1. Android Overview

2. Mobile Applications What are they? Types
Any application that runs on a mobile device
Types
Web apps: run in a web browser
HTML, JavaScript, Flash, server-side components, etc.
Native: compiled binaries for the device
Often make use of web services

3. Mobile Devices: Advantages
Always with the user
Typically have Internet access
Typically GPS enabled
Most have cameras & microphones
Many apps are free or low-cost
Maybe more profitable with ads than actually selling the app

4. Mobile Devices: Disadvantages
Limited screen size
Limited battery life
Limited processor speed
Limited and sometimes slow network access
Limited input: phone keypad, touch screen, stylus etc
Limited web browser functionality
Range of platforms & configurations across devices

5. Why Mobile App Development?
Why Android?
Transferring app to phone is trivial
Can distribute by putting it on the web
Android Market (now Google Play) for wider distribution

6. What is Google Android?
A software stack for mobile devices that includes
An operating system
Middleware
Key Applications
Uses Linux to provide core system services
Security
Memory management
Process management
Power management
Hardware drivers

7. Version
Code name
Release date
API level
DVM/ART
Distribution
8.1
Oreo
October 25, 2017 27
ART
8.0
August 21, 2017 26
0.2%
7.1
Nougat
October 4, 2016 25
2.0%
7.0
August 22, 2016 24
15.8%
6.0
Marshmallow
October 5, 2015 23
32.0%
5.1
Lollipop
March 9, 2015 22
21.0%
5.0
November 3, 2014 21
ART 2.1.0
6.7%
4.4
KitKat
October 31, 2013 19
DVM (and ART 1.6.0)
14.5%
4.3
Jelly Bean
July 24, 2013 18
DVM
1.0%
4.2
November 13, 2012 17
3.3%
4.1
July 9, 2012 16
2.3%
4.0
Ice Cream Sandwich
October 19, 2011 15
0.6%
2.3
Gingerbread
February 9, 2011 10
DVM 1.4.0

9. Android Apps Built using Java and new SDK libraries
No support for some Java libraries like Swing & AWT
Java code compiled into Dalvik byte code (.dex)
Optimized for mobile devices (better memory management, battery utilization, etc.)
Dalvik VM runs .dex files

10. Applications Written in Java (it’s possible to write native code)
Good separation (and corresponding security) from other applications:
Each application runs in its own process
Each process has its own separate VM
Each application is assigned a unique Linux user ID – by default files of that application are only visible to that application

11. Android Architecture
The linux kernel 2.6 is the hardware abstraction layer (HAL) between the hardware and the android software stack.

12. Activity Manager – Life Cycle / Navigation
within and among applications
Content Provider – encapsulate data
Location Manager – aware of its physical location
Notification Manager – users informed about events
Package Manager – infn. about other appln. Pkgs
Resource Manager – lets appln accesses its resources

13. Telephony Manager – to learn about device telephony services
View System – manages UI elements / events
Window Manager – perform Window related operations
ices

14. Free Type: for bitmap and vector font rendering
Libc : standard C System library
Mediaframework: supports many audio & Video formats / image files / playback & recording
OpenGL/ES: for 3D graphics libraries
SGL: 2D graphics engine – scalable graphics lib
SQLite: provides lightweight RDB engine
SSL: SSL based security for NW communication
Surface Manager: manages accesses to the display subsystem – 2D & 3D graphics layers
Maybe more profitable with ads than actually selling the app

15. Application Components
Activities – visual user interface focused on a single thing a user can do (presents UI)
Services – no visual interface – they run in the background
User selects a song through an activity and a separate service is started
Broadcast Receivers – receive and react to broadcast announcements
Battery life / timezone changed etc
Content Providers – allow data exchange between applications

16. Activities Basic component of most applications
Most applications have several activities that start each other as needed
Each is implemented as a subclass of the base Activity class

17. Activities – The View Each activity has a default window to draw in
The content of the window is a view or a group of views (derived from View or ViewGroup)
Example of views: buttons, text fields, scroll bars, menu items, check boxes, etc.
View(Group) made visible via Activity.setContentView() method.

18. Services Does not have a visual interface
Runs in the background indefinitely
Examples
Network Downloads
Playing Music
TCP/UDP Server
You can bind to an existing service and control its operation

19. Broadcast Receivers Receive and react to broadcast announcements
Extend the class BroadcastReceiver
Examples of broadcasts:
Low battery, power connected, shutdown, timezone changed, etc.
Other applications can initiate broadcasts

20. Content Providers
Makes some of the application data available to other applications
It’s the only way to transfer data between applications in Android (no shared files, shared memory, pipes, etc.)
Extends the class ContentProvider;
Other applications use a ContentResolver object to access the data provided via a ContentProvider

21. Intents An intent is an Intent object with a message content.
Describe operations – send an
Activities, services and broadcast receivers are started by intents. ContentProviders are started by ContentResolvers:
An activity is started by Context.startActivity(Intent intent) or Activity.startActivityForResult(Intent intent, int RequestCode)
A service is started by Context.startService(Intent service)
An application can initiate a broadcast by using an Intent in any of Context.sendBroadcast(Intent intent), Context.sendOrderedBroadcast(), and Context.sendStickyBroadcast()

22. Android Manifest
Its main purpose in life is to declare the components to the system:
<?xml version="1.0" encoding="utf-8"?> <manifest >     <application >         <activity android:name="com.example.project.FreneticActivity"                                                        >         </activity>             </application> </manifest>

23. Building and running
ADB is a client server program that connects clients on developer machine to devices/emulators to facilitate development.
An IDE like Eclipse handles this entire process for you.
Compiled resources
(xml files)
Android Debug Bridge

24. Components
Fragments
Represents a portion of user interface in an Activity.
Views
UI elements that are drawn on-screen including buttons, lists forms etc.
Layouts
View hierarchies that control screen format and appearance of the views.
Intents
Messages wiring components together.
Resources
External elements, such as strings, constants and drawable pictures.
Manifest
Configuration file for the application.

25. Java
This contains the .java source files for your project. By default, it includes an MainActivity.java source file having an activity class
res/drawable-hdpi
This is a directory for drawable objects that are designed for high-density screens
res/layout
This is a directory for files that define your app's user interface
res/values
This is a directory for other various XML files that contain a collection of resources, such as strings and colours definitions.
AndroidManifest.xml
This is the manifest file which describes the fundamental characteristics of the app and defines each of its components.

26. MyProject/
app/
manifest/
AndroidManifest.xml
java/
MyActivity.java
res/
drawable/
icon.png
layout/
activity_main.xml
info.xml
values/
strings.xml