Google Developer Group(GDG) DevFest Event 2012 Android talk

Android Application Development
DevFest event 2012
@Pear Continental, Karachi

Presenter: Imam Raza

Speaker.bio.toString()
• Senior Software Architect @ Folio3.
• Specialties: Enterprise Software Architecture,
Mobile Software Architecture, Software Best
Practices(TDD,CI ,AOP, IOC).
• Master in computer science from KU
• B.E (Mechanical) from NED University

Monday, September 19, 2011

Me.loveQuestions==true


Agenda
• Market Statistics
• The Android Work in Pakistan
• Android Basics
• Hello World
• Main Building Blocks
• Android Best Practices

SmartPhone Vs PC sales 2011
Category Q4 2011 Growth Full year 2011 Growth
shipments Q4’11/Q4’10 shipments 2011/2010
(millions) (millions)
Smart Phones 158.5 56.6% 487.7 62.7%

Total Client Pcs 120.2 16.3% 414.6 14.8%

-pads 26.5 186.2% 63.2 274.2%

-netbooks 6.7 -32.4% 29.4 -25.3%

-notebooks 57.9 7.3% 209.6 7.5%

-Desktops 29.1 -3.6% 112.4 2.3%

Market Share Q2 2012
Smart Phone %percentage Unit sold (millions)

Android 68.1% 104.8

iOS 16.9% 26

Black Berry 4.8% 7.4

Symbian 4.4% 6.8

Windows 3.5% 5.4

Agenda
Market Statistics
The Android Work in Pakistan
Android Basics
Hello World
Main Building Blocks
Android Best Practices

Android Apps
• Myomo MyProgress
• Sony Socom Android App
• Bitzer
• NSDroid (NetSuite CRM)
• Hiplink

Linux Kernel
• Android runs on Linux. Linux
provides:
– Hardware abstraction
layer
– Memory
management
– Process management
– Networking
• Users never see Linux sub
system
• The adb shell command opens
Linux shell

Native Libraries
• Pieces borrowed from other
open source projects:
– Bionic, a super fast and
small license-friendly
libc library optimized
for Android
• WebKit library for fast HTML
rendering
• OpenGL for graphics
• Media codecs offer support for
major audio/video codecs
• SQLite database ..Much more…

Question: Difference between
Java VM and Dalvik VM?

Dalvik VM
• 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

Application Framework
• The rich set of system services wrapped in an
intuitive Java API.
• This ecosystem that developers can easily tap
into is what makes writing apps for Android easy.
• Location, web, telephony, WiFi, Bluetooth,
notifications, media, camera, just to name a few.

Applications

• Dalvik Executable +
Resources = APK
• Must be signed (but
debug key is okay
for development)
• Many markets with
different policies

Question: What is the
difference between Android
and Java?

Android and Java
Android Java
=
Java SE
–
AWT/Swing
+
Android API

Android SDK- what is in box?
SDK
Tools
Docs
Platforms
– Data
– Skins
– Images
– Samples
Add-ons
– Google

Hello World-Create New
Project
Use the Eclipse tool to create a new Android
project.
Here are some key constructs:

Hello World-Anatomy of App
Java Code
+
XML / Other
Resources
+
Manifest File
=
Android App

HelloWorld-Manifest File
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.folio3"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="10" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".HelloworldActivity"
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></manifest>

HelloWorld- Layout Resource
File
<?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>

HelloWorld-JAVA File
package com.folio3;
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);
}
}

Main Building Blocks
• Activities
• Intents
• Services
• Content Providers
• Broadcast Receivers
• Fragments

Activities
An activity represents a screen
or windows

Activity LifeCycle
Activity have well-defined
lifecycle. The android OS
manages your activity by
changing its state.
You fill in the blanks

Intents
• Intents represent
events or actions.
• They are to Android
apps what hyperlinks
are to websites. Sort
of.
• Intents can be
implicit or explicit.

Services
Services are code that runs in the background.
They can be started and stopped. Services
doesn’t have UI.

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.

Content Provider
• Content Providers share
content with applications
across application
boundaries.
• Examples of built-in
Content Providers are:
– Contacts,
– MediaStore,
– Settings and
more.

