InterstitialAd

public abstract class InterstitialAd

public class MyActivity extends Activity {
    private InterstitialAd interstitialAd;
    private Button nextLevelButton;
    private TextView textView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Create a full screen content callback.
        FullScreenContentCallback fullScreenContentCallback = new FullScreenContentCallback() {
            @Override
            public void onAdDismissedFullScreenContent() {
               interstitialAd = null;
               // Proceed to the next level.
               goToNextLevel();
            }
        };

        // Load an interstitial ad. When a natural transition in the app occurs (such as a level
        // ending in a game), show the interstitial. In this simple example, the press of a
        // button is used instead.
        //
        // If the button is clicked before the interstitial is loaded, the user should proceed to
        // the next part of the app (in this case, the next level).
        //
        // If the interstitial is finished loading, the user will view the interstitial before
        // proceeding.
        InterstitialAd.load(
            this,
            "myAdUnitId",
            new AdRequest.Builder().build(),
            new InterstitialAdLoadCallback() {
                @Override
                public void onAdLoaded(@NonNull InterstitialAd ad) {
                    interstitialAd = ad;
                    interstitialAd.setFullScreenContentCallback(fullScreenContentCallback);
                }

                @Override
                public void onAdFailedToLoad(@NonNull LoadAdError adError) {
                    // Code to be executed when an ad request fails.
                }
            });

        // Create the button to go to the next level.
        nextLevelButton = new Button(this);
        nextLevelButton.setText("Next Level");
        nextLevelButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // Show the interstitial if it is ready. Otherwise, proceed to the next level
                // without ever showing it.
                if (interstitialAd != null) {
                    interstitialAd.show(MyActivity.this);
                } else {
                    // Proceed to the next level.
                    goToNextLevel();
                }
            }
        });

        // Add the next level button to the layout.
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        layout.addView(nextLevelButton);

        // Create a TextView to display the current level.
        textView = new TextView(this);
        textView.setText("Level 1");
        layout.addView(textView);

        setContentView(layout);
    }

    public void goToNextLevel() {
        // Show the next level, and disable the next level button since there are no more levels.
        nextLevelButton.setEnabled(false);
        textView.setText("Level 2");
    }
}