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Notifications

A notification is a message you display to the user outside of your app's normal UI. When you tell the system to issue a notification, it first appears as an icon in the notification area. To see the details of the notification, the user opens the notification drawer. Both the notification area and the notification drawer are system-controlled areas that the user can view at any time.

The notifications area.

Figure 1. Notifications in the notification area.

The notifications drawer.

Figure 2. Notifications in the notification drawer.

In supported launchers and on devices running Android 8.0 (API level 26) and higher:

Notification badges displaying on a variety of launcher icons and a
       folder.

Figure 3. Notification badges display on icons and folders.

A long-press menu displays a summary of notifications for an app.

Figure 4. Users can long-press on an app icon to glance at notifications.

Note: Except where noted, this guide refers to the NotificationCompat.Builder class in the version 4 Support Library. The class Notification.Builder was added in Android 3.0 (API level 11).

Design considerations

Notifications, as an important part of the Android user interface, have their own design guidelines. The material design changes introduced in Android 5.0 (API level 21) are of particular importance, and you should review the Material Design training for more information. To learn how to design notifications and their interactions, read the Notifications design guide.

Managing notification channels

Starting in Android 8.0 (API level 26), notification channels allow you to create a user-customizable channel for each type of notification you want to display. Notification channels provide a unified system to help users manage notifications. When you target Android 8.0 (API level 26), you must implement one or more notification channels to display notifications to your users. If you don't target Android 8.0 (API level 26) but your app is used on devices running Android 8.0 (API level 26), your app behaves the same as it would on devices running Android 7.1 (API level 25) or lower.

You can create an instance of NotificationChannel for each distinct type of notification you need to send. You can also create notification channels to reflect choices made by users of your app. For example, you may set up separate notification channels for each conversation group created by a user in a messaging app.

Users can manage most of the settings associated with notifications using a consistent system UI. All notifications posted to the same notification channel have the same behavior. When a user modifies the behavior for any of the following characteristics, it applies to the notification channel:

Users can visit Settings, or long-press a notification to change these behaviors, or even block a notification channel at any time. You can't programmatically modify the behavior of a notification channel after it's created and submitted to the notification manager; the user is in charge of those settings after creation. You can however rename a notification channel or update its description after creation.

Creating a notification channel

To create a notification channel:

  1. Construct a notification channel object with an ID that's unique within your package.
  2. Configure the notification channel object with any desired initial settings, such as an alert sound, as well as an optional description visible to the user.
  3. Submit the notification channel object to the notification manager.

Attempting to create an existing notification channel with its original values performs no operation, so it's safe to perform the preceding sequence of steps when starting an app. The following code sample demonstrates creating a notification channel with a high importance level and a custom vibration pattern:

NotificationManager mNotificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// The id of the channel.
String id = "my_channel_01";
// The user-visible name of the channel.
CharSequence name = getString(R.string.channel_name);
// The user-visible description of the channel.
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_HIGH;
NotificationChannel mChannel = new NotificationChannel(id, name, importance);
// Configure the notification channel.
mChannel.setDescription(description);
mChannel.enableLights(true);
// Sets the notification light color for notifications posted to this
// channel, if the device supports this feature.
mChannel.setLightColor(Color.RED);
mChannel.enableVibration(true);
mChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
mNotificationManager.createNotificationChannel(mChannel);

You can also create multiple notification channels in a single operation by calling createNotificationChannels().

Creating a notification channel group

If your app supports multiple user accounts, you can create a notification channel group for each account. Notification channel groups allow you to manage multiple notification channels with identical names within a single app. For example, a social networking app might include support for personal and business user accounts. In this scenario, each user account might require multiple notification channels with identical functions and names.

Organizing the notification channels associated with each user account in this example into dedicated groups ensures that users can easily distinguish between them in Settings. Each notification channel group requires an ID that must be unique within your package, as well as a user-visible name. The following snippet demonstrates how to create a notification channel group.

// The id of the group.
String group = "my_group_01";
// The user-visible name of the group.
CharSequence name = getString(R.string.group_name);
NotificationManager mNotificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
mNotificationManager.createNotificationChannelGroup(new NotificationChannelGroup(group, name));

After you've created a new group, you can call setGroup() to associate a new channel with the group. You can only modify the association between notification channels and groups before you submit the channel to the notification manager.

Reading notification channel settings

Users can modify the settings for notification channels, including behaviors such as vibration and alert sound. You can call the following two methods to discover the settings a user has applied to a notification channel:

After you have the NotificationChannel, you can use methods such as getVibrationPattern() and getSound() to find out what settings the user currently has. To find out if a user blocked a notification channel, you can call getImportance(). If the notification channel is blocked, getImportance() returns IMPORTANCE_NONE.

Updating notification channel settings

After you create a notification channel, the user is in charge of its settings and behavior. You can call createNotificationChannel() and then submit the notification channel again to the notification manager to rename an existing notification channel, or update its description.

The following sample code describes how you can redirect a user to the settings for a notification channel by creating an intent to start an activity. In this case, the intent requires extended data, including the ID of the notification channel and the package name of your app.

