Develop Reference

Android application which you cannot close

Is there any programming tricks that makes your application unclosable?
For example: You touch the back or the home button, but they don't do anything.
Or at least is there a way that your application blocks some applications to open?

I don't think you can stop user from moving your application to background unless it's some kiosk mode app. And the method to do that is to become device administrator and override all possible callback methods - home, back, settings, notification area etc.
If you just want to prevent your app from getting closed due to user activity you can show a persistent notification. This will allow you app to run in background even if user presses home button.

Make a launcher/Home screen app:
When users click the home button, your app will show.
You control ALL apps that can be started

On devices running android lolipop, you can use the screen pinning option available in your ROM.
NOTE: This is ROM feature, you don't have to do anything in your app.
See this great article about it.

yes its to get set the on backpressed method to.
moveTaskToBack(true);
finish();

Are you trying to hack in android OS ? Let me tell you that android apps are sandboxed, which isolates your app data and code execution from other apps.

Android - Application Launchs the Main Activity always

We have an issue with android application. We created a Sample project which has 3 screens. LoginScreen, WelcomeScreen,HomeScreen.
When user login, will navigate to Welcome Screen and from Welcome screen place a button to navigate to Home Screen.
Application works fine as expected. We are facing an issue with the Device's Home Button. When user clicks on Home button the application quits and device home screen will appear to the user, and when the user opens the application again, the application should open the page, from where the user quits.
If the user quit from WelcomeScreen, welcome screen should be launched when the user open the app again, if its HomeScreen, then HomeScreen should be launched. When the connect the device in my laptop and try running directly application working fine as expected, but Issue is with copy paste the apk file.
If i copy the apk and paste that in my Device storage and run the application, its always opening the LoginScreen when the user quits from welcomeScreen or HomeScreen and click on the App icon again. Can you please help me to resolve this? Thank you so much.

I think you need to uninstall the application from your device delete all apk from the devices and then you should build directly into your device so that you can get the latest version of app installed in your device.Do this I hope that it will work.

Prevent an app to show on recent application list on android kitkat 4.4.2

I was just bored of iOS and I recently changed to Android. I have a Nexus 5 device, and I've just finished installing my favourite apps in my device.
One of those apps is Line, the famous communication app from naver. I installed it and I configured it with a passcode in order to secure access to it, so no one despite me could see the "confidential" conversations inside.
The problem is even if I have the passcode enabled on line, if someone presses the "Recent list applications" button, they can see perfectly a screenshot of Line with my last conversation, so anyone could see what I was doing in Line.
I made the same test on iPhone and .. surprise ... iOS is taking the snapshot AFTER the passcode screen is enabled, so anyone could see nothing. It seems that in Android the snapshot is taken BEFORE passcode screen is enabled so anyone could see what last line screen looks like :)
So, having read other threads on this forums, I'm supposed to have several ways to solve this:
Wait for LINE's company NAVER to add an option to prevent this app to show on recent app list (adding android:excludeFromRecents="true" on THEIR manifest) [that won't be soon]
Wait for LINE's company NAVER to force the snapshot after passcode screen is enabled [maybe soon but not in company'sroadmap]
Decompile apk and change manifest on my own - or use FLAG_SECURE - (I tried it but when I launch the new app it suddenly dies on startup with a message "Application stopped". I thing LINE's server verifies on startup that the client app is what is expected to be, comparing sizes or something else)
So I don't know more ways to get around this. Do you have any more idea? I'm stucked on it.
Thank you a lot.

Detect when LINE has left foreground
Create a background service that detects if LINE is on foreground and when it leaves the foreground. (https://stackoverflow.com/a/14044662/1683141)
When line has left foreground, you should take action:
A. Stop the line app completely
OR
B. Open & "close" the line app so it will show a locked state in the multitask thumbnail
A possible way to accomplish situation B:
Optionally: detect which app the user has now opened and remember it
Wait a few seconds and open the LINE app again after the user closed it (by intent for example)
Now the LINE app will show the lock screen
Now let the background service open the home screen (or make an intent to the remembered activity)
Now the LINE app is back to the background and it will have a multitask-thumbnail showing the locked screen.
Ofcourse, this will create a loop, and this isn't a stable solution
-Option A is a relatively reliable, and a (in my opinion) good way to accomplish what you want: no one can see your secure chat. Disadvantage is that the application is now removed from multitasking.
-Option B is only an idea, but maybe, if it's done the right way, It could work.
Edit: Option A will not work. The application will not be removed from multitasking if the task is killed.

