Android 9 Development Cookbook - Third Edition

How to do it...

Our activity layout will consist of just a ToggleButton to control the flashlight mode. We'll be using the same setTorchMode() code as the Lights, Action, and Sound - getting the user's attention! recipe presented earlier, and will add a Heads-Up Notification. We'll need permission to use the vibrate option, so start by opening the Android Manifest and following these steps:

1. Add the following permission:

<uses-permission android:name="android.permission.VIBRATE"/>

2. Specify that we only want a single instance of MainActivity by adding android:launchMode="singleInstance" to the <MainActivity> element. It will look as follows:

<activity android:name=".MainActivity" 
    android:launchMode="singleInstance">