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      1 page.title=Adding an Action to a Message
      2 page.tags="Snackbar" "action" "popup"
      3 helpoutsWidget=true
      4 trainingnavtop=true
      5 
      6 @jd:body
      7 
      8 <div id="tb-wrapper">
      9   <div id="tb">
     10 
     11 <!--
     12     <h2>This lesson teaches you to</h2>
     13 
     14     <ol>
     15       <li>
     16         <a href="#id">heading</a>
     17       </li>
     18 
     19       <li>
     20         <a href="#id">heading</a>
     21       </li>
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     24 
     25     <h2>See Also</h2>
     26     <ul>
     27       <li><a href="{@docRoot}guide/topics/ui/ui-events.html">
     28           Input Events</a></li>
     29     </ul>
     30 
     31 
     32   </div>
     33 </div>
     34 
     35 <p>
     36   You can add an action to a {@link android.support.design.widget.Snackbar},
     37   allowing the user to respond to your message. If you add an action to a
     38   {@link android.support.design.widget.Snackbar}, the
     39   {@link android.support.design.widget.Snackbar} puts a button
     40   next to the message text. The user can trigger your action by pressing the
     41   button. For example, an email app might put an <em>undo</em> button on its
     42   "email archived" message; if the user clicks the <em>undo</em> button, the
     43   app takes the email back out of the archive.
     44 </p>
     45 
     46 <img src="{@docRoot}images/training/snackbar/snackbar_undo_action_2x.png"
     47   srcset="{@docRoot}images/training/snackbar/snackbar_undo_action.png 1x,
     48       {@docRoot}images/training/snackbar/snackbar_undo_action_2x.png 2x"
     49   width="400" alt="">
     50 
     51 <p class="img-caption">
     52   <strong>Figure 1.</strong> This Snackbar has an <strong>Undo</strong>
     53   button, which restores the item that was just removed.
     54 </p>
     55 
     56 <p>
     57   To add an action to a {@link android.support.design.widget.Snackbar} message,
     58   you need to define a listener object that implements the {@link
     59   android.view.View.OnClickListener} interface. The system calls your
     60   listener's {@link android.view.View.OnClickListener#onClick onClick()} method
     61   if the user clicks on the message action. For example, this snippet shows a
     62   listener for an undo action:
     63 </p>
     64 
     65 <pre>public class MyUndoListener implements View.OnClickListener{
     66 
     67     &amp;Override
     68     public void onClick(View v) {
     69 
     70         // Code to undo the user's last action
     71     }
     72 }</pre>
     73 
     74 <p>
     75   Use one of the
     76   {@link android.support.design.widget.Snackbar#setAction(int, android.view.View.OnClickListener)
     77   SetAction()} methods to attach the listener to your {@link
     78   android.support.design.widget.Snackbar}. Be sure to attach the listener
     79   before you call {@link android.support.design.widget.Snackbar#show show()},
     80   as shown in this code sample:
     81 </p>
     82 
     83 <pre>Snackbar mySnackbar = Snackbar.make(findViewById(R.id.myCoordinatorLayout),
     84                                 R.string.email_archived, Snackbar.LENGTH_SHORT);
     85 <strong>mySnackbar.setAction(R.string.undo_string, new MyUndoListener());</strong>
     86 mySnackbar.show();</pre>
     87 
     88 <p class="note">
     89   <strong>Note:</strong> A {@link android.support.design.widget.Snackbar}
     90   automatically goes away after a short time, so you can't count on the user
     91   seeing the message or having a chance to press the button. For this reason,
     92   you should consider offering an alternate way to perform any {@link
     93   android.support.design.widget.Snackbar} action.
     94 </p>
     95