Activities
Activities
The Activity class is a Building Block of the Android apps. Unlike other paradigms, the launching point is not a main() function, instead is a MainActivity class and is initialised with specific callbacks methods that correspond to specific stages of its #Lifecycle.
Why Activities
The concept of an Activity comes from the different way that a mobile app is used from a desktop app. In which the user can land into your app in different ways i.e; Tapping on the app should open the Home, but tapping into a link that opens someone's profile should show a different screen, meaning, a different activity. The Activity class was created to allow this kind of workflows.
- An activity serves an an entry point for an app's interaction with the user
- An activity provides the window in which the app draws the UI, this can fit the screen or be smaller
- Each activity can call another activity
- If you want an activity to be accessible form other apps you have to declare it into the Manifest
Lifecycle
For more information see Android Activity Lifecycle
Declaring activities
All the usable Activities in your app must be registered in the AndroidManifest, weather you want to navigate from one activity to another, allow that activity to be launched from other apps or your app launch another app.
Basic Navigation
You can navigate with intents as follows:
Intent intent = new Intent(this, TargetActivity.class);
startActivity(intent);