View? {
      // Inflate the layout for this fragment
      return inflater.inflate(R.layout.fragment_football, container, false)
   }
}

fragment_footbal.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".Football">
<!-- TODO: Update blank fragment layout -->
<TextView
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:text="Football Fragment"
   android:textAlignment="center"
   android:textSize="16sp"
   android:textStyle="bold" />
</FrameLayout>

NBA.kt

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
class NBA : Fragment() {
   override fun onCreateView(
   inflater: LayoutInflater, container: ViewGroup?,
   savedInstanceState: Bundle?
   ): View? {
      // Inflate the layout for this fragment
      return inflater.inflate(R.layout.fragment_n_b_a, container, false)
   }
}

fragment_n_b_a.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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=".NBA">
<!-- TODO: Update blank fragment layout -->
<TextView
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:text="NBA Fragment"
   android:textAlignment="center"
   android:textSize="16sp"
   android:textStyle="bold" />
</FrameLayout>

Step 6 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen