Android Developer Fundamentals V2
Alarms and
Schedulers
Lesson 8
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8.1 Notifications
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Contents
● What are notifications? ● Tap action and action buttons
● Notification channels ● Expanded view notifications
● Creating a notification channel ● Delivering notifications
● Creating notifications ● Managing Notifications
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What Are
Notifications?
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What is a notification?
Message displayed to user outside regular app UI
■ Small icon
■ Title
■ Detail text
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How are notifications used?
● Android issues a notification that appears as
icon on the status bar.
● To see details, user opens the notification
drawer.
● User can view notifications any time in the
notification drawer.
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App icon badge
Available only on the devices running Android 8.0 (API level 26) and higher.
● New notifications are displayed as a colored
"badge" (also known as a "notification dot") on
the app icon.
● Users can long-press on an app icon to see the
notifications for that app. Similar to the
notification drawer.
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Notification
Channels
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Notification channels
● Used to create a user-customizable channel for each type
of notification to be displayed.
● More than one notification can be grouped in to a channel.
● Set notification behavior like sound, light, vibrate and so on,
applied to all the notifications in that channel.
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Notification channels are mandatory
● Notification channels are introduced in Android 8.0 (API
level 26)
● All notifications must be assigned to a channel starting
from Android 8.0 (API level 26), else your notifications will
not be displayed.
● For the apps targeting lower than Android 8.0 (API level
26), no need to implement notification channels.
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Notification channels in Settings
● Notification channels appear as
Categories under App
notifications in the device
Settings.
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Creating a
Notification
channel
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Create a Notification channel
● Notification channel instance is created using NotificationChannel
constructor.
● You must specify:
○ An ID that's unique within your package.
○ User visible name of the channel.
○ The importance level for the channel.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationChannel notificationChannel =
new NotificationChannel(CHANNEL_ID, "Mascot Notification",
NotificationManager.IMPORTANCE_DEFAULT);
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Importance level
● Available in Android 8.0 (API level 26) and higher.
● Sets the intrusion level, like the sound and visibility for all
notifications posted in the channel.
● Range from IMPORTANCE_NONE(0) to
IMPORTANCE_HIGH(4).
● To support earlier versions of Android (Lower than API level 26),
set the priority.
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Notification priority
● Determines how the system displays the notification with
respect to other notifications, in Android version Lower
than API level 26.
● Set using the setPriority() method for each
notification.
● Range from PRIORITY_MIN to PRIORITY_MAX.
setPriority(NotificationCompat.PRIORITY_HIGH)
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Importance level and priority constants
Importance (Android 8.0 Priority (Android 7.1
User-visible importance level
and higher) and lower)
Urgent
PRIORITY_HIGH or
Makes a sound and appears as a heads-up IMPORTANCE_HIGH
PRIORITY_MAX
notification
High
IMPORTANCE_DEFAULT PRIORITY_DEFAULT
Makes a sound
Medium
IMPORTANCE_LOW PRIORITY_LOW
No sound
Low
No sound and doesn't appear in the status bar IMPORTANCE_MIN PRIORITY_MIN
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Creating
Notifications
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Creating Notification
● Notification is created using NotificationCompat.Builder class.
● Pass the application context and notification channel ID to the
constructor.
● The NotificationCompat.Builder constructor takes the notification
channel ID, this is only used by Android 8.0 (API level 26) and higher, but
this parameter is ignored by the older versions.
NotificationCompat.Builder mBuilder = new
NotificationCompat.Builder(this, CHANNEL_ID);
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Setting notification contents
1. A small icon, set by setSmallIcon().
This is the only content that's required.
1. A title, set by setContentTitle().
2. The body text, set by
setContentText(). This is the
notification message.
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Setting notification contents
NotificationCompat.Builder mBuilder =
new NotificationCompat.Builder(this, CHANNEL_ID)
.setSmallIcon(R.drawable.android_icon)
.setContentTitle("You've been notified!")
.setContentText("This is your notification text.");
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Tap action
and
Action buttons
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Add notification tap action
● Every notification must respond when it is tapped, usually
launching an Activity in your app.
● Set an content intent using setContentIntent() method.
● Pass the Intent wrapped in a PendingIntent object.