Intent intent = new Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS);
intent.putExtra(Settings.EXTRA_CHANNEL_ID, mChannel.getId());
intent.putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName());
startActivity(intent);

Deleting a notification channel

You can delete notification channels by calling deleteNotificationChannel(). The following sample code demonstrates how to complete this process:

NotificationManager mNotificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// The id of the channel.
String id = "my_channel_01";
mNotificationManager.deleteNotificationChannel(id);

Creating a notification

You specify the UI information and actions for a notification in a NotificationCompat.Builder object. To create the notification itself, you call NotificationCompat.Builder.build(), which returns a Notification object containing your specifications. To issue the notification, you pass the Notification object to the system by calling NotificationManager.notify().

Required notification contents

A Notification object must contain the following:

Optional notification contents and settings

All other notification settings and contents are optional. To learn more about them, see the reference documentation for NotificationCompat.Builder.

Notification actions

An action allows users to go directly from the notification to an Activity in your app, where they can look at one or more events or do further work.

A notification can provide multiple actions. Make sure you always define the action that's triggered when the user clicks the notification; usually this action opens an Activity in your app. You can also add buttons to the notification that perform additional actions such as snoozing an alarm or responding immediately to a text message; this feature is available as of Android 4.1. If you use additional action buttons, you must also make their functionality available in an Activity in your app; see the section Handling compatibility for more details.

Inside a Notification, the action itself is defined by a PendingIntent containing an Intent that starts an Activity in your app. To associate the PendingIntent with a gesture, call the appropriate method of NotificationCompat.Builder. For example, if you want to start Activity when the user clicks the notification text in the notification drawer, you add the PendingIntent by calling setContentIntent().

Starting an Activity when the user clicks the notification is the most common action scenario. You can also start an Activity when the user dismisses a notification. In Android 4.1 and later, you can start an Activity from an action button. To learn more, read the reference guide for NotificationCompat.Builder.

Notification priority and importance

If you wish, you can set the priority of a notification on Android 7.1 (API level 25) and lower. The priority acts as a hint to the device UI about how the notification should be displayed. To set a notification's priority, call NotificationCompat.Builder.setPriority() and pass in one of the NotificationCompat priority constants. There are five priority levels, ranging from PRIORITY_MIN (-2) to PRIORITY_MAX (2); if not set, the priority defaults to PRIORITY_DEFAULT (0).

For information about setting an appropriate priority level, see "Correctly set and manage notification priority" in the Notifications Design guide.

Android 8.0 (API level 26) deprecates the ability to set the priority levels of individual notifications. Instead, you can set a recommended importance level when creating a notification channel. The importance level you assign to a notification channel applies to all notification messages that you post to it. You can configure a channel with one of five importance levels that configure the amount a channel can interrupt a user, ranging from IMPORTANCE_NONE(0) to IMPORTANCE_HIGH(4). The default importance level is 3 which displays everywhere, makes noise, but doesn't visually intrude on the user. After you create a notification channel, only the system can modify its importance.

Creating a simple notification

Remember that Android 8.0 (API level 26) and higher requires that you post notifications to a notification channel. To learn how to create a notification channel, see Creating a notification channel. The following snippet illustrates a simple notification that specifies an activity to open when the user clicks the notification. Notice that the code creates a TaskStackBuilder object and uses it to create the PendingIntent for the action. This pattern is explained in more detail in the section Preserving Navigation when Starting an Activity:

// The id of the channel.
String CHANNEL_ID = "my_channel_01";
NotificationCompat.Builder mBuilder =
        new NotificationCompat.Builder(this, CHANNEL_ID)
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle("My notification")
            .setContentText("Hello World!");
// Creates an explicit intent for an Activity in your app
Intent resultIntent = new Intent(this, ResultActivity.class);

// The stack builder object will contain an artificial back stack for the
// started Activity.
// This ensures that navigating backward from the Activity leads out of
// your app to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(ResultActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent =
        stackBuilder.getPendingIntent(
            0,
            PendingIntent.FLAG_UPDATE_CURRENT
        );
mBuilder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
    (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

// mNotificationId is a unique integer your app uses to identify the
// notification. For example, to cancel the notification, you can pass its ID
// number to NotificationManager.cancel().
mNotificationManager.notify(mNotificationId, mBuilder.build());

That's it. Your user has now been notified.

Applying an expanded layout to a notification

To have a notification appear in an expanded view, first create a NotificationCompat.Builder object with the normal view options you want. Next, call Builder.setStyle() with an expanded layout object as its argument.

Remember that expanded notifications are not available on platforms prior to Android 4.1. To learn how to handle notifications for Android 4.1 and for earlier platforms, read the section Handling compatibility.

For example, the following code snippet demonstrates how to alter the notification created in the previous snippet to use the expanded layout:

NotificationCompat.Builder mBuilder =
        new NotificationCompat.Builder(this, CHANNEL_ID)
            .setSmallIcon(R.drawable.notification_icon)
            .setContentTitle("Event tracker")
            .setContentText("Events received");
NotificationCompat.InboxStyle inboxStyle =
        new NotificationCompat.InboxStyle();
String[] events = new String[6];
// Sets a title for the Inbox in expanded layout
inboxStyle.setBigContentTitle("Event tracker details:");
...
// Moves events into the expanded layout
for (int i=0; i < events.length; i++) {
    inboxStyle.addLine(events[i]);
}
// Moves the expanded layout object into the notification object.
mBuilder.setStyle(inboxStyle);
...
// Issue the notification here.

