docs/html/training/wearables/notifications/stacks.jd

page.title=Stacking Notifications

@jd:body

<div id="tb-wrapper">
<div id="tb">

<h2>This lesson teaches you to</h2>
<ol>
  <li><a href="#AddGroup">Add Each Notification to a Group</a></li>
  <li><a href="#AddSummary">Add a Summary Notification</a></li>
</ol>

</div>
</div>
<img src="/wear/images/11_bundles_B.png" height="200" width="169"
    style="margin:0 0 20px 20px; clear:both; float:right" alt="">
<img src="/wear/images/11_bundles_A.png" height="200" width="169"
    style="margin:0 20px 20px 20px; float:right" alt="">
<p>When creating notifications for a handheld device, you should always aggregate similar
notifications into a single summary notification. For example, if your app creates notifications
for received messages, you should not show more than one notification
on a handheld device&mdash;when more than one is message is received, use a single notification
to provide a summary such as "2 new messages."</p>

<p>However, a summary notification is less useful on an Android wearable because users
are not able to read details from each message on the wearable (they must open your app on the
handheld to view more information). So for the wearable device, you should
group all the notifications together in a stack. The stack of notifications appears as a single
card, which users can expand to view the details from each notification separately. The new
{@link android.support.v4.app.NotificationCompat.Builder#setGroup setGroup()} method makes this
possible while allowing you to still provide only one summary notification on the handheld device.</p>

<h2 id="AddGroup" style="clear:right">Add Each Notification to a Group</h2>

<p>To create a stack, call {@link android.support.v4.app.NotificationCompat.Builder#setGroup setGroup()}
for each notification you want in the stack and specify a
group key. Then call {@link android.support.v4.app.NotificationManagerCompat#notify notify()}
to send it to the wearable.</p>

<pre style="clear:right">
final static String GROUP_KEY_EMAILS = "group_key_emails";

// Build the notification, setting the group appropriately
Notification notif = new NotificationCompat.Builder(mContext)
         .setContentTitle("New mail from " + sender1)
         .setContentText(subject1)
         .setSmallIcon(R.drawable.new_mail);
         .setGroup(GROUP_KEY_EMAILS)
         .build();

// Issue the notification
NotificationManagerCompat notificationManager =
        NotificationManagerCompat.from(this);
notificationManager.notify(notificationId1, notif);
</pre>

<p>Later on, when you create another notification, specify
the same group key. When you call
{@link android.support.v4.app.NotificationManagerCompat#notify notify()},
this notification appears in the same stack as the previous notification,
instead of as a new card:</p>

<pre style="clear:right">
Notification notif2 = new NotificationCompat.Builder(mContext)
         .setContentTitle("New mail from " + sender2)
         .setContentText(subject2)
         .setSmallIcon(R.drawable.new_mail);
         .setGroup(GROUP_KEY_EMAILS)
         .build();

notificationManager.notify(notificationId2, notif2);
</pre>

<p>By default, notifications appear in the order in which you added them, with the most recent
  notification visible at the top.  You can order notifications in another fashion by calling
  {@link android.support.v4.app.NotificationCompat.Builder#setSortKey setSortKey()}.</p>


<h2 id="AddSummary">Add a Summary Notification</h2>

<img src="{@docRoot}wear/images/notif_summary_framed.png" height="242" width="330" style="float:right;margin:0 0 20px 40px" alt="" />

<p>It's important that you still provide a summary notification that appears on handheld devices.
So in addition to adding each unique notification to the same stack group, also add a summary
notification and call {@link android.support.v4.app.NotificationCompat.Builder#setGroupSummary setGroupSummary()}
on the summary notification.</p>

<p>This notification does not appear in your stack of notifications on the wearable, but
appears as the only notification on the handheld device.</p>

<pre style="clear:right">
Bitmap largeIcon = BitmapFactory.decodeResource(getResources(),
        R.drawable.ic_large_icon);

// Create an InboxStyle notification
Notification summaryNotification = new NotificationCompat.Builder(mContext)
        .setContentTitle("2 new messages")
        .setSmallIcon(R.drawable.ic_small_icon)
        .setLargeIcon(largeIcon)
        .setStyle(new NotificationCompat.InboxStyle()
                .addLine("Alex Faaborg   Check this out")
                .addLine("Jeff Chang   Launch Party")
                .setBigContentTitle("2 new messages")
                .setSummaryText("johndoe@gmail.com"))
        .setGroup(GROUP_KEY_EMAILS)
        .setGroupSummary(true)
        .build();

notificationManager.notify(notificationId3, summaryNotification);
</pre>

<p>
This notification uses {@link android.support.v4.app.NotificationCompat.InboxStyle},
which gives you an easy way to create notifications for email or messaging apps.
You can use this style, another one defined in {@link android.support.v4.app.NotificationCompat},
or no style for the summary notification.
</p>

<p class="note"><b>Tip:</b>
To style the text like in the example screenshot, see
<a href="{@docRoot}guide/topics/resources/string-resource.html#StylingWithHTML">Styling
with HTML markup</a> and
<a href="{@docRoot}guide/topics/resources/string-resource.html#StylingWithSpannables">Styling
with Spannables</a>.
</p>

<p>Summary notifications can also affect notifications on wearables without being displayed on them.
When creating a summary notification, you can use the
{@link android.support.v4.app.NotificationCompat.WearableExtender} class and call
{@link android.support.v4.app.NotificationCompat.WearableExtender#setBackground setBackground()} or
{@link android.support.v4.app.NotificationCompat.WearableExtender#addAction addAction()} to set
a background image or an action that applies to the entire stack on the wearable. For instance,
to set the background for an entire stack of notifications:
</p>

<pre>
Bitmap background = BitmapFactory.decodeResource(getResources(),
        R.drawable.ic_background);

NotificationCompat.WearableExtender wearableExtender =
        new NotificationCompat.WearableExtender()
        .setBackground(background);

// Create an InboxStyle notification
Notification summaryNotificationWithBackground =
        new NotificationCompat.Builder(mContext)
        .setContentTitle("2 new messages")
        ...
        .extend(wearableExtender)
        .setGroup(GROUP_KEY_EMAILS)
        .setGroupSummary(true)
        .build();
</pre>