In this android kotlin source code example, we are going to create a nested graph with Android Component Navigation in Kotlin.
You can copy and adopt this source code example to your Kotlin android project without reinventing the wheel.
Below is a step by step source code to create a nested graph with Android Component Navigation in Kotlin.
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
tools:context=".Navigation.NavigationActivity12">
<fragment
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph12"/>
</androidx.constraintlayout.widget.ConstraintLayout>
navigation/nav_graph12.xml
<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/nav_graph12"
app:startDestination="@id/navFragment12">
<fragment
android:id="@+id/navFragment12"
android:name="com.bluapp.kotlinview.Navigation.NavFragment12"
android:label="@string/app_name"
tools:layout="@layout/fragment_nav_fragment12">
<action
android:id="@+id/navFragment12tonav_graph121"
app:destination="@id/nav_graph121"/>
</fragment>
<navigation
android:id="@+id/nav_graph121"
app:startDestination="@id/navFragment121">
<fragment
android:id="@+id/navFragment121"
android:name="com.bluapp.kotlinview.Navigation.NavFragment121"
android:label="@string/app_name"
tools:layout="@layout/fragment_nav_fragment121">
<action
android:id="@+id/navFragment121tonavFragment122"
app:destination="@id/navFragment122"/>
</fragment>
<fragment
android:id="@+id/navFragment122"
android:name="com.bluapp.kotlinview.Navigation.NavFragment"
android:label="@string/app_name"
tools:layout="@layout/fragment_nav" />
</navigation>
</navigation>
MainActivity.kt
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.bluapp.kotlinview.R
class NavigationActivity12 : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_navigation12)
}
}
fragment_nav_fragment12.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/constraintlayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Navigation.NavFragment12">
<androidx.appcompat.widget.AppCompatButton
android:id="@+id/startBtn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Start Nested Graph"
android:background="@color/colorAccent"
android:textColor="#ffffff"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
NavFragment12.kt
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.appcompat.widget.AppCompatButton
import androidx.navigation.Navigation
import com.bluapp.kotlinview.R
class NavFragment12 : Fragment() {
private var startBtn: AppCompatButton? = null
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_nav_fragment12, container, false)
startBtn = view.findViewById(R.id.startBtn) as AppCompatButton
startBtn!!.setOnClickListener {
Navigation.findNavController(view).navigate(R.id.navFragment12tonav_graph121);
}
return view
}
}
fragment_nav_fragment121.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/constraintlayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Navigation.NavFragment121">
<androidx.appcompat.widget.AppCompatButton
android:id="@+id/startBtn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Start Fragment"
android:background="@color/colorAccent"
android:textColor="#ffffff"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
NavFragment121.kt
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.appcompat.widget.AppCompatButton
import androidx.navigation.Navigation
import com.bluapp.kotlinview.R
class NavFragment121 : Fragment() {
private var startBtn: AppCompatButton? = null
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_nav_fragment121, container, false)
startBtn = view.findViewById(R.id.startBtn) as AppCompatButton
startBtn!!.setOnClickListener {
Navigation.findNavController(view).navigate(R.id.navFragment121tonavFragment122);
}
return view
}
}
fragment_nav.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
tools:context=".Navigation.NavFragment">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NavFragment"
android:textSize="20sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
NavFragment.kt
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import com.bluapp.kotlinview.R
class NavFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_nav, container, false)
}
}
app/build.gradle
implementation 'androidx.navigation:navigation-fragment:2.1.0'
implementation 'androidx.navigation:navigation-ui:2.1.0'
implementation 'androidx.navigation:navigation-fragment-ktx:2.1.0'
implementation 'androidx.navigation:navigation-ui-ktx:2.1.0'
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