Develop Reference

For Android Lock Task Mode is activityManager.lockTaskModeState always "LOCK_TASK_MODE_NONE"

I'm following the developer guide for Lock Task Mode. It's clear for the most part, but I think needs a bit of work in some areas.
It seems to provide instructions on the presumption that you're starting another activity, though it does mention restarting one in the foreground:
Start lock task mode
"In Android 9.0 (API level 28) or higher, you can start another app’s activity in lock task mode. If an activity is already running in the foreground or background, you need to relaunch the activity. Call ActivityOptions.setLockTaskEnabled() and supply these options when starting the activity."
So what I'm trying to achieve is that when my MainActivity's fragment resumes for the first time, it checks if Lock Task Mode is enabled, and if it isn't, it turns it on. I use the following code, from one of the link's samples, to make the check:
private fun lockTaskModeNotRunning(): Boolean {
// Check if this app is in lock task mode. Screen pinning doesn't count.
var isLockTaskModeRunning = false
val activityManager = context
?.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
isLockTaskModeRunning = activityManager.lockTaskModeState == ActivityManager.LOCK_TASK_MODE_LOCKED
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Deprecated in API level 23.
isLockTaskModeRunning = activityManager.isInLockTaskMode
}
return !isLockTaskModeRunning
}
And I restart the app as described in the above quote. But this code infinitely runs because the line activityManager.lockTaskModeState == ActivityManager.LOCK_TASK_MODE_LOCKED is always false. lockTaskModeState is always set to LOCK_TASK_MODE_NONE, even after starting the activity with setLockTaskEnabled as true. The deprecated field, activityManager.isInLockTaskMode, is also always false.
I must be missing something pretty straight forward. The weird part is, if I stop code execution, the app is indeed in Lock Task Mode (only back button appears, can't go to homescreen).
I'll post my fragment's onResume code as it's relevant too:
override fun onResume() {
super.onResume()
val context = requireContext()
val devicePolicyManager = context.getSystemService(Context.DEVICE_POLICY_SERVICE)
as DevicePolicyManager
val deviceAdminReceiver = ComponentName(context, MyDeviceAdminReceiver::class.java)
devicePolicyManager.setLockTaskPackages(deviceAdminReceiver, APP_PACKAGES)
if (devicePolicyManager.isLockTaskPermitted(KIOSK_PACKAGE)) {
// Set an option to turn on lock task mode when starting the activity.
val options = ActivityOptions.makeBasic()
options.setLockTaskEnabled(true)
if (lockTaskModeNotRunning()) {
// Start our kiosk app's main activity with our lock task mode option.
val packageManager = context.packageManager
val launchIntent = packageManager.getLaunchIntentForPackage(KIOSK_PACKAGE)
if (launchIntent != null) {
context.startActivity(launchIntent, options.toBundle())
}
}
}
}

How to force kill Picture and Picture activity on cross icon click?

i am trying to kill activity from tasks after picture and picture mode was activated and so far I tried finish(), finishAffinity(), onBackPressed(), programmatically set excludeFromRecent but activity still lives on in background..
We can see same behavior in Google Maps when we click on that cross icon. App still lives in background, but i need to brutally kill it :)
<activity
android:name=".PipActivity"
android:launchMode="singleInstance"
android:supportsPictureInPicture="true"
android:resizeableActivity="true"
android:taskAffinity=".PipAffinity"
android:configChanges="orientation|smallestScreenSize|screenLayout|screenSize"
android:windowSoftInputMode="adjustPan|stateHidden"/>
This is how i fire intent:
Intent(context, PipActivity::class.java)
.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK))
Important note: when this activity is not going to PiP mode everything works as expected and activity kills itself normally when i need it!
when i click o this cross icon:
onStop in pipActivity gets called:
override fun onStop() {
cleanView()
finish()
finishAffinity()
setExcludeRecentToKillActivity()
}
private fun setExcludeRecentToKillActivity() {
val am = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
val tasks = am.appTasks
if (tasks != null && tasks.size > 0) {
tasks[0].setExcludeFromRecents(true)
}
}
At this point UI is cleaned and connection interrupted. But System still holds task in background and when i click on it it restarts itself.
I dont want this. The task on right is that closed PiP activity that should not be alive. I want to kill it. Is it possible?

