Android for Java Developers presentation that Marko did at AnDevCon in SF.

1. Android
for
Java
Developers
Marko
Gargenta
marakana.com
© 2011

2. About
Marko
Gargenta
Developer of Android Bootcamp for Marakana.
Instructor for 1,000s of developers on Android at
Qualcomm, Cisco, Motorola, Texas Instruments, Sony-
Ericsson, Sharp, NetGear, DoD and other great orgs.
Author of Learning Android published by O’Reilly.
Speaker at OSCON, ACM, IEEE, SDC, AnDevCon.
Founder of SFAndroid.org
© 2011

3. Agenda
• The
Stack
• Hello
World!
• Main
Building
Blocks
• Designing
an
Android
App
• Android
User
Interface
• OperaEng
System
Features
• Debugging
and
Tools
• Summary
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4. ANDROID
STACK
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5. The
Stack
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6. Linux
Kernel
Android runs on Linux. Applications
Home Contacts Phone Browser Other
Linux provides:
Hardware abstraction layer Application Framework
Memory management Activity Window Content View
Process management
Manager Manager Providers System
Package Telephony Resource Location Notiication
Networking Manager Manager Manager Manager Manager
Libraries
Users never see Linux sub system Surface Media
SQLite Android Runtime
Manager Framework
Core Libs
The adb shell command opens OpenGL FreeType WebKit
Delvik
Linux shell SGL SSL libc
VM
Display Camera Linux Kernel Flash Binder
Driver Driver Driver Driver
Keypad WiFi Audio Power
Driver Driver Driver Mgmt
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7. NaEve
Libraries
Pieces borrowed from other Applications
open source projects: Home Contacts Phone Browser Other
Bionic, a super fast and small Application Framework
license-friendly libc library optimized Activity
Manager
Window
Manager
Content
Providers
View
System
for Android Package Telephony Resource Location Notiication
Manager Manager Manager Manager Manager
WebKit library for fast HTML Libraries
rendering Surface
Manager
Media
Framework
SQLite Android Runtime
Core Libs
OpenGL FreeType WebKit
OpenGL for graphics Delvik
VM
SGL SSL libc
Media codecs offer support for
major audio/video codecs Display Camera Linux Kernel Flash Binder
Driver Driver Driver Driver
Keypad WiFi Audio Power
Driver Driver Driver Mgmt
SQLite database
Much more…
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8. Dalvik
Dalvik VM is Android implementation of
Java VM
Dalvik is optimized for mobile devices:
• Battery consumption
• CPU capabilities
Key Dalvik differences:
• Register-based versus stack-based VM
• Dalvik runs .dex files
• More efficient and compact implementation
• Different set of Java libraries than JDK
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9. ApplicaEon
Framework
The rich set of system services Applications
wrapped in an intuitive Java API. Home Contacts Phone Browser Other
This ecosystem that developers Application Framework
can easily tap into is what makes Activity Window Content View
writing apps for Android easy.
Manager Manager Providers System
Package Telephony Resource Location Notiication
Manager Manager Manager Manager Manager
Location, web, telephony, WiFi, Libraries
Bluetooth, notifications, media, Surface
Manager
Media
Framework
SQLite Android Runtime
camera, just to name a few. Core Libs
OpenGL FreeType WebKit
Delvik
VM
SGL SSL libc
Display Camera Linux Kernel Flash Binder
Driver Driver Driver Driver
Keypad WiFi Audio Power
Driver Driver Driver Mgmt
© 2011

10. ApplicaEons
Dalvik Executable + Resources = APK
Must be signed (but debug key is okay
for development)
Many markets with different policies
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11. Android
and
Java
Android Java
=
Java SE
–
AWT/Swing
+
Android API
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12. HELLO
WORLD!
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13. Android
SDK
-­‐
What’s
In
The
Box
SDK
Tools
Docs
Platforms
Data
Skins
Images
Samples
Add-ons
Google
© 2011

14. Create
New
Project
Use the Eclipse tool to create a new
Android project.
Here are some key constructs:
Project
Eclipse
construct
Target
minimum
to
run
App
name
whatever
Package
Java
package
AcEvity
Java
class
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15. Anatomy
of
An
App
Java Code
+
XML and Other
Resources
+
Manifest File
=
Android App
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16. The
Manifest
File
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.marakana"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon"
android:label="@string/app_name">
<activity android:name=".HelloAndroid"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="5" />
</manifest>
© 2011

17. The
Layout
Resource
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
</LinearLayout>
© 2011

18. The
Java
File
package com.marakana;
import android.app.Activity;
import android.os.Bundle;
public class HelloAndroid extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
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19. Running
on
Emulator
Emulator, not a simulator
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20. MAIN
BUILDING
BLOCKS
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21. Yamba
Demo
Let’s see a real-world medium
complexity Android app in action:
Yamba: Yet Another Micro Blogging App
© 2011

22. AcEviEes
Android Application
An Activity
represents a screen Main Activity
Another
Activity
Another
Activity
or a window. Sort of.
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23. AcEvity
Lifecycle
Activities have a well-
defined lifecycle. The
Android OS manages
your activity by
changing its state.
You fill in the blanks.
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24. Intents
Intents represent
events or actions.
They are to
Android apps what
hyperlinks are to
websites. Sort of.
Intents can be
implicit or explicit.
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25. Services
Services are code that runs in the background. They
can be started and stopped. Services doesn’t have
UI.
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26. Service
Lifecycle
Service also has a lifecycle, but it’s much simpler than
activity’s.
An activity typically starts and stops a service to do some
work for it in the background, such as play music, check for
new tweets, etc.
Services can be bound or unbound.
© 2011

