CODEWITHSUNDEEP
android
frangulyan
frangulyan

Reputation: 3847

Android: how to know previous app

I have 2 different applications A and B and I want to create a special animation from B to A, that is when A is opened after B was visible. This means that I need to somehow know the previous app after which my app was opened. I can have different scenarios of going from B to A - using Recent Apps (multitasking) button, using Back button, using Home button (application A is a custom home screen). Are there any ideas how to do this? Some functions in ActivityManager might help, but they have comments in documentation saying not to use them for implementing logic and control flow.

Upvotes: 0

Views: 89

Answers (2)

frangulyan
frangulyan

Reputation: 3847

I managed to figure out how to implement this, its working for me.

I used this answer, but replaced the ActivityManager.getRunningTasks() with ActivityManager.getRecentTasks() supplying RECENT_WITH_EXCLUDED | RECENT_IGNORE_UNAVAILABLE, and took the component name from baseIntent member of the result. The info at index 1 is the one that was running before the current app was opened, irrelevant of the fact how you get back to your app - back button, home button, recents button or opened from another app.

NOTE: This works when your app is started, like in onResume() but doesn't work when your app is closed (when called in onPause()) because the new task is not yet loaded into the activity manager. So if you need to also know to which app are you going then it might be a bit more complex.

NOTE2: Although the documentation tells not to use the API above for any kind of logic and control flow, I saw that the multitasking/recent app's code is doing exactly the same, so in my opinion it should not be as risky as they write it docs.

NOTE3: Don't forget to follow all the steps in the answer I mentioned above, like adding needed permissions, otherwise you will get exceptions. Being part of the system in my case makes it much easier for me.

Upvotes: 0

ssawchenko
ssawchenko

Reputation: 1228

Not sure if this will work across different applications, but how about getCallingActivity() or getCallingPackage()?

If that doesn't work, could you pass along some 'extra' data in the bundle when you launch the intent that indicates the launching application?

Upvotes: 1

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