android: broadcast receiver for screen on and screen off

Question

I was just wondering if it is possible to register a broadcast receiver that detects Screen ON/OFF in the application manifest. The reason why I don't like the programmable method is that it requires the app to be running in order to detect such a thing, while: "Applications with Broadcast Receivers registered in the manifest don’t have to be running when the Intent is broadcast for the receivers to execute" (source: Professional Android 2 Application Development book)

My app is actually a lockscreen app which by using the programmable way needs to be running all the time :S

Is there a way around it?

I'm trying the following in the manifest:

<receiver android:name=".MyBroadCastReciever">
    <intent-filter>
        <action android:name="android.intent.action.SCREEN_OFF"/>
        <action android:name="android.intent.action.SCREEN_ON"/>
    </intent-filter>
</receiver>

and simple MyBroadCastReciever class:

public class MyBroadCastReciever extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
            Log.i("Check","Screen went OFF");
            Toast.makeText(context, "screen OFF",Toast.LENGTH_LONG).show();
        } else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
            Log.i("Check","Screen went ON");
            Toast.makeText(context, "screen ON",Toast.LENGTH_LONG).show();
        }
    }
}

Answer 1

The two actions for screen on and off are:

android.intent.action.SCREEN_OFF
android.intent.action.SCREEN_ON

But if you register a receiver for these broadcasts in a manifest, then the receiver will not receive these broadcasts.

For this problem, you have to create a long running service, which is registering a local broadcast receiver for these intents. If you do this way, then your app will look for screen off only when your service is running which won't irritate user.

P.S.: Start the service in the foreground to make it run longer.

A simple code snippet (in the foreground service class) will be something like this:

private val mScreenStateReceiver: BroadcastReceiver = object : BroadcastReceiver() {
    override fun onReceive(myContext: Context, myIntent: Intent) {
        if (myIntent.action == Intent.ACTION_SCREEN_OFF) {
            println("Screen off.")
        }
        if (myIntent.action == Intent.ACTION_SCREEN_ON) {
            println("Screen on.")
        }
    }
}

override fun onCreate() {
    super.onCreate()

    val screenStateFilter = IntentFilter()
    screenStateFilter.addAction(Intent.ACTION_SCREEN_ON)
    screenStateFilter.addAction(Intent.ACTION_SCREEN_OFF)
    registerReceiver(mScreenStateReceiver, screenStateFilter)
}

Don't forget to unregister the receiver in the Service's onDestroy:

unregisterReceiver(mScreenStateReceiver)

Just in case for people who are asking why the receiver does not work with the declare broadcasts in manifest for ACTION_SCREEN_ON and ACTION_SCREEN_OFF:

https://developer.android.com/reference/android/content/Intent.html#ACTION_SCREEN_ON https://developer.android.com/reference/android/content/Intent.html#ACTION_SCREEN_OFF

You cannot receive this through components declared in manifests, only by explicitly registering for it with Context.registerReceiver().

This is a protected intent that can only be sent by the system.