Using home button on android phone

In iphone when we exit app and start app again by clicking launcher icon the app start from screen which was open last time before exiting app.
We can achieve same in android when we exit app using center or home button on android phone. In android app if app is exited by pressing home button and started again by clicking on launcher icon the app start from activity which was open last time before exiting app.
Is that functionality similar to iphone in terms of keeping app in memory longer? Will that work in android all time because I think android system will remove app from memory after sometime or will it remain in memory longer? Can I depend on this functionality in android and expect it to work all time.
I have a project in android which client has asked me to have iphone like functionality if we exit app and start app again it should open from screen which was opened last time before exiting. Now this is possible in android only if we use centre button. And also if user has exited using centre button and started it again, app should check for user current location and do some other operations. If app is launched and user navigate to any activity is there any way to check if app was exited using back button or centre button so that I can run code if app is exited using center button.
Thanks

We can achieve same in android when we exit app using center or home button on android phone.
The HOME button does not "exit app".
The HOME button brings the home screen to the foreground, just as the CAMERA button (where available) brings the camera application to the foreground, the CALL button (where available) brings the dialer to the foreground, tapping on a Notification may bring something else to the foreground (e.g., SMS client) based on the Notification, etc.
In android app if app is exited by pressing home button and started again by clicking on launcher icon the app start from activity which was open last time before exiting app.
No. If you tap on a launcher icon, and the app's process is still in memory, the existing app instance will be brought to the foreground, returning you to whatever activity you had been on. If you tap on a launcher icon, and the app's process had been terminated to free up RAM for other apps, you launch a fresh copy of the app and bring up whatever the ACTION_MAIN/CATEGORY_LAUNCHER activity was that the user tapped upon.
Will that work in android all time because I think android system will remove app from memory after sometime or will it remain in memory longer?
The length of time that a non-foreground app's process will be in memory is indeterminate and will be based on what is going on with the device, plus the device capabilities (e.g., how much RAM). I suggest you read more about the process lifecycle.
Now this is possible in android only if we use centre button.
It is not possible "if we use centre button" (what Android developers refer to as the HOME button). It may happen automatically, but if the app's process has been terminated, it will not happen automatically.
If app is launched and user navigate to any activity is there any way to check if app was exited using back button or centre button so that I can run code if app is exited using center button.
You should not care whether the "app was exited using back button or centre button".
You should care whether you have your data and how old that data is, refreshing it if it is stale.
Whether the user left your app via HOME, BACK, CAMERA, CALL, a Notification, the recent tasks list, an incoming phone call, by smashing their phone to bits with a rock and replacing it with an exact duplicate, or by any other means, should not matter to you.
To draw an analogy, think of a Web app. In a Web app, you care about whether you have a session cookie and whether that session is stale (e.g., to force a fresh login). Whether the page request came because the user clicked a link within the app, or clicked on a link from a third party site pointing to your app, or refreshed their page, or used a bookmark to get at another page in your app, or double-clicked on a desktop icon that brings up your app, or right-clicked on a link and opened a fresh tab, or anything else, should not matter to you.

Review the Android Activity Lifecycle at http://developer.android.com/reference/android/app/Activity.html. If you do nothing, you have no guarantee of your app starting at the same point it left off, however you have control here. You can, for example, overload the onPause() method to save your state to a file, and onResume() to restore it.

How can I update a home application without being asked to redefine the default home?

I have developed an application set as a home onto my Android device. On my device I set it as the default home application. That way, each time I click the home button, I am redirected to this app.
The problem I have is that I have to produce some updates. But when the app has been updated, the device ask to define the default home once anew.
I would like the update to be performed without the user having to define the default home again.

There isnt a way to do this. Each time your app is updated the user will have the opportunity to chose whether they want to keep it as the default home application. It is a means of Android showing a user he or she is in control of there device at all times.
If im wrong someone please correct me.