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      1 page.title=Hiding the Navigation Bar
      2 
      3 trainingnavtop=true
      4 
      5 @jd:body
      6 
      7 <div id="tb-wrapper">
      8 <div id="tb">
      9 
     10 <!-- table of contents -->
     11 <h2>This lesson teaches you to</h2>
     12 <ol>
     13   <li><a href="#40">Hide the Navigation Bar on 4.0 and Higher</a></li>
     14   <li><a href="#behind">Make Content Appear Behind the Navigation Bar</a></li>
     15 </ol>
     16 
     17 
     18 <!-- other docs (NOT javadocs) -->
     19 <h2>You should also read</h2>
     20 
     21 <ul>
     22     <li>
     23         <a href="{@docRoot}guide/topics/ui/actionbar.html">Action Bar</a> API Guide
     24     </li>
     25     <li>
     26         <a href="{@docRoot}design/index.html">
     27         Android Design Guide
     28         </a>
     29     </li>
     30 </ul>
     31 
     32 <h2>Try it out</h2>
     33 
     34 <div class="download-box">
     35   <a href="{@docRoot}samples/ImmersiveMode/index.html"
     36 class="button">Get the sample</a>
     37  <p class="filename">ImmersiveMode sample</p>
     38 </div>
     39 
     40 </div>
     41 </div>
     42 
     43 <p>This lesson describes how to hide the navigation bar, which was introduced in
     44 Android 4.0 (API level 14).</p>
     45 
     46 <p>Even though this lesson focuses on hiding the
     47 navigation bar, you should design your app to hide the status bar
     48 at the same time, as described in <a href="status.html">Hiding the Status Bar</a>.
     49 Hiding the navigation and status bars (while still keeping them readily accessible)
     50 lets the content use the entire display space, thereby providing a more immersive
     51 user experience. </p>
     52 
     53 <img src="{@docRoot}images/training/navigation-bar.png"
     54   alt="system bars">
     55 <p class="img-caption"><strong>Figure 1.</strong> Navigation bar.</p>
     56 
     57 
     58 
     59 <h2 id="40">Hide the Navigation Bar on 4.0 and Higher</h2>
     60 
     61 <p>You can hide the navigation bar on Android 4.0 and higher using the
     62 {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} flag. This snippet hides both
     63 the navigation bar and the status bar:</p>
     64 <pre>View decorView = getWindow().getDecorView();
     65 // Hide both the navigation bar and the status bar.
     66 // SYSTEM_UI_FLAG_FULLSCREEN is only available on Android 4.1 and higher, but as
     67 // a general rule, you should design your app to hide the status bar whenever you
     68 // hide the navigation bar.
     69 int uiOptions = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
     70               | View.SYSTEM_UI_FLAG_FULLSCREEN;
     71 decorView.setSystemUiVisibility(uiOptions);</pre>
     72 
     73 <p>Note the following:</p>
     74 
     75 <ul>
     76   <li>With this approach, touching anywhere on the screen causes the navigation bar (and
     77   status bar) to reappear and remain visible. The user interaction causes the flags to be
     78   be cleared.</li>
     79 <li>Once the flags have been cleared, your app needs to reset them if you
     80 want to hide the bars again. See <a href="visibility.html">Responding to UI Visibility Changes</a> for a
     81 discussion of how to listen for UI visibility changes so that your app can
     82 respond accordingly.</li>
     83 
     84 <li>Where you set the UI flags makes a difference. If you hide the system bars in your activity's
     85  {@link android.app.Activity#onCreate onCreate()} method and the user presses Home, the system bars will
     86  reappear. When the user reopens the activity, {@link android.app.Activity#onCreate onCreate()}
     87 won't get called, so the system bars will remain visible. If you want system UI changes to
     88 persist as the user navigates in and out of your activity, set UI flags in
     89 {@link android.app.Activity#onResume onResume()}
     90 or {@link android.view.Window.Callback#onWindowFocusChanged onWindowFocusChanged()}.</li>
     91 
     92   <li>The method {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} only
     93   has an effect if the view you call it from is visible.</li>
     94   <li>Navigating away from the view causes flags
     95   set with {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()}
     96   to be cleared.</li>
     97 </ul>
     98 
     99 <h2 id="behind">Make Content Appear Behind the Navigation Bar</h2>
    100 <p>On Android 4.1 and higher, you can set your application's content to appear behind
    101 the navigation bar, so that the content doesn't resize as the navigation bar hides and
    102 shows. To do this, use
    103 {@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION}.
    104 You may also need to use
    105 {@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_STABLE} to help your app maintain a
    106 stable layout.</p>
    107 
    108 <p>When you use this approach, it becomes your responsibility to ensure that critical parts
    109 of your app's UI don't end up getting covered by system bars. For more
    110 discussion of this topic, see the <a href="status.html#behind">
    111 Hiding the Status Bar</a> lesson.</p>
    112