这些答案大部分似乎都过时了。Developer.android.com建议这样做:

科特林：

private fun hideSystemBars() {
    val windowInsetsController = ViewCompat.getWindowInsetsController(window.decorView) ?: return
    windowInsetsController.systemBarsBehavior = WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE
    windowInsetsController.hide(WindowInsetsCompat.Type.systemBars())
}

Java:

private void hideSystemBars() {
    WindowInsetsControllerCompat windowInsetsController = ViewCompat.getWindowInsetsController(getWindow().getDecorView());
    if (windowInsetsController == null) {
        return;
    }
    windowInsetsController.setSystemBarsBehavior(WindowInsetsControllerCompat.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE);
    windowInsetsController.hide(WindowInsetsCompat.Type.systemBars());
}

更多信息:https://developer.android.com/training/system-ui/immersive

科特林

遵循谷歌文档，有一个简单的方法:

override fun onWindowFocusChanged(hasFocus: Boolean) {
super.onWindowFocusChanged(hasFocus)
if (hasFocus) hideSystemUI() }


private fun hideSystemUI() {
// Enables regular immersive mode.
// For "lean back" mode, remove SYSTEM_UI_FLAG_IMMERSIVE.
// Or for "sticky immersive," replace it with SYSTEM_UI_FLAG_IMMERSIVE_STICKY
window.decorView.systemUiVisibility = (View.SYSTEM_UI_FLAG_IMMERSIVE
        // Set the content to appear under the system bars so that the
        // content doesn't resize when the system bars hide and show.
        or View.SYSTEM_UI_FLAG_LAYOUT_STABLE
        or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
        or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
        // Hide the nav bar and status bar
        or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
        or View.SYSTEM_UI_FLAG_FULLSCREEN)      }


// Shows the system bars by removing all the flags
// except for the ones that make the content appear under the system bars.
private fun showSystemUI() {
window.decorView.systemUiVisibility = 
(View.SYSTEM_UI_FLAG_LAYOUT_STABLE
        or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
        or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN)       }

谷歌文档

在Android 10上，没有一款适合我。

但我工作得很好(oncreate的第一行):

    View decorView = getWindow().getDecorView();
    int uiOptions = View.SYSTEM_UI_FLAG_IMMERSIVE;
    decorView.setSystemUiVisibility(uiOptions);

    setContentView(....);

    if (getSupportActionBar() != null) {
        getSupportActionBar().hide();
    }

享受:)

如果你不想使用主题@android:style/ theme . notitlebar。因为你已经在使用你自己的主题，你可以使用android:windowFullscreen。

在AndroidManifest.xml:

<activity
  android:name=".ui.activity.MyActivity"
  android:theme="@style/MyTheme">
</activity>

在styles.xml:

<style name="MyTheme"  parent="your parent theme">
  <item name="android:windowNoTitle">true</item>
  <item name="android:windowFullscreen">true</item> 
</style>

使用Android Studio(当前版本是2.2.2)很容易添加一个全屏活动。

请看步骤:

右键单击你的java主包，选择“新建”，选择“活动”，然后点击“全屏活动”。

自定义活动(“活动名称”，“布局名称”等)，点击“完成”。

完成了!

现在你有一个全屏的活动很容易(查看java类和活动布局，以了解事情是如何工作的)!

谢谢你的回答@克里斯蒂安，我得到了错误

android.util.AndroidRuntimeException:必须调用requestFeature() 添加内容前

我用

@Override
protected void onCreate(Bundle savedInstanceState) {

    requestWindowFeature(Window.FEATURE_NO_TITLE);

    super.onCreate(savedInstanceState);

    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.activity_login);

    -----
    -----
}