Google Android @ AlphaCSP's JavaEdge

Title

Sub Title

Nadav

Wiener

Google Andro

id

Breaking The

Mobile Mo

ld

Decem

ber 18

th 2008

Hello Android

2

Target Audience

• Mobile software developers

• People shopping for a phone in 2009

3

Agenda

• Hello Android

• Architecture Overview, Features and

Components

• Android Software Development

• Live Demo

4

Hello Android

5

• Android is a platform for mobile

computing

• Android is Linux based

• But development is in Java

Hello Android

6

• Why did Google make Android?

• IPhone does not support Java

• JavaME’s CLDC+MIDlets are getting old

• Leaves lots of mobile developers in search of a platform

• Profit – ads, market

• Clean break from J2ME

Hello Android::Timeline

As published by Google

7



• We’ll have a look at

some of the winners

later on



• Only free applications for

now

• Eventually, Google will

take a 30% cut

Hello Android::Devices

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• HTC G1, Lenovo OPhone (expected),

Kogan Agora

Hello Android::ADC

• The Android Developer Challenge

• 10,000,000$ in prizes

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Hello Android::ADC

• ADC I concluded:

• 5M$ in prizes

• Over 1,700 submissions

• Announcement regarding

ADC II is expected soon16

Hello Android::ADC Winners & Market

• Wikitude (Philipp Breuce)

• Wikipedia overlaid on camera view

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• BreadCrumbz (Amos Yoffe)

• Navigate using maps and pictures (like Myst)

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• Amazon MP3 for Android

• Preinstalled on HTC G1 phones

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• Compare Everywhere (Jeffrey Sharkey)

• Capture barcodes, search for better deals nearby

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Agenda

• Hello Android


Components


• Live Demo

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Architecture Overview

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Linux Kernel

Device Drivers

Inter Process Comms. Security

Power Management

Native Libraries

Media Framework

SQLiteDatabase

WebKit Browser

Graphics Libraries

Android Runtime Apache Harmony Dalvik VM

Android Application Framework

ActivitiesPackage

ManagementContent ProvidersViews Services

Applications

•Implement and leverage framework concepts•Use framework components and services


• Let’s examine some of these boxes,

beginning with Linux:

Linux Kernel


• From Linux Android gains:

• A stable common base for Dalvik applications

• Fine grained power management

• Unique user per bundle – sandboxing

• Much more…

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• Native libraries provide functionality

Native Libraries

Linux Kernel


• WebKit

• Same browser engineused in IPhone,Google Chrome,Safari

• Strong performer

• Memory efficient

• Good standards support

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• Location Services & Mapping

• Google Maps

• Street view

• GPS

• Trigger proximityalerts


• Graphics

• SGL – 2D scalable graphics

• OpenGL ES

• Surface Manager composes surfaces together

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• Media Framework

• Player and codecs

• SQLite

• Lightweight RDBMS also on IPhone

• ... and Telephony too!

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Architecture Overview::

Android Runtime

Moving on to the “Java” runtime

environment:

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Linux Kernel

Native Libraries Android Runtime


Dalvik Virtual Machine

• Java has a stack based VM

• Dalvik is a register based VM

• Better interpreter performance

• No JIT

• Bottom line:

• Lower throughput

• Better startup & responsiveness

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Dalvik Virtual Machine

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• You still get to develop in

Java

• Excellent learning curve

• What, no JVM!?

Architecture Overview::Zygote

• Quick Dalvik process startup is

essential for good responsiveness

• During boot, Android creates a fully

bootstrapped Dalvik process

• Sends it to sleep

• Forks it on demand

• Forks are copy-on-write

• Near instantaneous startup!33


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Linux Kernel

Device Drivers

Inter Process Comms. Security

Power Management

Native Libraries

Media Framework

SQLiteDatabase

WebKit Browser

Graphics Libraries

Android Runtime Apache Harmony Dalvik VM


ActivitiesPackage

ManagementContent ProvidersViews Services

Applications

•Implement and leverage framework concepts•Use framework components and services

Agenda

• Hello Android


Components


• Live Demo

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• Building Blocks

• Application Model

• UI Perspective

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Building Blocks

• Four building blocks

• Activities and Intents

• Broadcast Receivers

• Services

• Content Providers

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Activities and Intents

Activities

Android documentation states:

• “An activity is a single, focused thing

that the user can do.”

