Move functionality from DemoApplication to DemoUtil

https://developer.android.com/reference/android/app/Application recommends
against subclassing application.

PiperOrigin-RevId: 322163812

demos/main/build.gradle

@@ -63,6 +63,7 @@ android {
 }
 
 dependencies {
+    compileOnly 'org.checkerframework:checker-qual:' + checkerframeworkVersion
     implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion
     implementation 'androidx.appcompat:appcompat:' + androidxAppCompatVersion
     implementation 'androidx.multidex:multidex:' + androidxMultidexVersion

demos/main/src/main/AndroidManifest.xml

@@ -35,7 +35,7 @@
       android:largeHeap="true"
       android:allowBackup="false"
       android:requestLegacyExternalStorage="true"
-      android:name="com.google.android.exoplayer2.demo.DemoApplication"
+      android:name="androidx.multidex.MultiDexApplication"
       tools:ignore="UnusedAttribute">
 
     <activity android:name="com.google.android.exoplayer2.demo.SampleChooserActivity"

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoDownloadService.java

@@ -15,7 +15,7 @@
  */
 package com.google.android.exoplayer2.demo;
 
-import static com.google.android.exoplayer2.demo.DemoApplication.DOWNLOAD_NOTIFICATION_CHANNEL_ID;
+import static com.google.android.exoplayer2.demo.DemoUtil.DOWNLOAD_NOTIFICATION_CHANNEL_ID;
 
 import android.app.Notification;
 import android.content.Context;
@@ -50,10 +50,9 @@ public class DemoDownloadService extends DownloadService {
   protected DownloadManager getDownloadManager() {
     // This will only happen once, because getDownloadManager is guaranteed to be called only once
     // in the life cycle of the process.
-    DemoApplication application = (DemoApplication) getApplication();
-    DownloadManager downloadManager = application.getDownloadManager();
+    DownloadManager downloadManager = DemoUtil.getDownloadManager(/* context= */ this);
     DownloadNotificationHelper downloadNotificationHelper =
-        application.getDownloadNotificationHelper();
+        DemoUtil.getDownloadNotificationHelper(/* context= */ this);
     downloadManager.addListener(
         new TerminalStateNotificationHelper(
             this, downloadNotificationHelper, FOREGROUND_NOTIFICATION_ID + 1));
@@ -68,10 +67,13 @@ public class DemoDownloadService extends DownloadService {
   @Override
   @NonNull
   protected Notification getForegroundNotification(@NonNull List<Download> downloads) {
-    return ((DemoApplication) getApplication())
-        .getDownloadNotificationHelper()
+    return DemoUtil.getDownloadNotificationHelper(/* context= */ this)
         .buildProgressNotification(
-            R.drawable.ic_download, /* contentIntent= */ null, /* message= */ null, downloads);
+            /* context= */ this,
+            R.drawable.ic_download,
+            /* contentIntent= */ null,
+            /* message= */ null,
+            downloads);
   }
 
   /**
@@ -101,12 +103,14 @@ public class DemoDownloadService extends DownloadService {
       if (download.state == Download.STATE_COMPLETED) {
         notification =
             notificationHelper.buildDownloadCompletedNotification(
+                context,
                 R.drawable.ic_download_done,
                 /* contentIntent= */ null,
                 Util.fromUtf8Bytes(download.request.data));
       } else if (download.state == Download.STATE_FAILED) {
         notification =
             notificationHelper.buildDownloadFailedNotification(
+                context,
                 R.drawable.ic_download_done,
                 /* contentIntent= */ null,
                 Util.fromUtf8Bytes(download.request.data));

demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoApplication.java → demos/main/src/main/java/com/google/android/exoplayer2/demo/DemoUtil.java

@@ -15,7 +15,7 @@
  */
 package com.google.android.exoplayer2.demo;
 
-import androidx.multidex.MultiDexApplication;
+import android.content.Context;
 import com.google.android.exoplayer2.DefaultRenderersFactory;
 import com.google.android.exoplayer2.RenderersFactory;
 import com.google.android.exoplayer2.database.DatabaseProvider;
@@ -38,53 +38,34 @@ import com.google.android.exoplayer2.util.Util;
 import java.io.File;
 import java.io.IOException;
 import java.util.concurrent.Executors;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
-/**
- * Placeholder application to facilitate overriding Application methods for debugging and testing.
- */
-public class DemoApplication extends MultiDexApplication {
+/** Utility methods for the demo app. */
+public final class DemoUtil {
 
   public static final String DOWNLOAD_NOTIFICATION_CHANNEL_ID = "download_channel";
 
