Как визуализировать нижнюю панель навигации и ящик с фрагментами в android studio 3.6.1

Question

То, что я сделал: Я добавил навигационный ящик и нижнюю панель навигации, как показано ниже. xml и хотел работать с обоими. Но когда я пытаюсь запустить его, он говорит, что

Причина: java .lang.ClassCastException: android .widget.RelativeLayout не может быть приведен к androidx.drawerlayout.widget.DrawerLayout

main. xml:

    <?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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity"
    tools:openDrawer="start">


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

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/navigationView" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/navigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/colorAccent"
        app:itemBackground="?selectableItemBackgroundBorderless"
        app:itemHorizontalTranslationEnabled="true"
        app:itemIconTint="@drawable/nav_item_color_state"
        app:itemTextColor="@drawable/nav_item_color_state"
        app:menu="@menu/bottom_nav" />


    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_menu"

        />


</RelativeLayout>

основной вид деятельности:

    public class MainActivity extends AppCompatActivity {

   Toolbar toolbar;
   private DrawerLayout drawerLayout;


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

        toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);


        drawerLayout =  findViewById(R.id.drawer_layout);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle( this,drawerLayout,toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close );
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();

        //loadFragment(new HomeFragment());
        getSupportFragmentManager().beginTransaction().replace(R.id.container,new HomeFragment()).commit();

        BottomNavigationView navigation = findViewById(R.id.navigationView);
        navigation.setOnNavigationItemSelectedListener(navigationItemSelectedListener);

    }

     private  BottomNavigationView.OnNavigationItemSelectedListener navigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener() {
         @Override
         public boolean onNavigationItemSelected(@NonNull MenuItem item) {

             //swith bottom nav clicked
             Fragment selectedFragment = null;

             switch (item.getItemId()){
                 case R.id.home:
                     selectedFragment = new HomeFragment();
                     break;
                 case R.id.calander:
                     selectedFragment = new CalenderFragment();
                     break;
                 case R.id.notes:
                     selectedFragment = new NoteFragment();
                     break;
             }
             //this is to load fragemt
             getSupportFragmentManager().beginTransaction().replace(R.id.container,selectedFragment).commit();

             return true;
         }
     };

    @Override
    public void onBackPressed() {
        if(drawerLayout.isDrawerOpen(GravityCompat.START)){
            drawerLayout.closeDrawer(GravityCompat.START);
        }else{
            super.onBackPressed();
        }

    }
}

Затем я изменил выше это: Относительный макет был удален и заменен на «макет ящика», но теперь при компиляции ошибки нет, но я могу видеть только блок навигации в полноэкранном режиме, но не нижнюю панель навигации, панель инструментов или фрагмент.

отредактированный основной. xml:

<?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:context=".MainActivity"
    tools:openDrawer="start">

<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

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

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/navigationView" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/navigationView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/colorAccent"
        app:itemBackground="?selectableItemBackgroundBorderless"
        app:itemHorizontalTranslationEnabled="true"
        app:itemIconTint="@drawable/nav_item_color_state"
        app:itemTextColor="@drawable/nav_item_color_state"
        app:menu="@menu/bottom_nav" />

</RelativeLayout>

    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_menu"

        />


</androidx.drawerlayout.widget.DrawerLayout>

отредактированный основной вид деятельности:

public class MainActivity extends AppCompatActivity {

   Toolbar toolbar;
   private DrawerLayout drawerLayout;

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

        toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);


        drawerLayout =  findViewById(R.id.drawer_layout);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle( this,drawerLayout,toolbar,R.string.navigation_drawer_open,R.string.navigation_drawer_close );
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();

        //loadFragment(new HomeFragment());
        getSupportFragmentManager().beginTransaction().replace(R.id.container,new HomeFragment()).commit();

        BottomNavigationView navigation = findViewById(R.id.navigationView);
        navigation.setOnNavigationItemSelectedListener(navigationItemSelectedListener);

    }

     private  BottomNavigationView.OnNavigationItemSelectedListener navigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener() {
         @Override
         public boolean onNavigationItemSelected(@NonNull MenuItem item) {

             //swith bottom nav clicked
             Fragment selectedFragment = null;

             switch (item.getItemId()){
                 case R.id.home:
                     selectedFragment = new HomeFragment();
                     break;

                 case R.id.calander:
                     selectedFragment = new CalenderFragment();
                     break;
                 case R.id.notes:
                     selectedFragment = new NoteFragment();
                     break;
             }
             //this is to load fragemt
             getSupportFragmentManager().beginTransaction().replace(R.id.container,selectedFragment).commit();

             return true;
         }
     };

    /*
    this is to load fragemt
     */
    /*
    private void loadFragment (Fragment fragment){
        //load fragment
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.container,fragment);
        transaction.addToBackStack(null);
        transaction.commit();
    }

     */

    @Override
    public void onBackPressed() {
        if(drawerLayout.isDrawerOpen(GravityCompat.START)){
            drawerLayout.closeDrawer(GravityCompat.START);
        }else{
            super.onBackPressed();
        }

    }
}

Буду очень признателен за любые предложения по улучшению этого. Спасибо!