android_frameworks_base/docs/html/training/snackbar/showing.jd

page.title=Building and Displaying a Pop-Up Message
page.tags="Snackbar" "popup" "pop-up"
helpoutsWidget=true
trainingnavtop=true

@jd:body

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

    <h2>This lesson teaches you to</h2>

    <ol>
      <li><a href="#coordinator">Use a CoordinatorLayout</a></li>
      <li><a href="#display">Display a Message</a></li>
    </ol>

    <h2>You should also read</h2>
    <ul>
      <li><a href="{@docRoot}tools/support-library/setup.html"
    >Support Library Setup</a></li>
    </ul>
  </div>
</div>


<p>
  You can use a {@link android.support.design.widget.Snackbar} to display a brief
  message to the user. The message automatically goes away after a short
  period. A {@link android.support.design.widget.Snackbar} is ideal
  for brief messages that the user doesn't necessarily need to act on. For
  example, an email app could use a {@link
  android.support.design.widget.Snackbar} to tell the user that the app
  successfully sent an email.
</p>

<h2 id="coordinator">Use a CoordinatorLayout</h2>

<p>
  A {@link android.support.design.widget.Snackbar} is attached to a view. The
  {@link android.support.design.widget.Snackbar} provides basic functionality
  if it is attached to any object derived from the {@link android.view.View}
  class, such as any of the common layout objects. However, if the
  {@link android.support.design.widget.Snackbar}
  is attached to a {@link android.support.design.widget.CoordinatorLayout}, the
  {@link android.support.design.widget.Snackbar} gains additional features:
</p>

<ul>
  <li>The user can dismiss the {@link android.support.design.widget.Snackbar}
  by swiping it away.
  </li>

  <li>The layout moves some other UI elements when the {@link
  android.support.design.widget.Snackbar} appears. For example, if the layout
  has a {@link android.support.design.widget.FloatingActionButton}, the layout
  moves the button up when it shows a {@link
  android.support.design.widget.Snackbar}, instead of drawing the {@link
  android.support.design.widget.Snackbar} on top of the button. You can see how
  this looks in Figure 1.
  </li>
</ul>

<p>
  The {@link android.support.design.widget.CoordinatorLayout} class provides a superset
  of the functionality of {@link android.widget.FrameLayout}. If your app
  already uses a {@link android.widget.FrameLayout}, you can just replace that
  layout with a {@link android.support.design.widget.CoordinatorLayout} to
  enable the full {@link android.support.design.widget.Snackbar} functionality.
  If your app uses other layout objects, the simplest thing to do is wrap your
  existing layout elements in a {@link
  android.support.design.widget.CoordinatorLayout}, as in this example:
</p>

<pre>&lt;android.support.design.widget.CoordinatorLayout
    android:id="@+id/myCoordinatorLayout"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"&gt;

    &lt;!-- Here are the existing layout elements, now wrapped in
         a CoordinatorLayout --&gt;
    &lt;LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"&gt;

        &lt;!-- …Toolbar, other layouts, other elements… --&gt;

    &lt;/LinearLayout>

&lt;/android.support.design.widget.CoordinatorLayout&gt;</pre>

<p>
  Make sure to set an <code>android:id</code> tag for your {@link
  android.support.design.widget.CoordinatorLayout}. You need the layout's ID
  when you display the message.
</p>

<div class="framed-nexus5-port-span-5" id="video-coord">
  <video class="play-on-hover" autoplay loop
    alt="If the Snackbar is attached to a CoordinatorLayout, the layout
        moves other elements up when it shows the Snackbar.">
  <!-- Preferred video size 216x384 (portrait) -->
    <source src="{@docRoot}images/training/snackbar/snackbar_button_move.mp4">
  </video>
</div>

<p class="img-caption">
  <strong>Figure 1.</strong> The {@link android.support.design.widget.CoordinatorLayout}
  moves the {@link android.support.design.widget.FloatingActionButton} up
  when the {@link android.support.design.widget.Snackbar} appears.
</p>

<h2 id="display">
  Display a Message
</h2>

<p>
  There are two steps to displaying a message. First, you create a {@link
  android.support.design.widget.Snackbar} object with the message text. Then,
  you call that object's {@link android.support.design.widget.Snackbar#show
  show()} method to display the message to the user.
</p>

<h3 id="create-snackbar">Creating a Snackbar object</h3>

<p>
  Create a {@link android.support.design.widget.Snackbar} object by
  calling the static {@link android.support.design.widget.Snackbar#make
  Snackbar.make()} method. When you create the {@link
  android.support.design.widget.Snackbar}, you specify both the message it
  displays, and the length of time to show the message:
</p>

<pre>Snackbar mySnackbar = Snackbar.make(viewId, stringId, duration);</pre>

<dl>
  <dt>
    <em>viewId</em>
  </dt>

  <dd>
    The view to attach the {@link android.support.design.widget.Snackbar} to.
    The method actually searches up the view hierarchy from the passed
    <em>viewId</em> until it reaches either a {@link
    android.support.design.widget.CoordinatorLayout}, or the window decor's
    content view. Ordinarily, it's simplest to just pass the ID of the {@link
    android.support.design.widget.CoordinatorLayout} enclosing your content.
  </dd>

  <dt>
    <em>stringId</em>
  </dt>

  <dd>
    The resource ID of the message you want to display. This can be formatted
    or unformatted text.
  </dd>

  <dt>
    <em>duration</em>
  </dt>

  <dd>
    The length of time to show the message. This can be either {@link
    android.support.design.widget.Snackbar#LENGTH_SHORT LENGTH_SHORT} or {@link
    android.support.design.widget.Snackbar#LENGTH_LONG LENGTH_LONG}.
  </dd>
</dl>

<h3 id="show-snackbar">Showing the message to the user</h3>

<p>
  Once you have created the {@link android.support.design.widget.Snackbar},
  call its {@link android.support.design.widget.Snackbar#show show()} method to
  display the {@link android.support.design.widget.Snackbar} to the user:
</p>

<pre>mySnackbar.show();</pre>

<p>
  The system does not show multiple {@link
  android.support.design.widget.Snackbar} objects at the same time, so if the
  view is currently displaying another {@link
  android.support.design.widget.Snackbar}, the system queues your {@link
  android.support.design.widget.Snackbar} and displays it after the current
  {@link android.support.design.widget.Snackbar} expires or is dismissed.
</p>

<p>
  If you just want to show a message to the user and won't need to call any of
  the {@link android.support.design.widget.Snackbar} object's utility methods,
  you don't need to keep the reference to the {@link
  android.support.design.widget.Snackbar} after you call {@link
  android.support.design.widget.Snackbar#show show()}. For this reason, it's
  common to use method chaining to create and show a {@link
  android.support.design.widget.Snackbar} in one statement:
</p>

<pre>Snackbar.make(findViewById(R.id.myCoordinatorLayout), R.string.email_sent,
                        Snackbar.LENGTH_SHORT)
        .show();</pre>