Merge "Notificiations Design for Android L Release" into lmp-dev

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>

  </div>

</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="layout-content-row">

  <div class="layout-content-col span-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="layout-content-col span-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="layout-content-row">

  <div class="layout-content-col span-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="layout-content-col span-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="layout-content-row">

  <div class="layout-content-col span-6">

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

  </div>

  <div class="layout-content-col span-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="layout-content-row">

  <div class="layout-content-col span-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="layout-content-col span-6">

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

  </div>

</div>

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

<div class="layout-content-row">

  <div class="layout-content-col span-6">

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

  </div>

  <div class="layout-content-col span-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="layout-content-row">

  <div class="layout-content-col span-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="layout-content-col span-6">

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

  </div>

</div>

<div class="layout-content-row">

  <div class="layout-content-col span-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 &

Acknowledging</a>.</p>

  </div>

</div>