Develop Reference

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.

Show *only* a toast (no UI) after sharing text into an app?

I'm a starting Android developer and would like to know how to achieve this:
1# User is using e.g. Chrome
2# User wants to share the page (meaning: the URL, which is text) into an app
3# User chooses the app from the share menu
4# The app shows only a small notification on top of Chrome (current foreground app, which is the sender of the intent)
So the app would receive the intent from Chrome and do something with it, but wouldn't change the foreground app. It would stay in the background and show only a very small notification to the user that the sharing of the URL into this app actually succeeded. Toast or something like that.
This is basically the way for instance Pocket handles sharing into it.
How can I achieve this? IntentService? I cannot seem to find the correct answer to this. Theme.NoDisplay, Intent, IntentService – I cannot figure out the correct way since I'm not too familiar with Android yet.
Thank you a lot in advance!

Use the NoDisplay theme (update activity declaration in manifest) in the activity that does your sharing work as follows:
android:theme="#android:style/Theme.NoDisplay"
This will prevent the activity from being displayed.
Then once the activity starts, do your sharing task, display the Toast and call finish()

finish your activity onResume(). It will not shows any of Your Activity.
You can do like this:
protected void onResume() {
super.onResume();
finish();
}

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)

Create new intent in background

I am looking for a way to launch another app from within my app but so that the focus is not changed from my app to the app launched.
I.e currently I have the new app launched via a intent, however when this is carried out the new app is launched and becomes the app in view, I need it to be kept in the background with my app still in view.
The reason for this?
I am developing an application for internal use that will act like a lock-screen to the device so although things must happen in the background the 'lock-screen' must always be on top.
I have done some research into intents and launching other apps but can not find anything about what I need.
Hope you can help thank you!
Currently the terminal is called like this:
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.setComponent(new ComponentName("jackpal.androidterm", "jackpal.androidterm.RemoteInterface"));
intent.setAction("jackpal.androidterm.RUN_SCRIPT");
intent.putExtra("jackpal.androidterm.iInitialCommand", cmdString);
The reason it needs to be running in the background is so that the app can run commands in terminal without the user having access, but then they 'unlock' the screen they need to then be able to view the terminal and what commands are being run etc

You can not startActivity in Background.Instead start the activity and minimise the activity(in your case this activity is of different application) using moveTaskToBack(true);
In your case, put a condition based on your intent and its params and use moveTaskToBack(true); so that activity will be minimised only when your application launches.

This won't be possible, you will have to start a background Service that does the actual work and only launch the Activity you want to navigate to once your foreground Activity is finished. Depending on your architecture, you can store the Activity to call when your foreground Activity is finished and change it from the service. That way you will have your desire behaviour without having to actually call the Activity.

In addition to the answer from #Meher, in the intent for your current starting activity, you can add the flag FLAG_FROM_BACKGROUND.
With this you get rid of the "blinking" effect (the one where your activity shows for one fraction of second while it discovers wether to go to background)

How to remove application from recent application list?

I guess that Android won't let people to do this, because they think they have perfect handle for the task/applications. However, I really need to do this in my case.
I have an activity A acting as the entry point of my application. In that activity, it reads the preference and decided which activity to start, say B or C. After that, it finishes itself. So, activity A never appears to the users.
My application stores things on sdcard, and reads from it constantly. So, when the sdcard is unmounted, I need to display a message to the user that the sdcard is unavailable, instead of opening B or C. I set a check in A to display that message when sdcard is unavilable. When that message is displayed, A will not try to start B or C.
Things works perfectly if user only enter my application from application launcher. However, I found that user can also enter my application by long pressing home and choose it from the recent application list, if he has opened it recently. When user does that, it skips A and goes directly to B or C. I don't have the check in both of them, so exception is thrown while I am trying to access sdcard, and force close dialog pops up.
I can simply move my check to both B and C to fix this problem. But in the future, the number of activities started from A will increase. If there are 6 of them, I'll need to copy this check to 6 places. Needless to say, this looks very ugly, and is a maintenance nightmare.
So, the best fix should be removing my application from recent application list when the sdcard is uunmounted. However, I can't find how to do this. Even killing the process or use ActivityManager.restartPackage, it still appears in the list. Can anyone tell me how to remove it from the list?

try
<activity android:name=".MainActivity"
android:excludeFromRecents="true" ...
in your AndroidManifest.xml's activity declaration.

Other attributes can help your activity isolate from other activities in the same package.
<activity
android:name=".aActivity"
android:excludeFromRecents="true"
android:taskAffinity=""
android:launchMode="singleInstance">

just add android:excludeFromRecents="true" in your activity's tag in the manifest file..its easy

You need to set below code in Launcher Activity in AndroidManifest.xml :
<activity>
...
android:excludeFromRecents="true"
...
</activity>
or start this activity from
intent.setFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
and also in AndroidManifest.xml
<activity>
...
android:label=""
...
</activity>
Setting label as empty will let this activity NOT be shown in Recent App list.

I would not recommend to do so but I would try the following options:
Option 1:
On B and C add:
protected void onPause() {
finish();
}
Option 2:
Add to B and C the following in the AndroidManifest:
android:noHistory= "true"

Removing your application from the recent apps list is probably not possible, and definitely not the best solution. That will just confuse the user who expects all apps to behave similarly.
Regardless, I don't think it will solve your problem. If the user hits home while on Activity B, then selects your app from the home page, it will start Activiy B again.
There are a number of ways to solve the real problem. One easy one might be to create a base Activity that performs the SD card check, and have all of your activities extend from it. That way the check is only in one place.

OK, I know for a fact that it can be done in 2.3.4. The app Toddler Lock when opened clears the recent app list so that when you "Lock" your phone if you long press home key the list is blank. Unfortunately I have not found how to do it. So for anyone who is looking and reading postf that say it is not possible don't give up. I sure heck am not.

if you wanna exit Application on Button click use this code :
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
startActivity(intent);
To kill the complete app and remove it from Runningapp list kill the app through its pid(its nasty)... use this lines before above code.
int pid = android.os.Process.myPid();
android.os.Process.killProcess(pid);

try this,
it will finish all activities and remove app from recents
private fun killCurrentApp() {
val am = this.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager?
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
val appTasks = am!!.getAppTasks()
if (appTasks.size > 0) {
val appTask = appTasks.get(0)
appTask.finishAndRemoveTask()
}
}
}