So actually i found the solution. finish() have to be changed for finishAndRemoveTask() and task will be closed in background correctly. So setExcludeRecentToKillActivity() is not needed anymore.
override fun onStop() {
cleanView()
finishAndRemoveTask()
finishAffinity()
}

Remove app from recent apps programmatically

I know that Activities can be declared in manifest as being excluded from recents with android:excludeFromRecents:
http://developer.android.com/guide/topics/manifest/activity-element.html#exclude
However, that's not what I'm looking for, I would like to know if there is a way to remove the app from recent apps programmatically

Yes, generally when you want to have special properties for an Activity when starting it you supply special flags to the Intent. In this case FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS.
Updated:
If you need to hide the current already running activity, you might be able to use this flag in combination with FLAG_ACTIVITY_CLEAR_TOP which would send the new Intent to the existing Activity. You'll have to think and perhaps experiment with what happens as the user moves around your stack though and whether that will make your app re-appear in the recent apps.

This can be done using the ActivityManager.AppTask functionality (starting in API 21)
ActivityManager am = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
if(am != null) {
List<ActivityManager.AppTask> tasks = am.getAppTasks();
if (tasks != null && tasks.size() > 0) {
tasks.get(0).setExcludeFromRecents(true);
}
}

Add these lines to the Activity from which you are exiting the application:
#Override
public void finish() {
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
super.finishAndRemoveTask();
}
else {
super.finish();
}
}

Following is the definition of the flag android:excludeFromRecents (which i know you have already seen):
Whether or not the task initiated by this activity should be excluded from the list of recently used applications ("recent apps").
That is, when this activity is the root activity of a new task, this
attribute determines whether the task should not appear in the list of
recent apps. "true" if the task should be excluded from the list;
"false" if it should be included. The default value is "false".
so to remove the app from the list of recent app you can set this flag on the first activity in your application since that activity launches the the task for you application. If you have multiple tasks (unlikely for most apps) in your application then you need o set this flag for root activity of all the task.

Call this when your activity is done and should be closed and the task should be completely removed as a part of finishing the root activity of the task.
finishAndRemoveTask();

After receiving the other answers, I managed to get to the following workaround: I have an Activity, let's call it XPTO, declared in manifest with
and basically, when I want app to disappear from the recents list, I finish all other activities, then start the XPTO, which basically kills the app (calling android.os.Process.killProcess(android.os.Process.myPid()); in its onResume()
If anyone has a better way of doing this, please share it

How to bring most recently used third party Activity to front?

In my app, I want to programmatically bring the most recently used third party Activity to the front. After looking at other answers here, I've tried relaunching the activity using the baseIntent returned from a list of recent tasks, but that does not seem to bring the activity to the front over whatever else is going on.
My end goal is to create an app that replaces the incoming call screen with a small overlay so the user is not pulled completely out of whatever app they are using when they get a call. I've found you can't replace the default incoming call screen (if this is not true, please let me know as I'd rather do that instead) so as a workaround, I am trying to call the most recently used app to the front of the screen (to overlay the incoming call screen) and then display my overlay on top of that.
Here's the code I am using (The activity is launched from a broadcast receiver)
public class BringMRUAppToFront extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
ActivityManager activityManager = (ActivityManager) getSystemService("activity");
List<RecentTaskInfo> recentTasks = activityManager.getRecentTasks(1, ActivityManager.RECENT_WITH_EXCLUDED);
if(recentTasks.size() > 2) {
RecentTaskInfo recentTask = recentTasks.get(2);
Intent testIntent = recentTask.baseIntent;
Log.i("MyApp", "Recent task - " + recentTask.baseIntent.getComponent().getPackageName());
testIntent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(testIntent);
}
finish();
}
}
Is there a reliable way to bring any third party activity to the front? The activity is guaranteed to be in memory (if one is not in memory, then I would just display the home screen), so there shouldn't be an issue there. I also don't believe it would be a security issue in this case as it would just be displaying an app that was visible right before the phone rang - though I do understand that opening this up in general in the SDK could pose a risk...still hoping it is possible.
EDIT: Modified the code slightly to reflect what I'm doing. The desired task will almost always be the 3rd task in the list - first is the current task and second is the task of the ringing phone. I am able to call the task to the front, but it is not always in the same state (going to the browser's page instead of the settings screen in the browser, for example). How does the recent tasks list do this?