Broadcast Receivers
An Intent-based publish-subscribe mechanism.
Great for listening system events such as SMS
messages.

Fragments
A Fragment represents a behavior or a portion of
user interface in an Activity.

Fragments
• Fragments were introduced in Android 3.0 (API
level 11), primarily to support more dynamic and
flexible UI designs on large screens, such as
tablets.
• Fragments are lot like an activity but it must
exists within the activity.
• DialogFragment makes it easy to show a Dialog
that is managed as part of the Activity lifecycle.
• ListFragment makes it easy to show a list of data.

Best Practices
• Use RoboGuice(DI based framework)
• Learn Activity Life Cycle
• Avoid getting activities thick
• Design views for multiple size/orientation.
• Use Fragments to better manage sub-portion of
Activity.
• Practice Good MVC.
• Use Source Code Analyzer Tools (findbugs,
checkstyle,PMD and CPD). Integrate these tools
with CI Tools like Teamcity.

RoboGuice
• It’s based on dependency injection pattern just
like Spring Framework in enterprise apps
• It takes the guesswork out of development. e.g
checking null for getIntent().getExtras(). Casting
findViewById().
• Make your writing unit test case easy
• It reduces your lines of code and hence the
number of bugs see next slide for code.


class AndroidWay extends Activity {
TextView name;
ImageView thumbnail;
LocationManager loc;
Drawable icon;
String myName;

name = (TextView) findViewById(R.id.name);
thumbnail = (ImageView) findViewById(R.id.thumbnail);
loc = (LocationManager)
getSystemService(Activity.LOCATION_SERVICE);
icon = getResources().getDrawable(R.drawable.icon);
myName = getString(R.string.app_name);
name.setText( "Hello, " + myName );
}
}

class RoboWay extends RoboActivity {
@InjectView(R.id.name) TextView name;
@InjectView(R.id.thumbnail) ImageView thumbnail;
@InjectResource(R.drawable.icon) Drawable icon;
@InjectResource(R.string.app_name) String myName;
@Inject LocationManager loc;

name.setText( "Hello, " + myName );
}
}

Compatibility
• Ability to install and run app on device.
• Huge variety of devices so developer need to
make sure about the Hardware/Software feature
his application needed to run.


Compatibility
• Specify uses-feature node for every API you use
• Mark essential features as required.
• Mark optional features as not required.
<uses-feature
Android:name=“android.hardware.gps”
Android:required=“true”/>


Compatibility
• Check for API existence in code.
PackageManager pm = getPackageManager();
Boolean hasCompass=
pm.hasSystemFeature(
PackageManager.FEATURE_SENSOR_COMPASS);
If(hasCompass){
//enable things are needed
}


Compatibility
Use dp and sp instead of px:
<Button android:layout_width=“wrap_content”
Android:layout_height=“wrap_content”
Android:layout_marginTop=“20dp”/>
<TextView android:layout_width=“match_parent”
Android:layout_height=“wrap_content”
Android:textsize=“20sp”/>

Compatibility


Compatibility-Test for different
device/screen size


Advance Task Killer App is
among 50 millions or more
install apps
Why?


Performance
• Avoid creating objects. (e.g use StringBuffer) .
• Prefer static over virtual.
• Use static final for constants.
• Avoid internal getter/Setter (with Proguard you
don’t need it.)
• Use Enhanced For Loop Syntax e.g:
for (Foo a : mArray) { sum += a.mSplat; }
• Use native methods.
• Avoid using Float and enums

Responsiveness


Responsiveness
• “Application Not Responding”
• Respond to user within 5 seconds
• Broadcast Receiver must complete within 10 seconds
• Use Threads and AsyncTasks within Services


Source Code Analyzer Tools
• FindBugs
• PMD
• CheckStyle
• CPD : Shows code duplication
• You can integrate them with CI Server like
Teamcity to get consolidated reports of code
quality of your team. We have been using it on
our company and its really helped us in
monitoring quality of code.

Google Developer Group(GDG) DevFest Event 2012 Android talk

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