docs/html/training/system-ui/status.jd

page.title=Hiding the Status Bar

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@jd:body

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<h2>This lesson teaches you to</h2>
<ol>
  <li><a href="#40">Hide the Status Bar on Android 4.0 and Lower</a></li>
  <li><a href="#41">Hide the Status Bar on Android 4.1 and Higher</a></li>

  <li><a href="#behind">Make Content Appear Behind the Status Bar</a></li>
  <li><a href="#action-bar">Synchronize the Status Bar with Action Bar Transition</a></li>
</ol>

<!-- other docs (NOT javadocs) -->
<h2>You should also read</h2>

<ul>
    <li>
        <a href="{@docRoot}guide/topics/ui/actionbar.html">Action Bar</a> API Guide
    </li>
    <li>
        <a href="{@docRoot}design/index.html">
        Android Design Guide
        </a>
    </li>
</ul>


</div>
</div>

<p>
    This lesson describes how to hide the status bar on different versions of
    Android. Hiding the status bar (and optionally, the navigation bar) lets the
    content use more of the display space, thereby providing a more immersive user experience.

</p>

<p>
 Figure 1 shows an app with a visible status bar:
</p>

<img src="{@docRoot}images/training/status_bar_show.png"
  alt="system bars">
<p class="img-caption"><strong>Figure 1.</strong> Visible status bar.</p>

<p>
 Figure 2 shows an app with a hidden status bar. Note that the action bar is hidden too.
 You should never show the action bar without the status bar.
</p>

<img src="{@docRoot}images/training/status_bar_hide.png"
  alt="system bars">
<p class="img-caption"><strong>Figure 2.</strong> Hidden status bar.</p>

<h2 id="40">Hide the Status Bar on Android 4.0 and Lower</h2>

<p>You can hide the status bar on Android 4.0 (API level 14) and lower by setting
{@link android.view.WindowManager} flags. You can do this programmatically or by
setting an activity theme in your app's manifest file. Setting an activity theme in your app's
manifest file is the preferred approach if the status bar should always remain
hidden in your app (though strictly speaking, you could programmatically override the
theme if you wanted to). For example:</p>

<pre>
&lt;application
    ...
    android:theme=&quot;@android:style/Theme.Holo.NoActionBar.Fullscreen&quot; &gt;
    ...
&lt;/application&gt;
</pre>

<p>The advantages of using an activity theme are as follows:</p>

<ul>
<li>It's easier to maintain and less error-prone than setting a flag programmatically.</li>
<li>It results in smoother UI transitions, because the system has the information it needs
to render your UI before instantiating your app's main activity.</li>
</ul>

<p>
Alternatively, you can programmatically set {@link android.view.WindowManager} flags.
This approach makes it easier to hide and show the status bar as the user interacts with
your app:</p>

<pre>public class MainActivity extends Activity {

    &#64;Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // If the Android version is lower than Jellybean, use this call to hide
        // the status bar.
        if (Build.VERSION.SDK_INT < 16) {
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
        }
        setContentView(R.layout.activity_main);
    }
    ...
}
</pre>

<p>When you set {@link android.view.WindowManager} flags (whether through an activity theme or
programmatically), the flags remain in effect unless your app clears them.</p>

<p>You can use
{@link android.view.WindowManager.LayoutParams#FLAG_LAYOUT_IN_SCREEN}
to set  your activity layout to use the same screen area that's available when you've enabled
{@link android.view.WindowManager.LayoutParams#FLAG_FULLSCREEN}. This prevents your
content from resizing when the status bar hides and shows.</p>


<h2 id="41">Hide the Status Bar on Android 4.1 and Higher</h2>

<p>You can hide the status bar on Android 4.1 (API level 16) and higher by
using {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()}.
{@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} sets UI flags at
the individual view level; these settings are aggregated to the window level. Using
{@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} to set UI flags
gives you more granular control over the system bars than using
{@link android.view.WindowManager} flags. This snippet hides the status bar:</p>

<pre>View decorView = getWindow().getDecorView();
// Hide the status bar.
int uiOptions = View.SYSTEM_UI_FLAG_FULLSCREEN;
decorView.setSystemUiVisibility(uiOptions);
// Remember that you should never show the action bar if the
// status bar is hidden, so hide that too if necessary.
ActionBar actionBar = getActionBar();
actionBar.hide();
</pre>

