Issue regarding Launch Modes in Android

Question

I have gone through below documentation link :

https://android.jlelse.eu/android-activity-launch-mode-e0df1aa72242

Here, I understood the working of all the four Launch Modes namely :

Standard, SingleTop, SingleTask, SingleInstance.

Also got cleared about doing it practically by adding attribute 'android:launchMode' in AndroidManifest.xml file.

Issue is with adding flags in Activity programmatically.

Now, From the Documentation it is said that :

FLAG_ACTIVITY_NEW_TASK

This flag works similar to “launchMode = singleTask”.

Now, To understood the behaviour of this, First I have checked it using AndroidManifest.xml. I have taken four Activities in my Project : A, B, C, D. Setted “launchMode = singleTask” to my Activity C.

Navigation is like this From A -> B -> C -> D and from D -> C.

So, When I going from D to C its not creating new Activity C but letting me to Activity C. This is fine. Understood.

Now, I want to understood the same thing Programmatically.

So, For that I have removed static “launchMode = singleTask” from the AndroidManifest.xml and doing it inside Activity C like below :

startActivity(Intent(ActivityC@this,ActivityD::class.java).setFlags(FLAG_ACTIVITY_NEW_TASK))

and In Activity DI have done as below :

startActivity(Intent(ActivityD@this,ActivityC::class.java))

But, this programmatic things not working like as I have done it with AndroidManifest.xml, It's opening New Activity C... instead of Going back towards Activity C.

What might be the issue ? or am I doing something wrong here ? Pls. guide. Thanks.

Answer 1

As per documentation,

FLAG_ACTIVITY_NEW_TASK produces the same behavior as the "singleTask" launchMode value.

So your going wrong in Activity D where you start Activity C. You should do,

startActivity(Intent(ActivityD@this,ActivityC::class.java)).setFlags(FLAG_ACTIVITY_NEW_TASK))

Setting FLAG_ACTIVITY_NEW_TASK when starting Activity D from C is not relevant.