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Notification action buttons
● Action buttons can perform a variety of actions on behalf
of your app, such as starting a background task, placing a
phone call and so on.
● Starting from Android 7.0 (API level 24) reply to messages
directly from notifications.
● To add an action button, pass a PendingIntent to the
addAction() method.
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Pending intents
● A PendingIntent is a description of an intent and target
action to perform with it.
● Give a PendingIntent to another application to grant it
the right to perform the operation you have specified as if
the other app was yourself.
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Methods to create a PendingIntent
To instantiate a PendingIntent, use one of the following
methods:
● PendingIntent.getActivity()
● PendingIntent.getBroadcast()
● PendingIntent.getService()
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PendingIntent method arguments
1. Application context
2. Request code—constant integer id for the pending intent
3. Intent to be delivered
4. PendingIntent flag determines how the system handles
multiple pending intents from same app
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Step 1: Create intent
Intent notificationIntent =
new Intent(this, MainActivity.class);
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Step 2: Create PendingIntent
PendingIntent notificationPendingIntent =
PendingIntent.getActivity(
this,
NOTIFICATION_ID,
notificationIntent,
PendingIntent.FLAG_UPDATE_CURRENT);
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Step 3: Add to notification builder
To set tap action to the notification:
.setContentIntent(notificationPendingIntent);
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Add action buttons
● Use NotificationCompat.Builder.addAction()
— pass in icon, caption, PendingIntent
.addAction(R.drawable.ic_color_lens_black_24dp,
"R.string.label",
notificationPendingIntent);
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Expanded
view
notifications
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Expandable notifications
● Notifications in the notification drawer appear in two main
layouts, normal view (which is the default) and expanded
view.
● Expanded view notifications were introduced in Android 4.1.
● Use them sparingly -- they take up more space and
attention.
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Big text
● For large-format notifications that
include a lot of text.
● Fits more text than a standard view.
● Use the helper class:
NotificationCompat.BigTextStyle
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Big image
● For large-format notifications that
include a large image attachment.
● Use the helper class:
NotificationCompa.BigPictureStyle
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Media
● For media playback notifications.
● Actions for controlling media
such as music
● Image for album cover
● Use the helper class:
● NotificationCompat.MediaStyle
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Managing
Setting styles
Notifications
To create expandable notification that appear, use one of the
helper classes to set the style using the setStyle() method.
mNotifyBuilder
.setStyle(new NotificationCompat.BigPictureStyle()
.bigPicture(myBitmapImage)
.setBigContentTitle("Notification!"));
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Delivering
Notifications
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Building a Notification
Delivering notifications
● Use the NotificationManager class to deliver
notifications.
○ Create an instance of NotificationManager
○ Call notify() to deliver the notification.
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Building a Notification
Instantiate NotificationManager
Call getSystemService(), passing in the NOTIFICATION_SERVICE
constant.
mNotifyManager = (NotificationManager)
getSystemService(NOTIFICATION_SERVICE);
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Building
Send notification
a Notification
● Call notify()to deliver the notification, passing in these
two values:
○ A notification ID, which is used to update or cancel the notification.
○ The NotificationCompat object that you created using the
NotificationCompat.Builder object.
mNotifyManager.notify(NOTIFICATION_ID, myNotification);
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Managing
Notifications
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Managingnotifications
Updating Notifications
1. Update a notification by changing and or adding some of its
content.
2. Issue notification with updated parameters using builder.
3. Call notify() passing in the same notification ID.
● If previous notification is still visible, system updates.
● If previous notification has been dismissed, new
notification is delivered.
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Managing notifications
Canceling Notifications
Notifications remain visible until:
● User dismisses it by swiping or by using "Clear All".
● Calling setAutoCancel() when creating the notification,
removes it from the status bar when the user clicks on it.
● App calls cancel() or cancelAll() on
NotificationManager.
mNotifyManager.cancel(NOTIFICATION_ID);
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Design guidelines
If your app sends too many notifications, users will disable
notifications or uninstall the app.
● Relevant: Whether this information is essential for the user.
● Timely: Notifications need to appear when they are useful.
● Short: Use as few words as possible.
● Give users the power to choose -- Use appropriate
notification channels to categorise your notifications.
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What's Next?
● Concept Chapter: 8.1 Notifications
● Practical: 8.1 Notifications
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The End
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