Open an external app and start it with an explicit activity

Question

Suppose I am in App1 and I want to open another app from my phone, App2, starting it with one of it's activities, SecondActivity. I need to do this with any of the apps that I have on my phone, so if I install new ones I need to be able to start them with any of their activity. I found this answer really useful, except from the fact that the activity I want to start with is declared in the manifest. If I have 10 installed apps with 10 activities each this solution doesn't help me at all.

How can I do something very similar to the link provided WITHOUT declaring the starting activity in the manifest ?

Answer 1

Intent intent = new Intent();
intent.setClassName("app2.package.name", "app2.fully.qualified.activity.name");
startActivity(intent);

This works without having to do anyhing to the manifest in either your app or the target app. You might want to set the flag Intent.FLAG_ACTIVITY_NEW_TASK if you want to launch the app in a task of its own (and not within your app's task).