How to always start from a startup activity on Android?

Question

There are three different cases:

1) A user launches an app, navigates in it, pressed home and click on the app icon again to launch our app again.

2) A user launches an app, navigates in it, presses home, chooses recent and click on the app to launch our app again.

3) A user launches an app, navigates in it, click something in the app (TextView with a link), which calls another app (as example Email) and user clicks back button, which bring us back to our app.

I know about flag "clearTaskOnLaunch" flag, it solves case #1.

I know about about flag "excludeFromRecents", it solves case #2 (may be not the most user friendly solution, but it works).

What about case #3? I have a workaround right now. However, I will have to put it on all activities which can be lead to another app. I wonder, whether there is better way to solve it (without handling it in all such activities).

Answer 1

This should be handled on the Application level.

For API level 14, you can register an ActivityLifeCycleCallback in your Application class

public void registerActivityLifecycleCallbacks (Application.ActivityLifecycleCallbacks callback)

You can use it, to know on an Application level, which activities are destroyed, paused, resumed etc etc. Whenever, an activity is paused, without a new activity being created/resumed, you should clear the Activity stack, and re-launch your startActivity

If you target SDK versions < 14, you should implement your own method, to know which activities are created/resumed and paused, and do the same whenever an activity is paused, without a new activity being created/resumed