The document provides information about notifications in Android L and best practices for implementing notifications. Some key points:
- Notifications in Android L receive visual, structural, and functional updates including new material design, availability on the lock screen, and heads-up notifications.
- Notifications should be used to inform users of relevant events and keep them updated when the app is not in use. Priority levels, categories, and expanded views are discussed.
- Guidelines are provided for making notifications personal, navigating to the right place, managing priority levels, summarizing notifications, using distinct icons, and more. When and when not to display notifications is also covered.
2. Notifications
• The notification system allows users to keep
informed about relevant and timely events in
your app, such as new chat messages from a
friend or a calendar event.
• Think of notifications as a news channel that
alerts the user to important events as they
happen or a log that chronicles events while the
user is not paying attention—and one that is
synced as appropriate across all their Android
devices.
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3. New in Android 5.0
In Android 5.0, notifications receive important updates: structurally, visually,
and functionally:
• Notifications have undergone visual changes consistent with the new
material design theme.
• Notifications are now available on the device lock screen, while sensitive
content can still be hidden behind it.
• High-priority notifications received while the device is in use now use a
new format called heads-up notifications.
• Cloud-synced notifications: Dismissing a notification on one of your
Android devices dismisses it on the others, as well.
Note: Notification design in this version of Android is a significant departure
from that of previous versions. For information about notification design in
previous versions, see Notifications in Android 4.4 and lower.
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4. Anatomy of a Notification
This section goes over basic parts of a notification and how
they can appear on different types of devices.
• Base layout
• At a minimum, all notifications consist of a base layout,
including:
• The notification's icon. The icon symbolizes the originating
app. It may also potentially indicate notification type if the
app generates more than one type.
• A notification title and additional text.
• A timestamp.
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Notifications created with Notification.Builder for previous
platform versions look and work the same in Android 5.0,
with only minor stylistic changes that the system handles
for you.
Base layout of a handheld notification (left) and the same notification on
Wear (right), with a user photo and a notification icon
6. Expanded layouts
• You can choose how much detail your app's notifications should
provide. They can show the first few lines of a message or show a
larger image preview.
• The additional information provides the user with more context,
and—in some cases—may allow the user to read a message in its
entirety.
• The user can pinch-zoom or perform a single-finger glide to toggle
between compact and expanded layouts.
• For single-event notifications, Android provides three expanded
layout templates (text, inbox, and image) for you to use in your
application. The following images show you how single-event
notifications look on handhelds (left) and wearables (right).
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Actions
Android supports optional actions that are displayed at the bottom of the
notification.
With actions, users can handle the most common tasks for a particular notification
from within the notification shade without having to open the originating
application. This speeds up interaction and, in conjunction with swipe-to-dismiss,
helps users focus on notifications that matter to them
11. Be judicious with how many actions you include with a notification. The more actions
you include, the more cognitive complexity you create. Limit yourself to the smallest
number of actions possible by only including the most imminently important and
meaningful actions.
• Good candidates for actions on notifications are actions that:
• Are essential, frequent, and typical for the content type you're displaying
• Allow the user to accomplish tasks quickly
Avoid actions that are:
• Ambiguous
• The same as the default action of the notification (such as "Read" or "Open")
• You can specify a maximum of three actions, each consisting of an action icon and
name. Adding actions to a simple base layout makes the notification expandable,
even if the notification doesn't have an expanded layout. Since actions are only
shown for expanded notifications and are otherwise hidden, make sure that any
action a user can invoke from a notification is available from within the associated
application, as well.
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When a high-priority notification arrives (see
right), it is presented to users for a short period
of time with an expanded layout exposing
possible actions.
After this period of time, the notification
retreats to the notification shade. If a
notification's priority is flagged as High, Max, or
full-screen, it gets a heads-up notification.
Good examples of heads-up notifications
•Incoming phone call when using a device
•Alarm when using a device
•New SMS message
•Low battery
Heads-up Notification
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Guidelines
Make it personal
For notifications of items sent by another person (such as a message or status
update), include that person's image using setLargeIcon(). Also attach information
about the person to the notification's metadata (see EXTRA_PEOPLE).
