Where exactly is the data structure for storing the navigation graph implemented in the system?

In Android, the data structure for storing a navigation graph is typically implemented within the Jetpack Navigation component.

The navigation graph is described in an XML resource file (nav_graph.xml), where fragments (nodes) and actions (edges) between them are defined.

At runtime, this graph is loaded and stored in a NavGraph object, which is part of the NavController. This object contains navigation nodes and connections between them, allowing management of transitions.

Thus, the data structure is implemented inside the Android Jetpack navigation component and stored in the application's memory as NavGraph objects and related classes.