-  private static final String TAG = "DemoApplication";
+  private static final String TAG = "DemoUtil";
   private static final String DOWNLOAD_ACTION_FILE = "actions";
   private static final String DOWNLOAD_TRACKER_ACTION_FILE = "tracked_actions";
   private static final String DOWNLOAD_CONTENT_DIRECTORY = "downloads";
 
-  private HttpDataSource.Factory httpDataSourceFactory;
-  private DatabaseProvider databaseProvider;
-  private File downloadDirectory;
-  private Cache downloadCache;
-  private DownloadManager downloadManager;
-  private DownloadTracker downloadTracker;
-  private DownloadNotificationHelper downloadNotificationHelper;
-
-  @Override
-  public void onCreate() {
-    super.onCreate();
-    CronetEngineWrapper cronetEngineWrapper = new CronetEngineWrapper(/* context= */ this);
-    String userAgent = Util.getUserAgent(this, "ExoPlayerDemo");
-    httpDataSourceFactory =
-        new CronetDataSourceFactory(
-            cronetEngineWrapper,
-            Executors.newSingleThreadExecutor(),
-            /* transferListener= */ null,
-            userAgent);
-  }
-
-  /** Returns a {@link DataSource.Factory}. */
-  public DataSource.Factory buildDataSourceFactory() {
-    DefaultDataSourceFactory upstreamFactory =
-        new DefaultDataSourceFactory(/* context= */ this, httpDataSourceFactory);
-    return buildReadOnlyCacheDataSource(upstreamFactory, getDownloadCache());
-  }
+  private static DataSource.@MonotonicNonNull Factory dataSourceFactory;
+  private static HttpDataSource.@MonotonicNonNull Factory httpDataSourceFactory;
+  private static @MonotonicNonNull DatabaseProvider databaseProvider;
+  private static @MonotonicNonNull File downloadDirectory;
+  private static @MonotonicNonNull Cache downloadCache;
+  private static @MonotonicNonNull DownloadManager downloadManager;
+  private static @MonotonicNonNull DownloadTracker downloadTracker;
+  private static @MonotonicNonNull DownloadNotificationHelper downloadNotificationHelper;
 
   /** Returns whether extension renderers should be used. */
-  public boolean useExtensionRenderers() {
+  public static boolean useExtensionRenderers() {
     return "withDecoderExtensions".equals(BuildConfig.FLAVOR);
   }
 
-  public RenderersFactory buildRenderersFactory(boolean preferExtensionRenderer) {
+  public static RenderersFactory buildRenderersFactory(
+      Context context, boolean preferExtensionRenderer) {
     @DefaultRenderersFactory.ExtensionRendererMode
     int extensionRendererMode =
         useExtensionRenderers()
@@ -92,61 +73,96 @@ public class DemoApplication extends MultiDexApplication {
                 ? DefaultRenderersFactory.EXTENSION_RENDERER_MODE_PREFER
                 : DefaultRenderersFactory.EXTENSION_RENDERER_MODE_ON)
             : DefaultRenderersFactory.EXTENSION_RENDERER_MODE_OFF;
-    return new DefaultRenderersFactory(/* context= */ this)
+    return new DefaultRenderersFactory(context.getApplicationContext())
         .setExtensionRendererMode(extensionRendererMode);
   }
 
-  public DownloadNotificationHelper getDownloadNotificationHelper() {
+  public static synchronized HttpDataSource.Factory getHttpDataSourceFactory(Context context) {
+    if (httpDataSourceFactory == null) {
+      context = context.getApplicationContext();
+      CronetEngineWrapper cronetEngineWrapper = new CronetEngineWrapper(context);
+      String userAgent = Util.getUserAgent(context, "ExoPlayerDemo");
+      httpDataSourceFactory =
+          new CronetDataSourceFactory(
+              cronetEngineWrapper,
+              Executors.newSingleThreadExecutor(),
+              /* transferListener= */ null,
+              userAgent);
+    }
+    return httpDataSourceFactory;
+  }
+
+  /** Returns a {@link DataSource.Factory}. */
+  public static synchronized DataSource.Factory buildDataSourceFactory(Context context) {
+    if (dataSourceFactory == null) {
+      context = context.getApplicationContext();
+      DefaultDataSourceFactory upstreamFactory =
+          new DefaultDataSourceFactory(context, getHttpDataSourceFactory(context));
+      dataSourceFactory = buildReadOnlyCacheDataSource(upstreamFactory, getDownloadCache(context));
+    }
+    return dataSourceFactory;
+  }
+
+  public static synchronized DownloadNotificationHelper getDownloadNotificationHelper(
+      Context context) {
     if (downloadNotificationHelper == null) {
       downloadNotificationHelper =
-          new DownloadNotificationHelper(this, DOWNLOAD_NOTIFICATION_CHANNEL_ID);
+          new DownloadNotificationHelper(context, DOWNLOAD_NOTIFICATION_CHANNEL_ID);
     }
     return downloadNotificationHelper;
   }
 
