Lesson 2: Introduction to Android App Programming

Android

It is an open source, Linux based operating system developed by Google that runs on wide variety of devices.

Android Project

It s organized similar to other Java projects, with a few important exceptions. The Android SDK automatically generates certain features specific to an Android project. 

View

It is the base class for widgets which are used to create interactive UI components and is responsible for event handling and drawing.

ViewGroup

It act as a base class for layouts and layout parameters that hold other Views or ViewGroups and to define the layout properties. They are generally called layouts.

setContentView()

To attach View Hierarcy to the screen (for rendering), call [blank] in the Activity

Gradle

is a build system (open source) which is used to automate building, testing, deployment, etc.

Build.gradle

are scripts where one can automate the tasks.

Top-level build.gradle

defines the build configurations that will be applied to all the modules in the project.

Module-level build.gradle

supports various build configurations

<manifest>

This is the root node of each AndroidManifest.xml. It contains the package-attribute, which points to any package in our Activity.

<application>

Root element in the AndroidManifest.xml containing declarations of the application-level components contained in the package.

<activity>

Is the primary thing in an AndroidManifest.xml for an application to interact with the user.

<intent - filter>

It declares what kind of Intents a component supports in an AndroidManifest.xml.

<action>

An action-type that the component supports in an AndroidManifest.xml

<category>

A category-type that the component supports in an AndroidManifest.xml

IntentReceiver

It allows an application to be told about changes to data or actions that happen, even if it is not currently running

ContentProvider

It is a component that manages persistent data and publishes it for access by other applications

application context

It is the central location for all top-level application functionality

Toast

It is a passive, non-blocking user notification that shows a simple message at the bottom of the user‘s screen. A toast typically displays for a few seconds and disappears. 

Snackbar

It is just like s Toast except that it can provide the user with the action button to interact with.

android:weight

It controls the resizing behavior of its child Views. The value is either 0 or 1. Using a weight of 1 makes the View stretch, while using 0 will make that View just as big as needed.

Application Name

The title that will be shown on Android Title bar

Package Name

Apps on particular Android device must have a unique packages, so use com.yourCompany.project

Minimum Required SDK

The minimum Android version that you want to use where your app will run.

Linear Layout

A type of layout. It is used to provide child View elements one by one either in a particular direction either horizontally or vertically based on the orientation property.

Relative Layout

A type of layout. It is used to specify the position of child View elements relative to each other like (A to the right of B) or relative to the parent (fix to the top of the parent).

Constraint Layout

A type of layout. It is used to specify the position of layout constraints for every child View relative to other views present.

Frame Layout

A type of layout. It is used to specify the position of View elements it contains on the top of each other to display only a single View inside the [blank].

Table Layout

A type of layout. It is used to display the child View elements in rows and columns.

Web View

A type of layout. It is a browser that is used to display the web pages in our activity layout.

List View

A type of layout. It is used to display scrollable lists of items in a single column.

Grid View

A type of layout. It is used to display a scrollable list of items in a grid view of rows and columns.

Java

Anatomy of Android Application. This contains the .java source files for your project.

res/drawable

Anatomy of Android Application. This is a directory for drawable objects included in your project

res/layout

Anatomy of Android Application. This is a directory for drawable objects included in your project

res/values

Anatomy of Android Application. This is a directory for files that define your app’s user interface

1. Java

2. res/drawable

3. res/layout

4. res/values

5. AndroidManifest,xml

6. Gradle Scripts

Anatomy of Android Applications

ID

Used if the Java code needs a reference to View

Used in RelativeLayout so XML can refer to earlier ids

Size

Specifies the width and height of the View or ViewGroup respectively

match_parent

• Fill the parent space (minus padding)

• Renamed from fill_parent in older versions

wrap_content

• use natural size (plus padding)

• An explicit size with a number and a dimension.

android:layout_weight

It controls the resizing behavior of its child Views. The value is either 0 or 1.

Using a weight of 1 makes the View stretch, while using 0 will make that View

just as big as needed.

android:layout_gravity

How the View is aligned within containing View. It specifies how child Views are positioned.

android:gravity

How the text or components inside the View are aligned.

Margins

Is the blank space outside an object

Padding

Is the blank space inside an object

Broadcast Receivers

is a component that responds to system-wide broadcast announcements.