android_frameworks_base/docs/html/design/patterns/notifications_k.jd

page.title=Notifications in Android 4.4 and Lower
@jd:body

<a class="notice-developers" href="{@docRoot}training/notify-user/index.html">
  <div>
    <h3>Developer Docs</h3>
    <p>Notifying the User</p>
  </div>
</a>

<a class="notice-designers" href="notifications.html">
  <div>
    <h3>Notifications in Android 5.0</h3>
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</a>

<p itemprop="description">The notification system allows your app to keep the
user informed about events, such as new chat messages 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.</p>

<h2>Anatomy of a notification</h2>

<div class="cols">
  <div class="col-6">
    <h4>Base Layout</h4>
    <p>At a minimum, all notifications consist of a base layout, including:</p>
    <ul>
      <li>the sending application's notification icon or the sender's photo</li>
      <li>a notification title and message</li>
      <li>a timestamp</li>
      <li>a secondary icon to identify the sending application when the sender's
image is shown for the main icon</li>
    </ul>
  </div>
  <div class="col-6">
    <img src="{@docRoot}design/media/notifications_pattern_anatomy.png">
    <div class="figure-caption">
      Base layout of a notification
    </div>
  </div>
</div>

<h4>Expanded layouts</h4>
<p>You have the option to provide more event detail. You can use this to show
the first few lines of a message or show a larger image preview. This provides
the user with additional context, and - in some cases - may allow the user to
read a message in its entirety. The user can pinch-zoom or two-finger glide in
order to toggle between base and expanded layouts. For single event
notifications, Android provides two expanded layout templates (text and image)
for you to re-use in your application.</p>

<img src="{@docRoot}design/media/notifications_pattern_expandable.png">

<h4>Actions</h4>
<div class="cols">
  <div class="col-6">
    <p>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 to streamline their
notification triaging experience.</p>
    <p>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 fewest number of actions possible by only including the most
imminently important and meaningful ones.</p>
    <p>Good candidates for actions on notifications are actions that are:</p>
    <ul>
      <li>essential, frequent and typical for the content type you're
displaying</li>
      <li>time-critical</li>
      <li>not overlapping with neighboring actions</li>
    </ul>
    <p>Avoid actions that are:</p>
    <ul>
      <li>ambiguous</li>
      <li>duplicative of the default action of the notification (such as "Read"
or "Open")</li>
    </ul>
  </div>
  <div class="col-7">
    <img src="{@docRoot}design/media/notifications_pattern_two_actions.png">
    <div class="figure-caption">
      Calendar reminder notification with two actions
    </div>
  </div>
</div>

<p>You can specify a maximum of three actions, each consisting of an action
icon and an action name. Adding actions to a simple base layout will make 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, you must make sure that any action a user can invoke from a
notification is available from within the associated application as well.</p>

<h2>Design guidelines</h2>
<div class="cols">
  <div class="col-6">
    <img src="{@docRoot}design/media/notifications_pattern_personal.png">
  </div>
  <div class="col-7">
    <h4>Make it personal</h4>
    <p>For notifications of items sent by another user (such as a message or
status update), include that person's image.</p>
    <p>Remember to include the app icon as a secondary icon in the
notification, so that the user can still identify which app posted it.</p>
  </div>
</div>

<h4>Navigate to the right place</h4>
<p>When the user touches the body of a notification (outside of the action
buttons), open your app to the place where the user can consume and act upon
the data referenced in the notification. In most cases this will be the detail
view of a
single data item such as a message, but it might also be a summary view if the
notification is stacked (see <em>Stacked notifications</em> below) and
references multiple items. If in any of those cases the user is taken to a
hierarchy level below your app's top-level, insert navigation into your app's
back stack to allow them to navigate to your app's top level using the system
back key. For more
information, see the chapter on <em>System-to-app navigation</em> in the <a
href="{@docRoot}design/patterns/navigation.html">Navigation</a> design
pattern.</p>

<h4>Correctly set and manage notification priority</h4>
<p>Starting with Jelly Bean, Android supports a priority flag for
notifications. This flag allows you to influence where your notification will
appear in comparison to other notifications and help to make sure that users
always see their most important notifications first. You can choose from the
following priority levels when posting a notification:</p>

<table>
  <tr>
    <th><strong>Priority</strong></th>
    <th><strong>Use</strong></th>
  </tr>
  <tr>
    <td>MAX</td>
    <td>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.</td>
  </tr>
  <tr>
    <td>HIGH</td>
    <td>Use high priority notifications primarily for important communication,
such as message or chat events with content that is particularly interesting
for the user.</td>
  </tr>
  <tr>
    <td>DEFAULT</td>
    <td>The default priority. Keep all notifications that don't fall into any
of the other categories at this priority level.</td>
  </tr>
  <tr>
    <td>LOW</td>
    <td>Use for notifications that you still want the user to be informed
about, but that rate low in urgency.</td>
  </tr>
  <tr>
    <td>MIN</td>
    <td>Contextual/background information (e.g. weather information, contextual
location information). Minimum     priority notifications will not show in the
status bar. The user will only discover them when they expand the notification
tray.</td>
  </tr>
</table>
<img src="{@docRoot}design/media/notifications_pattern_priority.png">

<h4>Stack your notifications</h4>
<p>If your app creates a notification while another of the same type is still
pending, avoid creating
an altogether new notification object. Instead, stack the notification.</p>
<p>A stacked notification builds a summary description and allows the user to
understand how many
notifications of a particular kind are pending.</p>
<p><strong>Don't</strong>:</p>