-  public DownloadManager getDownloadManager() {
-    initDownloadManager();
+  public static synchronized DownloadManager getDownloadManager(Context context) {
+    ensureDownloadManagerInitialized(context);
     return downloadManager;
   }
 
-  public DownloadTracker getDownloadTracker() {
-    initDownloadManager();
+  public static synchronized DownloadTracker getDownloadTracker(Context context) {
+    ensureDownloadManagerInitialized(context);
     return downloadTracker;
   }
 
-  private synchronized Cache getDownloadCache() {
+  private static synchronized Cache getDownloadCache(Context context) {
     if (downloadCache == null) {
-      File downloadContentDirectory = new File(getDownloadDirectory(), DOWNLOAD_CONTENT_DIRECTORY);
+      File downloadContentDirectory =
+          new File(getDownloadDirectory(context), DOWNLOAD_CONTENT_DIRECTORY);
       downloadCache =
-          new SimpleCache(downloadContentDirectory, new NoOpCacheEvictor(), getDatabaseProvider());
+          new SimpleCache(
+              downloadContentDirectory, new NoOpCacheEvictor(), getDatabaseProvider(context));
     }
     return downloadCache;
   }
 
-  private synchronized void initDownloadManager() {
+  private static synchronized void ensureDownloadManagerInitialized(Context context) {
     if (downloadManager == null) {
-      DefaultDownloadIndex downloadIndex = new DefaultDownloadIndex(getDatabaseProvider());
+      DefaultDownloadIndex downloadIndex = new DefaultDownloadIndex(getDatabaseProvider(context));
       upgradeActionFile(
-          DOWNLOAD_ACTION_FILE, downloadIndex, /* addNewDownloadsAsCompleted= */ false);
+          context, DOWNLOAD_ACTION_FILE, downloadIndex, /* addNewDownloadsAsCompleted= */ false);
       upgradeActionFile(
-          DOWNLOAD_TRACKER_ACTION_FILE, downloadIndex, /* addNewDownloadsAsCompleted= */ true);
+          context,
+          DOWNLOAD_TRACKER_ACTION_FILE,
+          downloadIndex,
+          /* addNewDownloadsAsCompleted= */ true);
       downloadManager =
           new DownloadManager(
-              /* context= */ this,
-              getDatabaseProvider(),
-              getDownloadCache(),
-              httpDataSourceFactory,
+              context,
+              getDatabaseProvider(context),
+              getDownloadCache(context),
+              getHttpDataSourceFactory(context),
               Executors.newFixedThreadPool(/* nThreads= */ 6));
       downloadTracker =
-          new DownloadTracker(/* context= */ this, buildDataSourceFactory(), downloadManager);
+          new DownloadTracker(context, buildDataSourceFactory(context), downloadManager);
     }
   }
 
-  private void upgradeActionFile(
-      String fileName, DefaultDownloadIndex downloadIndex, boolean addNewDownloadsAsCompleted) {
+  private static synchronized void upgradeActionFile(
+      Context context,
+      String fileName,
+      DefaultDownloadIndex downloadIndex,
+      boolean addNewDownloadsAsCompleted) {
     try {
       ActionFileUpgradeUtil.upgradeAndDelete(
-          new File(getDownloadDirectory(), fileName),
+          new File(getDownloadDirectory(context), fileName),
           /* downloadIdProvider= */ null,
           downloadIndex,
           /* deleteOnFailure= */ true,
@@ -156,18 +172,18 @@ public class DemoApplication extends MultiDexApplication {
     }
   }
 
