*Creating a notification*
- To create:
- call `Notification.Builder.build()`, which returns a Notification object containing your specifications
- issue the notification by calling `notify()` (passes the Notification object to the system)
- A Notification object must contain:
- A small icon, set by `setSmallIcon()`
- A title, set by `setContentTitle()`
- Detail text, set by `setContentText()`
- A valid notification channel ID, set by `setChannelId()`
- If you target Android O and post a notification without specifying a valid notifications channel, the notification fails to post and the system logs an error.
- Note: You can turn on a new setting in Android O to display an on-screen warning that appears as a toast when an app targeting Android O attempts to post without a notification channel. To turn on the setting for a development device running Android O, navigate to Settings > Developer options and toggle Show notification channel warnings to on.
- Code example (code associates the notification with a notification channel using the channel’s ID):
```java {code}
mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
// Sets an ID for the notification, so it can be updated.
int notifyID = 1;
// The id of the channel.
String CHANNEL_ID = "my_channel_01";
// Create a notification and set the notification channel.
Notification notification = new Notification.Builder(MainActivity.this)
.setContentTitle("New Message")
.setContentText("You've received new messages.")
.setSmallIcon(R.drawable.ic_notify_status)
.setChannelId(CHANNEL_ID)
.build();
// Issue the notification.
mNotificationManager.notify(id, notification);
``` {code}
_*Reading notification channel settings*_
- Users can modify the settings for notification channels, including behaviors such as vibration and alert sound. You can discover the settings a user has applied to a notification channel by the following:
- To retrieve a single notification channel, you can call `getNotificationChannel()`.
```java {code}
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
NotificationChannel notificationChannel = notificationManager.getNotificationChannel("some_id");
``` {code}
- To retrieve all notification channels belonging to your app, you can call `getNotificationChannels()`.
```java {code}
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
List<NotificationChannel> notificationChannels = notificationManager.getNotificationChannels();
``` {code} |
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