Handling compatibility

Not all notification features are available for a particular version, even though the methods to set them are in the support library class NotificationCompat.Builder. For example, action buttons, which depend on expanded notifications, only appear on Android 4.1 and higher, because expanded notifications themselves are only available on Android 4.1 and higher.

To ensure the best compatibility, create notifications with NotificationCompat and its subclasses, particularly NotificationCompat.Builder. In addition, follow this process when you implement a notification:

  1. Provide all of the notification's functionality to all users, regardless of the version they're using. To do this, verify that all of the functionality is available from an Activity in your app. You may want to add a new Activity to do this.

    For example, if you want to use addAction() to provide a control that stops and starts media playback, first implement this control in an Activity in your app.

  2. Ensure that all users can get to the functionality in the Activity, by having it start when users click the notification. To do this, create a PendingIntent for the Activity. Call setContentIntent() to add the PendingIntent to the notification.
  3. Now add the expanded notification features you want to use to the notification. Remember that any functionality you add also has to be available in the Activity that starts when users click the notification.

Managing notifications

When you need to issue a notification multiple times for the same type of event, you should avoid making a completely new notification. Instead, you should consider updating a previous notification, either by changing some of its values or by adding to it, or both.

For example, Gmail notifies the user that new emails have arrived by increasing its count of unread messages and by adding a summary of each email to the notification. This is called "stacking" the notification; it's described in more detail in the Notifications Design guide.

Note: This Gmail feature requires the "inbox" expanded layout, which is part of the expanded notification feature.

The following section describes how to update notifications and also how to remove them.

Updating notifications

To set up a notification so it can be updated, issue it with a notification ID by calling NotificationManager.notify(). To update this notification after you've issued it, update or create a NotificationCompat.Builder object, build a Notification object from it, and issue the Notification with the same ID you used previously. If the previous notification is still visible, the system updates it from the contents of the Notification object. If the previous notification has been dismissed, a new notification is created instead.

The following snippet demonstrates a notification that is updated to reflect the number of events that have occurred. It stacks the notification, showing a summary:

mNotificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// Sets an ID for the notification, so it can be updated
int notifyID = 1;
mNotifyBuilder = new NotificationCompat.Builder(this, CHANNEL_ID)
    .setContentTitle("New Message")
    .setContentText("You've received new messages.")
    .setSmallIcon(R.drawable.ic_notify_status);
numMessages = 0;
// Start of a loop that processes data and then notifies the user
...
    mNotifyBuilder.setContentText(currentText)
        .setNumber(++numMessages);
    // Because the ID remains unchanged, the existing notification is
    // updated.
    mNotificationManager.notify(
            notifyID,
            mNotifyBuilder.build());
...

Removing notifications

Notifications remain visible until one of the following happens:

Notification badges

Android 8.0 (API level 26) introduces functionality for displaying notification badges on app icons in supported launchers. Notification badges show notifications associated with one or more notification channels in an app, which the user has not yet dismissed or acted on. Users can turn off badges for notification channels or apps from the Settings app. Notification badges are also known as notification dots).

Users can also long-press on an app icon to glance at the notifications associated with a notification badge in supported launchers. Users can then dismiss or act on notifications from the long-press menu in a similar way to the notification drawer.

By default, each new notification in a channel increments the number displayed on the associated launcher long-press menu by one. After a user dismisses a notification or triggers a related action, that number decrements to reflect the change. You can override the count displayed in the long-press menu as a result of a notification. For example, you can set the value for the number of incoming messages to display in a long-press menu when creating a notification for a messaging app. To learn how to override the count displayed in the long-press menu, see Adjusting notification badges.

A long-press menu displays a custom count of notifications for an
     app.

Figure 5. You can override the notification count displayed in the long-press menu.

A folder's notification badge indicates the presence of notification badges for one or more of the apps inside the folder.

Caution: Don't badge every notification, as there are cases where badges don't make sense. Consider the following examples when planning to create notifications in a notification channel for your app:

  • Ongoing notifications: Most ongoing notifications, such as image processing, media playback controls, or current navigation instructions, don't make sense as a badge.
  • Calendaring apps: Avoid badging events occurring at the current time.
  • Clock or alarm apps: Avoid badging notifications related to current alarms.

Adjusting notification badges

By default, each notification channel reflects its active notifications in your app's launcher icon badge. You can use the setShowBadge() method to stop the presence of notifications from a channel being reflected by a badge. You can't programmatically modify this setting for a notification channel after it's created and submitted to the notification manager.