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• This how an activity will look like:

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• Well, actually: “An activity is usually a

single screen in your application.”

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• Activities communicate with each other

using Intents

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? !

new Intent(Intent.ACTION_PICK, new Uri("content://contacts"))

• The Intent is resolved to another

Activity, by matching it against an

Intent Filter.

new Intent(Intent.ACTION_DIAL, new Uri(“tel:555-1234"))

new Intent(Intent.ACTION_VIEW, new Uri(“geo:38.8995,-

77.0364"))


• Intents convey

• Data

• Action

•

• and Categories

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This is how

Intent Filters

match Intents

that are valid

for the Activity


• Activities are managed on

a stack

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• Once you go back they pop!


• Activities have a life cycle

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NewActivity

Stopped Activity

Paused Activity

Running...

Processes with non-running Activities may be killed to free resources

Broadcast Receivers

• Listens for Intents

• Incoming call

• Network availability changes

• Alarms

• Application doesn't have to be running

once a Receiver is registered

• Does not display UI

• May use notifications45

Services

• Services perform long running actions

• i.e. Play music, factor primary numbers

• Services are defined via AIDL

• Yet another “Interface Definition Language”

• Service lifecycle: manual or automatic

• Can be run either in-process or

in another process46

Content Providers

• Android likes to expose content in a

RESTful manner

• All content items have a unique URI

• Goes really well with Activity history

• Content Providers are used for CRUD

operations over arbitrary content

repositories

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Content Providers

• The interface has a strong relational

feel

• Hard to adapt to POJO backends like DB4O and Perst

• Despite looking relational, the interface encourages static joins

• Data returned should have a uniform shape

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Application Model

• Android Package (.apk)

• Compiled code & resources

• Manifest

• Must be signed (like jar)

• Task

• “perceived” application

• May span activities across several packages and processes

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UI Perspective

• Views

• From very simple:

• EditText, CheckBox, Button, Radio

• To more specialized:

• DatePicker, AutoComplete

• ViewGroups (layout)

• Relative, Table, Linear, …

• Web, Video, Map, Gallery...50

UI Perspective

• Sometimes the border between Views

and Activities isn't clear

• MapView

• MapActivity

• Choose MapActivity for a mashup

• Choose MapView for your own Activity

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Android Software Development

• Let's have a look at a “hello world”

sample provided by the SDK:

• Activity source file

• Layout file

• Android Manifest

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package com.example.android.helloactivity; //... /** * A minimal "Hello, World!" application. */ public class HelloActivity extends Activity { /** * Called with the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set the layout for this activity. You can find it // in res/layout/hello_activity.xml setContentView(R.layout.hello_activity); } }


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<EditText

xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/text"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:textSize="18sp"

android:autoText="true"

android:capitalize="sentences"

android:text="hello, world!" />


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<manifest

xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.android.helloactivity">

<application android:label="Hello, Activity!">

<activity android:name="HelloActivity">

<intent-filter>

<action android:name="android.intent.action.MAIN"/>

<category android:name="android.intent.category.LAUNCHER"/>

</intent-filter>

</activity>

</application>

</manifest>


• After build and deployment to the

emulator:

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UI Perspective

• Android UI lends itself to a clear flow

between simple screens

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UI Perspective

• Rich clients, on the other hand…

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… Don’t translate that well.

Porting Scenarios

• Opera

• Opera Mini uses

• Jetty has been ported

• local web applications

• Apache Felix has been ported

• OSGi bundles

• Alef Arendsen’s session covers OSGi in Spring

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Tool Support

• Android SDK and Eclipse plugin:

http://code.google.com/android/

• IntelliJ IDEA plugin is available here:

http://code.google.com/p/idea-android/

• SDK can create IDEA project files

• NetBeans plugin available here:

http://kenai.com/projects/nbandroid/

• DroidDraw is an Android UI builder:

http://www.droiddraw.org/ 60

References

• Android homepage:

http://code.google.com/android/index.html

• Open Handset Alliance:

http://www.openhandsetalliance.com/

• Android Market:

http://www.android.com/market/

• Android documentation: http://code.google.com/android/documentation.html

• Android open source project:

http://source.android.com/

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Apps for Android:http://code.google.com/p/apps-for-android

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DemoDemo

Google Android @ AlphaCSP's JavaEdge

Technology

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