你只需要进入mainactivity。java

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Window g = getWindow();
        g.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);

        setContentView(R.layout.activity_main);

    }

在你的XML中使用这段代码，你将能够在你的活动中看到时间条:

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

这招对我很管用:

<item name="android:statusBarColor">@android:color/transparent</item>
<item name="android:navigationBarColor">@android:color/transparent</item>
<item name="android:windowTranslucentStatus">false</item>
<item name="android:windowTranslucentNavigation">false</item>

这是一个简单的方法，我找到了很多搜索。

步骤1

在你的主题里放这个项目

        <item name="android:statusBarColor" tools:targetApi="lollipop">@android:color/transparent</item>

步骤2

主要活动

WindowCompat.setDecorFitsSystemWindows(window, false)

非常重要，如果你使用底部导航栏

在一些设备中，API 30+ u会发现系统导航栏与底部导航栏重叠，如果在你的应用中使用它。

这就解决了这个问题。

  if (Build.VERSION.SDK_INT >= 30) {
        // Root ViewGroup of my activity
        val root = findViewById<ConstraintLayout>(R.id.root)

        ViewCompat.setOnApplyWindowInsetsListener(root) { view, windowInsets ->

            val insets = windowInsets.getInsets(WindowInsetsCompat.Type.systemBars())

            // Apply the insets as a margin to the view. Here the system is setting
            // only the bottom, left, and right dimensions, but apply whichever insets are
            // appropriate to your layout. You can also update the view padding
            // if that's more appropriate.

            view.layoutParams =  (view.layoutParams as FrameLayout.LayoutParams).apply {
                leftMargin = insets.left
                bottomMargin = insets.bottom
                rightMargin = insets.right
            }

            // Return CONSUMED if you don't want want the window insets to keep being
            // passed down to descendant views.
            WindowInsetsCompat.CONSUMED
        }

    }

这应该可以

//在Activity的onCreate()中为实例

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
    Window w = getWindow();
    w.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
}

下面的代码将使你的状态栏和导航栏透明(注意，这将使你的布局成为像游戏中使用的布局一样的全屏布局):

@Override
public void onWindowFocusChanged(boolean hasFocus) {
    super.onWindowFocusChanged(hasFocus);
    if (hasFocus) {
        hideSystemUI();
    }
}

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

要了解更多，请访问这个链接。