refactor(admob): use Jetpack's Navigation Component

admob/app/build.gradle

@@ -28,8 +28,8 @@ android {
     }
 
     buildFeatures {
-  viewBinding = true
-}
+        viewBinding = true
+    }
 }
 
 dependencies {
@@ -38,10 +38,10 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'com.google.android.material:material:1.2.1'
     implementation 'androidx.browser:browser:1.0.0'
+    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.2'
+    implementation 'androidx.navigation:navigation-ui-ktx:2.3.2'
 
-    // [START gradle_play_config]
     implementation 'com.google.android.gms:play-services-ads:19.6.0'
-    // [END gradle_play_config]
 
     // Import the Firebase BoM (see: https://firebase.google.com/docs/android/learn-more#bom)
     implementation platform('com.google.firebase:firebase-bom:26.1.1')
@@ -50,6 +50,7 @@ dependencies {
     // for Google Analytics. This is recommended, but not required.
     implementation 'com.google.firebase:firebase-analytics'
 
+    debugImplementation "androidx.fragment:fragment-testing:1.2.5"
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
     androidTestImplementation 'androidx.test:rules:1.3.0'
     androidTestImplementation 'androidx.test:runner:1.3.0'

admob/app/src/androidTest/java/com/google/samples/quickstart/admobexample/InterstitialAdTest.java

@@ -1,17 +1,13 @@
 package com.google.samples.quickstart.admobexample;
 
 
-import androidx.test.espresso.IdlingRegistry;
+import androidx.fragment.app.testing.FragmentScenario;
 import androidx.test.espresso.ViewInteraction;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
-import androidx.test.rule.ActivityTestRule;
 import androidx.test.filters.LargeTest;
 
-import com.google.samples.quickstart.admobexample.java.MainActivity;
+import com.google.samples.quickstart.admobexample.kotlin.FirstFragment;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -28,26 +24,9 @@
 @RunWith(AndroidJUnit4.class)
 public class InterstitialAdTest {
 
-    private AdViewIdlingResource mAdResource;
-
-    @Rule
-    public ActivityTestRule<MainActivity> mActivityTestRule = new ActivityTestRule<>(MainActivity.class);
-
-    @Before
-    public void setUp() {
-        mAdResource = new AdViewIdlingResource(mActivityTestRule.getActivity().getAdView());
-        IdlingRegistry.getInstance().register(mAdResource);
-    }
-
-    @After
-    public void tearDown() {
-        IdlingRegistry.getInstance().unregister(mAdResource);
-    }
-
     @Test
     public void interstitialAdTest() {
-        // Wait for ad to load
-        mAdResource.setIsLoadingAd(true);
+        FragmentScenario<FirstFragment> fragment = FragmentScenario.launchInContainer(FirstFragment.class);
 
         // Confirm that banner ad appears
         onView(withId(R.id.adView))
@@ -66,7 +45,7 @@ public void interstitialAdTest() {
         closeInterstitialButton.perform(click());
 
         // Confirm that we're on the second activity
-        onView(withText(R.string.second_activity_content))
+        onView(withText(R.string.second_fragment_content))
                 .check(matches(isDisplayed()));
     }
 }

admob/app/src/main/AndroidManifest.xml

@@ -35,6 +35,7 @@
         </activity>
 
         <activity android:name=".java.MainActivity" />
+        <activity android:name=".kotlin.MainActivity" />
         <!-- [SNIPPET add_activity_config_changes]
             Include the AdActivity configChanges and theme.
             [START add_activity_config_changes] -->
@@ -43,23 +44,6 @@
             android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
             android:theme="@android:style/Theme.Translucent" />
         <!-- [END add_activity_config_changes] -->
-        <activity
-            android:name=".java.SecondActivity"
-            android:label="@string/second_activity_title"
-            android:parentActivityName=".java.MainActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value=".java.MainActivity" />
-        </activity>
-        <activity android:name=".kotlin.MainActivity" />
-        <activity
-            android:name=".kotlin.SecondActivity"
-            android:label="@string/second_activity_title"
-            android:parentActivityName=".java.MainActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value=".java.MainActivity" />
-        </activity>
     </application>
 
 </manifest>

admob/app/src/main/java/com/google/samples/quickstart/admobexample/java/FirstFragment.java

