Android equivalent of: void main() / Sub Main?

Question

I am trying to make my Android application run some code when run from the launcher, BEFORE launching into an activity. That is to say I want my app to start with a Sub Main as opposed to going into an Activity first.

Essentially, in pseudo, I want to do something like this:

void main() {
    doSomeInitializationStuff();

    startActivity(myFirstActivity);
}

According to this question, it looks like Android does not have this concept literally. So I was looking at creating an invisible Activity as my entry point, but cannot figure out how to make an activity invisible. I've tried these two methods, which seem to be the only ones coming up in my searches, but they don't seem to actually do anything...

this.setVisible(false); this.setTheme(android.R.style.Theme_Translucent_NoTitleBar);

Answer 1

Instead of creating an invisible activity you can create a splash activity and start all your initializations there .

I have not tried this but you can extend the application class and use onCreate in your application class to initialize what you need.

Here is the JavaDoc for onCreate of the application class

/**
 * Called when the application is starting, before any other application
 * objects have been created.  Implementations should be as quick as
 * possible (for example using lazy initialization of state) since the time
 * spent in this function directly impacts the performance of starting the
 * first activity, service, or receiver in a process.
 * If you override this method, be sure to call super.onCreate().
 */
public void onCreate() {
}

You will need to let the app know that you are using a custom application class by using the the android:name parameter in the tag of the Android manifest file.

Answer 2

In most of the Android application there is concept of SplashScreen one can use that screen to accomplish such behaviour and the real motif is of this SplashScreen is to proccess such tasks in background while advertising for the app itself and various things related to that

Answer 3

One option would be to not have an invisible Activity, but a SplashScreen. This has the advantage that the user already sees something happening when the app starts up, so that he does not get the impression it is no working. For an example see e.g. this class; you would put the doSomeInitStuff() at around line 54

Otherwise I think, you can just not load a layout in onCreate() of the first activity and then forward from there.