Error coming when trying to change fragment from bottom navigation bar

Question

public class home_fragment extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    private AppBarConfiguration mAppBarConfiguration;
    private DrawerLayout drawer;
    private ImageView profilepic;
    private DatabaseReference mDatabaseRef;
    private FirebaseAuth mAuth;
    private StorageReference storageReference;
    FirebaseUser firebaseUser;

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.navi_home:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,new com.example.docsapp.HomeFragment()).commit();
                    break;
                case R.id.navi_favourites:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,new FavouriteFragment()).commit();
                    break;
                case R.id.navi_search:
                    getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,new SearchFragment()).commit();
                    break;
            }
            return true;
        }

    };

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

        mAuth=FirebaseAuth.getInstance();
        firebaseUser = mAuth.getCurrentUser();

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer,toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();


        try {
            BottomNavigationView navigation =  findViewById(R.id.nav_view);
            navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
        }catch (Exception e){
            FancyToast.makeText(getApplicationContext(),e.getMessage(),FancyToast.LENGTH_LONG,FancyToast.ERROR,true).show();
        }


        if (savedInstanceState==null){
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new HomeFragment()).commit();
            try {
                getSupportFragmentManager().beginTransaction().replace(R.id.nav_host_fragment,new com.example.docsapp.HomeFragment()).commit();
            }catch (Exception e){
                FancyToast.makeText(getApplicationContext(),e.getMessage(),FancyToast.LENGTH_LONG,FancyToast.ERROR,true).show();
            }

        }

        UpdateNavHeader();

    }

Below is the code of activity_home

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">



    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <androidx.appcompat.widget.Toolbar
            android:layout_width="match_parent"
            android:layout_height="?android:actionBarSize"
            android:background="@color/colorPrimary"
            android:id="@+id/toolbar"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            android:elevation="4dp"/>
        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/fragment_container"/>

    </LinearLayout>

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_home"
        app:menu="@menu/drawer_menu" />

</androidx.drawerlayout.widget.DrawerLayout>

Below is the code of home_fragment

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/navi_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/windowBackground"
        app:menu="@menu/bottom_nav_menu"
        android:layout_alignParentBottom="true"/>

    <include
        android:id="@+id/nav_host_fragment"
        layout="@layout/fragment_home"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="8dp" />

</RelativeLayout>

I am trying to open a fragment from a fragment.The fragment im trying to open is showing error.The home fragment consists of a navigation drawer as well as bottom navigation.
I am trying to open a fragment from a fragment.The fragment im trying to open is showing error.The home fragment consists of a navigation drawer as well as bottom navigation.

Error shown while runtime is shown here .

Answer 1

your mistake is in findViewById :

 NavigationView navigationView = findViewById(R.id.nav_view); \\ These lines are same
        navigationView.setNavigationItemSelectedListener(this);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer,toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();


        try {
            BottomNavigationView navigation =  findViewById(R.id.nav_view); \\  These lines are same
.
.
.

try to edit your layouts:

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout 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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">



    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <androidx.appcompat.widget.Toolbar
            android:layout_width="match_parent"
            android:layout_height="?android:actionBarSize"
            android:background="@color/colorPrimary"
            android:id="@+id/toolbar"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            android:elevation="4dp"/>
        <FrameLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/fragment_container"/>

    </LinearLayout>

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_home"
        app:menu="@menu/drawer_menu" />

     <include \\ this line
        layout="@layout/home_fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.drawerlayout.widget.DrawerLayout>