When my application is idle, Android kills the process.
If user reopens the application after some time, only the top Activity is created - this is a problem for me because the activity depends on initialization of other objects (which are now destroyed).
What I want to do in that case is to re-launch the application.
How can I do that?
Just identify that your Application is being launched after it was previously destroyed by Android, you could do this by keeping a variable in a custom Application class, and set it to true after your applicaiton is initialized. So when the applicaction is re-launched, this flag is false, and then just make an Intent to launch your main Activity specifying FLAG_ACTIVITY_CLEAR_TOP :
Intent reLaunchMain=new Intent(this,MainActivity.class);
reLaunchMain.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(reLaunchMain);
I think this answer only for you.
After finish progress call this
finish();
Intent intent = new Intent(this, sameactivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
You should probably be looking at storing such Objects in your app's implementation of the Application class.
If these objects contain state that needs to be more persistent, you should save the state of such Objects in each Activity's onPause() method, either to the database, in SharedPreferences or remotely.
Related
This question already has answers here:
Finish all activities at a time
(21 answers)
Closed 3 years ago.
I want to kill my app from a exit button on my navigation drawer. the drawer has a exit button that is suppose to just kill the whole app (all activity) and gets the user out of the app .
When i am using finish() in the first activity its working but when i go into the app and call finish() the activity gets killed and returns to previous activity but never really kills the app.
Tried to use System.exit(0) but no luck.
Extra Information Might Help
I have all my activity started with android:launchMode="singleTop" . it means all those activities that are already created will not be created again and just reordered to front on calling.
Do anyone have any suggestion for this , please do help.
Update
I want to make some updates here as my question looks like this SO Question.
As i have already said i am using a android:launchMode="singleTop" . and this answer is not working for my case. I have to call onCreate() to make this happen but it is not my case.
Use below code
public void AppExit()
{
this.finish();
Intent intent= new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
System.exit(0);
}
Call above function to exit from App.
First, you need to decide if you just need to take the user out of the app, or if you also need to finish() all of your activities. It depends on your needs, but my guess is that in most cases most users won't know the difference, and Android is designed to have many apps having activities still running. If this is all you need, then you can just use an Intent to take the user to the home screen.
Intent intent = new Intent(Intent.
intent.addCategory(Intent.CATEGORY_HOME);
startActivity(intent);
If you actually want to finish() your activities, then you need a mechanism to inform all currently running activities that the user is exiting the app. You can use something like EventBus to send an event that will be received by all registered subscribers; if you don't want to use a third-party library, you can do the same type of thing with LocalBroadcastManager. To do that, you would register a BroadcastReceiver with an IntentFilter for a custom action and broadcast an Intent with that action when the user wants to exit.
In either case, every activity should receive the signal and call finish() on itself. Note that the subscription (in the EventBus case) or the registration of a receiver (in the LocalBroadcastManager case) must be still active after onStop(), so I would register in onCreate() and unregister in onDestroy().
Use below code in your exit button
Intent intent = new Intent(this, ActivityOne.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.putExtra("EXIT", true);
startActivity(intent);
And, in your ActivityOne.class oncreate() method just put below code
if (getIntent().getBooleanExtra("EXIT", false))
{
finish();
}
As a few answers say, call finish(); after you start an intent from an activity. That will make sure the current activity is the only running activity. Also try super.finish(), which will call finish() at parent activity.
You can alternatively use only one activity with many fragments. That way, if you call finish() in the exit button OnClickListener code, you'll exit the app. This will also save a lot of coding since you will be defining the navigation drawer once.
First of all, Android apps are not intended to be killed other that by the system, which attempts to keep them in memory in case the user will return.
But, if you have to do it, try this:
android.os.Process.killProcess(android.os.Process.myPid());
I read several similar questions here, but I didn't find a clear reply to my question.
I launch my Android App and I have my main ActivityA in foreground
after some time I push a button (of ActivityA) and I open (and put in foreground, then visible and ontop) ActivityB. I do it simply by the command myContext.startActivity(myIntent);
It means that now ActivityA is in background (onPause()), then not visible.
After some time I push another button of ActivityB with the target to put in foreground (then visible and ontop) again previous ActivityA
What is the correct and best way to do it? According to my understanding (but I'm not sure it's correct.) it shouldn't be by startActivity(), because startActivity() creates another instance of ActivityA (it calls onCreate() ) and then there will be 2 instances of ActivityA running (one in foreground and one in background). What I want to get is a calling of onResume() for ActivityA (and not of onCreate() ).
The second question is: how can I know if ActivityA is still alive in background? Maybe after sometime the system killed it to free resources.