-  private DatabaseProvider getDatabaseProvider() {
+  private static synchronized DatabaseProvider getDatabaseProvider(Context context) {
     if (databaseProvider == null) {
-      databaseProvider = new ExoDatabaseProvider(this);
+      databaseProvider = new ExoDatabaseProvider(context);
     }
     return databaseProvider;
   }
 
-  private File getDownloadDirectory() {
+  private static synchronized File getDownloadDirectory(Context context) {
     if (downloadDirectory == null) {
-      downloadDirectory = getExternalFilesDir(null);
+      downloadDirectory = context.getExternalFilesDir(/* type= */ null);
       if (downloadDirectory == null) {
-        downloadDirectory = getFilesDir();
+        downloadDirectory = context.getFilesDir();
       }
     }
     return downloadDirectory;
@@ -181,4 +197,6 @@ public class DemoApplication extends MultiDexApplication {
         .setCacheWriteDataSinkFactory(null)
         .setFlags(CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR);
   }
+
+  private DemoUtil() {}
 }

demos/main/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -315,7 +315,7 @@ public class PlayerActivity extends AppCompatActivity
       boolean preferExtensionDecoders =
           intent.getBooleanExtra(IntentUtil.PREFER_EXTENSION_DECODERS_EXTRA, false);
       RenderersFactory renderersFactory =
-          ((DemoApplication) getApplication()).buildRenderersFactory(preferExtensionDecoders);
+          DemoUtil.buildRenderersFactory(/* context= */ this, preferExtensionDecoders);
 
       trackSelector = new DefaultTrackSelector(/* context= */ this, trackSelectionFactory);
       trackSelector.setParameters(trackSelectorParameters);
@@ -357,7 +357,7 @@ public class PlayerActivity extends AppCompatActivity
 
     List<MediaItem> mediaItems =
         IntentUtil.createMediaItemsFromIntent(
-            intent, ((DemoApplication) getApplication()).getDownloadTracker());
+            intent, DemoUtil.getDownloadTracker(/* context= */ this));
     boolean hasAds = false;
     for (int i = 0; i < mediaItems.size(); i++) {
       MediaItem mediaItem = mediaItems.get(i);
@@ -439,7 +439,7 @@ public class PlayerActivity extends AppCompatActivity
 
   /** Returns a new DataSource factory. */
   protected DataSource.Factory buildDataSourceFactory() {
-    return ((DemoApplication) getApplication()).buildDataSourceFactory();
+    return DemoUtil.buildDataSourceFactory(/* context= */ this);
   }
 
   // User controls

demos/main/src/main/java/com/google/android/exoplayer2/demo/SampleChooserActivity.java

@@ -114,9 +114,8 @@ public class SampleChooserActivity extends AppCompatActivity
       Arrays.sort(uris);
     }
 
-    DemoApplication application = (DemoApplication) getApplication();
-    useExtensionRenderers = application.useExtensionRenderers();
-    downloadTracker = application.getDownloadTracker();
+    useExtensionRenderers = DemoUtil.useExtensionRenderers();
+    downloadTracker = DemoUtil.getDownloadTracker(/* context= */ this);
     loadSample();
 
     // Start the download service if it should be running but it's not currently.
@@ -247,8 +246,8 @@ public class SampleChooserActivity extends AppCompatActivity
           .show();
     } else {
       RenderersFactory renderersFactory =
-          ((DemoApplication) getApplication())
-              .buildRenderersFactory(isNonNullAndChecked(preferExtensionDecodersMenuItem));
+          DemoUtil.buildRenderersFactory(
+              /* context= */ this, isNonNullAndChecked(preferExtensionDecodersMenuItem));
       downloadTracker.toggleDownload(
           getSupportFragmentManager(), playlistHolder.mediaItems.get(0), renderersFactory);
     }

library/ui/src/main/java/com/google/android/exoplayer2/ui/DownloadNotificationHelper.java

@@ -31,7 +31,6 @@ public final class DownloadNotificationHelper {
 
   private static final @StringRes int NULL_STRING_ID = 0;
 
-  private final Context context;
   private final NotificationCompat.Builder notificationBuilder;
 
   /**
@@ -39,14 +38,14 @@ public final class DownloadNotificationHelper {
    * @param channelId The id of the notification channel to use.
    */
   public DownloadNotificationHelper(Context context, String channelId) {
-    context = context.getApplicationContext();
-    this.context = context;
-    this.notificationBuilder = new NotificationCompat.Builder(context, channelId);
+    this.notificationBuilder =
+        new NotificationCompat.Builder(context.getApplicationContext(), channelId);
   }
 
