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Android for Java Developers
Denver Java Users Group
Jan 11, 2012
-Mike Wolfson
@mikewolfson
Why Android?
Open APIs – everyone’s equal Low Barrier to entry
Run app on your own device - $0Sell through Google Market - $25
Easy to develop apps Especially for Java DevelopersPlatform agnostic
Open Market (or download from anywhere) Feature Rich platform
Framework Overview
http://developer.android.com/guide/basics/what-is-android.html
Framework – Linux Kernel
Core system services
Handles security, memory management, process management, network access, etc
Abstraction layer between OS and hardware
Framework - Dalvik
Virtual Machine Optimized for mobile devices Every app runs in its own instance of VM Runs classes compiled by Java, and transformed
into .dex files
Framework - Libraries
Variety of libraries to provide built in functionality.
Framework – Application Framework
Provides functionality to allow Applications to interact with underlying OS and other applications
Designed to simplify the reuse of components, and allow applications to publish, or make use of the capabilities of other applications
Framework – Applications
The layer where custom-built applications live.
This is the place where most mobile developers will interact with Android.
Your App Here!
Framework Overview
Get Developer Tools
SDK http://developer.android.com/sdk/index.html Requires Java SDK (5.0 +) Updating versions What the different versions mean
ADT Plugin (for Eclipse) http://developer.android.com/guide/developing/tools/adt.html Need Eclipse Ganymede (3.4+) Update site: https://dl-ssl.google.com/android/eclipse
Can develop without Eclipse
Developer Tools (cont)
Android command Emulator
Android Virtual Devices (AVD) Android Debug Bridge (ADB)
Command line tool for interacting with phone/emulator.
Dalvik Debug Monitor Server (DDMS)Debugging tool providing: screen capture, memory
info, logging, info spoofing)http://developer.android.com/guide/developing/tools/index.html
Developing an App
1. Create a new project Project content overview
2. Code
3. Test on emulator (or device)
4. Debug
5. Sign
6. Export to device As APK (Android PacKage file)
Terminology
Most Commonly used elements• Activity
• Intent
• Manifest file
• Resources and Assets
• Layout
• Fragment
Terminology - Layout
Layout – describes the UI of an activity Enables separation of UI from
logicThere are a variety of layouts you
can use including: Linear, Table, Relative, and Frame
Terminology - Activity
Activity – (Noun) A single screen, your application is made up of one or more of these.Always extends Activity
Terminology - Intent
Intent – (Verb) code to perform an action Wiring between activities, services,
broadcast receivers, or other functionsfacility for late run-time binding between
components in the same or different applications
Rich set of Intent in Android provide excellent way of executing specific actions
Fragments
Fragments represent a behavior or portion of a UI.
Designed to collect a unit of UI and behavior into a reusable component
Don’t have own lifecycle – and must be embedded in an Activity
Fragments
Terminology - Manifest
Manifest File – describes your app always named AndroidManifest.xml declares the components of an
application, describes security permissions required by the app, and lists required library dependencies
Terminology - Resources
Resource – text, pictures, sound, etcare all abstracted from the code and
logiccompiled and managed by system
generated R.class fileInstantiate by getting reference to
object
Resources
Multiple Layouts and Graphic Assets
Can also be Used for language localization
Tip: use Density Independent Pixels (DP)
Draw9Patch
Terminology - APK
Android Application File User can install apps from many sources Developer can upload updates easily
Terminology – cont.
Other important elements• Widget
• Service
• Broadcast Receiver
• Security and Permission
• Content Provider
Learn More
http://developer.android.com Denver Droids
http://www.denverdroids.com/ http://forum.xda-developers.com http://www.stackoverflow.com http://developer.android.com Google Groups (Forums)
Questions?
@mikewolfson Google +: Mike Wolfson [email protected] Slideshare:
http://www.slideshare.net/mswolfson Dropbox:
http://dl.dropbox.com/u/23589031/DJUG.zip Beer?!
