Develop Reference

FLAG_SHOW_WHEN_LOCKED doesn't always work

I am trying to display my application over the lock screen on android.
I have it working some of the time. But certain scenarios will not work.
I am starting my activity which extends a React Native Activity from a service like so:
Intent callIntent = new Intent(context, MainActivity.class);
callIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(callIntent);
And I am setting the flags on the window like this in the onCreate method:
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
When it works:
If the activity has been started when the device is unlocked and the app is still in recents. The device will wake and the activity will be displayed over the lock screen.
Activity state changes witnessed:
onRestarted
onStarted
onResumed
onPaused
onResumed
When it doesn't work:
If the app hasn't been run since boot or the app has been removed from the recents. The device will sometimes wake and sometimes the app will flash for a second before returning to the lock screen. When the device is unlocked the app is running.
Activity state changes witnessed:
onCreated
onStarted
onResumed
onPaused
onStopped
I'm not sure if this is specific to React Native or not.

How can I set my WatchFaceService as the default launch activity in Android Studio

I have a WatchFaceService (WatchFace) and every time I run my application it switches to the SimpleFace and then I have to set mine as the watchFace which ends up to be quite frustrating after many restarts.
To notice this does happen with the new Android Studio 2
I read around S.O. how to set the default activity but that does not do the same job as my WatchFaceService is not an activity but a service.
Also via the UI of Android Studio 2 it cannot be selected.
Is there a way to achieve this ? I think it might be difficult because actually it's not running an app, but setting the watch's Watchface at every run.
Any ideas?

The short answer is that this isn't possible. Your watch face is a Service, after all, so there's no way that it can be the default (launch) Activity for your app. They're completely different component classes.
But you can get close.
What you need to do is create a tiny little shell Activity that contains only the following code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent intent = new Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER)
.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
new ComponentName(getPackageName(),
MyWatchFaceService.class.getName()));
startActivity(intent);
finish();
}
...where MyWatchFaceService is the class name of your watch face service (surprise). You'll also need to declare it in your manifest, of course:
<activity android:name=".FaceActivity"
android:enabled="true"
android:exported="true">
</activity>
Finally, configure your Wear module in Android Studio to launch FaceActivity when you run the app. This is under the Run menu, in Edit Configurations.
Having done that, run your app from AS onto the watch, and it'll open the watch face chooser on-device, with your face selected. From there, one tap will start it.
I can't see a way to eliminate that single tap, though.

Starting activity from service on lock screen turns on the screen but does not show the activity itself

I'm trying to start an activity from a service I had already acquired the lock for as follows:
Intent i = new Intent(context, MyActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NO_USER_ACTION);
startActivity(i);
The activity manifest is declared as follows:
<activity
android:name=".MyActivity"
android:configChanges="orientation|screenSize|keyboardHidden|keyboard|navigation"
android:excludeFromRecents="true"
android:launchMode="singleInstance"
android:screenOrientation="nosensor"
android:showOnLockScreen="true"
android:taskAffinity=""
android:theme="#style/MyTheme" />
And finally, on onCreate() or on onAttachedToWindow() (I tried on both), I add the following flags:
final Window win = getWindow();
win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
| WindowManager.LayoutParams.FLAG_ALLOW_LOCK_WHILE_SCREEN_ON);
The problem is that the first time I call startActivity() from my service, the screen turns on but the activity itself does not show up. It shows the lock screen instead. Every subsequent call of startActivity() works properly but I can't find a reason for this odd behavior.
I tried already suggestions to get a full wakelock instead of partial, change the flags and values in the manifest according to the following SO answers:
Android Activity Not Showing When Screen is Woken Up and Lock Screen Not Disabling
how to unlock the screen when BroadcastReceiver is called?
Programmatically turn screen on in android
Android Galaxy S4 -- Activity that is visible over lock screen
Note that my theme is not a dialog but a fullscreen activity.
Any other ideas?

I'm facing the same problem, after a lot of searching here and google, found this which unlocked the screen and popped my activity but it only works for me when the app is running (foreground/background).
import android.view.Window;
import android.view.WindowManager.LayoutParams;
Window window = this.getWindow();
window.addFlags(LayoutParams.FLAG_DISMISS_KEYGUARD);
window.addFlags(LayoutParams.FLAG_SHOW_WHEN_LOCKED);
window.addFlags(LayoutParams.FLAG_TURN_SCREEN_ON);
i'm trying to start an activty when app is closed... (using broadcast receiver)
in the docs (for example here) and most of the answers on SO the flags are added this way:
getWindow().addFlags(WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
but when i tried the way it is like in the example it unlocked the screen instead of just turning on the screen.
hope this help . it still didn't solve my problem completely.
EDIT:
found this post which solved my problem.
there is a comment there on NOT using a dialog theme which solved it for me

Step 1: Add below code in your activity before
setContentView(R.layout.activity_about_us);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON|
WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD|
WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED|
WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
Step 2: Lock your mobile than you will see activity in which you have added this code.
You can implement this if you want to open particular screen by notification occurrence like skype call.

