Android Fragment - How to create and adding fragments in activity in Android Studio using Kotlin

Last updated Dec 20, 2021

In this android example tutorial, we will see how to create a fragment and add to the activity in Android Studio by using Kotlin Language.

What is Fragments in Android?
Android Fragment is a type of activity that is also referred to as a sub-activity. An action may contain multiple fragments. Fragments are many screens contained within a single activity. Because fragments are included in activity, the lifecycle of an Android fragment is influenced by the lifecycle of an activity.

Lifecycle of Fragment:

Android Fragment Lifecycle Methods:

onAttach(Activity)	Called only once when it is attached with activity.
onCreate(Bundle)	Used to initialize the fragment.
onCreateView(LayoutInflater, ViewGroup, Bundle)	Creates and returns view hierarchy.
onActivityCreated(Bundle)	Invoked after the completion of onCreate() method.
onStart()	Makes the fragment visible.
onResume()	Makes the fragment interactive.
onPause()	Called when fragment is no longer interactive.
onStop()	Called when fragment is no longer visible.
onDestroyView()	Allows the fragment to clean up resources.
onDestroy()	Allows the fragment to do final clean up of fragment state.
onDetach()	Called immediately prior to the fragment no longer being associated with its activity.

Implementation:

Step 1: Create a new Project in android studio.

Go to File > New > New Project > Empty Activity > Next > Enter Name > Select Language Kotlin > Finish.

Step 2: Go to activity_main.xml file and add the following code

</RelativeLayout>

The screen ui will be like after adding above xml.

Step 3: Create a new package for fragments

app > java > com.example.fragment > right-click > new > package> Enter name (Fragment) > OK.

Step 4: Create a new fragment inside Fragment package

app > java > com.example.Fragment > Fragment > right-click > new > Fragment > Blank Fragment > enter name (HomeFragment) > FINISH.

By using same create one more fragment name SettingsFragment.

Your view of project be like:

Step 5: Open MainActivity.kt file and add the following code below setContentView(R.layout.activity_main).

val icHome = findViewById(R.id.ic_home)
val icSettings = findViewById(R.id.ic_settings)

replaceFragment(HomeFragment())

icHome.setOnClickListener {
replaceFragment(HomeFragment())

}
icSettings.setOnClickListener {
replaceFragment(SettingsFragment())

}
}

fun replaceFragment(fragment: Fragment) {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.frame, fragment)
transaction.commit()
}

At runtime, a FragmentManager can add, remove, replace, and perform other actions with fragments in response to user interaction. Each collection of fragment changes that you commit is referred to as a transaction, and you can specify what to do inside the transaction using the FragmentTransaction class's APIs. Many actions can be combined into a single transaction.
For example, a transaction can add or change multiple fragments.

You can get an instance of FragmentTransaction from the FragmentManager by calling beginTransaction(), as shown in the following example:

val transaction = supportFragmentManager.beginTransaction()

We use the replace method to replace the fragment with another fragment and activity & commit the fragment.

transaction.replace(R.id.frame, fragment)
transaction.commit()

Step 6: Open fragment_home.xml from res => layout folder and add the following.

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:background="#ABADBC"
tools:context=".Fragment.HomeFragment">

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Home" />

Step 7: HomeFragment.kt file be like:

class HomeFragment : Fragment() {

override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_home, container, false)
}
}

Step 8: Open fragment_settings.xml and add the following code:

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#B0B6D8"
tools:context=".Fragment.SettingsFragment">

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Settings" />

Step 9: SettingsFragment.kt file be like:

class SettingsFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_settings, container, false)
}
}

Step 10: Run the app on emulator or real device, you will get the output as given below

OUTPUT:

Complete Source Code of Fragments in Activity Example

activity_main.xml file

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

android:id="@+id/frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/navBottomBar">
android:id="@+id/navBottomBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="12dp"
android:padding="10dp"
android:layout_alignParentBottom="true"
>
android:id="@+id/ic_home"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1">
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:weightSum="2"
android:orientation="vertical">
android:layout_width="26dp"
android:layout_height="26dp"
android:background="@drawable/home"
android:layout_weight="1">
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="Home"
android:textStyle="bold"
android:textColor="@color/black"
android:layout_weight="1">

android:id="@+id/ic_settings"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1">
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:weightSum="2"
android:orientation="vertical">
android:layout_width="26dp"
android:layout_height="26dp"
android:background="@drawable/ic_baseline_settings_24"
android:backgroundTint="@color/black"
android:layout_weight="1">
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="Settings"
android:textStyle="bold"
android:textColor="@color/black"
android:layout_weight="1">

MainActivity.kt file

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.FrameLayout
import androidx.fragment.app.Fragment
import com.nishajain.fragmentskotlin.Fragment.HomeFragment
import com.nishajain.fragmentskotlin.Fragment.SettingsFragment

class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val icHome = findViewById(R.id.ic_home)
val icSettings = findViewById(R.id.ic_settings)

replaceFragment(HomeFragment())

icHome.setOnClickListener {
replaceFragment(HomeFragment())

}
icSettings.setOnClickListener {
replaceFragment(SettingsFragment())

}
}

fun replaceFragment(fragment: Fragment) {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.frame, fragment)
transaction.commit()
}
}

fragment_home.xml file

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Home" />

HomeFragment.kt file

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.nishajain.fragmentskotlin.R

class HomeFragment : Fragment() {

override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_home, container, false)
}
}

fragment_settings.xml file

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#B0B6D8"
tools:context=".Fragment.SettingsFragment">

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Settings" />

SettingsFragment.kt file

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.nishajain.fragmentskotlin.R

Conclusion : In this article we have covered how to create fragments and add to activity in Android Studio by using Kotlin Language.

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

MainActivity.kt file

replaceFragment(HomeFragment())

icHome.setOnClickListener {
replaceFragment(HomeFragment())

}
icSettings.setOnClickListener {
replaceFragment(SettingsFragment())

}
}

fun replaceFragment(fragment: Fragment) {
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.frame, fragment)
transaction.commit()
}
}

fragment_home.xml file

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Home" />

HomeFragment.kt file

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.nishajain.fragmentskotlin.R

class HomeFragment : Fragment() {

override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_home, container, false)
}
}

fragment_settings.xml file

xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#B0B6D8"
tools:context=".Fragment.SettingsFragment">

android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="30sp"
android:textColor="@color/black"
android:text="My Settings" />

SettingsFragment.kt file

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.nishajain.fragmentskotlin.R

Conclusion : In this article we have covered how to create fragments and add to activity in Android Studio by using Kotlin Language.

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