The following sample code illustrates how to hide badges in association with notifications from a notification channel:

NotificationManager mNotificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// The ID of the channel.
String id = "my_channel_01";
// The user visible name of the channel.
CharSequence name = getString(R.string.channel_name);
// The user visible description of the channel.
String description = getString(R.string.channel_description);
int importance = NotificationManager.IMPORTANCE_LOW;
NotificationChannel mChannel = new NotificationChannel(id, name, importance);
// Configure the notification channel.
mChannel.setDescription(description);
mChannel.setShowBadge(false);
mNotificationManager.createNotificationChannel(mChannel);

You can call setNumber() to set a custom number to display in the long-press menu of an app in supported launchers, as illustrated by the following sample code for a messaging app:

mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
int notificationID = 1;
String CHANNEL_ID = "my_channel_01";
// Set a message count to associate with this notification in the long-press menu.
int messageCount = 3;
// Create a notification and set a number to associate with it.
NotificationCompat notification =
        new NotificationCompat.Builder(MainActivity.this, CHANNEL_ID)
            .setContentTitle("New Messages")
            .setContentText("You've received 3 new messages.")
            .setSmallIcon(R.drawable.ic_notify_status)
            .setNumber(messageCount)
            .build();
// Issue the notification.
mNotificationManager.notify(notificationID, notification);

The long-press menu displays the large or small icon associated with a notification if available. By default, the system displays the large icon, but you can call NotificationCompat.Builder.setBadgeIconType() and pass in the BADGE_ICON_SMALL constant to display the small icon.

If your app creates a notification that duplicates a shortcut, you can temporarily hide the shortcut while the notification is active. To hide a shortcut while a notification is active, call setShortcutId() and pass the ID of the shortcut. For more information on shortcuts, see App Shortcuts.

Replying to notifications

Starting in Android 7.0 (API level 24), users can respond directly to text messages or update task lists from within the notification dialog. On a handheld, the inline reply action appears as an additional button displayed in the notification. When a user replies via keyboard, the system attaches the text response to the intent you had specified for the notification action and sends the intent to your handheld app.

Figure 6. The Reply action button.

Adding inline reply actions

To create a notification action that supports direct reply:

  1. Create an instance of RemoteInput.Builder that you can add to your notification action. This class's constructor accepts a string that the system uses as the key for the text input. Later, your handheld app uses that key to retrieve the text of the input.
    // Key for the string that's delivered in the action's intent.
    private static final String KEY_TEXT_REPLY = "key_text_reply";
    String replyLabel = getResources().getString(R.string.reply_label);
    RemoteInput remoteInput = new RemoteInput.Builder(KEY_TEXT_REPLY)
            .setLabel(replyLabel)
            .build();
    
  2. Create a PendingIntent for the reply action.
    // Build a PendingIntent for the reply action to trigger.
    PendingIntent replyPendingIntent =
            PendingIntent.getBroadcast(getApplicationContext(),
                    conversation.getConversationId(),
                    getMessageReplyIntent(conversation.getConversationId()),
                    PendingIntent.FLAG_UPDATE_CURRENT);
    

    Caution: If you resue a PendingIntent, a user may reply to a different conversation than the one they thought they did. You must either provide a request code that is different for each conversation or provide an intent that doesn't return true when you call equals() on the reply intent of any other conversation. The conversation ID is frequently passed as part of the intent's extras bundle, but is ignored when you call equals().

  3. Attach the RemoteInput object to an action using addRemoteInput().
    // Create the reply action and add the remote input.
    Notification.Action action =
            new Notification.Action.Builder(R.drawable.ic_reply_icon,
                    getString(R.string.label), replyPendingIntent)
                    .addRemoteInput(remoteInput)
                    .build();
    
  4. Apply the action to a notification and issue the notification.
    // Build the notification and add the action.
    Notification newMessageNotification =
            new Notification.Builder(mContext, CHANNEL_ID)
                .setSmallIcon(R.drawable.ic_message)
                .setContentTitle(getString(R.string.title))
                .setContentText(getString(R.string.content))
                .addAction(action))
                .build();
    
    // Issue the notification.
    NotificationManager notificationManager =
            NotificationManager.from(mContext);
    notificationManager.notify(notificationId, newMessageNotification);
    
    

The system prompts the user to input a response when they trigger the notification action.

Figure 7. The user inputs text from the notification shade.

Retrieving user input from the inline reply

To receive user input from the notification interface to the activity you declared in the reply action's intent:

  1. Call getResultsFromIntent() by passing the notification action's intent as the input parameter. This method returns a Bundle that contains the text response.
    Bundle remoteInput = RemoteInput.getResultsFromIntent(intent);
    
  2. Query the bundle using the result key (provided to the RemoteInput.Builder constructor). You can complete this process and retrieve the input text by creating a method, as in the following code snippet:
    // Obtain the intent that started this activity by calling
    // Activity.getIntent() and pass it into this method to
    // get the associated string.
    
    private CharSequence getMessageText(Intent intent) {
        Bundle remoteInput = RemoteInput.getResultsFromIntent(intent);
        if (remoteInput != null) {
            return remoteInput.getCharSequence(KEY_TEXT_REPLY);
        }
        return null;
     }
    
  3. Build and issue another notification, using the same notification ID that you provided for the previous notification. The progress indicator disappears from the notification interface to inform users of a successful reply. When working with this new notification, use the context that gets passed to the receiver's onReceive() method.
    // Build a new notification, which informs the user that the system
    // handled their interaction with the previous notification.
    Notification repliedNotification =
            new Notification.Builder(context, CHANNEL_ID)
                .setSmallIcon(R.drawable.ic_message)
                .setContentText(getString(R.string.replied))
                .build();
    
    // Issue the new notification.
    NotificationManager notificationManager =
            NotificationManager.from(context);
    notificationManager.notify(notificationId, repliedNotification);
    

For interactive apps, such as chats, you can include additional context when handling retrieved text. For example, these apps could show multiple lines of chat history. When the user responds via RemoteInput, you can update the reply history using the setRemoteInputHistory() method.

