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After closing activity Android goes back to activity that should no longer b in the stack

I have activity A->B in the stack, and to launch activity C, I call
Intent starter = new Intent(context, MainActivity.class);
starter.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
context.startActivity(starter);
This all works fine, Activity A and B both have OnDestroy called. If I press the hardware 'back' button now, the activity appropriately finishes and is hidden. The problem is now however, if I return to the application through the application by clicking the hardware recent apps button, it will return to Activity A. Activity was destroyed and not in the stack. In the manifest, none of activities have had a android:launchMode set, so they are on default.
The only other possible piece of relevant information is that there is an Activity X that is a launcher Activity that is android:launchMode="singleInstance" and it launches activity A, that being said, it gets destroyed and it shouldn't be in that activity stack anyways.

While pressing back button While in Activity C may called onDestroy() of actvity C.
please insert logs to see whether it is called or not. This is the only reason why your activity A launch again.
please refer Android Back button calls ondestroy?
please let me know if these not work for you.

The hardware back-button can be overwritten by the follwing code :
#Override
public void onBackPressed() {
//put Intent to go back here
}
You could just overwrite it with your code written above

How to open a previous instance of an Activity and recreate it?

Basically what I need is to recreate one Activity each time I call startActivity() moving the instance to the front and not destroy the other activities.
For instance, if I have in the activity stack
A->B->C->D
and from D I want to open B, the flag I currently use is FLAG_ACTIVITY_REORDER_TO_FRONT which leave the Activity stack in this state: A->C->D->B. That order in the activity stack is perfect, however, with that flag the Activity is not recreated and onNewIntent() is called.
Because the complexity of the Activity I do not want to refactor a lot of things, what I want is to recreate B from scratch (onCreate() has to be called) instead of execute my logic in onNewIntent() method. The activity stack should have the same state as if I use FLAG_ACTIVITY_REORDER_TO_FRONT. Any idea? Your help will be much appreciated. :)

If all of your work happens in onCreate() and you want the same stuff to work within onNewIntent(), then you could do potentially get away with a simple re-factor. Where all your code is in the setupActivity() call.
public void onCreate (Bundle savedInstanceStateF)
{
super.onCreate (savedInstanceStateF);
setupActivity();
}
public void onNewIntent(Intent intentF)
{
super.onNewIntent(intentF);
setupActivity();
}

Create a Button to Close the Program

My project has 4 activities and users from activity A go to B after that to C and D. I need to create a button in activity D to close program directly because if user has to close all activities ( D ->C -> B -> A-> close) it would be unfriendly.

Register a broadcast receiver in each of the activities, listening for the "close all action", when the button in the last activity is pressed, send that broadcast, so all the activities register will execute their "onReceive" method on the broadcastreceiver, and there all them will be finished as long as they are registered.
This will definitely do the trick, although to be honest is quiet a poor implementation, chances that you are doing something wrong in the navigation are high, maybe fragments or a tab would be better suited for what you are trying, in stead of creating such a stack of activities...
Hope this helps...
Regards!

I think onActivityResult could be the better option.You could finish the activity if required task is being completed otherwise just backtrack on previous activity

You should override onBackPressed() from each Activity and call finish().

Assume the first activity in your application is named ActivityMain. Presumably it will be the oldest one on the stack.
Create an intent to start ActivityMain using the flag FLAG_ACTIVITY_CLEAR_TOP. Set an extra in that intent to indicate this is an application exit, and call startActivity() with that intent. This will clear the stack and get you back to Activity main.
In ActivityMain call getIntent() then check for the exiting application Extra value. If it is set, call finish().

A not so elegant solution:
Instead of calling startActivity, call startActivityForResult, from A to D.
On Activity D, when your button is pressed, set any result (let's say Activity.RESULT_OK) and call finish().
On each Activity (from A to C), override the method onActivityResult to check for the result. If the result is Activity.RESULT_OK, then you set the same result and call finish() again.
If you want, instead of just setting the result, add an Intent with some flag to tell the previous Activities to finish themselves.

Simply do one thing . In your activities add an overriden method onPause
onPause(){
finish();
}
This will close all your activities once you press back from any activity.

Run Activity B from Notification and force back button to run Activity A

I have an Android application that contains two Activities.
Activity A has a button that launches Activity B using Context.startActivity(Intent intent).
There is also a Notification that opens Activity in the same way.
If I start B from this notification and press back button - it just closes B and does not shows A like I go there with normal case.
Is it possible to force B to bo back to A if started from notification without history stack ?
Solution
As stefan and Paul Lammertsma mentioned, the best way is to start A from notification and in A create new intent with B - but not in onCreate() !
I dig this a bit and found that if I set in AndroidManifest a new property for A activity:
android:launchMode="singleTask"
there will be in A activity called
onNewIntent(Intent intent)
And there we should checl if Intent containst extra value passed from notification - and if so, then we call new B intent.
Thank you both and good luck with it for next devs ;-)

I would suggest having the notification call Activity A (instead of B directly) with some flag in its extras bundle. In A's onCreate(), check for the flag, and immediately launch Activity B. This will ensure that pressing back on B will return to A.

An easy way to achieve this would be to actually start Activity A from your Notification with a flag to call Activity B instantly.
So you just have to put an extra to your intent you are starting in your Notification and you have to check in Activity A if this extra exists and if it exists then you start Activity B.
Update: another way, but in my opinion not so good, would be to override the onPause() method of your Activity B and call Activity A there.

Maybe not the prettiest solution, but nevertheless a quick one;
add a boolean extra to the intent launching B, "launchedFromNotification" or something like that.
In activity Bs onCreate() you store that boolean value for later use.
In activity Bs onBackPressed() you can check the value of your boolean and if true, launch activity A before calling finish();
A prettier solution may be to launch activity A from the notification, with an extra telling it to directly launch activity B.

Update the first screen automatically even if it is declared as android:launchMode="singleTask"

I have 2 activities. Activity A and Activity B. Both calling each other though intent. Activity A calls Activity B. Activity B accesses database and sends it back to activity A through putExtra() and getExtra().
Now my activity A is in declared like this android:launchMode="singleTask"
When I go back to activity A I want my this activity A to be updated or refreshed automatically. But to my wonder what I understood on debugging that if I declare an activity as launchMode="singleTask" then it just brings forth the screen to top from the stack. It does not actually go inside the code.
Is the concept what I understood correct ?
The solution I see is have a refresh button and on click of that access the code and update screen. But I do not want to do that. Do you think there is any other alternative ? I do not want to change launchMode="singleTask"
Thanks in Advance.

Try startActivityForResult(intent); and while you have finished in B setResult(RESULT_OK); and finish(); the B activity, and in A onActivityResult(int,int,intent); catch the result code if it is RESULT_OK update your A.

No matter which launchMode, when you switch from Activity B to Activity A, the onResume() method must be invoked. You can put your refresh code there to get your activity A updated.

put your refresh part in the onResume method .Once Activity B completed your onResume method will be invoked in Activity A.