Navigation Component (Java)

The Navigation Component replaces manual FragmentTransaction code with a declarative nav graph, a NavHostFragment container, and a NavController that handles back stack, transitions, and Up behavior. With Safe Args you also get type-safe argument passing in Java.

Why Use It?

Setup (Gradle)

// Project build.gradle (settings may vary)
buildscript {
  dependencies {
    classpath 'androidx.navigation:navigation-safe-args-gradle-plugin:2.7.7'
  }
}

// Module: app/build.gradle
plugins {
  id 'com.android.application'
  id 'androidx.navigation.safeargs'     // Java Safe Args
}
dependencies {
  implementation 'androidx.navigation:navigation-fragment:2.7.7'
  implementation 'androidx.navigation:navigation-ui:2.7.7'
  implementation 'com.google.android.material:material:1.12.0'
}

Create the Nav Host

Add a NavHostFragment container (usually in your Activity layout). It swaps in/out destination fragments.

<!-- res/layout/activity_main.xml -->
<androidx.fragment.app.FragmentContainerView
    android:id="@+id/nav_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:navGraph="@navigation/nav_graph"
    app:defaultNavHost="true" />

Build the Navigation Graph

<!-- res/navigation/nav_graph.xml -->
<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/firstFragment">

  <fragment
      android:id="@+id/firstFragment"
      android:name="com.example.FirstFragment"
      android:label="First">

    <!-- Type-safe argument for destination -->
    <argument android:name="userName"
               app:argType="string"
               android:defaultValue="Guest"/>

    <!-- Action to navigate to SecondFragment -->
    <action
        android:id="@+id/action_first_to_second"
        app:destination="@id/secondFragment"
        app:popUpTo="@id/firstFragment"
        app:popUpToInclusive="false" />

  </fragment>

  <fragment
      android:id="@+id/secondFragment"
      android:name="com.example.SecondFragment"
      android:label="Second" />

</navigation>

MainActivity: App Bar + Up Button

// MainActivity.java
public class MainActivity extends AppCompatActivity {
  private AppBarConfiguration appBarConfiguration;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Toolbar toolbar = findViewById(R.id.toolbar); // if using a Toolbar
    setSupportActionBar(toolbar);

    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    appBarConfiguration = new AppBarConfiguration.Builder(navController.getGraph()).build();
    NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
  }

  @Override
  public boolean onSupportNavigateUp() {
    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    return NavigationUI.navigateUp(navController, appBarConfiguration) || super.onSupportNavigateUp();
  }
}

Navigating in Java (with Safe Args)

Inside FirstFragment, create a click listener that navigates to SecondFragment with a typed argument.

// FirstFragment.java
NavController nav = NavHostFragment.findNavController(this);

// Using generated Directions class:
FirstFragmentDirections.ActionFirstToSecond action =
        FirstFragmentDirections.actionFirstToSecond();
action.setUserName("Sonu");
nav.navigate(action);

In SecondFragment, read the argument safely:

// SecondFragment.java
SecondFragmentArgs args = SecondFragmentArgs.fromBundle(getArguments());
String name = args.getUserName(); // "Sonu"

NavigationUI with BottomNavigationView

Hook your bottom nav to the controller and declare top-level destinations (no Up arrow among them).

<!-- res/layout/activity_main.xml (excerpt) -->
<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/bottom_nav"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:menu="@menu/menu_bottom" />

// MainActivity.java (after navController creation)
BottomNavigationView bottom = findViewById(R.id.bottom_nav);
NavigationUI.setupWithNavController(bottom, navController);

appBarConfiguration = new AppBarConfiguration.Builder(
        R.id.homeFragment, R.id.searchFragment, R.id.profileFragment  // top-level IDs
).build();

Deep Links

Open screens via URLs/intent filters. Add a deep link to a destination:

<!-- In nav_graph destination -->
<deepLink app:uri="https://codingwithsonu.com/user/{userId}" />

And in the manifest for NavHostActivity (your activity):

<activity android:name=".MainActivity"
          android:exported="true">
  <nav-graph android:value="@navigation/nav_graph" />
  <intent-filter>
    <action android:name="android.intent.action.VIEW" />
    <category android:name="android.intent.category.DEFAULT" />
    <category android:name="android.intent.category.BROWSABLE" />
    <data android:scheme="https"
          android:host="codingwithsonu.com" />
  </intent-filter>
</activity>

Pop Behavior & Back Stack Control

Property / Flag	Effect	When to Use
popUpTo	Pop stack up to a destination	Clear intermediate screens
popUpToInclusive	Include the target in the pop	Reset to root/home
app:launchSingleTop	Avoid multiple copies on top	Idempotent navigations

Custom Animations (optional)

<action ...
    app:enterAnim="@anim/slide_in_right"
    app:exitAnim="@anim/slide_out_left"
    app:popEnterAnim="@anim/slide_in_left"
    app:popExitAnim="@anim/slide_out_right" />

Manual Transactions vs Navigation

Aspect	Manual FragmentTransaction	Navigation Component
Back stack	Dev must manage	Managed by graph/controller
Args	Bundles (unsafe types)	Safe Args (generated classes)
Deep links	Manual parsing	Built-in destinations
Up button	Manual	NavigationUI handles
Transitions	Manual anim logic	Per-action attributes

Dialog Destinations

You can add a <dialog> destination (DialogFragment) in the graph and navigate to it like any other destination.

Troubleshooting

Hands-On Exercise

1. Create FirstFragment and SecondFragment with an action and an argument (userName).
2. Navigate via a button in First; show the name in Second using SecondFragmentArgs.
3. Add a third fragment and use popUpTo to clear intermediate screens.
4. Attach a BottomNavigationView to 3 top-level fragments via NavigationUI.