Figured it out by looking at the Android source code - this is exactly what the Recent Tasks screen does, both pre- and post-Honeycomb:
RecentTaskInfo recentTask = recentTasks.get(1); // task 0 is current task
// maintains state more accurately - only available in API 11+ (3.0/Honeycomb+)
if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.HONEYCOMB) {
final ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
am.moveTaskToFront(recentTask.id, ActivityManager.MOVE_TASK_WITH_HOME);
} else { // API 10 and below (Gingerbread on down)
Intent restartTaskIntent = new Intent(recentTask.baseIntent);
if (restartTaskIntent != null) {
restartTaskIntent.addFlags(Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY);
try {
startActivity(restartTaskIntent);
} catch (ActivityNotFoundException e) {
Log.w("MyApp", "Unable to launch recent task", e);
}
}
}
Permission android.permission.REORDER_TASKS is necessary for this to work correctly.

Start from Android L, getRecentTasks() returns application’s own tasks and possibly some other non-sensitive tasks (such as Home), so you can not do such job.
References: https://developer.android.com/preview/api-overview.html#Behaviors

Why dont you use a global static variable that is accessed by all activities and on its onPause just set that variable to that activity value
Eg
I am placing a static variable called ActivityName
public static String ActivityName = "";
and in the onPause of every activity just assign it the activities pacakage name
#Override
public void onPause() {
super.onPause();
// The static global variable
com.pacakagename.Utls.ActivityName = "com.pacakagename.Act1";
}
So when any of the activity pauses the value is assinged and you will come to know of the most recent paused activity and you can restart it using Class.forName(ActivityName)

Two instances of my android application are running....How to avoid this?

Here is my problem -
I copied my .apk file onto phone memory card and launch my application clicking on it and it allows me to install my application.I install my application.Finally,I got system installation pop up containing two options "Open" and "Done".When i click "Open" my application got launched.Up to this point everything is working without any problem.
Now in my application I click on a button and some download is taking place as a result(Showing progress dialog).Now I press a Home button,so my application goes to background.
Now I again launch my application by going inside Menu and clicking on my application icon.
Expected result - Still I Should see Progress Dialog for downloading.
Actual result - A new instance/session of my application is getting started.
So how to avoid this so that only one and one instance/session of my application should run.

#Palejandro, here you are. Put the code below into your main activity onCreate() method:
// Possible work around for market launches. See
// http://code.google.com/p/android/issues/detail?id=2373
// for more details. Essentially, the market launches the main activity
// on top of other activities.
// We never want this to happen. Instead, we check if we are the root
// and if not, we finish.
if (!isTaskRoot()) {
final Intent intent = getIntent();
final String intentAction = intent.getAction();
if (intent.hasCategory(Intent.CATEGORY_LAUNCHER) && intentAction != null && intentAction.equals(Intent.ACTION_MAIN)) {
Log.w(TAG, "Main Activity is not the root. Finishing Main Activity instead of launching.");
finish();
return;
}
}
I used this piece of code in my projects and it works fine!

I believe you need to put
<activity
android:launchMode="singleInstance"
</activity>
in the manifest file.

what do your OnPause, OnResume and OnCreate?
I will bet money you are not saving anything OnPause, and starting a new instance all the time via OnCreate.
You should read the notes on Activity Lifecycles.

If you haven't got this sorted yet, I would say your app is actually being killed when home is pressed, or perhaps you have a bug that doesn't latch onto whatever object is keeping state.

// put below code in your launcher activity before call super and setcontentview()
ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
// get the info from the currently running task
List< ActivityManager.RunningTaskInfo > taskInfo = am.getRunningTasks(10);
boolean alreadyTask=false;
for(ActivityManager.RunningTaskInfo info : taskInfo){
ComponentName componentInfo = info.topActivity;
String value= componentInfo.getPackageName();
if(value.contains(getPackageName()) && !info.topActivity.getClassName().contains(getPackageName()+".LauncherActivity")){
alreadyTask=true;
Log.i(TAG, "second instance found!!!");
break;
}
}
if(alreadyTask){
finish();
}

I don't have a solution but the problem is that the intent used to start the app is different when you open it directly from install compared to opening it from your home screen. Since it will get started by two different intents it will open a new instance the second time round.
A quick work around is to avoid pressing "Open" when you have installed the application. Press "Done" and then find the application yourself.
See: http://code.google.com/p/android/issues/detail?id=2373