<p>Note the following:</p>

<ul>
<li>Once UI flags have been cleared (for example, by navigating away from the
activity), your app needs to reset them if you want to hide the bars again.
See <a href="visibility.html">Responding to UI Visibility Changes</a> for a
discussion of how to listen for UI visibility changes so that your app can
respond accordingly.</li>

<li>Where you set the UI flags makes a difference. If you hide the system bars in your activity's
 {@link android.app.Activity#onCreate onCreate()} method and the user presses Home, the system bars will
 reappear. When the user reopens the activity, {@link android.app.Activity#onCreate onCreate()}
won't get called, so the system bars will remain visible. If you want system UI changes to
persist as the user navigates in and out of your activity, set UI flags in
{@link android.app.Activity#onResume onResume()}
or {@link android.view.Window.Callback#onWindowFocusChanged onWindowFocusChanged()}.</li>

  <li>The method {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()}
  only has an effect if the view you call it from is visible.</li>

  <li>Navigating away from the view causes flags
  set with {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()}
  to be cleared.</li>
</ul>


 </p>

 <h2 id="behind">Make Content Appear Behind the Status Bar</h2>
<p>On Android 4.1 and higher, you can set your application's content to appear behind
the status bar, so that the content doesn't resize as the status bar hides and shows.
To do this, use
{@link android.view.View#setSystemUiVisibility setSystemuiVisibility(SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)}.
You may also need to use
{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_STABLE} to help your app maintain a
stable layout.</p>

<p>When you use this approach, it becomes your responsibility to ensure that critical parts
of your app's UI (for example, the built-in controls in a Maps application) don't end up
getting covered by system bars. This could make your app unusable. In most cases you can
handle this by adding the {@code android:fitsSystemWindows} attribute to your XML layout file, set to
{@code true}. This adjusts the padding of the parent {@link android.view.ViewGroup}
to leave space for the system windows. This is sufficient for most applications.</p>

<p>In some cases, however, you may need to modify the default padding to get the desired
layout for your app. To directly manipulate how your
content lays out relative to the system bars (which occupy a space known as the window's
"content insets"), override {@link android.view.View#fitSystemWindows fitSystemWindows(Rect insets)}.
The {@link android.view.View#fitSystemWindows fitSystemWindows()} method is called by the
view hierarchy when the content insets for a window have changed, to allow the window to
adjust its content accordingly. By overriding this method you can handle the
insets (and hence your app's layout) however you want. </p>

 <h2 id="action-bar">Synchronize the Status Bar with Action Bar Transition</h2>

  <p>On Android 4.1 and higher, to avoid resizing your layout when the action bar hides and
  shows, you can enable overlay mode for the <a href="{@docRoot}guide/topics/ui/actionbar.html">action bar</a>.
  When in overlay mode, your activity layout uses all the
  space available as if the action bar is not there and the system draws the action bar in
  front of your layout. This obscures some of the layout at the top, but now when the
  action bar hides or appears, the system does not need to resize your layout and the
  transition is seamless.</p>

  <p>To enable overlay mode for the action bar, you need to create a custom theme that
  extends an existing theme with an action bar and set the
  {@code android:windowActionBarOverlay} attribute
  to {@code true}. For more discussion of this topic, see
  <a href="{@docRoot}training/basics/actionbar/overlaying.html#EnableOverlay">
  Overlaying the Action Bar</a> in the <a href="{@docRoot}training/basics/actionbar/index.html">
  Adding the Action Bar</a> class.</p>


<p>Then use
{@link android.view.View#setSystemUiVisibility setSystemuiVisibility(SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)},
as described above,
to set  your activity layout to use the same screen area that's available when you've enabled
{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}.

When you want to hide the system UI, call
{@link android.view.View#setSystemUiVisibility setSystemUiVisibility(SYSTEM_UI_FLAG_FULLSCREEN)}.
This also hides the action bar (because {@code windowActionBarOverlay=”true”)} and does
so with a coordinated animation when both hiding and showing the two.</p>