   /**
    * Returns a progress notification for the given downloads.
    *
+   * @param context A context.
    * @param smallIcon A small icon for the notification.
    * @param contentIntent An optional content intent to send when the notification is clicked.
    * @param message An optional message to display on the notification.
@@ -54,6 +53,7 @@ public final class DownloadNotificationHelper {
    * @return The notification.
    */
   public Notification buildProgressNotification(
+      Context context,
       @DrawableRes int smallIcon,
       @Nullable PendingIntent contentIntent,
       @Nullable String message,
@@ -95,6 +95,7 @@ public final class DownloadNotificationHelper {
       indeterminate = allDownloadPercentagesUnknown && haveDownloadedBytes;
     }
     return buildNotification(
+        context,
         smallIcon,
         contentIntent,
         message,
@@ -109,37 +110,47 @@ public final class DownloadNotificationHelper {
   /**
    * Returns a notification for a completed download.
    *
+   * @param context A context.
    * @param smallIcon A small icon for the notifications.
    * @param contentIntent An optional content intent to send when the notification is clicked.
    * @param message An optional message to display on the notification.
    * @return The notification.
    */
   public Notification buildDownloadCompletedNotification(
-      @DrawableRes int smallIcon, @Nullable PendingIntent contentIntent, @Nullable String message) {
+      Context context,
+      @DrawableRes int smallIcon,
+      @Nullable PendingIntent contentIntent,
+      @Nullable String message) {
     int titleStringId = R.string.exo_download_completed;
-    return buildEndStateNotification(smallIcon, contentIntent, message, titleStringId);
+    return buildEndStateNotification(context, smallIcon, contentIntent, message, titleStringId);
   }
 
   /**
    * Returns a notification for a failed download.
    *
+   * @param context A context.
    * @param smallIcon A small icon for the notifications.
    * @param contentIntent An optional content intent to send when the notification is clicked.
    * @param message An optional message to display on the notification.
    * @return The notification.
    */
   public Notification buildDownloadFailedNotification(
-      @DrawableRes int smallIcon, @Nullable PendingIntent contentIntent, @Nullable String message) {
+      Context context,
+      @DrawableRes int smallIcon,
+      @Nullable PendingIntent contentIntent,
+      @Nullable String message) {
     @StringRes int titleStringId = R.string.exo_download_failed;
-    return buildEndStateNotification(smallIcon, contentIntent, message, titleStringId);
+    return buildEndStateNotification(context, smallIcon, contentIntent, message, titleStringId);
   }
 
   private Notification buildEndStateNotification(
+      Context context,
       @DrawableRes int smallIcon,
       @Nullable PendingIntent contentIntent,
       @Nullable String message,
       @StringRes int titleStringId) {
     return buildNotification(
+        context,
         smallIcon,
         contentIntent,
         message,
@@ -152,6 +163,7 @@ public final class DownloadNotificationHelper {
   }
 
   private Notification buildNotification(
+      Context context,
       @DrawableRes int smallIcon,
       @Nullable PendingIntent contentIntent,
       @Nullable String message,

library/ui/src/main/java/com/google/android/exoplayer2/ui/DownloadNotificationUtil.java

@@ -52,7 +52,7 @@ public final class DownloadNotificationUtil {
       @Nullable String message,
       List<Download> downloads) {
     return new DownloadNotificationHelper(context, channelId)
-        .buildProgressNotification(smallIcon, contentIntent, message, downloads);
+        .buildProgressNotification(context, smallIcon, contentIntent, message, downloads);
   }
 
   /**
@@ -72,7 +72,7 @@ public final class DownloadNotificationUtil {
       @Nullable PendingIntent contentIntent,
       @Nullable String message) {
     return new DownloadNotificationHelper(context, channelId)
-        .buildDownloadCompletedNotification(smallIcon, contentIntent, message);
+        .buildDownloadCompletedNotification(context, smallIcon, contentIntent, message);
   }
 
   /**
@@ -92,6 +92,6 @@ public final class DownloadNotificationUtil {
       @Nullable PendingIntent contentIntent,
       @Nullable String message) {
     return new DownloadNotificationHelper(context, channelId)
-        .buildDownloadFailedNotification(smallIcon, contentIntent, message);
+        .buildDownloadFailedNotification(context, smallIcon, contentIntent, message);
   }
 }