STEP 4: JAVA SOURCE
Locate and open your app activity.java, on src folder.



You should see some errors on source code.

First replace imports

import com.google.ads.AdRequest;
import com.google.ads.AdSize;
import com.google.ads.AdView;

with

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdSize;
import com.google.android.gms.ads.AdView;

Add the following line to manage ads layout

import android.widget.LinearLayout;

Then you should have the old AdMob code to generate banners, right below super.loadUrl() code, similar to this:

AdView adView = new AdView(this, AdSize.BANNER, "xxxxxxxxxxxxxx");
LinearLayout layout = super.root;
layout.addView(adView);
layout.setHorizontalGravity(android.view.Gravity.CENTER_HORIZONTAL);
adView.loadAd(new AdRequest());

This code is no longer working, replace all block with the following:

AdView adView = new AdView(this);
adView.setAdSize(AdSize.BANNER);
adView.setAdUnitId("ca-app-pub-xxxxxxxxxxxxxxxx/xxxxxxxxxx");
LinearLayout layout = super.root;
layout.addView(adView);
layout.setHorizontalGravity(android.view.Gravity.CENTER_HORIZONTAL);
AdRequest adRequest = new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR).build();
adView.loadAd(adRequest);

Replace the setAdUnitId with the ad unit id of your app.
AdSize.BANNER constant can be changed depending of your needings, we prefer SMART_BANNER constant for cross-devices compatibility and a better result.
Remember to add emulator and/or your phisical test devices to avoid troubles on your AdMob account.
Further info about this step can be found at this page.

STEP 5: TEST AND PUBLiSH