We can launch the app in two ways, 1 is form the app, clicking on device back button till we reach the android home screen and launching the app or 2nd is from the app we can click the device home button and then we can launch.
How can we differentiate these to launches? In 2nd type launch onrestart will be called, onrestart will be called in some other cases also.
I want to do something in the 2nd type of launch.
Can any one tel me how to do this...
Thanks in advance.
When it comes to what happens when the activity is started, you may want to look at the following link in the developer site.
http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle
You may want to code based on the lifecycle of the activity rather than if the application was pushed to the background by the home key vs. by the back key. There could be different reasons the application was pushed to the background or closed. This is the expected way to handle application events.
Related
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.
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
I developed an android application with two screens. The application is working with android devices good. But i installed application in amazon kindle fire tablet launched the application started good. I navigated from 1st screen to 2nd screen and pressed home button.
And again i launched application from applications menu. application is showing 1st screen instead of 2nd screen. Common behavior of android is should show the second screen.
What i know is while press on home button the application will go for onPause() state and launch application form launcher icon it will go fore onResume and show the screen where it has previously.
But application every time calling onCreate when launching from launcher icon. This happened in Amazon kinlde fire tablet only.
I am starting the 2nd activity from 1st activity using startActivity(intent); method
May i need to use any flag for kindle fire tablet.
Please suggest me as ASAP.
Thanks in advance.
Android doesn't guarantee that once you press back from an activity, it will remain in the onPause state. It depends on how aggressive the memory killer is, or how low the device memory is. What this means is, don't count on your application being in onPause state ever.
What you could do is, save the activity state in a shared preference, and let the Application object launch the corresponding activity, restoring UI state if required.
Can anyone tell me what the difference is between opening an app from the applications screen and opening it from that recently used apps list that pops up when you long-press the home button?
I didn't even know that recently used list existed until a friend managed to break my app by launching it from there. He tried twice and got the same force quit, but when he launched it from the applications screen it opened fine.
The error log told me that a nullPointerException occurred in the getCount method on my ArrayAdaptor for my ListView.
Anyway I just wondered if there was a difference that I need to know about and adapt my code to deal with?
AFAIK, If your application is completely shutted down, launch from applications screen and recently used apps list should have no difference, both refresh start your application and open your application's MainActivity (by stack-push your application's MainActivity into a newly created task)
However, as Android is multi-task OS, your application can be put into background in standby mode i.e. open your application then short-press home button, this is not same as press back button. If you haven't override these key pressed in your application, press back button several times with pop all your activities off from activity stack and finally kill your application, whereas press home button will bring System's HomeActivity into foreground hence flip your application (AKA. task with activity stack) into background.
Things becomes more interesting here, depend on which value your configure your activity's android:launchMode in AndroidManifest.xml, if you use standard or singleTop:
1. launch app from recently used apps list always bring your standby activity back to foreground, i.e. re-order activity stack.
2. launch app from applications screen will create a new instance of your MainActivity and open it, i.e. push a newly created MainActivity into activity stack, so now you have two instances in your application's activity stack
If you use singleTask or singleInstance:
2. launch app from applications screen will use the standby MainActivity (if exist) in your application's activity stack and re-open it, i.e. re-order activity stack.
Checkout Tasks and Back Stack to see how different configurations may affect your application's activity stack behaviour.
I believe there should be no difference. These are the lifecycle methods I typically see when pressing the home button from an activity, on android 2.3.4
onPause
onStop
then when I use either the icon or previous applications to navigate back, I see
onRestart
onStart
onResume
Now, in some cases the system will tell your activity to finish while you are away (or immediately when you return if an orientation change occurred). Then you will see onDestroy, and the following when you navigate back
onCreate
onStart
onResume
I don't think there is anything mysterious going on here. According to the Activity documentation, there are only four states that a process can be in, and both of these fall under background activity.
There shouldn't be any difference in how the activity is launched from history, apart from the fact that the launching Intent will have the FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY set.
Here's an easy way to think about it. All of your activities are launched form Intents. Holding down the home button allows you to open that activity using the last intent that launched it. This can give you some unexpected results however. For instance, if you are able to launch your activity from something special like a widget.
Hi I have application with more than 20 activities.I want to close my app when Home button is pressed.
There is no notion of "close my app" in Android. Android will get rid of your activities, followed by your process, after some period of inactivity by the user.
You could use the launchMode and clearTaskOnLaunch flags on your root activity from your AndroidManifest.xml:
android:launchMode="singleTask"
android:clearTaskOnLaunch="true"
When you again start your app, all activities will be killed.
You don't want to do System.exit() -- that's not how the Android Activity Lifecycle normally works (read this also).
What you should do is move the App to the background with moveTaskToBack(). Android will then keep your app running in the background, and kill it if it's unused and something needs its resources later.
If you want it to close all of the open Activities when your App is no longer visible, you can set noHist = "True" for all of the child activities (leave the main activity with noHist = "False", though). This will make it where instead of reopening your application on the last Activity they were on, it will open it on the "main" activity (i.e. it will be as if they just restarted the app).
Anyhow, read through the following answers for more information: Close application and launch home screen on Android
I have the same problem. Im writing a banking app and am required, by contract, to log off the user (or exit) when the app is put into background. There are obvious security concerns there.
There are a couple of ways Im looking to do this:
1. Intercept home button (and back button for the root activity) key press events to call logoff and/or finish()
2. In the onStop() method, for every activity, detect whether the activity is being stopped due to a new activity being show - if not, assume app is being put to background so logoff and/or finish()
The first may not work if a notification is brought to the front then the user clicks home (I havent investigated yet). Or maybe there are other ways for an app to be put into the background without pressing these buttons
The second way sounds messy & difficult to maintain
Id welcome any other ideas
Drapes
I know android has been designed this way, but it seems naive to think that apps wouldnt want an applicationOnStop event
Hi guys what I understood is that u need to know when app goes in background and how to detect it and if I am wrong plz correct me----
The user can go in background if ur app does not provide any way by pressing Back key or Home Key.
You need to use methods "dispatchKeyEvent(KeyEvent event)" to get home key event or back key event and after getting the event you can execute your task.
you can even restrict user from pressing any key but u can not control the home key.