I have an application with 2 activities, LogonAct and MainAct. LogonAct is a logon activity which I want to force the user to go through each time they return to the application. I've set android:clearTaskOnLaunch="true" on LogonAct.
When I first start the app I go through this sequence of screens,
Home -> LogonAct -> MainAct -> Home
I then follow this sequence,
LogonAct -> Back -> MainAct
Why is it bringing me back to MainAct? Shouldn't that activity haven been closed since LogonAct has android:clearTaskOnLaunch="true". I expected to be brought back to Home when I hit the Back button from LogonAct.
Relevant snippets from AndroidManifest.xml,
<activity android:name=".LogonAct"
android:clearTaskOnLaunch="true">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<activity android:name=".MainAct">
<meta-data android:name="android.app.default_searchable"
android:value=".SearchResults" />
</activity>
I'm using 1.5.
Any help appreciated.
You can do following:
1. set clearTaskOnLaunch = "true" in AndroidManifest, in declaration of main activity
2. in activity that must close:
#Override
public void onBackPressed(){
moveTaskToBack(true);
}
so if user presses back - it comes back to homescreen
if user launches aplication again - task stack clears and he comes to root main activity
The docs for android:clearTaskOnLaunch mention that this attribute applies "whenever [the Activity] is re-launched from the home screen".
However, in your case you're pressing the Home button to return to the Home screen, rather than pressing the Back button. This means your application isn't actually relaunched because the MainAct was not "finished". That only happens when you press Back (or if Android kills the task to save resources etc.).
As you only have two activities in your application, you could set the android:noHistory attribute on MainAct, thus ensuring that users can never return to it and must pass through the LogonAct.
As an aside, it seems a bit annoying to force users to re-login every time they navigate away from the app (for example when they receive a phone call).
You could retain a session token with timeout in your app's persistent storage, or hold a network connection open using a service if that's how your app works — but of course that's up to you and your requirements. :)
Related
the flow is like below.
MainActivity -> Second Activity
Press home key then device main screen shown.
Enter to app box and click the application icon.
I expect the second activity should be launched but main activity launched.
is there any way that I control it -?!
The default Android behaviour when you press the home button is that the current activity is pushed onto the stack, unless you called finish() in your activity. Whenever you open your application it will launch the activity that's on top of your stack.
I'ts based on your system memory. If you don't have enough memory to keep your activity backgrounded then Android will kill your activity and its state to recoup some memory. I'm thinking that perhaps your phone (or emulated device) is running short of memory.
Check if you are using for that activity, any android:noHistory="true" within your App's manifest. Try removing it.
You filtered your main activity by
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
so it should get launched when you click on the icon in your launcher. I think you should handle your pages with fragments to have the behavior you want.
boolean isSentToBackground = false;
public void onResume(){
if(isSentToBackground) {
finish();
}
}
public void onPause(){
isSentToBackground = true;
}
I encountered strange problem, lets say I have two activities A and B, app starts with Activity A, I proceed to activity B press Android Home Button, return to app which brings me back to Activity B. Then I press Back button (either hardware on in toolbar) and this closes app, but it should return me to Activity A. Activity B has no override of onBackPressed and has Activity A stated as PARENT_ACTIVITY in manifest. I'm starting it with Intent with no flags. Any idea why this happens ? Thanks
The behaviour of back buttons depends on system version. There is support for providing back navigation in older Android versions, described here:
https://developer.android.com/training/implementing-navigation/ancestral.html
<application ... >
...
<!-- The main/home activity (it has no parent activity) -->
<activity
android:name="com.example.myfirstapp.MainActivity" ...>
...
</activity>
<!-- A child of the main activity -->
<activity
android:name="com.example.myfirstapp.DisplayMessageActivity"
android:label="#string/title_activity_display_message"
android:parentActivityName="com.example.myfirstapp.MainActivity" >
<!-- Parent activity meta-data to support 4.0 and lower -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.myfirstapp.MainActivity" />
</activity>
</application>
The best and most convenient way to debug back stack issues is to enable 'Don't keep activities' option in developer options.
That's my best guess. Good luck!
