Implementing banner ads in Android

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;

import com.unity3d.ads.IUnityAdsInitializationListener;
import com.unity3d.ads.UnityAds;
import com.unity3d.services.banners.BannerErrorInfo;
import com.unity3d.services.banners.BannerView;
import com.unity3d.services.banners.UnityBannerSize;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;

public class ShowBanners extends AppCompatActivity implements IUnityAdsInitializationListener {

  String unityGameID = "1234567";
  Boolean testMode = true;
  String topAdUnitId = "topBanner";
  String bottomAdUnitId = "bottomBanner";

  // Listener for banner events:
  private BannerView.IListener bannerListener = new BannerView.IListener() {
     @Override
     public void onBannerLoaded(BannerView bannerAdView) {
        // Called when the banner is loaded.
        Log.v("UnityAdsExample", "onBannerLoaded: " + bannerAdView.getPlacementId());
        // Enable the correct button to hide the ad
        (bannerAdView.getPlacementId().equals("topBanner") ? hideTopBannerButton : hideBottomBannerButton).setEnabled(true);
     }

     @Override
     public void onBannerFailedToLoad(BannerView bannerAdView, BannerErrorInfo errorInfo) {
        Log.e("UnityAdsExample", "Unity Ads failed to load banner for " + bannerAdView.getPlacementId() + " with error: [" + errorInfo.errorCode + "] " + errorInfo.errorMessage);
        // Note that the BannerErrorInfo object can indicate a no fill (see API documentation).
     }

     @Override
     public void onBannerClick(BannerView bannerAdView) {
        // Called when a banner is clicked.
        Log.v("UnityAdsExample", "onBannerClick: " + bannerAdView.getPlacementId());
     }

     @Override
     public void onBannerLeftApplication(BannerView bannerAdView) {
        // Called when the banner links out of the application.
        Log.v("UnityAdsExample", "onBannerLeftApplication: " + bannerAdView.getPlacementId());
     }
  };

  // This banner view object will be placed at the top of the screen:
  BannerView topBanner;
  // This banner view object will be placed at the bottom of the screen:
  BannerView bottomBanner;
  // View objects to display banners:
  RelativeLayout topBannerView;
  RelativeLayout bottomBannerView;
  // Buttons to show the banners:
  Button showTopBannerButton;
  Button showBottomBannerButton;
  // Buttons to destroy the banners:
  Button hideTopBannerButton;
  Button hideBottomBannerButton;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);
     // Initialize Unity Ads:
     UnityAds.initialize(getApplicationContext(), unityGameID, testMode, this);

     // Set up a button to load the top banner when clicked:
     showTopBannerButton = findViewById(R.id.loadTopBanner);
     // Set up a button to load the bottom banner when clicked:
     showBottomBannerButton = findViewById(R.id.loadBottomBanner);
     // Set up a button to destroy the top banner when clicked:
     hideTopBannerButton = findViewById(R.id.hideTopBanner);
     // Set up a button to destroy the bottom banner when clicked:
     hideBottomBannerButton = findViewById(R.id.hideBottomBanner);

     showTopBannerButton.setEnabled(false);
     showBottomBannerButton.setEnabled(false);
     hideTopBannerButton.setEnabled(false);
     hideBottomBannerButton.setEnabled(false);

     showTopBannerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
           showTopBannerButton.setEnabled(false);
           // Create the top banner view object:
           topBanner = new BannerView(view.getContext(), topAdUnitId, new UnityBannerSize(320, 50));
           // Set the listener for banner lifecycle events:
           topBanner.setListener(bannerListener);
           topBannerView = findViewById(R.id.topBanner);
           LoadBannerAd(topBanner, topBannerView);
        }
     });

     showBottomBannerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
           showBottomBannerButton.setEnabled(false);
           // Create the bottom banner view object:
           bottomBanner = new BannerView(view.getContext(), bottomAdUnitId, new UnityBannerSize(320, 50));
           // Set the listener for banner lifecycle events:
           bottomBanner.setListener(bannerListener);
           bottomBannerView = findViewById(R.id.bottomBanner);
           LoadBannerAd(bottomBanner, bottomBannerView);
        }
     });

     hideTopBannerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
           // Remove content from the banner view:
           topBannerView.removeAllViews();
           // Remove the banner variables:
           topBannerView = null;
           topBanner = null;
           showTopBannerButton.setEnabled(true);
        }
     });

     hideBottomBannerButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
           // Remove content from the banner view:
           bottomBannerView.removeAllViews();
           // Remove the banner variables:
           bottomBannerView = null;
           bottomBanner = null;
           showBottomBannerButton.setEnabled(true);
        }
     });
  }

  public void LoadBannerAd(BannerView bannerView, RelativeLayout bannerLayout) {
     // Request a banner ad:
     bannerView.load();
     // Associate the banner view object with the banner view:
     bannerLayout.addView(bannerView);
  }

  @Override
  public void onInitializationComplete() {
     // Enable the show ad buttons since ads can now be loaded
     showTopBannerButton.setEnabled(true);
     showBottomBannerButton.setEnabled(true);
  }

  @Override
  public void onInitializationFailed(UnityAds.UnityAdsInitializationError error, String message) {

  }
}