Fix demo app download notification

PiperOrigin-RevId: 294503035

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

@@ -25,6 +25,7 @@ import com.google.android.exoplayer2.offline.DefaultDownloadIndex;
 import com.google.android.exoplayer2.offline.DefaultDownloaderFactory;
 import com.google.android.exoplayer2.offline.DownloadManager;
 import com.google.android.exoplayer2.offline.DownloaderConstructorHelper;
+import com.google.android.exoplayer2.ui.DownloadNotificationHelper;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DefaultDataSourceFactory;
 import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
@@ -45,6 +46,8 @@ import java.io.IOException;
  */
 public class DemoApplication extends Application {
 
+  public static final String DOWNLOAD_NOTIFICATION_CHANNEL_ID = "download_channel";
+
   private static final String TAG = "DemoApplication";
   private static final String DOWNLOAD_ACTION_FILE = "actions";
   private static final String DOWNLOAD_TRACKER_ACTION_FILE = "tracked_actions";
@@ -57,6 +60,7 @@ public class DemoApplication extends Application {
   private Cache downloadCache;
   private DownloadManager downloadManager;
   private DownloadTracker downloadTracker;
+  private DownloadNotificationHelper downloadNotificationHelper;
 
   @Override
   public void onCreate() {
@@ -93,6 +97,14 @@ public class DemoApplication extends Application {
         .setExtensionRendererMode(extensionRendererMode);
   }
 
+  public DownloadNotificationHelper getDownloadNotificationHelper() {
+    if (downloadNotificationHelper == null) {
+      downloadNotificationHelper =
+          new DownloadNotificationHelper(this, DOWNLOAD_NOTIFICATION_CHANNEL_ID);
+    }
+    return downloadNotificationHelper;
+  }
+
   public DownloadManager getDownloadManager() {
     initDownloadManager();
     return downloadManager;

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

@@ -15,6 +15,8 @@
  */
 package com.google.android.exoplayer2.demo;
 
+import static com.google.android.exoplayer2.demo.DemoApplication.DOWNLOAD_NOTIFICATION_CHANNEL_ID;
+
 import android.app.Notification;
 import android.content.Context;
 import com.google.android.exoplayer2.offline.Download;
@@ -29,35 +31,29 @@ import java.util.List;
 /** A service for downloading media. */
 public class DemoDownloadService extends DownloadService {
 
-  private static final String CHANNEL_ID = "download_channel";
   private static final int JOB_ID = 1;
   private static final int FOREGROUND_NOTIFICATION_ID = 1;
 
-  private DownloadNotificationHelper notificationHelper;
-
   public DemoDownloadService() {
     super(
         FOREGROUND_NOTIFICATION_ID,
         DEFAULT_FOREGROUND_NOTIFICATION_UPDATE_INTERVAL,
-        CHANNEL_ID,
+        DOWNLOAD_NOTIFICATION_CHANNEL_ID,
         R.string.exo_download_notification_channel_name,
         /* channelDescriptionResourceId= */ 0);
   }
 
   @Override
-  public void onCreate() {
-    super.onCreate();
-    notificationHelper = new DownloadNotificationHelper(this, CHANNEL_ID);
-  }
-
-  @Override
   protected DownloadManager getDownloadManager() {
-    DownloadManager downloadManager = ((DemoApplication) getApplication()).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();
+    DownloadNotificationHelper downloadNotificationHelper =
+        application.getDownloadNotificationHelper();
     downloadManager.addListener(
         new TerminalStateNotificationHelper(
-            this, notificationHelper, FOREGROUND_NOTIFICATION_ID + 1));
+            this, downloadNotificationHelper, FOREGROUND_NOTIFICATION_ID + 1));
     return downloadManager;
   }
 
@@ -68,8 +64,10 @@ public class DemoDownloadService extends DownloadService {
 
   @Override
   protected Notification getForegroundNotification(List<Download> downloads) {
-    return notificationHelper.buildProgressNotification(
-        R.drawable.ic_download, /* contentIntent= */ null, /* message= */ null, downloads);
+    return ((DemoApplication) getApplication())
+        .getDownloadNotificationHelper()
+        .buildProgressNotification(
+            R.drawable.ic_download, /* contentIntent= */ null, /* message= */ null, downloads);
   }
 
   /**