27. Remote
Services
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28. Content
Providers
Content Providers share
content with applications
across application
boundaries.
Examples of built-in
Content Providers are:
Contacts, MediaStore,
Settings and more.
© 2011

29. Content
Provider
Example
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30. Broadcast
Receivers
An Intent-based publish-subscribe mechanism. Great for listening
system events such as SMS messages.
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31. Architecture
of
An
App
An Android application is a collection of many different
building blocks. They are loosely coupled and can be
reconfigured by the developer easily, or at least that’s
the intention.
Let’s look at 7 stages of Yamba next.
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32. Yamba
Part
1
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33. Yamba
Part
2
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34. Yamba
Part
3
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35. Yamba
Part
4
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36. Yamba
Part
5
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37. Yamba
Part
6
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38. Yamba
Part
7
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39. ANDROID
USER
INTERFACE
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40. Two
UI
Approaches
Procedural
DeclaraAve
You
write
Java
code
You
write
XML
code
Similar
to
Swing
or
AWT
Similar
to
HTML
of
a
web
page
You can mix and match both styles. Best practice:
• Start with XML and declare most of UI
• Switch to Java and implement the UI logic
© 2011

41. XML-­‐Based
User
Interface
Use WYSIWYG tools to build powerful XML-based UI.
Easily customize it from Java. Separate concerns.
© 2011

42. Views
and
Layouts
Layouts contain widgets and other
layouts forming a “composite” pattern.
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43. Linear
Layout
One of the most commonly
used layouts. It lays its
children next to each other,
either horizontally or vertically.
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44. RelaEve
Layout
Children of relative layout are
placed in relationship to each
other. This layout is efficient.
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45. Table
Layout
Table layout puts its children
into table rows and columns.
It is similar to an HTML table.
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46. Frame
Layout
Frame layout places its
children on top of each other,
like a deck of cards. It is
useful for widgets such as
tabs or as a placeholder for
views added
programmatically.
© 2011

47. Common
UI
Components
Android UI includes many
common modern UI
widgets, such as Buttons,
Tabs, Progress Bars, Date
and Time Pickers, etc.
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48. SelecEon
Components
Some UI widgets may
be linked to zillion
pieces of data.
Examples are ListView
and Spinners
(pull-downs).
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49. Adapters
Adapter Data
Source
To make sure they run smoothly, Android uses
Adapters to connect them to their data sources. A
typical data source is an Array or a Database.
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50. Complex
Components
Certain high-level components are simply
available just like Views. Adding a Map or a
Video to your application is almost like adding a
Button or a piece of text.
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51. Menus
and
Dialogs
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52. Graphics
&
AnimaEon
Android has rich support for 2D graphics.
You can draw & animate from XML.
You can use OpenGL for 3D graphics.
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53. MulEmedia
AudioPlayer lets you simply specify
the audio resource and play it.
VideoView is a View that you can
drop anywhere in your activity, point
to a video file and play it.
XML:
<VideoView
android:id="@+id/video"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center” />
Java:
player = (VideoView) findViewById(R.id.video);
player.setVideoPath("/sdcard/samplevideo.3gp");
player.start();
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54. OPERATING
SYSTEM
FEATURES
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55. File
System
The file system has three main mount points. One
for system, one for the apps, and one for whatever.
Each app has its own sandbox easily accessible to
it. No one else can access its data. The sandbox is
in /data/data/com.marakana/
SDCard is expected to always be there. It’s a good
place for large files, such as movies and music.
Everyone can access it.
© 2011

56. Cloud
to
Device
Push
Big deal for many pull-based apps. Will make devices use less battery.
© 2011

57. Preferences
Your app can support complex
preferences quite easily.
You define your preferences in an
XML file and the corresponding UI and
data storage is done for free.
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58. SQLite
Database
Android ships with SQLite3
SQLite is a
• Zero configuration
• Serverless
• Single database file
• Cross-Platform
• Compact
• Public Domain
Database engine.
May you do good and not evil
May you find forgiveness for yourself and forgive others
May you share freely, never taking more than you give.
© 2011

59. DEBUGGING
ANDROID
APPS
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60. LogCat
The universal, most
versatile way to track
what is going on in
your app.
Can be viewed via
command line or
Eclipse.
Logs can be
generated both from
SDK Java code, or
low-level C code via
Bionic libc extension.
© 2011

61. Debugger
Your standard debugger is included in SDK, with all the usual bells & whistles.
© 2011

62. TraceView
TraceView helps you profile you application and find bottlenecks. It shows
execution of various calls through the entire stack. You can zoom into specific
calls.
© 2011

63. Hierarchy
Viewer
Hierarchy Viewer helps
you analyze your User
Interface.
Base UI tends to be the
most “expensive” part of
your application, this tool
is very useful.
© 2011

64. Summary
Android is open and complete system for
mobile development. It is based on Java
and augmented with XML, with lower
levels written in C/C++.
It takes about 3-5 days of intensive
training to learn Android application
development for someone who has basic
Java (or similar) experience.
Marko Gargenta, Marakana.com
marko@marakana.com
+1-415-647-7000
© 2011