The notification must be either updated or cancelled after the app has received remote input. When the user replies to a remote update using Direct Reply, do not cancel the notification. Instead, update the notification to display the user's reply. For notifications using MessagingStyle, you should add the reply as the latest message. When using other templates, you can append the user's reply to the remote-input history.

Bundling notifications

Starting in Android 7.0 (API level 24), Android provides developers with a way to represent a queue of notifications: bundled notifications. This is similar to the Notification Stacks feature in Android Wear. For example, if your app creates notifications for received messages, when more than one message is received, bundle the notifications together as a single group. You can use the Builder.setGroup() method to bundle similar notifications.

A notification group imposes a hierarchy on the notifications comprising it. At the top of that hierarchy is a parent notification that displays summary information for the group. The user can progressively expand the notification group, and the system shows more information as the user drills deeper. When the user expands the bundle, the system reveals more information for all its child notifications; when the user expands one of those notifications, the system reveals its entire content.

Figure 8. The user can progressively expand the notification group.

Note: If the same app sends four or more notifications and does not specify a grouping, the system automatically groups them together.

To learn how to add notifications to a group, see Add Each Notification to a Group.

Best practices for bundled notifications

This section provides guidelines about when to use notification groups instead of the InboxStyle notifications available in Android 6.0 and previous versions.

When to use bundled notifications

You should use notification groups only if all of the following conditions are true for your use case:

Examples of good use cases for notification groups include: a messaging app displaying a list of incoming messages, or an email app displaying a list of received emails.

Examples of cases where a single notification is preferable include individual messages from a single person, or a list representation of single-line text items. You can use (InboxStyle or BigTextStyle) to accomplish this.

Displaying bundled notifications

The app should always post a group summary, even if the group contains just a single child. The system will suppress the summary and directly display the child notification if it only contains a single notification. This ensures that the system can provide a consistent experience when the user swipes away children of a group.

Peeking notifications

While the system usually displays child notifications as a group, you can set them to temporarily appear as heads-up notifications. This feature is especially useful because it allows immediate access to the most recent child and the actions associated with it.

Backwards compatibility

Both notification groups and remote input have been a part of the Notification API since Android 5.0 (API level 21) to support Android Wear devices. If you've already built notifications with these APIs, the only action you must take is to verify that the app behavior corresponds to the guidelines described above, and to consider implementing setRemoteInputHistory().

In order to support backward compatibility, the same APIs are available with the support library's NotificationCompat class, allowing you to build notifications that works on versions of Android less than 5.0 (API level 21). On handhelds and tablets, users only see the summary notification, so an app should still have an inbox style or an equivalent notification representative for the whole information content of the group. As Android Wear devices allow users to see all child notifications even on older platform levels, you should build child notifications regardless of API level.

Preserving navigation when starting an activity

When you start an Activity from a notification, you must preserve the user's expected navigation experience. Clicking Back should take the user back through the app's normal work flow to the Home screen, and clicking Recents should show the Activity as a separate task. To preserve the navigation experience, you should start the Activity in a fresh task. How you set up the PendingIntent to give you a fresh task depends on the nature of the Activity you're starting. There are two general situations:

Regular activity
You're starting an Activity that's part of the app's normal workflow. In this situation, set up the PendingIntent to start a fresh task, and provide the PendingIntent with a back stack that reproduces the app's normal Back behavior.

Notifications from the Gmail app demonstrate this. When you click a notification for a single email message, you see the message itself. Touching Back takes you backwards through Gmail to the Home screen, just as if you had entered Gmail from the Home screen rather than entering it from a notification.

This happens regardless of the app you were in when you touched the notification. For example, if you're in Gmail composing a message, and you click a notification for a single email, you go immediately to that email. Touching Back takes you to the inbox and then the Home screen, rather than taking you to the message you were composing.

Special activity
The user only sees this Activity if it's started from a notification. In a sense, the Activity extends the notification by providing information that would be hard to display in the notification itself. For this situation, set up the PendingIntent to start in a fresh task. There's no need to create a back stack, though, because the started Activity isn't part of the app's activity flow. Clicking Back will still take the user to the Home screen.

Setting up a regular activity PendingIntent

To set up a PendingIntent that starts a direct entry Activity, follow these steps:

  1. Define your app's Activity hierarchy in the manifest.
    1. Add support for Android 4.0.3 and lower. To do this, specify the parent of the Activity you're starting by adding a <meta-data> element as the child of the <activity>.