In order to run a new activity without destroying the old one, you have to add the flag FLAG_ACTIVITY_NEW_TASK to the intent that will run the activity:
Intent intent = new Intent(MainActivity.this, MainActivity2.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
as when setting this flag:
this activity will become the start of a new task on this history
stack. A task (from the activity that started it to the next task
activity) defines an atomic group of activities that the user can move
to. Tasks can be moved to the foreground and background; all of the
activities inside of a particular task always remain in the same order.
so the activity which started it will remain in the stack, and hence you can call it again, and hence it also can be called automatically again when pressing BACK_BUTTON even if you pressed the HOME_BUTTON earlier.
and you have to combine #gduh answer with mine, as for sure you must make sure that you are not calling finish(); in ActivityA while calling the ActivityB.
thanks for help, problem was caused by this flag for activity in manifest android:launchMode=singleinstance (it's not originally my project so I missed that, I just hope I didn't screw something else up by removing it)
In your activity A when you call your activity B, maybe you have the following command :
finish();
If yes, you should remove this line. Then when you press back key from your activity B you should return A.
If not, maybe try to share your code.
I am trying to solve an issue sort of similar to what was done here (link text)
Except in my case where Activity A, started Activity B, started Activity C, when the user resumes the app after pressing the home button - I want C, the last Activity, to be displayed. Instead what is happening is I am back to A.
Also on a side note I have discovered that even when I exit the application, if I hold down the Home button, my app is still listed as an active app even though in the LogCat I can see that it exited OK.
Also, in case it matters, I did recently add android:launchMode ="singleTask" in order to make some notification logic work correctly. I was seeing the Home button behavior before that though.
I really appreciate any ideas you might have.
[edit - adding some code snippets]
<activity
android:name =".connection.ActivityA"
android:label ="#string/app_name"
android:configChanges="orientation|keyboardHidden"
android:theme ="#android:style/Theme.NoTitleBar"
android:launchMode ="singleTask"
android:screenOrientation="portrait" >
<intent-filter>
<action android:name ="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name =".screens.AvtivityB"
android:label ="#string/app_name"
android:configChanges="orientation|keyboardHidden"
android:theme ="#android:style/Theme.NoTitleBar"
android:launchMode ="singleTask"
android:screenOrientation="portrait" >
</activity>
<activity android:name =".screens.ActivityC"
android:label ="#string/app_name"
android:configChanges="orientation|keyboardHidden"
android:theme ="#android:style/Theme.NoTitleBar"
android:screenOrientation="portrait" >
</activity>
Then here is how I kick off each Activity:
In Activity A:
private void startActivityB()
{
Intent activityBIntent = new Intent(this, ActivityB.class);
this.startActivityForResult(activityBIntent , ACTIVITYB_TAG);
}
Activity B actually has several Activities that it chooses from (it has a list of Intents) to display based on input it receives but launches them all the same way as Activty A launched B. Once the first Activity is displayed the user swipe the screen to navigate to the left or right screen. When the user swipes left or right, the current activity puts info in its return Intent that Activity B uses to display the next Activity. Also since logic outside of the user's control could prompt a change in the screen displayed, each Activty calls finish on itself in onStop to avoid back-button issues.
When you long press home it is showing a list of recently active applications, not applications that are currently running. So you should still see your app in the list, even if it is closed.
As the docs note:
The other modes — singleTask and
singleInstance — are not appropriate
for most applications, since they
result in an interaction model that is
likely to be unfamiliar to users and
is very different from most other
applications.
I'd imagine that your using singleTask is affecting the history stack, and thus preventing Activity C from being remembered. If you remove that from Activity C, does it resolve the problem?
Otherwise, I'd look at what you are doing in onPause/onDestroy etc for Activity C. Are you doing something that would cause it to finish or close?
Do you get this behavior only when running from Eclipse?
Check your "Run Configurations". There is a "Launch Action" that can be set to "Do Nothing".
