CODEWITHSUNDEEP
android
Rahul
Rahul

Reputation: 1667

How to detect the event when device is locked?

In my code I am trying to understand the intents that get launched when the device is locked.

Eg: Suppose my activity is running, and I press the power button to lock the phone. INTENT.ACTION_SCREEN_OFF is launched. The activity is paused and the screen goes blank.

So what i want is whenever the device is locked by the user i dont want to finish my activity, but if the user press home button or back button i am finishing the activity. So for that i have written a code but its not working.

Code i have used

public void onResume()
{
    super.onResume();
    m_ScreenLocked = false;

    // Intent and receiver to listen to screen lock
    m_IntentFilter = new IntentFilter(Intent.ACTION_SCREEN_ON);
    m_IntentFilter.addAction(Intent.ACTION_SCREEN_OFF);
    m_BroadcastReceiver = new ScreenStateBroadcastReceiver();
    registerReceiver(m_BroadcastReceiver, m_IntentFilter);
}

private final class ScreenStateBroadcastReceiver extends BroadcastReceiver 
{
    @Override
    public void onReceive(final Context context, final Intent intent) 
    {
         if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) 
         {
            m_ScreenLocked = true;
         } 
         else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) 
         {
             //other stuff
         }
    }
}

@Override
public void onStop()
{
    super.onStop();
    m_NoteManagerObject.setPageViewRunning(false);

    if (!m_ScreenLocked)
    {
         unregisterReceiver(m_BroadcastReceiver);
         finish();
     }
     else
     {
         unregisterReceiver(m_BroadcastReceiver);
     }
}

Upvotes: 1

Views: 1340

Answers (1)

Jeffrey Blattman
Jeffrey Blattman

Reputation: 22647

when you register a receiver programmtically in your activity, it won't get broadcasts when your activity is paused. the docs are fuzzy here as they simply "recommend" unregistering in onPause(), but do not say that the receiver won't work when your activity is paused.

the real question however is why you want to do that. as a user, i'd be miffed if my screen went off when i was using your app, and when i unlocked the screen, the app was gone. remember that you can't differentiate between the user pressing the power button and the screen simply timing out.

anyway, a possible fix is to register your activity to receive those actions in your manifest. that won't necessarily work though as not all intents can be registered for in a manifest intent filter. if i recall, the ACTION_SCREEN_* intents can't be registered for in your manifest.

another way would be to listen for those intents in a service that is running along side your activity, then be able to send a different intent to your activity to tell it to finish itself.

Upvotes: 1

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