      For this element, set android:name="android.support.PARENT_ACTIVITY". Set android:value="<parent_activity_name>" where <parent_activity_name> is the value of android:name for the parent <activity> element. See the following XML for an example.

    2. Also add support for Android 4.1 and later. To do this, add the android:parentActivityName attribute to the <activity> element of the Activity you're starting.

    The final XML should look like this:

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".ResultActivity"
        android:parentActivityName=".MainActivity">
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value=".MainActivity"/>
    </activity>
    
  2. Create a back stack based on the Intent that starts the Activity:
    1. Create the Intent to start the Activity.
    2. Create a stack builder by calling TaskStackBuilder.create().
    3. Add the back stack to the stack builder by calling addParentStack(). For each Activity in the hierarchy you've defined in the manifest, the back stack contains an Intent object that starts the Activity. This method also adds flags that start the stack in a fresh task.

      Note: Although the argument to addParentStack() is a reference to the started Activity, the method call doesn't add the Intent that starts the Activity. Instead, that's taken care of in the next step.

    4. Add the Intent that starts the Activity from the notification, by calling addNextIntent(). Pass the Intent you created in the first step as the argument to addNextIntent().
    5. If you need to, add arguments to Intent objects on the stack by calling TaskStackBuilder.editIntentAt(). This is sometimes necessary to ensure that the target Activity displays meaningful data when the user navigates to it using Back.
    6. Get a PendingIntent for this back stack by calling getPendingIntent(). You can then use this PendingIntent as the argument to setContentIntent().

The following code snippet demonstrates the process:

...
Intent resultIntent = new Intent(this, ResultActivity.class);
TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
// Adds the back stack
stackBuilder.addParentStack(ResultActivity.class);
// Adds the Intent to the top of the stack
stackBuilder.addNextIntent(resultIntent);
// Gets a PendingIntent containing the entire back stack
PendingIntent resultPendingIntent =
        stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
...
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
builder.setContentIntent(resultPendingIntent);
NotificationManager mNotificationManager =
    (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
mNotificationManager.notify(id, builder.build());

Setting up a special activity PendingIntent

The following section describes how to set up a special activity PendingIntent.

A special Activity doesn't need a back stack, so you don't have to define its Activity hierarchy in the manifest, and you don't have to call addParentStack() to build a back stack. Instead, use the manifest to set up the Activity task options, and create the PendingIntent by calling getActivity():

  1. In your manifest, add the following attributes to the <activity> element for the Activity
    android:name="activityclass"
    The activity's fully-qualified class name.
    android:taskAffinity=""
    Combined with the FLAG_ACTIVITY_NEW_TASK flag that you set in code, this ensures that this Activity doesn't go into the app's default task. Any existing tasks that have the app's default affinity are not affected.
    android:excludeFromRecents="true"
    Excludes the new task from Recents, so that the user can't accidentally navigate back to it.

    This snippet shows the element:

    <activity
        android:name=".ResultActivity"
    ...
        android:launchMode="singleTask"
        android:taskAffinity=""
        android:excludeFromRecents="true">
    </activity>
    ...
    
  2. Build and issue the notification:
    1. Create an Intent that starts the Activity.
    2. Set the Activity to start in a new, empty task by calling setFlags() with the flags FLAG_ACTIVITY_NEW_TASK and FLAG_ACTIVITY_CLEAR_TASK.
    3. Set any other options you need for the Intent.
    4. Create a PendingIntent from the Intent by calling getActivity(). You can then use this PendingIntent as the argument to setContentIntent().

    The following code snippet demonstrates the process:

    // Instantiate a Builder object.
    NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
    // Creates an Intent for the Activity
    Intent notifyIntent =
            new Intent(this, ResultActivity.class);
    // Sets the Activity to start in a new, empty task
    notifyIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                            | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    // Creates the PendingIntent
    PendingIntent notifyPendingIntent =
            PendingIntent.getActivity(
            this,
            0,
            notifyIntent,
            PendingIntent.FLAG_UPDATE_CURRENT
    );

    // Puts the PendingIntent into the notification builder builder.setContentIntent(notifyPendingIntent); // Notifications are issued by sending them to the // NotificationManager system service. NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); // Builds an anonymous Notification object from the builder, and // passes it to the NotificationManager mNotificationManager.notify(id, builder.build());

Displaying progress in a notification

Notifications can include an animated progress indicator that shows users the status of an ongoing operation. If you can estimate how long the operation takes and how much of it is complete at any time, use the "determinate" form of the indicator (a progress bar). If you can't estimate the length of the operation, use the "indeterminate" form of the indicator (an activity indicator).

Progress indicators are displayed with the platform's implementation of the ProgressBar class.

To use a progress indicator on platforms starting with Android 4.0, call setProgress(). For previous versions, you must create your own custom notification layout that includes a ProgressBar view.

The following sections describe how to display progress in a notification using setProgress().

Displaying a fixed-duration progress indicator

To display a determinate progress bar, add the bar to your notification by calling setProgress(max, progress, false) and then issue the notification. As your operation proceeds, increment progress, and update the notification. At the end of the operation, progress should equal max. A common way to call setProgress() is to set max to 100 and then increment progress as a "percent complete" value for the operation.

