Tablayout tab icons are not appearing on runtime ?

    <?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tablayout_main"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:layout_margin="0dp"
        android:background="@color/teal_200"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <com.google.android.material.tabs.TabItem
            android:id="@+id/Scan_Tab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:icon="@drawable/scan_icon"
            android:text="Scan" />

        <com.google.android.material.tabs.TabItem
            android:id="@+id/History_Tab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:icon="@drawable/history_icon"
            android:text="History" />

        <com.google.android.material.tabs.TabItem
            android:id="@+id/Setting_Tab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:icon="@drawable/setting_icon"
            android:text="Settings" />


    </com.google.android.material.tabs.TabLayout>

    <androidx.viewpager2.widget.ViewPager2
        android:layout_margin="0dp"
        android:id="@+id/viewPager2"
        android:layout_width="match_parent"
        android:layout_height="488dp"
        app:layout_constraintBottom_toTopOf="@+id/Banner_adView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/tablayout_main"
        app:layout_constraintVertical_bias="0.365" />

    <com.google.android.gms.ads.AdView
        android:layout_margin="0dp"
        android:id="@+id/Banner_adView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        app:adSize="FULL_BANNER"
        app:adUnitId="@string/BANNER_AD_ID"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

    </com.google.android.gms.ads.AdView>


</androidx.constraintlayout.widget.ConstraintLayout>

// NOTE : Using the Fake AdUnit ID & APP ID for now. Change it when publishing to play store.
    
    public class MainActivity extends AppCompatActivity {
    
        private AdView mAdView;
        TabLayout tabLayout_main;
        ViewPager2 viewPager2;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            // Google Admob Method
            MobileAds.initialize(this, new OnInitializationCompleteListener() {
                @Override
                public void onInitializationComplete(InitializationStatus initializationStatus) {
                }
            });
    
            init();
            setBannerAd();
    
        }
    
        private void init(){
    
            tabLayout_main = findViewById(R.id.tablayout_main);
            viewPager2 = findViewById(R.id.viewPager2);
    
            // setting adapter to viewpager2
            pagerAdapter adapter = new pagerAdapter(this);
            viewPager2.setAdapter(adapter);
    
            // connecting tablayout tabs with viewpager2
            new TabLayoutMediator(tabLayout_main, viewPager2, (tab, position) -> {
                String[] tab_names = {"SCAN","HISTORY","SETTING"};
                tab.setText(tab_names[position]);
            }).attach();
    
    
        }
    
        private void setBannerAd() {
    
            // Loading MainActivity BannerAd
            mAdView = findViewById(R.id.Banner_adView);
            AdRequest adRequest1 = new AdRequest.Builder().build();
            mAdView.loadAd(adRequest1);
    
            // MainActivity BannerAd listener
            mAdView.setAdListener(new AdListener() {
                @Override
                public void onAdLoaded() {
                    // Code to be executed when an ad finishes loading.
    
                    super.onAdLoaded();
                }
    
                @Override
                public void onAdFailedToLoad(LoadAdError adError) {
                    // Code to be executed when an ad request fails.
    
                    super.onAdFailedToLoad(adError);
    
                    // Try again to load the ad
                    mAdView.loadAd(adRequest1);
                }
    
                @Override
                public void onAdOpened() {
                    // Code to be executed when an ad opens an overlay that
                    // covers the screen.
    
                    super.onAdOpened();
                }
    
                @Override
                public void onAdClicked() {
                    // Code to be executed when the user clicks on an ad.
                    super.onAdClicked();
                }
    
                @Override
                public void onAdClosed() {
                    // Code to be executed when the user is about to return
                    // to the app after tapping on an ad.
                    super.onAdClosed();
                }
            });
        }
    
    
    }