An Android app is a state machine in which each state is called an activity. An activity has a life cycle. For example, it can be created, paused, resumed, and finished. During a transition between activities, the paused or finished activity can send data to the created or resumed activity. An app can define many activities and transition between them in any order. It can even transition between activities defined by the Android SDK or by other apps.
For more information about Android activities and their life cycles, see the official documentation at http://developer.android.com/guide/components/activities.html. For more information about OpenCV's Android and Java APIs (used throughout our activity class), see the official Javadocs at https://docs.opencv.org/master/javadoc/index.html.
OpenCV provides classes and interfaces...