Your notification's main icon is still shown, so the user can associate it with the icon
visible in the status bar.
Notification that shows the person who triggered it and the content they sent.
14. Navigate to the right place
• When the user touches the body of a notification (outside of the
action buttons), open your app to the place where the user can
view and act upon the data referenced in the notification.
• In most cases, this will be the detailed view of a single data item
such as a message, but it might also be a summary view if the
notification is stacked.
• If your app takes the user anywhere below your app's top level,
insert navigation into your app's back stack so that the user can
press the system back button to return to the top level.
• For more information, see Navigation into Your App via Home
Screen Widgets and Notifications in the Navigation design pattern.
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15. Correctly set and manage notification priority
• Android supports a priority flag for
notifications.
• This flag allows you to influence where your
notification appears, relative to other
notifications, and helps ensure that users
always see their most important notifications
first.
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Priority Use
MAX Use for critical and urgent notifications that alert the user to a condition
that is time-critical or needs to be resolved before they can continue with a
particular task.
HIGH Use primarily for important communication, such as message or chat
events with content that is particularly interesting for the user. High-
priority notifications trigger the heads-up notification display.
DEFAULT Use for all notifications that don't fall into any of the other priorities
described here.
LOW Use for notifications that you want the user to be informed about, but that
are less urgent. Low-priority notifications tend to show up at the bottom of
the list, which makes them a good choice for things like public or
undirected social updates: The user has asked to be notified about them,
but these notifications should never take precedence over urgent or direct
communication.
MIN Use for contextual or background information such as weather information
or contextual location information. Minimum-priority notifications do not
appear in the status bar. The user discovers them on expanding the
notification shade.
17. How to choose an appropriate priority
DEFAULT, HIGH, and MAX are interruptive priority levels, and risk
interrupting the user in mid-activity. To avoid annoying your app's
users, reserve interruptive priority levels for notifications that:
• Involve another person
• Are time-sensitive
• Might immediately change the user's behavior in the real world
Notifications set to LOW and MIN can still be valuable for the user:
Many, if not most, notifications just don't need to command the user's
immediate attention, or vibrate the user's wrist, yet contain
information that the user will find valuable when they choose to look
for notifications.
Criteria for LOW and MIN priority notifications include:
• Don't involve other people
• Aren't time sensitive
• Contain content the user might be interested in but could choose to
browse at their leisure
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CATEGORY_CALL Incoming call (voice or video) or similar synchronous communication request
CATEGORY_MESSAGE Incoming direct message (SMS, instant message, etc.)
CATEGORY_EMAIL Asynchronous bulk message (email)
CATEGORY_EVENT Calendar event
CATEGORY_PROMO Promotion or advertisement
CATEGORY_ALARM Alarm or timer
CATEGORY_PROGRESS Progress of a long-running background operation
CATEGORY_SOCIAL Social network or sharing update
CATEGORY_ERROR Error in background operation or authentication status
CATEGORY_TRANSPORT Media transport control for playback
CATEGORY_SYSTEM System or device status update. Reserved for system use.
CATEGORY_SERVICE Indication of running background service
CATEGORY_RECOMMENDATION A specific, timely recommendation for a single thing. For example, a news app might want to recommend a news story it
believes the user will want to read next.
CATEGORY_STATUS Ongoing information about device or contextual status
Set a notification category
If your notification falls into one of the predefined categories (see below), assign
it accordingly.
Aspects of the system UI such as the notification shade (or any other notification
listener) may use this information to make ranking and filtering decisions.
20. Summarize your notifications
• If a notification of a certain type is already
pending when your app tries to send a new
notification of the same type, combine them
into a single summary notification for the app.
Do not create a new object.
• A summary notification builds a summary
description and allows the user to understand
how many notifications of a particular kind are
pending.
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You can provide more detail
about the individual
notifications that make up a
summary by using the
expanded digest layout.
This approach allows users
to gain a better sense of
which notifications are
pending and if they are
interesting enough to read
in detail within the
associated app.
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Make notifications optional
Users should always be in control of
notifications.
Allow the user to disable your app's
notifications or change their alert
properties, such as alert sound and
whether to use vibration, by adding a
notification settings item to your application
settings.
