Android When restoring app from homescreen, switch to different activity - android

I have three activities, lets call them Act1, Act2 and Act3. There is a login form on Act1 which (upon successful login) goes to Act2 which has two options (1. Go to Act3, Go to Act3 with some extra data). The user then goes to Act3.
Of course, when the user presses the "home" button the android device, the application is minimized and held in memory until android needs to use the memory (in which case the App is destroyed). However, when the user presses the "home" button and then opens the app up again quickly, the app is restored to the Activity that was in the foreground before it was minimized.
I want to be able to minimize the app, and then once re-opened go straight to Act1 to prompt the user to login again. I do not want the app to be able to resume in Act2 or Act3.

Unless your application is really security-sensitive, the default behavior should be better for the user: typing their login and password every single time they launch the app can be very annoying. Take for example the native GMail application: it doesn't require you to reauthenticate every time it opens.
Now, if your application really needs that behavior (say it's a credit card safe or something like that), then my first guess would be to handle Act3's onPause() and call finish() from there. Just be careful not to call finish() twice (see isFinishing()).
Also, since this is a breakage of the user's expectations, make it clear to the user that your app behaves like that for their security, not because it wants to be annoying.

When the user moves away from your activity (pressing the home button for example), the onPause() method is called first. You should be able to handle your logic there (for example, calling finish() on Act2 or Act3).
Edit: heh, yeah, what he said :D

Related

Activity Lifecycle. When application already opened (Collapsed) is closing and starting again on icon click?

Can you please explain to me why my activity which is currently (onStop) is go to OnDestroy event and restarting again after clicking on the app icon in the interface.
Because of that i have problem with user data saving. I'm using event OnDestroy to ask user if he want to save the data. Because of my misunderstanding when i collapse the app and click to it again i am waiting to my activity to have all the data in it but instead i see saving dialog from the previous activity whiсh goes to onDestroy event.
Other apps don't act like this.
What should i check?
Your description is not very clear, so my answer may not help you.
Research the app life cycle here: https://developer.android.com/guide/components/activities/activity-lifecycle.html
Your app will enter onStop is before onDestroy. This can happen if user activates another app. (So the user may no longer see any prompts that you display e.g. To ask to save or not.) Android may choose to destroy your app based on its rules after that point, even if the user clicks on the app icon to start it again.
Perhaps you can test what happens if the user switches back to the app (not clicking the icon), but use the "Recent apps" button and select it.

Prevent certain activities from starting without being started from another activity

The main activity that starts when my app launches is shown with a bunch of menu items but access to some of the activities that are launched by some of the menu items require a username and password. After the user enters their credentials correctly, they have access to those activities. They can also use the back button and return to the main activity where the menu is located and I don't require them to re-enter their credentials again, as long as they remain within the app.
If however they hit the Back button while in the main activity, I terminate the app with finish();
The problem I am seeing is that if the user presses and holds the Home button, the list of apps is shown and if they tap on my app, they could end up being taken to one of the "secured" activities that requires a username and password. This can happen if they were using one of those activities and hit the Home button.
The solution I came up with is just to use a global variable that indicates that they are signed in and clear this when they hit the Back button from within the main activity.
But I need to check for this flag in the onResume of every activity to see whether they are signed in or not and if not, I do a finish() in the onResume preventing them from accessing the activity.
Is there a better way of doing this? Perhaps a way of terminating all the activities that are spawned when the user enters a "secured" activity? Or better yet, terminate all activities within my app? As it stands, I have a lot of activities and repeating the code in my onResume seems kind of senseless.

what exactly android's home button doing?

What I do know is that the current activity get into the onPause() mode, and the home screen activity brought to front.
My confusion starts with situation you can re-open the application from the recent tasks menu.
so what exactly happening when I'm opening the application from the recent tasks manager?
Is the activity that was foreground when the home button pressed is still somewhere in the stack?
Is there more then one activity stack on the same time?
As far as I understand it, there is no real stack (of applications). Is just that your activity has states, so whenever you are pressing the HOME button your activity in your current application just "pauses" like if it was a stand-by state so multiple applications can be in this state as long as the system doesnt require memory and kill the tasks.
So whenever you open the activity from the recent tasks its just telling the application to wake up.
First of all, here is everything you need to know about the concept of the "Up Button":
Navigation with Back and Up and some of the implementation details: Providing Ancestral and Temporal Navigation.
Generally speaking, the Up button lets you navigate up in the application hierarchy, instead of just navigating back in the application(s) back-stack.
For example, if you work with some kind of app and you get the email notification, you can open the mail client by pressing the notification. Then you can go back to you application you were working with by pressing the Back button ( back-stack ) or you can press the Up button in order to go to the mail client's 'parent' activity ( for example from some EmailMessageActivity to EmailHomeActivity ) to work with the mail client application instead of the initial application ( the back-stack usually is cleared then, so you can only go back with the Back button as far as the the Android Home screen ).
The "Recent Tasks" factor is irrelevant and misleading, it's just another way of starting a new Activity.

Returning to calling client with Back button when normally Back is disabled

My app is designed to run as a single instance and the Back button does not allow you to exit the app and return to the Start screen because it is used internally to navigate a hierarchy of screens where each screen can be an activity.
However, an external app can launch one of the app's internal activities. When the user is done with whatever the activity is designed for, the user's intuitive action is to hit the Back button to return back to the calling client. But because I prevent the Back button from exiting, the user cannot return.
I can add code to override this when the code detects that the activity is being launched by a client. The problem however is that if the app closes to return, the user might return to the app from where they left off. But since I closed the app to return to the calling client, the user cannot return back to the app as it was last opened. My app needs to remain as a single instance, so the activity that gets launched cannot be created more than once. Any suggestions on how to return back to the calling client but also keep the app running if it was running when the calling client used one of its activities?
In general, you can programmatically control the back navigation trail. Take a look at
TaskStackBuilder and the documentation for handling notifications Responding to Notifications. It seems that what you're trying to do is control the so-called "back stack". If you use TaskStackBuilder, the behavior will match the platform version you're on.
In pre 3.0 platforms, the Back button went all the way through the back stack to the first task the user did since the phone was turned on. Post 3.0, back does not traverse task boundaries; to get to other tasks, the user clicks the "Recent Items" icon. There's also the "up" icon in an app to navigate to the "beginning" of a task within an app. TaskStackBuilder will "do the right thing" for all versions.
In the current platform version, not allowing Back to exit your app is OK, because Back should only go to the first Activity in the current task. In versions previous to 3.0, not allowing Back to exit the app is more problematic, and I personally wouldn't do it that way, but it's up to you.
What happens when the user clicks Back after an Intent starts your app should be clear from the documentation I've cited. Basically, what you want to do is go back to the previous task.

Home Button and Back to Same Activity

I have an application that starts with a login screen and the goes to a gridview and continues the flow. When the user presses the Home Button I want to do something in such a way that when he starts [clicks in the .apk again] the application restores his PHP session id, identifying that he was logged, and goes straight to this other activity that manages the gridview...
In few words: the user press home button and when start the application again he is already logged in and goes directly to the activity he was...
You need to go through this which explains the different available data-storage mechanism in android.
For your problem the answer is here. You save a preference and when the user restarts you can check for the preference value and do whatever is needed.

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