Main Activity does not have a NavController

Question

During one of the launches of the application, log issued such a stack of errors:

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.nikitafront.schooldiary, PID: 29751
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nikitafront.schooldiary/com.nikitafront.schooldiary.MainActivity}: java.lang.IllegalStateException: Activity com.nikitafront.schooldiary.MainActivity@4801345 does not have a NavController set on 2131296534
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3754)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3912)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2319)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:239)
    at android.app.ActivityThread.main(ActivityThread.java:8205)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:626)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1016)
 Caused by: java.lang.IllegalStateException: Activity com.nikitafront.schooldiary.MainActivity@4801345 does not have a NavController set on 2131296534
    at androidx.navigation.Navigation.findNavController(Navigation.java:61)
    at com.nikitafront.schooldiary.MainActivity.onCreate(MainActivity.java:53)
    at android.app.Activity.performCreate(Activity.java:8119)
    at android.app.Activity.performCreate(Activity.java:8103)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1359)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3727)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3912) 
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2319) 
    at android.os.Handler.dispatchMessage(Handler.java:106) 
    at android.os.Looper.loop(Looper.java:239) 
    at android.app.ActivityThread.main(ActivityThread.java:8205) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:626) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1016) 

Before this I was only experimenting with app themes, but after I returned everything to its original state nothing has changed

P.S. I tried solve the problem by clearing the cache and restart IDE, but this way doesn`t worked too.

MainActivity.java code

package com.nikitafront.schooldiary;

import android.content.res.Configuration;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.CheckBox;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.Spinner;

import com.google.android.material.bottomnavigation.BottomNavigationView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.fragment.NavHostFragment;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;

import com.nikitafront.schooldiary.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {

private ActivityMainBinding binding;
private CheckBox checkBoxAuto;
private Spinner dropDownList;
private LinearLayout byHandLesson;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    binding = ActivityMainBinding.inflate(getLayoutInflater());
    setContentView(binding.getRoot());

    BottomNavigationView navView = findViewById(R.id.nav_view);
    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
            R.id.nav_write, R.id.nav_do, R.id.nav_account)
            .build();


    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_activity_main);
    NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
    NavigationUI.setupWithNavController(binding.navView, navController);


    checkBoxAuto = (CheckBox) findViewById(R.id.checkBoxAuto);
    dropDownList = (Spinner) findViewById(R.id.dropDownListLesson);
    byHandLesson = (LinearLayout) findViewById(R.id.byHandLesson);

}

@Override
protected void onStart() {
    super.onStart();
    checkBoxAuto.setOnClickListener(this::selectFillLesson);

    int currentNightMode = getApplicationContext().getResources().getConfiguration().uiMode & Configuration.UI_MODE_NIGHT_MASK;

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && currentNightMode == Configuration.UI_MODE_NIGHT_YES) {
        getWindow().setNavigationBarColor(ContextCompat.getColor(this, R.color.my_black));
    }
}

public void selectFillLesson(View view) {
    if (checkBoxAuto.isChecked()) {
        byHandLesson.setAlpha((float) 0.7);
    } else {
        byHandLesson.setAlpha((float) 1);
    }
    dropDownList.setEnabled(!(checkBoxAuto.isChecked()));
}

public void selectCheckBox(View view) {
    checkBoxAuto.setChecked(!checkBoxAuto.isChecked());
    selectFillLesson(checkBoxAuto);
}

public void addHomework(View view) {

}
}

main_activity.xml code

<?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"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/nav_view"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:menu="@menu/bottom_nav_menu" />

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/nav_host_fragment_activity_main"
    android:name="androidx.navigation.fragment.NavHostFragment"
    class="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true"
    app:layout_constraintBottom_toTopOf="@id/nav_view"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:navGraph="@navigation/mobile_navigation" />

</androidx.constraintlayout.widget.ConstraintLayout>

Manifest.xml code

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.nikitafront.schooldiary">

<application
    android:allowBackup="true"
    android:icon="@drawable/homework_icon"
    android:label="@string/app_name"
    android:roundIcon="@drawable/homework_icon"
    android:supportsRtl="true"
    android:theme="@style/Theme.SchoolDiary">
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

Answer 1

Navigating to a destination is done using a NavController, an object that manages app navigation within a NavHost. Each NavHost has its own corresponding NavController.

Write your code like below:

Kotlin

val bottomNavigationView = findViewById<BottomNavigationView>(R.id.nav_view)
val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment_activity_main) as NavHostFragment
bottomNavigationView.setupWithNavController(navHostFragment.navController)

Java

BottomNavigationView bottomNavigationView = findViewById<BottomNavigationView>(R.id.nav_view);
NavHostFragment navHostFragment = (NavHostFragment) supportFragmentManager.findFragmentById(R.id.nav_host_fragment_activity_main);
bottomNavigationView.setupWithNavController(navHostFragment.navController);

Answer 2

As it was described in the reference:

When creating the NavHostFragment using FragmentContainerView or if manually adding the NavHostFragment to your activity via a FragmentTransaction, attempting to retrieve the NavController in onCreate() of an Activity via Navigation.findNavController(Activity, @IdRes int) will fail. You should retrieve the NavController directly from the NavHostFragment instead.

Looks like you should use

NavHostFragment navHostFragment =
        (NavHostFragment) supportFragmentManager.findFragmentById(R.id.nav_host_fragment);
NavController navController = navHostFragment.getNavController();

instead of

 NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_activity_main);