@@ -0,0 +1,154 @@
+package com.google.samples.quickstart.admobexample.java;
+
+import android.os.Bundle;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
+import androidx.fragment.app.Fragment;
+import androidx.navigation.fragment.NavHostFragment;
+
+import com.google.android.gms.ads.AdListener;
+import com.google.android.gms.ads.AdRequest;
+import com.google.android.gms.ads.AdView;
+import com.google.android.gms.ads.InterstitialAd;
+import com.google.android.gms.ads.LoadAdError;
+import com.google.android.gms.ads.MobileAds;
+import com.google.samples.quickstart.admobexample.R;
+import com.google.samples.quickstart.admobexample.databinding.FragmentFirstBinding;
+
+class FirstFragment extends Fragment {
+
+    private static final String TAG = "MainActivity";
+    private static final String TEST_APP_ID = "ca-app-pub-3940256099942544~3347511713";
+
+    private AdView mAdView;
+    private InterstitialAd mInterstitialAd;
+    private Button mLoadInterstitialButton;
+    private FragmentFirstBinding binding;
+
+    @Nullable
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
+        binding = FragmentFirstBinding.inflate(inflater, container, false);
+        return binding.getRoot();
+    }
+
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+        checkIds();
+
+        // Initialize the Google Mobile Ads SDK
+        MobileAds.initialize(getContext());
+
+        mAdView = binding.adView;
+        AdRequest adRequest = new AdRequest.Builder().build();
+        mAdView.loadAd(adRequest);
+
+        // AdMob ad unit IDs are not currently stored inside the google-services.json file.
+        // Developers using AdMob can store them as custom values in a string resource file or
+        // simply use constants. Note that the ad units used here are configured to return only test
+        // ads, and should not be used outside this sample.
+
+        // Create an InterstitialAd object. This same object can be re-used whenever you want to
+        // show an interstitial.
+        mInterstitialAd = new InterstitialAd(getContext());
+        mInterstitialAd.setAdUnitId(getString(R.string.interstitial_ad_unit_id));
+
+        mInterstitialAd.setAdListener(new AdListener() {
+            @Override
+            public void onAdClosed() {
+                requestNewInterstitial();
+                beginSecondActivity();
+            }
+
+            @Override
+            public void onAdLoaded() {
+                // Ad received, ready to display
+                if (mLoadInterstitialButton != null) {
+                    mLoadInterstitialButton.setEnabled(true);
+                }
+            }
+
+            @Override
+            public void onAdFailedToLoad(LoadAdError error) {
+                Log.w(TAG, "onAdFailedToLoad:" + error.getMessage());
+            }
+        });
+
+        mLoadInterstitialButton = binding.loadInterstitialButton;
+        mLoadInterstitialButton.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                if (mInterstitialAd.isLoaded()) {
+                    mInterstitialAd.show();
+                } else {
+                    beginSecondActivity();
+                }
+            }
+        });
+
+        // Disable button if an interstitial ad is not loaded yet.
+        mLoadInterstitialButton.setEnabled(mInterstitialAd.isLoaded());
+    }
+
+    /**
+     * Load a new interstitial ad asynchronously.
+     */
+    private void requestNewInterstitial() {
+        AdRequest adRequest = new AdRequest.Builder().build();
+
+        mInterstitialAd.loadAd(adRequest);
+    }
+
+    private void beginSecondActivity() {
+        NavHostFragment.findNavController(this).navigate(R.id.action_FirstFragment_to_SecondFragment);
+    }
+
+    /** Called when leaving the activity */
+    @Override
+    public void onPause() {
+        if (mAdView != null) {
+            mAdView.pause();
+        }
+        super.onPause();
+    }
+
+    /** Called when returning to the activity */
+    @Override
+    public void onResume() {
+        super.onResume();
+        if (mAdView != null) {
+            mAdView.resume();
+        }
+        if (!mInterstitialAd.isLoaded()) {
+            requestNewInterstitial();
+        }
+    }
+
+    /** Called before the activity is destroyed */
+    @Override
+    public void onDestroy() {
+        if (mAdView != null) {
+            mAdView.destroy();
+        }
+        super.onDestroy();
+    }
+
+    @VisibleForTesting
+    public AdView getAdView() {
+        return mAdView;
+    }
+
+    private void checkIds() {
+        if (TEST_APP_ID.equals(getString(R.string.admob_app_id))) {
+            Log.w(TAG, "Your admob_app_id is not configured correctly, please see the README");
+        }
+    }
+}