Use distinct icons
By glancing at the notification area, the
user should be able to discern what kinds
of notifications are currently pending.
24. Do
• Look at the notification icons Android apps already provide and create notification
icons for your app that are sufficiently distinct in appearance.
Do
• Use the proper notification icon style for small icons, and the Material Light action
bar icon stylefor your action icons.
Do
• Keep your icons visually simple, avoiding excessive detail that is hard to discern.
Don't
• Place any additional alpha (dimming or fading) into your small icons and action
icons; they can have anti-aliased edges, but because Android uses these icons as
masks (that is, only the alpha channel is used), the image should generally be
drawn at full opacity.
Don't
• Use color to distinguish your app from others. Notification icons should only be a
white-on-transparent background image.
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25. Pulse the notification LED appropriately
• Many Android devices contain a notification LED, which
is used to keep the user informed about events while
the screen is off.
• Notifications with a priority level of MAX, HIGH,
or DEFAULT should cause the LED to glow, while those
with lower priority (LOW and MIN) should not.
• The user's control over notifications should extend to
the LED.
• When you use DEFAULT_LIGHTS, the LED will glow
white. Your notifications shouldn't use a different color
unless the user has explicitly customized it.
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Building Notifications That Users Care About
To create an app that users love, it is important to design your notifications carefully.
Notifications embody your app's voice, and contribute to your app's personality.
Unwanted or unimportant notifications can annoy the user or make them resent how
much attention the app wants from them, so use notifications judiciously.
.
27. When to display a notification
• To create an application that people enjoy using, it's important to
recognize that the user's attention and focus is a resource that must
be protected.
• While Android's notification system has been designed to minimize
the impact of notifications on the user's attention, it is still
important to be aware of the fact that notifications are interrupting
the user's task flow.
• As you plan your notifications, ask yourself if they are important
enough to warrant an interruption.
• If you are unsure, allow the user to opt into a notification using
your apps notification settings, or adjust the notifications priority
flag to LOW or MIN to avoid distracting the user while they are
doing something else
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Examples of time-sensitive
notification
While well-behaved apps generally only speak
when spoken to, a few cases do merit an app's
interrupting the user with an unprompted
notification.
Use notifications primarily for time-sensitive
events, especially if these synchronous events
involve other people.
For instance, an incoming chat is a real-time
and synchronous form of communication:
Another user actively waiting on your
response.
Calendar events are another good example of
when to use a notification and grab the user's
attention, because the event is imminent, and
calendar events often involve other people.
30. When not to display a notification
In many other cases, notifications aren't appropriate:
• Avoid notifying the user of information that is not directed specifically at
them, or information that is not truly time-sensitive.
• For instance, the asynchronous and undirected updates flowing through a
social network generally do not warrant a real-time interruption. For the
users who do care about them, allow them to opt-in.
• Don't create a notification if the relevant new information is currently on
screen.
• Instead, use the UI of the application itself to notify the user of new
information directly in context. For instance, a chat application should not
create system notifications while the user is actively chatting with another
user.
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31. • Don't interrupt the user for low-level technical operations, like
saving or syncing information, or updating an application if the app
or system can resolve the issue without involving the user.
• Don't interrupt the user to inform them of an error if it is possible
for the application to recover from the error on its own without the
user taking any action.
• Don't create notifications that have no true notification content and
merely advertise your app. A notification should provide useful,
timely, new information and should not be used merely to launch
an app.
• Don't create superfluous notifications just to get your brand in front
of users. Such notifications frustrate and likely alienate your
audience. The best way to provide small amounts of updated
information and keep them engaged with your app is to develop a
widget that they can choose to place on their home screen.
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32. Interacting with Notifications
• Notifications are indicated by icons in the
status bar, and can be accessed by opening
the notification drawer.
• Touching a notification opens the associated
app to detailed content that matches the
notification.
• Swiping left or right on a notification removes
it from the drawer.
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33. Ongoing notifications
• Ongoing notification due to music playback
• Ongoing notifications keep users informed about an
ongoing process in the background. For example, music
players announce the currently playing track in the
notification system and continue to do so until the user
stops the playback.