<img src="{@docRoot}design/media/notifications_pattern_additional_fail.png">

<p><strong>Do</strong>:</p>

<img src="{@docRoot}design/media/notifications_pattern_additional_win.png">

<p>You can provide more detail about the individual notifications that make up
a stack by using the expanded digest layout. This allows users to gain a better
sense of which notifications are pending and if they are interesting enough to
be read in detail within the associated app.</p>

<img src="{@docRoot}design/media/notifications_expand_contract_msg.png">

<h4>Make notifications optional</h4>
<p>Users should always be in control of notifications. Allow the user to
disable your apps 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.</p>
<h4>Use distinct icons</h4>
<p>By glancing at the notification area, the user should be able to discern
what kinds of notifications are currently pending.</p>

<div class="do-dont-label good"><strong>Do</strong></div>
<p style="margin-top:0;">Look at the notification icons the Android apps
already provide and create notification icons for your app that are
sufficiently distinct in appearance.</p>
<div class="do-dont-label good"><strong>Do</strong></div>
<p style="margin-top:0;">Use the proper <a
href="{@docRoot}design/style/iconography.html#notification">notification icon
style</a> for small icons, and the Holo Dark <a
href="{@docRoot}design/style/iconography.html#action-bar">action bar icon
style</a> for your action icons.</p>
<div class="do-dont-label good"><strong>Do</strong></div>
<p style="margin-top:0;">Keep your icons visually simple and avoid excessive
detail that is hard to discern.</p>
<div class="do-dont-label bad"><strong>Don't</strong></div>
<p style="margin-top:0;">Use color to distinguish your app from others.</p>

<h4>Pulse the notification LED appropriately</h4>
<p>Many Android devices contain a tiny lamp, called the notification <acronym
title="Light-Emitting Diode">LED</acronym>, 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.</p>

<p>The user's control over notifications should extend to the LED. By default,
the LED will glow with a white color. Your notifications shouldn't use a
different color unless the user has explicitly customized it.</p>

<h2>Building notifications that users care about</h2>
<p>To create an app that feels streamlined, pleasant, and respectful, 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, so use them judiciously.</p>

<h4>When to display a notification</h4>
<p>To create an application that people love, 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 users attention, it is
nonetheless still important
to be aware of the fact that notifications are potentially interrupting the
users 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.</p>
<p>While well behaved apps generally only speak when spoken to, there are some
limited cases where an
app actually should interrupt the user with an unprompted notification.</p>
<p>Notifications should be used primarily for <strong>time sensitive
events</strong>, and especially if these
synchronous events <strong>involve other people</strong>. For instance, an
incoming chat is a real time and
synchronous form of communication: there is another user actively waiting on
you to respond.
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.</p>

<img src="{@docRoot}design/media/notifications_pattern_real_time_people.png">

<div class="vspace size-2">&nbsp;</div>

<div class="cols">
  <div class="col-7">

<h4>When not to display a notification</h4>
<p>There are however many other cases where notifications should not be
used:</p>
<ul>
<li>
<p>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 that do care about them,
allow them to opt-in.</p>
</li>
<li>
<p>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.</p>
</li>
<li>
<p>Don't interrupt the user for low level technical operations, like saving or
syncing information, or updating an application, if it is possible for the
system to simply take care of itself without involving the user.</p>
</li>
<li>
<p>Don't interrupt the user to inform them of an error if it is possible for
the application to quickly recover from the error on its own without the user
taking any action.</p>
</li>
<li>
<p>Don't create notifications that have no true notification content and merely
advertise your app. A notification should inform the user about a state and
should not be used to merely launch an app.</p>
</li>
<li>
<p>Don't create superfluous notifications just to get your brand in front of
users. Such
notifications will only frustrate and likely alienate your audience. The best
way to provide the
user with a small amount of updated information and to keep them engaged with
your application is to
develop a widget that they can choose to place on their home screen.</p>
</li>
</ul>

  </div>
  <div class="col-6">
    <img src="{@docRoot}design/media/notifications_pattern_social_fail.png">
  </div>
</div>

<h2 id="interacting-with-notifications">Interacting With Notifications</h2>

<div class="cols">
  <div class="col-6">

    <img src="{@docRoot}design/media/notifications_pattern_phone_icons.png">

  </div>
  <div class="col-6">

  <p>Notifications are indicated by icons in the notification area and can be
accessed by opening the notification drawer.</p>
  <p>Inside the drawer, notifications are chronologically sorted with the
latest one on top. Touching a notification opens the associated app to detailed
content matching the notification. Swiping left or right on a notification
removes it from the drawer.</p>

  </div>
</div>

<div class="cols">
  <div class="col-6">

<p><h4>Ongoing notifications</h4>
<p>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. They can also be used to show the user feedback for longer tasks like
downloading a file, or encoding a video. Ongoing notifications cannot be
manually removed from the notification drawer.</p></p>

  </div>
  <div class="col-6">

    <img src="{@docRoot}design/media/notifications_pattern_ongoing_music.png">

  </div>
</div>

<div class="cols">
  <div class="col-12">
    <h4>Dialogs and toasts are for feedback not notification</h4>
    <p>Your app should not create a dialog or toast if it is not currently on
screen. Dialogs and Toasts should only be displayed as the immediate response
to the user taking an action inside of your app. For further guidance on the
use of dialogs and toasts, refer to <a
href="{@docRoot}design/patterns/confirming-acknowledging.html">Confirming &amp;
Acknowledging</a>.</p>
  </div>
</div>