A Beginner s Guide to Android

7/31/2019 A Beginner s Guide to Android

1/51


2/51

Beginner's Guide to Android

Nick Butcher9th May 2011

@craftyhashtags: #iobootcamp #android


3/51

Session Feedback

http://www.speakermeter.com/talks/guide-android/http://goo.gl/XLLgk


4/51

Agenda

Android platform

Writing your app Anatomy of an app Building your app Surfacing your Content Hardware Sensors

Quality Tools

Publishing your app Registering for Android Market Targeting


5/51

Many Devices, One Platform

170+ devices in 100+ countries

Shipping 350K+ devices per day 1 year ago was 60K per day! > 1m new potential users every 3 days!!

Any device with Google services must passthe Compatibility Test Suite

Contract of device capabilities & APIs Support many screen sizes/resolutions Market filters on hardware availability


6/51

Many Devices, One Platform

New Platform/SDKreleases

Target latest but supportolder

Gracefully degradefunctionality

Source: Date collected during two weeks ending on April 1, 2011


7/51

Writing your app


8/51

An Android application is actually acollection of several components, eachdefined in AndroidManifest.xml


9/51

Anatomy of an App

Activity Service Content Provider Broadcast Receiver

Intents Manifest


10/51

Anatomy of an AppActivity

A single screen with auser interface

Independent butwork together to forma cohesive whole

Possible to invokefrom other applications

Extends the Activityclass


11/51

Perform long-running operations in the background Does not provide a user interface Other components can bind/interact Extends the Service class

Anatomy of an AppService


12/51

Anatomy of an AppContent provider

Manages a shared set of application data Consistent interface to retrieve/store data

RESTful model CRUD operations

Can be backed by different stores

e.g. File System, SQLite DB, Web Can expose your data to other applications Can consumer data from other Content Providers

e.g. Contacts or Call Log Extend the ContentProviderclass


13/51

Anatomy of an AppBroadcast receiver

Respond to system wide messages Messages can be initiated by the system or an app 2 type of broadcast:

Normal - delivered async to all receivers Ordered - delivered in priority order & can be aborted

Can programatically register or statically register via themanifest

Should be very light, pass any work onto a Service Extend the BroadcastReceiverclass


14/51

Anatomy of an AppIntents

Intents are the messages that link app components together Explicit / implicit An abstract description of an operation to be performed

An Action to be performed The Data to operate upon

Extra metadata Standardise on a common vocabulary of Actions

e.g. 'View', 'Edit', 'Send' Apps register their ability to handle Actions for a given data type

via IntentFilter


15/51


Publish an 'Intent API' Specify Action & Extras to invoke your component


16/51


Achieve complex tasks by calling other Application'sIntents, e.g. scanning a barcode


17/51



Intent intent =newIntent("com.google.zxing.client.android.SCAN");

intent.setPackage("com.google.zxing.client.android");

intent.putExtra("SCAN_MODE","QR_CODE_MODE");

startActivityForResult(intent,0);

publicvoid onActivityResult(int requestCode,int resultCode,Intent intent){

if(resultCode == RESULT_OK){

String contents = intent.getStringExtra("SCAN_RESULT");

String format = intent.getStringExtra("SCAN_RESULT_FORMAT");

}elseif(resultCode == RESULT_CANCELED){

// Handle cancel }

}


18/51



Intent intent =newIntent("com.google.zxing.client.android.SCAN");


intent.putExtra("SCAN_MODE","QR_CODE_MODE");

startActivityForResult(intent, 0);

public void onActivityResult(int requestCode, int resultCode, Intent intent) {

if (resultCode == RESULT_OK) {



} else if (resultCode == RESULT_CANCELED) {

// Handle cancel}

}


19/51



Intent intent = new Intent("com.google.zxing.client.android.SCAN");


intent.putExtra("SCAN_MODE", "QR_CODE_MODE");

startActivityForResult(intent,0);






// Handle cancel}

}


20/51







publicvoid onActivityResult(int requestCode,int resultCode,Intent intent){

if(resultCode == RESULT_OK){



}elseif(resultCode == RESULT_CANCELED){

// Handle cancel }

}


21/51












// Handle cancel}

}


22/51

Anatomy of an AppManifest

Declarecomponents of yourapp

Declare requiredfeatures for your app

State permissionsrequired by your app

State platform versions

app is compatible with

...

...

...

...


23/51

Anatomy of an AppActivity lifecycle

Running in a multitaskingenvironment

Users switch apps, calls

come in, system runs low onmemory System invokes callbacks in

your app The system will kill your app Be sure to save state!