You can either leave the progress bar showing when the operation is done, or remove it. In either case, remember to update the notification text to show that the operation is complete. To remove the progress bar, call setProgress(0, 0, false). For example:

...
mNotifyManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
mBuilder = new NotificationCompat.Builder(this, CHANNEL_ID);
mBuilder.setContentTitle("Picture Download")
    .setContentText("Download in progress")
    .setSmallIcon(R.drawable.ic_notification);
// Start a lengthy operation in a background thread
new Thread(
    new Runnable() {
        @Override
        public void run() {
            int incr;
            // Do the "lengthy" operation 20 times
            for (incr = 0; incr <= 100; incr+=5) {
                    // Sets the progress indicator to a max value, the
                    // current completion percentage, and "determinate"
                    // state
                    mBuilder.setProgress(100, incr, false);
                    // Displays the progress bar for the first time.
                    mNotifyManager.notify(0, mBuilder.build());
                        // Sleeps the thread, simulating an operation
                        // that takes time
                        try {
                            // Sleep for 5 seconds
                            Thread.sleep(5*1000);
                        } catch (InterruptedException e) {
                            Log.d(TAG, "sleep failure");
                        }
            }
            // When the loop is finished, updates the notification
            mBuilder.setContentText("Download complete")
            // Removes the progress bar
                    .setProgress(0,0,false);
            mNotifyManager.notify(ID, mBuilder.build());
        }
    }
// Starts the thread by calling the run() method in its Runnable
).start();

Displaying a continuing activity indicator

To display an indeterminate activity indicator, add it to your notification with setProgress(0, 0, true) (the first two arguments are ignored), and issue the notification. The result is an indicator that has the same style as a progress bar, except that its animation is ongoing.

Issue the notification at the beginning of the operation. The animation will run until you modify your notification. When the operation is done, call setProgress(0, 0, false) and then update the notification to remove the activity indicator. Always do this; otherwise, the animation will run even when the operation is complete. Also remember to change the notification text to indicate that the operation is complete.

To see how activity indicators work, refer to the preceding snippet. Locate the following lines:

// Sets the progress indicator to a max value, the current completion
// percentage, and "determinate" state
mBuilder.setProgress(100, incr, false);
// Issues the notification
mNotifyManager.notify(0, mBuilder.build());

Replace the lines you've found with the following lines:

// Sets an activity indicator for an operation of indeterminate length
mBuilder.setProgress(0, 0, true);
// Issues the notification
mNotifyManager.notify(0, mBuilder.build());

Notification metadata

On devices running Android 8.0 (API level 26) and higher, notifications may be sorted according to metadata that you assign when creating a NotificationChannel. Remember that a user can visit Settings, or long-press a notification to change the metadata, or even block a notification channel at any time. For more information on notification channel behaviors, see Managing notification channels.

On devices running Android 7.1 (API level 25) and lower, notifications may be sorted according to metadata that you assign with the following NotificationCompat.Builder methods:

Figure 9. Fullscreen activity showing a heads-up notification

Heads-up notifications

With Android 5.0 (API level 21), notifications can appear in a small floating window (also called a heads-up notification) when the device is active (that is, the device is unlocked and its screen is on). These notifications appear similar to the compact form of your notification, except that the heads-up notification also shows action buttons. Users can act on, or dismiss, a heads-up notification without leaving the current app.

Examples of conditions that may trigger heads-up notifications include:

Lock screen notifications

With the release of Android 5.0 (API level 21), notifications may now appear on the lock screen. Your app can use this functionality to provide media playback controls and other common actions. Users can choose via Settings whether to display notifications on the lock screen, and you can designate whether a notification from your app is visible on the lock screen.

Setting visibility

Your app can control the level of detail visible in notifications displayed on a secure lock screen. You call setVisibility() and specify one of the following values:

When VISIBILITY_PRIVATE is set, you can also provide an alternate version of the notification content which hides certain details. For example, an SMS app might display a notification that shows You have 3 new text messages, but hides the message contents and senders. To provide this alternative notification, first create the replacement notification using NotificationCompat.Builder. When you create the private notification object, attach the replacement notification to it through the setPublicVersion() method.

Controlling media playback on the lock screen

In Android 5.0 (API level 21) the lock screen no longer displays media controls based on the RemoteControlClient, which is now deprecated. Instead, use the NotificationCompat.MediaStyle template with the addAction() method, which converts actions into clickable icons.

