Integrate Admob pub Android

MainActivity.java

/**
* Tuto Admob Android
* @author Zied Rebhi
* http://www.tutozone.info
*/
public class MainActivity extends Activity {
	 private InterstitialAd interstitial;
	 
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
        // Prepare the Interstitial Ad
        interstitial = new InterstitialAd(MainActivity.this);
        // Insert the Ad Unit ID
        interstitial.setAdUnitId("ca-app-pub-13456789");
 
        //Locate the Banner Ad in activity_main.xml
        AdView adView = (AdView) this.findViewById(R.id.adView);
 
        // Request for Ads
        AdRequest adRequest = new AdRequest.Builder()
 
        // Add a test device to show Test Ads
         .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
         .addTestDevice("E3476884AF84FA254EC41B585B555338")
                .build();
        
        // Load ads into Banner Ads
        adView.loadAd(adRequest);
 
        // Load ads into Interstitial Ads
        interstitial.loadAd(adRequest);
 
        // Prepare an Interstitial Ad Listener
        interstitial.setAdListener(new AdListener() {
            public void onAdLoaded() {
                // Call displayInterstitial() function
                displayInterstitial();
            }
        });
    }
    public void displayInterstitial() {
        // If Ads are loaded, show Interstitial else show nothing.
        if (interstitial.isLoaded()) {
            interstitial.show();
        }
    }
}