android kotlin - app running after phone is locked/screen turn off

Question

I have the following code, I tried to do some work when the phone is turned on or unlocked, this code is working. However, when I tried to run when the phone is off or locked. it is not work

class ScreenReceiver : BroadcastReceiver() {
    internal var screen: ScreenReceiver? = null
    internal var context: Context? = null
    override fun onReceive(context: Context, intent: Intent) {
        this.context = context
        if (intent.action == Intent.ACTION_SCREEN_ON) {
            // do some work here
        }
        if (intent.action == Intent.ACTION_SCREEN_OFF) {
            // do some work here. But it does not seem to work
        }
    }
}

Andridmanifest.xml

<receiver
            android:name=".ScreenReceiver"
            android:enabled="true">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
                <action android:name="android.intent.action.SCREEN_OFF" />
                <action android:name="android.intent.action.SCREEN_ON" />
                <action android:name="android.intent.action.USER_PRESENT" />


                <category android:name="android.intent.category.DEFAULT"></category>
            </intent-filter>
        </receiver>

Can anyone help me why it does not work and how to fix it?

Thanks

Answer 1

You must register the broadcast with registerReceiver(BroadcastReceiver, IntentFilter) . Declaring a receiver in the manifest does not work. You can register your broadcast like this in your code:

val filter = IntentFilter(Intent.ACTION_SCREEN_ON)
filter.addAction(Intent.ACTION_SCREEN_OFF)
filter.addAction(Intent.ACTION_USER_PRESENT)
filter.addAction(Intent.ACTION_BOOT_COMPLETED)
registerReceiver(ScreenReceiver(), filter)

Beginning with Android 8.0 (API level 26), the system imposes additional restrictions on manifest-declared receivers. If your app targets API level 26 or higher, you cannot use the manifest to declare a receiver for most implicit broadcasts (broadcasts that do not target your app specifically).

Refer https://developer.android.com/guide/components/broadcasts for additional detail.