The "face" of a program or application, everything that a program user can see and/or interact with
User Interface Element Builder Objects
View Object
ViewGroup Object
View Object
Draws something on the screen that the user can interact with
App Bar (or Action Bar)
Provides visual structure and interactive elements that are familiar to users, indicates the user's location, provides access to important actions, supports navigation and view-switching
Dialog
A small window that prompts the user to make a decision or enter additional information, does not fill the screen, used to require users to take an action before proceeding
Notifications
Messages displayed outside of the application's normal interface, first appear as an icon in the notification area, details can be seen by opening the notification drawer
Layout
The "framework" of an interface that arranges its contents in a pleasing or orderly manner, defines the visual structure for a user interface
Two ways to declare layouts in Android projects
Declared UI elements in XML
Instantiation of Elements at Runtime
Linear Layout
Aligns all children in a single direction, vertically or horizontally, creates a scrollbar if the length exceeds the screen
List View
Displays items in a vertically scrolling list, dependent on the swipe function
Buttons
Can contain text, icon, or both
Buttons
Button class creates a text button
ImageButton class creates an icon button
Button class with android:drawableLeft attribute creates a button with both an icon and text