Matt
I'm not sure this is what it happening to you, but the answer below solved my problem and I wanted the same behavior as you - that is, getting to the same activity when re-opening after home has been pushed (though in my case, I did actually want the first activity, just not a new one):
Save activity state in android when home button pressed
Now I realize you want to keep the activity stack intact and not go to the first activity like me. But if it is the same problem, then it is not from the fact that the activity stack is torn down, but because a new one (with the opening activity) is added when re-opening after home has been pressed on first install. I hope this is fairly legible, even though I (clearly) found it difficult to explain.
Edit: This is better described here and here.
I have the following activity structure in my application
A simple "splash screen" activity is started when the application is fired up (let's call it "Splash"). This activity starts the main activity when the user presses a button (I will call it "Main").
Main can in turn start two activities from the menu. The first activity presents a simple form (let's call this one "Form"), the second is a MapActivity that presents a map (it is called "Map").
Main, Form, and Map are declared exactly the same in the manifest:
<activity android:name="fully qualified activity class"
android:screenOrientation="landscape"
android:configChanges="keyboard|keyboardHidden|orientation"
>
<intent-filter>
<action android:name="android.intent.action.DEFAULT" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
When Main is active and I start Form and press "back", Main comes up again. Pressing "back" again brings up "Splash". Nothing strange here.
Now comes the strange part: when I am in Main, start Map, and press "back", Main comes up as expected. But pressing "back" again just restarts Main. A second press on "back" is needed to bring me back to Splash!
So it seems that starting the Map activity somehow results in Main ending up on the activity stack twice while starting the Form activity does not!
Both Form and Map are started like this:
startActivity(new Intent(this, MyActivity.class));
I don not catch the back key in any activity.
Any clues on what is going on or how to debug this?
I think I have seen this behavior before in one of my projects. Try setting the launchMode property of your launcher activity ( in your case Splash ) to - android:launchMode="singleTask" in the manifest file.
This should help clarify: http://developer.android.com/guide/topics/fundamentals.html#acttask
I'm having trouble with my activities when they go in the background. I have two activities, A and B. Only A can launch B (manifest copied below). This is what I do:
Launch the app from the app drawer (activity A)
There's a button on A to launch B, B now is displayed.
Hit the Home key, my app is now in the background.
Go to the app drawer again, hit my app icon.
Instead of resuming at ActivityB, Activity A is launched again. Why?
If I hit the Back key now, I get shown the old ActivityB. What?
This is very confusing. It's like Android knows my app is running, and puts a new instance of A on top of the old B instance running. I'd just expect that the application gets paused in-place, and whenever the user hits the app icon again, it just picks up where it left off (in this case, just show B again!) Below is the manifest, and the activity classes for this test are completely empty (except A which has a button to launch B).
<activity android:name=".ActivityA"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".ActivityB"
android:label="#string/app_name">
<intent-filter>
<!--
<action android:name="android.intent.action.VIEW" />
-->
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
If I had to take a guess because inside your app drawer is your .apk reference for your Program A. Regardless if B is already launched, the INTENT of the application when selected is to launch Program A.
I have only read a little on Android, so I can not say with 100% certainty, but that is my guess.
I hope this helps.
EDIT:
Holding down the Home key on the Android phone, shows the list of background apps, can you do the same inside of the emulator and see if Program B pops up? Or same problem occurs?
After reading things around Google, I came across this here is a little snippet:
All the activities in a task move together as a unit. The entire task (the entire activity stack) can be brought to the foreground or sent to the background. Suppose, for instance, that the current task has four activities in its stack — three under the current activity. The user presses the HOME key, goes to the application launcher, and selects a new application (actually, a new task). The current task goes into the background and the root activity for the new task is displayed. Then, after a short period, the user goes back to the home screen and again selects the previous application (the previous task). That task, with all four activities in the stack, comes forward. When the user presses the BACK key, the screen does not display the activity the user just left (the root activity of the previous task). Rather, the activity on the top of the stack is removed and the previous activity in the same task is displayed.
I hope this points you in the right direction
I'm experiencing this bug:
http://code.google.com/p/android/issues/detail?id=2373#makechanges
Thanks for your help, this has been so confusing.
Have you set the following property in your activity's xml definition?
android:launchMode="singleTop"