04 - User Interface

layout

defines the structure for an app's user interfacem

View (widget)

draws something the user can see and interact with

ViewGroup (layout)

an invisible container that defines the layout structure for View and other ViewGroup objects

Declare UI elements in XML

The presentation of the app can be separated from the code that controls its behavior

Instantiate layout elements at runtime

The View and ViewGroup objects can be created and their properties can be manipulated programmatically

Context

is an interface to global information about an application environment

wrap_content

sets the size of the view to the dimensions required by its content

match_parent

sets the view to be as big as its parent view group will allow

Constraint Layout

creates large and complex layouts with a flat view hierarchy

Linear Layout

organizes its child view elements into a single horizontal or vertical row

Relative Layout

is used to specify the location of child objects relative to each other or to the parent

Web View

is used for displaying web pages

Frame Layout

is designed to block out an area on the screen to display a single item

Table Layout

arranges its child objects into rows and columns

Grid Layout

arranges its child objects in a rectangular grid that can be scrolled

notification

is a message that Android displays outside the app's UI to provide the user with reminders, communication from other people, or other timely information from the app

notification drawer

allows to view more details and take actions with the notification

app bar/action bar

provides a visual structure and interactive elements that are familiar to users

toast

provides simple feedback about an operation in a small popup

Snackbar

provides a quick pop-up message to the user.

dialog

is a small window that prompts the user to make a decision or enter additional information. It is not designed to fill the screen

menu

is used to present user actions and other options in the app's activities