package com.example.navigationdemo
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
}
// MainFragment.kt
package com.example.navigationdemo
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.navigation.fragment.findNavController
import com.example.navigationdemo.databinding.FragmentMainBinding
class MainFragment : Fragment() {
private var _binding: FragmentMainBinding? = null
private val binding get() = _binding!!
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
_binding = FragmentMainBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.buttonGoSecond.setOnClickListener {
findNavController().navigate(R.id.action_mainFragment_to_secondFragment)
}
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
// SecondFragment.kt
package com.example.navigationdemo
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.navigation.fragment.findNavController
import com.example.navigationdemo.databinding.FragmentSecondBinding
class SecondFragment : Fragment() {
private var _binding: FragmentSecondBinding? = null
private val binding get() = _binding!!
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
_binding = FragmentSecondBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.buttonBackMain.setOnClickListener {
findNavController().navigate(R.id.action_secondFragment_to_mainFragment)
}
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
// 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=".MainActivity">
<fragment
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:navGraph="@navigation/nav_graph"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
// nav_graph.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"
android:id="@+id/nav_graph"
app:startDestination="@id/mainFragment">
<fragment
android:id="@+id/mainFragment"
android:name="com.example.navigationdemo.MainFragment"
android:label="Main Screen">
<action
android:id="@+id/action_mainFragment_to_secondFragment"
app:destination="@id/secondFragment" />
</fragment>
<fragment
android:id="@+id/secondFragment"
android:name="com.example.navigationdemo.SecondFragment"
android:label="Second Screen">
<action
android:id="@+id/action_secondFragment_to_mainFragment"
app:destination="@id/mainFragment" />
</fragment>
</navigation>
// fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<Button
android:id="@+id/buttonGoSecond"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go to Second" />
</FrameLayout>
// fragment_second.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<Button
android:id="@+id/buttonBackMain"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Back to Main" />
</FrameLayout>This solution sets up the Android Navigation Component with two fragments: MainFragment and SecondFragment.
The activity_main.xml contains a NavHostFragment which hosts the navigation graph defined in nav_graph.xml. This graph defines the two fragments and the actions to navigate between them.
Each fragment has a simple layout with a button. In MainFragment, the button navigates to SecondFragment using findNavController().navigate(). In SecondFragment, the button navigates back to MainFragment.
View binding is used for safe and easy access to views.
This setup follows Android best practices for navigation and keeps UI and navigation logic clean and simple.