Since my application already includes a Service, this is what I do: if the screen is locked, I register a broadcast receiver (a bit simpler than this one, since it reacts only on unlocking) that starts the Activity as soon as the screen gets unlocked.

Exclude current activity from Recent Tasks

My app, running in background, at some point displays activity to purposefully interrupt user's flow. My activity starts a new task, which appears in "Recent Tasks" lists while being in foreground. Is there any way it could be prevented? Setting android:excludeFromRecents does not work - activity is not presented anymore in "Recent Tasks" only after is has been paused.
Manifest looks like:
<activity
android:name="com.example.recenttasks.MainActivity"
android:excludeFromRecents="true">
</activity>
and activity is started this way:
#Override
public void onReceive(Context context, Intent intent) {
Intent i = new Intent(context, MainActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
}

The key thing you mentioned is
appears in "Recent Tasks" lists while being in foreground
I think you can't change that behavior. I just tested on my app and the same thing happens. If I press the "recent tasks" button while having my activity in the foreground, it appears listed there. The moment I move out of it to another activity or to my phone's main screen, the activity is not listed anymore.
I also tested this on the built-in DeskClock app that comes with recent Android versions and the same behavior is present there when a new alarm is triggered. Note that the AlarmAlertFullscreen activity of that app has the same parameters you mentioned in your question.
I'm not sure you can circumvent this or why you would need to in the first place since the activity is not listed anymore once it loses the focus.

you are defined it in manifest that is enough but it is not coming..
ok..try add this flag also to your Intnet and start the Activity..
intnet.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);

Should the user be able to return to it? (Meaning if it shows and user clicks recents, have they lost their chance to see the hidden activity or should it still be there?)
If they cannot return to it anyway then the best action would be to finish() the activity onPause(). This will mean that as long as you have used android:excludeFromRecents and android:noHistory="true", there will be no item in recents.
If however you do wish to return to the 'interruption' activity (but do not want a recents entry) you could consider still finishing the activity onPause - but also recording a preference flag (something like IS_INTERSTITIAL). Your other activities can then check this preference in onResume and, if it is true, send an Intent to restart the Interstitial instead - To the user it will just appear they are resuming the app in the same state as they left it (interstitial)
Edit: If the screen needs to stay (rather than be re-instantiated) it may be possible to use a DialogFragment, although then you must worry about configuration changes. There is one hack you could try (explained in this answer) -
Set your label empty By using android:label="" your recent task is excluded. however this is a definite hack which may produce inconsistent results (as I haven't tested it to be sure)

Starting multiple instances of the same Activity from Service

I want to start multiple instance of the same Activity class from a Service. The reason I'm doing this, is because I have a Service that runs a "scan" daily, and if it finds any malfunctions it should display a popup for each malfunction.
The Activity that I'm starting is more like a Dialog, has a Dialog theme to display info about the malfunction.
Manfiest:
<activity
android:name=".ui.dialogs.MalfunctionActivity"
android:theme="#style/MyDialog"
android:launchMode="standard">
Intent to start the activity from Service:
Intent displayMalf=new Intent(this, MalfunctionActivity.class);
displayMalf.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(displayMalf);
PROBLEM: to start the Activity from a Service I need the FLAG_ACTIVITY_NEW_TASK which somehow cancels the launchMode="standard" from the manifest, and gives me just one Activity even if I try to start multiple diffrent instances.
Is there anyway in which I can achieve this?

It was so simple. There is the flag FLAG_ACTIVITY_MULTIPLE_TASK which according to the documentation :
Used in conjunction with FLAG_ACTIVITY_NEW_TASK to disable the behavior of bringing an existing task to the foreground. When set, a new task is always started to host the Activity for the Intent, regardless of whether there is already an existing task running the same thing.
Was exactly what I need. Thanks and sorry for answering on my question. It is not a habit. :)

Service will take the flag FLAG_ACTIVITY_NEW_TASK to start the activity but here you can try like this:
Set the instance of the handler of the activity of which you want multiple instances, in the service.
When you want the new instance of the activity use handler.sendMessage(msg) and on receiving this msg in your activity, start this activity again.

I guess your app works in the background and will display the popups even if the app is not in the foreground at the moment, right?
Otherwise I would use normal popup's (AlertViews) instead of starting new activities all the time.
If the app works in the background, you could tell the user with the first popup that your app has found one or more malfunctions and that he should activate the app for more details