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_splash_screen);
    getSupportActionBar().hide();

}

AndroidManifest.xml

<activity ...
          android:theme="@style/FullScreenTheme"
    >
</activity>

I.你的主应用的主题是theme . appcompat . light . darkactionbar

隐藏ActionBar / StatusBar style.xml

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    ...
</style>

<style name="FullScreenTheme" parent="AppTheme">
    <!--this property will help hide the ActionBar-->
    <item name="windowNoTitle">true</item>
    <!--currently, I don't know why we need this property since use windowNoTitle only already help hide actionbar. I use it because it is used inside Theme.AppCompat.Light.NoActionBar (you can check Theme.AppCompat.Light.NoActionBar code). I think there are some missing case that I don't know-->
    <item name="windowActionBar">false</item>
    <!--this property is used for hiding StatusBar-->
    <item name="android:windowFullscreen">true</item>
</style>

隐藏系统导航栏

public class MainActivity extends AppCompatActivity {

    protected void onCreate(Bundle savedInstanceState) {
        getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
        setContentView(R.layout.activity_main)
        ...
    }
 }

2你的主应用主题是theme . appcompat . light . noactionbar

隐藏ActionBar / StatusBar style.xml

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    ...
</style>

<style name="FullScreenTheme" parent="AppTheme">
    <!--don't need any config for hide ActionBar because our apptheme is NoActionBar-->
    <!--this property is use for hide StatusBar-->
    <item name="android:windowFullscreen">true</item> // 
</style>

隐藏系统导航栏

类似于theme。appcompat。light。darkactionbar。

演示

在onCreate()中的setContentView之后使用这个方法，并通过getWindow()传递Window对象。

    public void makeActivityFullScreen(Window window){
    View decorView = window.getDecorView();
    //        int uiOptions = View.SYSTEM_UI_FLAG_FULLSCREEN;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
       window.getAttributes().layoutInDisplayCutoutMode = WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES;
    }
    decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE
            | View.SYSTEM_UI_FLAG_FULLSCREEN
            | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
            | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
    );
}

此代码也将适用于缺口屏幕。要检查缺口全屏，你需要安卓P，但如果你有一个缺口显示手机，然后去设置->显示设置->应用程序显示比例->选择你的应用程序->有两个安全的选项是显示和全屏，请选择全屏并运行应用程序，你可以看到缺口的全屏也没有安卓派

只需将此代码粘贴到onCreate()方法中

requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);

首先，你必须设置你的应用主题与“NoActionBar”如下所示

<!-- Application theme. -->
<style name="AppTheme" parent="@style/Theme.AppCompat.Light.NoActionBar" />

然后在全屏活动中添加这些行。

public class MainActiviy extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                                  WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.main);
    }
}

它将隐藏动作栏/工具栏和状态栏在你的全屏活动

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