51.3 Coordinating the RecyclerView and Toolbar
Load the activity_main.xml file into the Layout Editor tool, switch to Code mode and review the XML layout design, the hierarchy of which is represented by the diagram in Figure 51-4:
At the top level of the hierarchy is the CoordinatorLayout which, as the name suggests, coordinates the interactions between the various child view elements it contains. As highlighted in “Working with the Floating Action Button and Snackbar” for example, the CoordinatorLayout automatically slides the floating action button upwards to accommodate the appearance of a Snackbar when it appears, then moves the button back down after the bar is dismissed.
The CoordinatorLayout can similarly be used to cause elements of the app bar to slide in and out of view based on the scrolling action of certain views within the view hierarchy. One such element within the layout hierarchy shown in Figure 51-4 is the ConstraintLayout. To...