To display media playback controls on the lock screen in Android 5.0, set the visibility to VISIBILITY_PUBLIC, as described above. Then add the actions and set the NotificationCompat.MediaStyle template, as described in the following sample code:

Notification notification =
        new NotificationCompat.Builder(context, CHANNEL_ID)
            // Show controls on lock screen even when user hides sensitive content.
            .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
            .setSmallIcon(R.drawable.ic_stat_player)
            // Add media control buttons that invoke intents in your media service
            .addAction(R.drawable.ic_prev, "Previous", prevPendingIntent) // #0
            .addAction(R.drawable.ic_pause, "Pause", pausePendingIntent)  // #1
            .addAction(R.drawable.ic_next, "Next", nextPendingIntent)     // #2
            // Apply the media style template
            .setStyle(new MediaStyle()
            .setShowActionsInCompactView(1 /* #1: pause button */)
            .setMediaSession(mMediaSession.getSessionToken()))
            .setContentTitle("Wonderful music")
            .setContentText("My Awesome Band")
            .setLargeIcon(albumArtBitmap)
            .build();

Note: The deprecation of RemoteControlClient has further implications for controlling media. See Media Playback Control for more information about the new APIs for managing the media session and controlling playback.

Custom notification layouts

The notifications framework allows you to define a custom notification layout, which defines the notification's appearance in a RemoteViews object. Custom layout notifications are similar to normal notifications, but they're based on a RemoteViews defined in a XML layout file.

The height available for a custom notification layout depends on the notification view. Normal view layouts are limited to 64 dp, and expanded view layouts are limited to 256 dp.

To define a custom notification layout, start by instantiating a RemoteViews object that inflates an XML layout file. Then, instead of calling methods such as setContentTitle(), call setContent(). To set content details in the custom notification, use the methods in RemoteViews to set the values of the view's children:

  1. Create an XML layout for the notification in a separate file. You can use any filename you wish, but you must use the extension .xml
  2. In your app, use RemoteViews methods to define your notification's icons and text. Put this RemoteViews object into your NotificationCompat.Builder by calling setContent(). Avoid setting a background Drawable on your RemoteViews object, because your text color may become unreadable.

The RemoteViews class also includes methods that you can use to easily add a Chronometer or ProgressBar to your notification's layout. For more information about creating custom layouts for your notification, refer to the RemoteViews reference documentation.

Caution: When you use a custom notification layout, take special care to ensure that your custom layout works with different device orientations and resolutions. While this advice applies to all View layouts, it's especially important for notifications because the space in the notification drawer is very restricted. Don't make your custom layout too complex, and be sure to test it in various configurations.

Using style resources for custom notification text

Always use style resources for the text of a custom notification. The background color of the notification can vary across different devices and versions, and using style resources helps you account for this. Starting in Android 2.3, the system defined a style for the standard notification layout text. If you use the same style in apps that target Android 2.3 or higher, you'll ensure that your text is visible against the display background.

Background colors

Starting from Android 8.0 (API level 26), you can set and enable a background color for a notification. You must only use this feature in notifications for ongoing tasks which are critical for the user to see at a glance. For example, you could set a background color for notifications related to driving directions, or a phone call in progress. You can also set the desired background color using setColor(). Doing so allows you to use setColorized() to enable the use of a background color for a notification.

Custom views

Starting from Android 7.0 (API level 24), you can customize notification views and still obtain system decorations like notification headers, actions, and expandable layouts.

To enable this capability, Android provides the following APIs to style your custom view:

DecoratedCustomViewStyle()
Styles notifications other than media notifications.
DecoratedMediaCustomViewStyle()
Styles media notifications.

To use this API, call the setStyle() method, passing to it the desired custom view style.

This snippet shows how to construct a custom notification object with the DecoratedCustomViewStyle() method.

Notification notification = new Notification.Builder(context, CHANNEL_ID)
           .setSmallIcon(R.drawable.ic_stat_player)
           .setLargeIcon(albumArtBitmap))
           .setCustomContentView(contentView);
           .setStyle(new Notification.DecoratedCustomViewStyle())
           .build();

Messaging style

Starting in Android 7.0 (API level 24), Android provides an API for customizing the style of a notification. Use the Notification.MessagingStyle class for notifications that are messaging-related. Using the Notification.MessagingStyle class, you can change several of the labels displayed on the notification, including the conversation title, additional messages, and the content view for the notification.

The following code snippet demonstrates how to customize a notification's style using the MessagingStyle class.

Notification notification = new Notification.Builder(context, CHANNEL_ID)
        .setStyle(new Notification.MessagingStyle("Me")
        .setConversationTitle("Team lunch")
        .addMessage("Hi", timestamp1, null) // Pass in null for user.
        .addMessage("What's up?", timestamp2, "Coworker")
        .addMessage("Not much", timestamp3, null)
        .addMessage("How about lunch?", timestamp4, "Coworker"))
        .build();

Starting in Android 8.0 (API level 26), notifications that use the Notification.MessagingStyle class display more content in their collapsed form. You can also use the addHistoricMessage() method to provide context to a conversation by adding historic messages to messaging-related notifications.

Best practices for notifications in messaging apps

To create an app that users care about, design your notifications carefully. When you plan your notifications, make sure that the app notifications do not interrupt the user's task flow. You can use the best practices listed here as a quick reference of what to keep in mind when creating notifications for your messaging and chat apps.

Use MessagingStyle

Use direct reply

Enable smart reply

Use notification metadata

Note: The android-ActiveNotifications, android-BasicNotifications, android-LNotifications, android-MessagingService, android-NotificationChannels and android-CustomNotifications samples further demonstrate the use of the APIs covered on this page.

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