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Why is launcher activity with launchMode="singleTask" always pushed to top of backstack even if another activity was on top? [duplicate]

This question already has answers here:
Android: bug in launchMode="singleTask"? -> activity stack not preserved
(12 answers)
Closed 2 years ago.
My launcher activity has the launchMode attribute set to singleTask due to certain requirements.
<activity
android:name=".map.MapsActivity"
android:launchMode="singleTask"
android:screenOrientation="portrait"
android:theme="#style/MapScreenTheme"
android:windowSoftInputMode="adjustPan">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
The problem I'm facing is that if I open another activity -> press home -> Click on app icon in launcher application -> It opens the MapActivity and not the activity that was previously open.
This however does not happen if I navigate to the app via the recents menu. Then the newly opened activity stays on top.
Can someone please explain what is happening here with regards to the backstack and why is the ActivityManagerService not taking into account that the app process already exists and yet decides to start the launcher app and clear the backstack and not simply bring the app forward?
This issue can be observed in a small sample app created here -
https://github.com/abhiank/SingleTaskActivity

I think this is the desired behavior of SingleTask launch mode. Keeping Launcher Activity as SingleTask has its consequences.
I can not think of an exact solution for this problem but some workaround will do the Job.
Adding the link below which i have mentioned in comment to go through.
Android: bug in launchMode="singleTask"? -> activity stack not preserved

I think, When you click on app icon again, It opens the Launcher Activity on top of your previously opened Activity. What you can do is apply a simple check whether there are any activity in the backstack apart from this, then finish this launcher activity, It will reveal previously opened screen. Try the below link.
https://stackoverflow.com/a/38450232/3497972
check these links too, they have other ways to maintain screen when launched app icon, when app is in background
How to make an android app return to the last open activity when relaunched?
Android app restarts when opened by clicking app icon
Determine when application icon is clicked to launch the app in android
What is the difference between launch app from "recent apps" and tapping app icon

There is some solution for case when your main activity would be launched only by other activities within your own application:
You can remove launchMode attribute from your main activity definition in manifest. And just pass Intent.FLAG_ACTIVITY_NEW_TASK to every intent that opens your MainActivity, for example like this:
Intent intent = new Intent(this, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
Be aware that behaviour of Intent.FLAG_ACTIVITY_NEW_TASK or launchMode="singleTask" within your own application only works in conjunction with taskAffinity attribute on activity definition in manifest.
I hope it will help you a little.

Sounds to me like you are seeing this nasty long-standing Android bug
Re-launch of Activity on Home button, but...only the first time
To test whether that is the case, please kill your app (settings->apps->your app->force quit). Then launch your app by tapping the app icon on the HOME screen. Do whatever you need to do to launch another Activity into the task. Press HOME. Now tap the icon on the HOME screen again. This should bring your task to the foreground in the same state you left it in.

Every activity in my app is added to app drawer

Well, just like the title suggests, every activity within my application is being added to the app drawer.... Im really hating this new ADT. First it was a problem with the app name appearing as the first activity name, now all the activities are showing up on the application list. If I go to uninstall it only shows 1. Anyone else having this problem and has figured out a work around?

for future cases specifically you can change in the android manifest under :
<intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
change to:
<intent-filter>
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
This will remove the activities' icon from the app drawer. As the OP says: sometimes the wizard puts this in the manifest for you.

Ok, figured it out... Everytime you create a new activity through the adt wizard (New -> Android Activity) it creates the code in your manifest for you.... the problem is that it added intent filters to it as well. Just remove those and they dont show up.... stupid adt.

I know when I am using IntelliJ as my IDE for Android programming, there is a box you can check when using the wizard to create a new Activity that says "Mark as start-up Activity".
Be aware of these types of things because that is what caused me to have the same problem you had Shaun.
I wouldn't completely erase the intent filters, simply have only the Activity you want as the "start-up" Activity marked as the "Launcher" in the Manifest file. All other Activities get "Default".

Changing launcher Activity name in a new application version

I have developed a new release of an application and I have changed the name of the activity which is launched.
Before the upgrade, in the manifest was:
<activity
android:name=".Splash"
android:label="#string/app_name"
android:screenOrientation="portrait"
android:theme="#android:style/Theme.NoTitleBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
and then I only changed the name and the package of the activity and now it is:
<activity
android:name=".view.SplashActivity"
... >
...
</activity>
what happens is that after people download the application from the market, the launcher is not refreshing and it still calls to the old path to the activity.
Do you know how to solve this?

Refer Things That Cannot Change
It says,
A subtle but important aspect of what constitutes a break in compatibility is the android:name attribute of your activity, service, and receiver components. This can be surprising because we think of android:name as pointing to the private code implementing our application, but it is also (in combination with the manifest package name) the official unique public name for that component, as represented by the ComponentName class.
Changing the component name inside of an application can have negative consequences for your users. Some examples are:
If the name of a main activity of your application is changed, any shortcuts the user made to it will no longer work. A shortcut is an Intent that directly specifies the ComponentName it should run.
If the name of a service implementing a Live Wallpaper changes, then a user who has enabled your Live Wallpaper will have their wallpaper revert to the system default when getting the new version of your app. The same is true for Input Methods, Accessibility Services, Honeycomb’s new advanced Widgets, and so on.
If the name of a receiver implementing a Device Admin changes, then as with the live wallpaper example, the device admin will be disabled when the application is updated. This also applies to other kinds of receivers, such as App Widgets.
So if possible, don't change the name of components declared in the manifest, or remove any icon pointing to that component using below code.
ComponentName componentToDisable = new ComponentName("application.package.name", "packagename.ActivityClassName");
getPackageManager().setComponentEnabledSetting(componentToDisable, PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
Also specify new launcher activity in manifest using <intent-filter>...</intent-filter> so that your new activity will be launched when user clicks launcher icon.

Does the activity is called correctly if you start the activity in debug mode on your phone.
If so check if you did something of the following:
you changed the whole package name
you signed it not at all or not correctly
Also you might check out http://developer.android.com/guide/publishing/publishing_overview.html
Anyway. If the application runs correctly on your debugging phone there is something wrong with your publishing parameters and you should go through the page above step by step.
If not you might check the path values, like package and name of the activity and the filters.

Android new task problem

I have two activities in my application.one of the activity started by service class ,so i have set the flag FLAG_ACTIVITY_NEW_TASK and start the activity.
in that activity i hide the status bar by using the following code .
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN)
The problem is some time the activity not hiding the statusbar.After doing several testing i found that the FLAG_ACTIVITY_NEW_TASK is creating problem.
how to solve this?

What if you do that directly in the XML:
<activity android:name=".ActivityName"
android:label="#string/app_name"
android:theme="#android:style/Theme.NoTitleBar.Fullscreen"/>

How to register a new activity in AndroidManifest.xml?

I always get an error when I run my created application and based on my research I haven't registered my Activity in the manifest. How can I register a new activity in AndroidManifest.xml?

Assuming you're using Eclipse,
Goto your Android Manifest, goto the Applications Tab (at the bottom), click on "Add", Choose Activity. On the right, next to Name: Click on Browse, to get a list of available activities, just add it and you're set! :)
You could right way just edit the Manifest XML aswell. It's upto you.

<activity android:name="com.kl.android.ReadSMS.ViewSMS" />

just use the class name after '.'
like the following
<activity android:name=".ViewSMS"/>

In Android Studio, Go to AndroidManifest.xml file and use
<activity android:name="YourPackageName.ClassName">
For example,
<activity android:name="com.android.favoritetoys.MainActivity">
For More List of activity attributes in AndroidManifest.xml