The document discusses 5 key user interface elements for Android apps: 1) Android UI layouts use Views and ViewGroups to create interactive components like buttons and text fields, 2) Android UI controls like TextViews and EditTexts are used to design interfaces, 3) Event handling captures user interactions with interface elements, 4) Styles and themes define looks and feels through centralized XML files, and 5) Custom components can be created to extend built-in views.

1. TOP 5 USER INTERFACE
ELEMENTS FOR ANDROID
APP
ANDROID UI LAYOUTS
The view is the base class for widgets, which are used to
create interactive UI components like buttons, text fields,
etc. The ViewGroup is a subclass of View and provides an
invisible container that holds other Views or other
ViewGroups and defines their layout properties.
ANDROID UI CONTROLS
Android UI Controls like Textview, EditText, Radio Button,
Checkbox are the interactive or View components that are
used to design the user interface of an application.
Generally, in android, the user interface of an app is made
with a collection of View and ViewGroup objects.
ANDROID EVENT
HANDLING
In Android, Input Events like Event Listeners, Event Handling
are used to capture the events, such as button clicks, edit
text touch, etc. from the View objects that defined in the
user interface of our application, when the user interacts
with it.
ANDROID STYLES AND
THEMES
Android allows you to define the look and feel, for example,
colors and fonts, of Android components in XML resource
files. This way you can set style-related attributes in one
central place. If the entry in the resource file is used to style
a view, it is referred to as a style.
ANDROID CUSTOM -
COMPONENTS
Android comes with some built-in views like TextView,
Button, EditText, ListView, etc. The Android framework is very
robust and it provides means of creating our own custom
components which we can customize to suit our needs.