docs/html/training/snackbar/action.jd

page.title=Adding an Action to a Message
page.tags="Snackbar" "action" "popup"
helpoutsWidget=true
trainingnavtop=true

@jd:body

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

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    <h2>See Also</h2>
    <ul>
      <li><a href="{@docRoot}guide/topics/ui/ui-events.html">
          Input Events</a></li>
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<p>
  You can add an action to a {@link android.support.design.widget.Snackbar},
  allowing the user to respond to your message. If you add an action to a
  {@link android.support.design.widget.Snackbar}, the
  {@link android.support.design.widget.Snackbar} puts a button
  next to the message text. The user can trigger your action by pressing the
  button. For example, an email app might put an <em>undo</em> button on its
  "email archived" message; if the user clicks the <em>undo</em> button, the
  app takes the email back out of the archive.
</p>

<img src="{@docRoot}images/training/snackbar/snackbar_undo_action_2x.png"
  srcset="{@docRoot}images/training/snackbar/snackbar_undo_action.png 1x,
      {@docRoot}images/training/snackbar/snackbar_undo_action_2x.png 2x"
  width="400" alt="">

<p class="img-caption">
  <strong>Figure 1.</strong> This Snackbar has an <strong>Undo</strong>
  button, which restores the item that was just removed.
</p>

<p>
  To add an action to a {@link android.support.design.widget.Snackbar} message,
  you need to define a listener object that implements the {@link
  android.view.View.OnClickListener} interface. The system calls your
  listener's {@link android.view.View.OnClickListener#onClick onClick()} method
  if the user clicks on the message action. For example, this snippet shows a
  listener for an undo action:
</p>

<pre>public class MyUndoListener implements View.OnClickListener{

    &amp;Override
    public void onClick(View v) {

        // Code to undo the user's last action
    }
}</pre>

<p>
  Use one of the
  {@link android.support.design.widget.Snackbar#setAction(int, android.view.View.OnClickListener)
  SetAction()} methods to attach the listener to your {@link
  android.support.design.widget.Snackbar}. Be sure to attach the listener
  before you call {@link android.support.design.widget.Snackbar#show show()},
  as shown in this code sample:
</p>

<pre>Snackbar mySnackbar = Snackbar.make(findViewById(R.id.myCoordinatorLayout),
                                R.string.email_archived, Snackbar.LENGTH_SHORT);
<strong>mySnackbar.setAction(R.string.undo_string, new MyUndoListener());</strong>
mySnackbar.show();</pre>

<p class="note">
  <strong>Note:</strong> A {@link android.support.design.widget.Snackbar}
  automatically goes away after a short time, so you can't count on the user
  seeing the message or having a chance to press the button. For this reason,
  you should consider offering an alternate way to perform any {@link
  android.support.design.widget.Snackbar} action.
</p>