Your Activity works? I miss the code for onCreate()!

Please add an id for the BottomNavigationView e.g.:

<com.google.android.material.bottomnavigation.BottomNavigationView
    android_id="@+id/navigation"
    android_layout_width="match_parent"
    android_layout_height="wrap_content"
    android_layout_gravity="bottom"
    android_background="?android:attr/windowBackground"
    app_menu="@menu/navigation" />

In your Activity must be code like this. Is it there?

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    BottomNavigationView navigation = findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener( mOnNavigationItemSelectedListener);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
             // ... implement code here
        }
        return false;
    }

};

Edit: are the icons (e.g. ic_home_black_24dp, see picture) in the drawable folder and shown in Android Studio when displaying menu.xml?

i found the answer here:

Rendering Issue in Android Studio

seems it was a rendering issue with the theme and had to change to appcompat.

thank you

I’m trying to make a bottom Nav using android studio, but it will not display. if I add height to it, I can see the BG color but still no content of the menu items

EDIT:
its treating the menu xml as empty.

here is my code, ive also tried changing the layout to linear, frame and constraint:

    <?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_layout_width="match_parent"
        android_layout_height="match_parent"
        tools_context=".HomeScreen">



    <com.google.android.material.bottomnavigation.BottomNavigationView
        android_layout_width="match_parent"
        android_layout_height="wrap_content"
        app_menu="@menu/menu"
    android_layout_alignParentBottom="true"
        android_background="@color/btnSignUp"/>
    </RelativeLayout>

here is my menu item, its located in a menu folder

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns_android="http://schemas.android.com/apk/res/android">

    <item
        android_id="@+id/nav_home"
        android_icon="@drawable/ic_home_black_24dp"
        android_title="Home"
        />

    <item
        android_id="@+id/nav_search"
        android_icon="@drawable/ic_search_black_24dp"
        android_title="Search"
        />

    <item
        android_id="@+id/nav_orders"
        android_icon="@drawable/ic_receipt_black_24dp"
        android_title="Orders"
        />

    <item
        android_id="@+id/nav_account"
        android_icon="@drawable/ic_person_black_24dp"
        android_title="My Account"
        />

</menu>

and lastly my dependencies:

implementation 'com.github.jd-alexander:android-flat-button:1.1'

    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation 'com.google.firebase:firebase-auth:19.2.0'
    implementation 'com.google.firebase:firebase-firestore:21.4.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.google.firebase:firebase-analytics:17.2.2'
    implementation 'com.google.firebase:firebase-database:19.2.1'
    implementation 'com.rengwuxian.materialedittext:library:2.1.4'
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.squareup.picasso:picasso:2.5.2'
    implementation 'com.google.android.material:material:1.1.0'