#MobileDevDay: A crash course in Android Development

8/4/2019 #MobileDevDay: A crash course in Android Development

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Android in 60 minutes

By Yap Wen Jiun @wenjiun

Multimedia University Lecturer

CodeAndroid Malaysia Co-founder


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What is Android?Android is a software stack for mobile devices

that includes:

operating system

middleware

key applications http://www.android.com/


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http://developer.android.com/guide/basics/what-is-android.html


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Java & AndroidAndroid Apps are written usingJava

Android runtime core libraries are a large

subset of Apache Harmony open source Java SE

libraries

Dalvik Virtual Machine is a Java VM optimized

for mobile that runs Dalvik Executables (.dex)which is converted from multiple .class files


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Development EnviromentAndroid SDK provides APIs & tools

http://developer.android.com/sdk

Recommended IDE Eclipse (3.5, 3.6 or 3.7)

requiresJDK 5 or 6

Bind the Android SDK to Eclipse with AndroidDevelopment Tools (ADT) plugin


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Android SDK

Updated with Android SDK & AVD Manager

In the SDK:

Core Libraries android.jar

Emulator Android Virtual Device (AVD)

Documentation & Sample Codes

Tools ADB, DDMS, draw9patch, ProGuard,

HierarchyViewer, SQLite3 etc.


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Android VersionVersion Nickname API Level Core Libraries size

1.5 Cupcake 3 3.0MB

1.6 Donut 4 3.1MB

2.1 Eclair 7 4.9MB

2.2 Froyo 8 5.2MB

2.3 2.3.2 Gingerbread 9 8.0MB

2.3.3 2.3.4 Gingerbread 10 9.5MB

3.0 Honeycomb 11 12.2MB

3.1 Honeycomb 12 12.4MB3.2 Honeycomb 13 12.8MB


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Android Version

http://developer.android.com/resources/dashboard/platform-versions.html

(as of 2 Sep 2011)
http://developer.android.com/resources/dashboard/platform-versions.htmlhttp://developer.android.com/resources/dashboard/platform-versions.html


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Android Virtual Device

Emulator to test Android Apps

Created with Android SDK & AVD Manager

Different Android API level

Whether to support Google APIs

Screen resolution & sizeSD Card support and its size


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Testing on Hardware

Windows PC requires USB driver

Linux PC requires UDEV rules file

Connect to PC with Android Debug Bridge (adb)

or Dalvik Debug Monitor Service (DDMS) similar

to AVDs


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Hello World

The default new Android project

Build Target not required to be the latest API

level, just enough for the features required

Minimum SDK Version usually lower than Build

Target to support more users with older devices Package name is the unique identifier


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What is Activity?The user interface screen

Implemented as a subclass derived from the

Activity base class

1 of the 4 Android Application Components

Each Activity is given a default window and the

visual content is provided by a hierarchy of

Views


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Activity Lifecycle


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Project Structure

src/ : Java source (*.java)

res/ : resources such as XML files, images

assets/ : assets, self-managed resources

bin/ : compiled binaries (*.apk)

gen/ : auto-generated (R.java)

libs/ : 3rd party Java libraries (*.jar)

AndroidManifest.xml


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Android ManifestProvides essential info such as

VersionCode for Apps updates

Components such as Activity are mandatory to

be declared

Permissions for inccurring cost, accesing

certain hardware or private dataEdited in various tabs within Android Manifest

Editor


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XML-based Layout

A specification of visual placements or

relationships for UI Widgets and Containers

Edited using Graphical Layout Editor

Stored in res/layout/

Attached in setContentView() in Activity's

onCreate() callback


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UI Widgets

Typical elements of Android GUI toolkit

TextView for text labels

Button for interactions

EditText for text inputs

ImageView for displaying images

CheckBox for selections between 2 states


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Identification in Layout XML

UI Widgets or Containers in layout XML that

need to be used in the Java source are identifiedby an ID with android:id="@+id/widgetID"

Java source access the identified widgets with

findViewById()


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Arrangment with Containers

The parent elements to place the UI Widgets

Lined up vertically or horizontally 1 by 1 in

LinearLayout Widgets are placed based on relationship with

others in RelativeLayout

Widgets are placed in a grid in TableLayout via

TableRow


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Handling UI Events

Using Event Listeners interface such as

OnClickListener(), OnCheckedChangeListener()

Register Event Listeners to UI Widgets or Activity

using methods such as setOnClickListener()

Event Listeners include callback methods such as

onClick() for OnClickListener()


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What is Intent?

Message that declares the intention to perform

an action, usually with a piece ofdata

Intents are passed to startActivity( ) to launch an

activity

Activity using Intent Filters to be notified by

Intents


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Launching Activity

Explicit Intent Start a new activity explicitly

by specifying the class

Used in multiple screens AppsImplicit Intent Start a new activity implicitly

by requesting an action be performed on a data

Useful for browsing, sharing, opening map ...


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Launching Sub-Activity

startActivityForResult( ) launches an activity as

a sub-activity

Useful in taking photo, scanning barcode

Sub-activity calls setResult() to return a result

to the parent activity and triggers an event

handler onActivityResult() within the parent

activity when it closes


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Options Menu

Let an Activity to have more options

Triggered by pressing the Menubutton

The first six menu items are in icon mode,

showing in a grid at the bottom of the screen

Menu is described in XML files stored in

res/menu/ & inflated into menu with

MenuInflater


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Honeycomb UI

Released for Android Tablets with Large screens

& Xlarge screens

With a larger screen estate,Fragments is used to create a multi-pane UI

Some Options Menu items are promoted into

the more accessible Action Bar


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Publishing

Published in Application Package (APK) format

that holds the Dalvik executable, resources,

assets, certificates & Android Manifest

Published on

Android Market

3rd-Party Market such as Amazon Appstore

Device or Telcos Market


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Signing

All APKs must be signed to be deployed

Developing using debug key

Publishing using own self-signed key via

Android Tools > Export Signed Application

Package in Eclipse


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Distributing via Web Site

Distributed viaPublic web site with ads or in-app purchase

Internal distribution for internal use only

Configure APK MIME type as

application/vnd.android.package-archive

Users download to SD Card via URL/QR Code

and install via default Package Installer


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Where to get help?

http://developer.android.com/ Books about Android with codes samples

SDK Samples such as API Demos (via Create

Project from existing example)

Google IO Android tracks videos

Android Developer Community meetup such as

CodeAndroid Malaysia

Documents

#MobileDevDay: A crash course in Android Development