24/51


Activitycreated

Simlpified, see http://developer.android.com/guide/topics/fundamentals/activities.html#Lifecycle for more


25/51


onCreate()

Activitycreated

onResume()

Activityrunning



26/51


onPause()

Call comesin

onResume()

Activity

running



27/51


onPause()

Call comesin

onResume()

Activity

running


Return toapp


28/51


onPause()

Call comesin

onResume()

Activity

running


Return toapp

LowMemory

Activitydestroyed


29/51

Surfacing Your Content

Android offers uniqueways to surface yourcontent


30/51


Event drivennotifications

Optional vibration /

audio / LED alert Ticker text / pull downdraw with more details

Custom expandedview

Deep link into yourapp witha PendingIntent

Unobtrusive notifications


31/51


Event drivennotifications

Optional vibration /

audio / LED alert Ticker text / pull downdraw with more details

Custom expandedview

Deep link into yourapp witha PendingIntent

Unobtrusive notifications


32/51


Display your app's infoon the homescreen

Updated regularly

App can offer multiplewidgets Great way to keep

user engaged withyour app

Widgets


33/51

Surfacing Your ContentCloud to Device Messages

Push messages from servers to app Send 'tickles' App doesn't have to be running App has full control over how it responds

Efficient, event driven updates

Uses existing network channel Minimal battery impact

Android 2.2+


34/51

Building your App

UI

Resource Framework Supporting Multiple Screens Hardware Sensors Background Tasks Accessibility

Quality Tools


35/51

Building your AppUI

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);setContentView(R.layout.main);

}

UI is a hierarchy ofView & ViewGroup

Definedprogramatically or

in XML Layout files Platform suppliescommon palette ofwidgets

Create your own

widgets


36/51

Building your AppResources framework

Resources live in the res folder Qualifiers provide specific resources for

different device configuration e.g. layout-land, drawable-hdpi

Resources IDs automatically generatedin R.java

e.g. R.layout.main

See http://developer.android.com/guide/topics/resources/index.html for more


37/51

Building your AppSupporting multiple screens


38/51



39/51


Use RelativeLayout Size with wrap_content, match_parent, weight Use dp units Think web style layout

Provide density specific assets

e.g. drawable-hdpi Provide size specific layouts e.g. layout-xlarge

Use 9-patch drawables


40/51

Building your App

Many devices have access to a variety of sensors Accelerometer, Gravity, Gyroscope, Light, Magnetic Field

Use SensorManager.getSensorList() to find out what is available SensorManager.registerListener() for sensor updates

Hardware Sensors

See http://developer.android.com/reference/android/hardware/Sensor.html for more


41/51

Building your AppBackground tasks

More than just multitasking Use background tasks to provide fresh information Use the AlarmManagerto schedule updates Use 'inexact repeating' to minimise power consumption

Regularly sync content from the web

Provide offline availability Great for regularly updated content e.g. news feeds


42/51

Building your AppAccessibility

Label controls and input widgets with android:contentDescription tag

allows built in accessibility to work Allow navigation with trackball / d-pad where available Follow Android UI Best Practices

http://developer.android.com/guide/practices/ui_guidelines/index.html

Back button should always move the user back one logical

step Try it in accessible mode!

Enable TalkBack in Settings -> Accessibility or downloadfrom Market

See http://developer.android.com/guide/practices/design/accessibility.html for more


43/51

Building your AppQuality

Work with the Activitylifecycle Offload any long running

operation to abackground thread

Stability, UIResponsiveness,Performance

Listen to your users,read their feedback

regularly Work with a designer


44/51

Tools

1. Download and Install the Android SDK

developer.android.com/sdk/index.html2. Download and Install Eclipse

http://eclipse.org3. Install the Android Development Tools (ADT) Eclipse Plugin

http://developer.android.com/sdk/eclipse-adt.html#installing

4. Use SDK & AVD Manager in Eclipse to install the latestAndroid packages.

Full guide: http://developer.android.com/sdk/installing.html


45/51

Publishing Your App


46/51

Register For

Create a developer profile Register at http://market.android.com/publish

One time $25 fee

No limit to number of apps you can publish Developer Distribution Agreement To sell apps, create a Checkout Merchant Account


47/51

Upload Your App

No review process

Publish as many updates as you like Updates available right away Supply promotional assets & video Max APK size 50MB Accessible on device & on Android Web Market

View crash reports online View application statistics


48/51

Targeting

Only target specific countries

Target specific hardware e.g. Telephony or OpenGL ES 2.0

Android Market will not show app to incompatible device

// in AndroidManifest.xml


49/51

Recap

Android platform

Writing your app Anatomy of an app Building your app Surfacing your Content Hardware Sensors

Quality Tools

Publishing your app Registering for Android Market Targeting


50/51

Session Feedback

http://www.speakermeter.com/talks/guide-android/http://goo.gl/XLLgk


51/51

Documents

A Beginner s Guide to Android