Android App Icon intent category seems inconsistent - android

Clicking my app icon will sometimes take me to the launcher activity, but other times it will resume the activity where it left off (emulates the behavior of clicking the application in recents).
I've read (can't find concrete docs about this, other than a one off post from 3 years ago by Diane Hackborn) that after about half an hour, the OS will make sure that when you click the app icon, it will relaunch the app, but sometimes it seems to do this directly after I exit the application (with the home button, not the back button as that will call finish on the activity).
Why is this?
Is there any way to force the launcher activity in the Android OS without killing the app first then restarting it? I need to test how my app handles the launcher activity after the application may already be running.

Android will free up memory whenever it feels necessary. For that, it will kill inactive apps. If your app goes to background, at some point Android will probably kill it. Matter of time.
You can kill your app, or you can make it kill itself when it goes to background. No more options.
in order to make your app kill itself, you should override the onPause() method (which is always called when the app goes to background) and add in it a call to onDestroy().

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How to restore a specific activity that is not the launcher activity and instantly navigate to it after the system has killed the app

I have multiple activities in my app and a specific problem in which after my app is killed by the system, upon reopening the app (icon or from the overview) it starts loading my launcher activity with the splash screen instead of loading the last activity that the app was using.
My launcher activity is essentially a form of a login screen which should be used only the first time the app is opened, but instead it is reopened every time the app is killed by the system and app reopened by the user.
I am inexperienced and do not know if this is the default behavior of Android or a bug, I have searched through stack overflow but could not find a conclusive answer.
Coincidentally this well known long standing Android bug has appeared. (https://issuetracker.google.com/issues/36941942)
I do not know if the two problems might coincide, and I cannot be sure when the longstanding bug has first appeared because previously I was testing through Instant Run which does not result in the bug, but am now forced to test through play because it does result in the bug.
Thanks.
I am inexperienced and do not know if this is the default behavior of Android or a bug
This is the default behavior of Android, if there is no current task associated with your app. That includes:
User swiping the task off of the overview screen
You terminating the process and task from inside Android Studio
All the time if the user has been out of the app for 30+ minutes
User using Force Stop on your app in Settings
And probably some other scenarios that I'm not thinking of right now
My launcher activity is essentially a form of a login screen which should be used only the first time the app is opened
I recommend that your launcher <intent-filter> be on your primary activity in the app. If that activity determines that the user has not logged in, it can do something to authenticate the user (display a fragment, start an activity, etc.).

Android studio App home button and re open

Android studio home button problem.
I have so many activities, when I press home buttom in any activities.
Then if I restart my app.
it started from splash activity(logo activity).
However, I want to start this from activity where I pressed home button.
Can anybody figure this out?
By default, Android handles this behavior. When you press the home button, the app should go to background and at the next time when you open it, it should start from where you left off. But, Android's memory management is designed to automatically terminate minimized apps that have not been accessed in a while when memory is needed for newly launched apps.
If there is enough memory available and still your app gets terminated, that means you are not using the API's correctly. Please read this [article] to know how to handle onPause() and onResume() to achieve this behavior.

How to return to already running Android activity

I am working on a fitness app which has a home activity which launches a workouts activity which launches a specific workout activity. In the workout activity, one may start a workout. Thereafter, one might want to then press the Home button and launch a music player or perhaps the web browser. At some point, one would probably launch the app again to return to the already running workout, but that ends up launching a new instance of the app. When I set the launchMode on the home activity to singleTask, it simply goes back to the existing home activity when I tap the launcher icon. What I would like is for it to go back to the workout in progress, which is where you would depart the app.
Essentially, I'm looking for behavior identical to iOS where it would simply restore the app to its current state if you "relaunched" the app and it was still running.
It is supposed to work as you've described. In most cases, it actually does work like that. However, there is a long-standing nasty Android bug which causes the behaviour you've described. This happens when you launch the app for the first time from an IDE (like Eclipse) or by clicking the "open" button on the Installer screen. To see if this is what you're seeing, just do this:
Go to Settings->Applications, choose your app and click "Force close"
Launch your app, do something, press the HOME button
Launch your app again.
You should return to where you left off. If not, something else bad is going on. If that is the case, please post your manifest in your question, because the problem is likely in these.
Don't try to use special launchModes to fix this. This just creates more problems.
See this answer for more information about the nasty long-standing Android bug.

What is the difference between launch app from "recent apps" and tapping app icon

I'm working on large project, so there is some logic for saving application state, and then opening correct activity(fragment) when it comes from background.
But anyway, I've found that if user navigates through my app and then minimize it - android opens it from background in different ways in following cases:
User taps on app icon (behavior: user see home activity, doesn't matter where he was, when application was minimized)
User select app from android "recent apps" (behavior: user see exactly what he saw, when the application was minimized)
So, what is the difference between launching application from background by this two ways? I always thought, that it is the same mechanism, but, obviously, I was wrong.
Thanks for any answers
You should pay atention on the folowing docs Activity and Tasks. In short words: if user start app from recents you will receive onRestart before onStart (without onCreate it means that your app was just "suspended"). You able to save screen state using onSaveInstanceState(). But in general starting from icon and from recents - different application behaviors and you should provide proper code for this ways.
UPD
As described below root cause of unexpected behaviour was additional lunchmode attribute.
From what I experience as an Android user, both are same.
The difference we usually see is how we close the app
Press back button until app close / finish()
On this state no matter how we open the apps it will go to the main screen
Press Home button
On this state depend on the app. If the app does not handle any Activity the app will same with the first state. But if the app handle something like when onPause() the Activity then finish() the apps, then whatever you open with app icon or recent apps will provide the same result.
Correct me if I am wrong

How to force all activities in an application to always be destroyed (for testing purposes)?

I am basically looking for the same functionality found in the DevTools (Development.apk) app that comes with the emulator. I am wanting to perform similar testing on an actual device but the DevTools app does not work properly on the device I have so I cannot use it.
I am looking to test in a similar way.
What this does is causes each Activity to be destroyed whenever it leaves the screen, holding onto its instance state just as if the system needed resources and had killed it. (So I can't just call finish)
Is there a way to do this?
Thanks
You can kill your app's process at any time using the DDMS stop button. highlight your application in the list and click the stop sign button. your application will be destroyed like it was killed by the system.
See the stop button in the left pane(Devices) above each device listing:

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