One of the questions I get asked again and again is how to validate a field value in an Acro Form with a custom validation script.Adobe provided a lot of infrastructure to do that with just a simple script.If not explicitly defined, Android creates a default application object for your application.
An Android application developer typically works with the two layers on top to create new Android applications.
An Android application can have several activities.
Activities use views and fragments to create their user interface and to interact with the user.
class which is instantiated before any other Android component.
It is the last component which is stopped during application shutdown.