Note: the solution in my case cannot be to use finish() to destroy ActivityA when I open ActivityB, and then to use startActivity() to reopen it, because I need ActivityA alive as much as possible.
Thank you very much in Advance
Fausto
What you need is the FLAG_ACTIVITY_REORDER_TO_FRONT when starting a new activity. This will cause a background activity to be be brought to the foreground if it's running, or create a new instance if it's not running at all.
From inside ActivityB:
Intent intent = new Intent(this, ActivityA.class);
intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(intent);
What is the correct and best way to do it?
Use startActivity(), with an Intent on which you have added Intent.FLAG_ACTIVITY_REORDER_TO_FRONT.
it shouldn't be by startActivity(), because startActivity() creates another instance of ActivityA
While that is the default behavior, Intent flags can alter that behavior.
how can I know if ActivityA is still alive in background?
If you did not finish() it, and your process has not been terminated, it exists.
Maybe after sometime the system killed it to free resources.
Android terminates processes to free up system RAM. It does not destroy activities on its own.
because I need Activity A alive as much as possible
To be honest, that suggests that you have other architectural issues. Bear in mind that activities are destroyed and recreated for various reasons, such as configuration changes (e.g., screen rotation). Activities should be very disposable.
You can use following
1. For launching new instance (current state of ActivityA) and get ActivityA on Top of Stack
Intent intent = new Intent(this, ActivityA.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
2. For launching old instance and get ActivityA on Top of Stack
Intent intent = new Intent(this, ActivityA.class);
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
For more detail please check
Task and Back Task
You can use StartActivityForResult in the place of StartActivity in activity A and on activity B you can setResult when you want to open Activity A again.In that case OnActivityResult() of activity A is called not onCreate().
How do I get my app to appear in on the screen after it has been replaced by some other screen/activity? Some network event occurs and my application wants to reappear in the foreground (presumably in a polite manner).
I think I need to do something like:
contxt.startActivity(myActivity);
I don't want to create another instance of my app or cause it to restart, but I want it to appear.
Use FLAG_ACTIVITY_NEW_TASK
Intent intent = new Intent(contxt, myActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
contxt.startActivity(intent);
In your myActivity onNewIntent is called. I assume myActivity is the top activity in your app current stack
When I create a Intent:
Intent in = new Intent(this, myclass.class);
this.startActivity(in);
I create a new Intent but the last Intent is not destroy
It's still in memory
How can I kill this last destroy?
So I want to create two Intents in two different classes:
in the first class I write this:
Intent in1 = new Intent(this, myclass2.class);
this.startActivity(in);
and in second class I write this:
Intent in2 = new Intent(this, myclass1.class);
this.startActivity(in2);
but when I Click in1 will create and the in2 will destroy, and when i Click on in2 the in2 will create and in1 will destroy.
a want to clean my phone memory.
You can prevent the user from going on to the previous Activity by overriding the back key functionality like this:
public void onBackPressed() {
//doing nothing on pressing Back key
return;
}
Though this approach is not encouraged.And as everybody knows, the Activity will be automatically killed when certain aspects come up like memory requirement. You cannot destroy one Activity at your free will.
Though for specific cases like a welcome splash screen maybe, you can do one of the following two things:
1) call finish() method on your current Activity as you move onto
your new Activity(generally done when using Thread).
2) use the following in your manifest:
<activity android:name=".WelcomeScreen" android:noHistory="true" ... />
This will tell the device to not keep this Activity on the Activity stack.
Activities remain in memory until Android decides it should be removed. Don't worry about it. It'll get destroyed when more memory is needed. It's effectively "unused" memory until your top activity uses it.
I'm not sure to understand your question...
You want to start a new activity and destroy the previous one?
If this is what you need, you can use:
startActivity(new Intent(this, myActivity.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
The "CLEAR_TOP" flag tell "Hey! I want to start this activity and kill all the other ones!"
Since the Android runtime environment uses garbage collection (just like "traditional" Java), you won't need to worry about manually destroying objects in most cases. The memory taken up by the unused Intent object will be recycled if the system needs additional space for new objects.
When I restart an Activity using
Intent intent = new android.content.Intent();
intent.setClass(this, this.getClass());
this.startActivity(intent);
A lot of the state is remembered, but I want to clear it all (its a rare exception handler that I am using to try to clear all).
What you'd have to do is kill the activity in the onPause() method (by calling finish()) . What happens is that when you call your intent and your activity was already created but it's sleeping, it doesn't call its onCreate(), it just calls onResume() and all the state would be there.
This may have other consequences, i.e. if the user is working on your app an a text or a phone call arrives your activity would be killed, losing all the state.