• Ongoing notifications can also show the user feedback
for longer tasks like downloading a file, or encoding a
video. A user cannot manually remove an ongoing
notification from the notification drawer.
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35. Media playback
• In Android 5.0, the lock screen doesn't show transport
controls for the deprecated RemoteControlClient class.
• But it does show notifications, so each app's playback
notification is now the primary way for users to control
playback from a locked state.
• This behavior gives apps more control over which
buttons to show, and in what way, while providing a
consistent experience for the user whether or not the
screen is locked.
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36. Dialogs and toasts
• Your app should not create a dialog or toast if
it is not currently on screen.
• A dialog or toast should only be displayed as
an immediate response to the user taking an
action inside of your app.
• For further guidance on the use of dialogs and
toasts, refer to Confirming & Acknowledging.
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37. Ranking and ordering
• Notifications are news, and so are essentially shown in reverse-chronological
order, with special consideration given to the app's stated notification priority.
• Notifications are a key part of the lock screen, and are featured prominently every
time the device display comes on. Space on the lock screen is tight, so it is more
important than ever to identify the most urgent or relevant notifications.
• For this reason, Android has a more sophisticated sorting algorithm for
notifications, taking into account:
• The timestamp and application's stated priority.
• Whether the notification has recently disturbed the user with sound or vibration.
(That is, if the phone just made a noise, and the user wants to know "What just
happened?", the lock screen should answer that at a glance.)
• Any people attached to the notification using EXTRA_PEOPLE, and, in particular,
whether they are starred contacts.
• To best take advantage of this sorting, focus on the user experience you want to
create, rather than aiming for any particular spot on the list.
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Gmail notifications are default priority, so they normally sort below messages
from an instant messaging app like Hangouts, but get a temporary bump
when new messages come in.
39. On the lock screen
• Because notifications are visible on the lock screen, user
privacy is an especially important consideration.
• Notifications often contain sensitive information, and
should not necessarily be visible to anyone who picks up
the device and turns on the display.
• For devices that have a secure lock screen (PIN, pattern, or
password), the interface has public and private parts.
• The public interface can be displayed on a secure lock
screen and therefore seen by anyone. The private interface
is the world behind that lock screen, and is only revealed
once the user has signed into the device.
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User control over information displayed on the secure
lock screen
Notifications on the lock screen, with contents revealed
after the user unlocks the device.
When setting up a secure lock screen, the user can choose
to conceal sensitive details from the secure lock screen.
In this case the System UI considers the notification's
visibility level to figure out what can safely be shown.
41. • To control the visibility level, callNotification.Builder.setVisibility(), and specify one
of these values:
• VISIBILITY_PUBLIC. Shows the notification's full content. This is the system default
if visibility is left unspecified.
• VISIBILITY_PRIVATE. On the lock screen, shows basic information about the
existence of this notification, including its icon and the name of the app that
posted it.
• The rest of the notification's details are not displayed. A couple of good points to
keep in mind are as follows:
– If you want to provide a different public version of your notification for the system to display
on a secure lock screen, supply a replacement Notification object in
theNotification.publicVersion field.
– This setting gives your app an opportunity to create a redacted version of the content that is
still useful but does not reveal personal information. Consider the example of an SMS app
whose notifications include the text of the SMS and the sender's name and contact icon. This
notification should beVISIBILITY_PRIVATE, but publicVersion could still contain useful
information like "3 new messages" without any other identifying details.
• Notification.VISIBILITY_SECRET. Shows only the most minimal information,
excluding even the notification's icon.
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42. Notifications on Android Wear
• Notifications and their actions are bridged over to
Wear devices by default.
• Developers can control which notifications bridge from
the phone to the watch, and vice-versa. Developers can
also control which actions bridge, as well.
• If your app includes actions that can't be accomplished
with a single tap, either hide these actions on your
Wear notification or consider hooking them up to a
Wear app, thus allowing the user to finish the action
on their watch.
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44. Unique actions to define for Wear
• There are some actions that you can
perform only on Wear. These include
the following:
• Quick lists of canned responses such as
"Be right back"
• Open on the phone
• A "Comment" or "Reply" action that
brings up the speech input screen
• Actions that launch Wear-specific apps
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