Android Workshop_1

ANDROIDBeginners Workshop
Nitin R Patel
Purvik N Rana

Outline
 Era of Mobile OS
 Android
• What it is..!
• Software stack
• Components
• App fundamentals
 Development Environments
• Tools/Setups
 Application Structure
 Layouts and View
 Activity
 Fragments
 Services

 Symbian
• low-end phones
 Android
• Sep 20th, 2008 (Astro)
 Apple iOS
• June 29th, 2007
 BlackBerry
• property of Research in Motion (RIM) found in1999
 Windows
• Started by Nokia to take his reputation back to forth
 BADA
• owns by Samsung

What it is..!!
 Free – open source OS (platform for app creation)
 Linux kernel based OS
 Developed by Google and later the Open Handset Alliance (OHA)
 Allow to write/manage code in the Java
 Core and third party app are equal
 Easy and fast app development
 Era of Android starts since 5 November 2007

OHA
 Open Handset Alliance
 Group of technology and mobile companies
 First free provided mobile platform is – Android
 Providing richer experience (with open standards)  main Goal
 Handset manufactures are free to pay licencing fees to load
Android

Version Codename API Distribution
4.0.3 -
4.0.4
Ice Cream
Sandwich
15 3.7%
4.2.x
Jelly Bean
17 15.2%
4.3 18 4.5%
4.4 KitKat 19 39.2%
5.0
Lollipop
21 15.9%
5.1 22 5.1%

Native Android Applications
 Home Screen
 Music Player, Picture Gallery
 SMS, E-mail
 Camera Apps
 Full PIM (Calendar, Contacts)
 Web Browsers
 Play Store
 Sensors
 Google Maps
 Google Talk
 Google Mail Client
 YouTube
 Data Stores
 Much more . . .

• Contain all the Low level drivers for various hardware components of
Android
• Relaying on Linux Kernel for core system services like
• Memory and process management
• Network stack
• Driver model
• Security
• Provide Abstraction between hardware and rest of the software stack
Linux Kernel

• Set of Core libraries – enable developers to write Android Apps using
Java Programming
• DVM – Dalvik Virtual Machine
Android Runtime

Dalvik Virtual Machine
 Provides environment to let us execute Android application
 Each Android application runs in its own process
• Have it’s own instance of the Dalvik VM
 Dalvik has been written such that a device can run multiple VMs
efficiently.
 Register-based virtual machine
• Executing the Dalvik Executable (.dex) format
• .dex format is optimized for minimal memory footprint.
 Compilation
• Relying on the Linux Kernel for: Threading & other Low-level
memory management

 Exposed to developers through the Android application framework
 Including a set of C/C++ libraries used by components of the Android system
 Code for main features
• SQLite library- data storage
• WebKit library – functions for web browsing and much more..
Libraries

 Expose various capabilities of Android – developers use them in their
Apps
 Enabling and simplifying the reuse of components
• Developers have full access to the same framework APIs used by
the core applications
• Users are allowed to replace components
Application Framework

 Apps that download and install from Android Market
 Android provides a set of core applications:
• Email Client
• SMS Program
• Calendar
• Maps
• Browser
• Contacts etc…
Applications

Android Components
 Activities
• Single UI that handle the user interaction, app contains one or more activities
 Services
• handle background processing for applications, doesn‟t have UI
 Broadcast Receivers
• handle communication between Android OS and applications
 Content Providers
• handle data and database management issues
 Views
• UI elements like Buttons, Textviews and many more…

Android Application Fundamental
 Individual app lives in its own world
• Each application has its own process
• Identify with unique Linux user ID
• File alteration only permitted – ID and apps (through permission)
 Applications in between can – process elements of each other

DEVELOPMENT ENVIRONMENT
Eclipse – Android Studio

System requirements
 OS
• Xp (32) , Vista (32 - 64), 7 (32 - 64)
• Mac OS (10.5.8 or later)
• Linux
 Eclipse IDE (3.6.2 or later)
 Android SDK
 ADT Plug In
 JDK 6 (or later)

Continue . .
 Remember to get download of right version of java
 Unpack ZIP of SDK at appropriate location
 Install additional version of Android as well as other packages
 Configure Android Development Environment on Eclipse
• Add New Software to Eclipse
• ADT Plug In configuration

First Hello World Example (Demo)

 Codes & Resources resides in Different Folders
 Can be added as needed
• src : all source codes
• gen : java files generated by ADT
• assets : store raw assests files
• bin : output directory
• res : resources of our application
• res/drawable : image/image-descriptor files
• res/layouts : layouts of application
• res/menus : application menus
• res/values : other resources of application like
• Strings, Styles, Colors and so on… (xml based)

 Benefits
• Good to keep code away from all other things
• Easy to maintain – update – manage
• Support different devices and localization
• Resource selection dynamically at runtime
 System resources defined under System.R

Colors.xml
 Efficient to group all colors in one separate file like strings the
same way…

Androidmenifest.xml
 Application descriptor file
 Properties like..
• Activities
• Content Providers
• Services
• Intent Receivers
• Permissions
• Version Number
• And much more . . .
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.svit.helloworld"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="19"
android:targetSdkVersion="21" />
<application android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity" 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>

Different language and hardware
 Dynamic resource collection mechanism
• Done with dynamic directory structure
• Specific language, location, hardware
• Alternatives described with – mark
 Like.
• res/layout/main.xml
• res/layout-land/main.xml
• res/values-fi/strings.xml
• res/values-en/strings/xml

Screen orientation support
 Portrait and Landscape mode can be done easily by resources
• Portrait – automatically
• Landscape – specified in layout-land
• Phone switches layout automatically by when orientation changes

 Android Application UI is built using Views and Viewgroups
 Different “Widgets” like Button, Textview, which are the UI
objects are the subclass of the class “View”
 “Layouts‟‟ are the subclass of Viewgroup
 Different types of Layouts are available in this class

 Various Layouts
• Arrange the views in Single Row or Single Column
Linear Layout
• Group views into rows and column
• <TableRow> - design a Row in the Table
Table Layout
• Enables you to set child position relative to each other
Relative Layout
• A blank space on the screen which can later be filled with a
single object
Frame Layout

Defining Layouts with xml
 Most common way is to use XML for declaring Layout
 Each element of XML is ether a View or a Viewgroup
 The Name of the XML element is like the java class that
represents like <TextView> element creates a Textview in the UI
 Android attach the view hierarchy tree to the screen
 Activity call the setContentView() method and pass the reference
to the root node object
 Then draw() method of the view is called to draw the widget on
screen

Common Input controls
 Input controls are the interactive components of
the application‟s User Interface
 Android provides wide variety of controls like
Buttons, Text fields, seekbars, checkboxes,
spinners, pickers and so on….
 Use drag and drop the controls from palette to
set controls to layout or edit in XML file
directory

Handling UI Events
 Many ways to intercept the events from a user‟s interaction
depends on the SDK version
 The approach is to capture the events from the specific view
object that the user interacts with
 Use different EventListeners with code or in XML
• onClick, onLongClick, onFocusChange, …….

basic
 App Component (UI) – user interact to do something
 One app – multiple activities
• Main activity – launch time presented activity
• Other – specified to particular tasks
 Each activity can start another activity
 Subclass of Activity class
 callBack methods – system calls different states of app activity
 Activities are set in the stacks – root activity (begin the Task of
Application)

 Three main states: running, paused, stopped
• Pasued/stoppped : system can drop it from
memory
• UI, data sources and EventHandlers are
bind in onCreate()
• After onResume() : activity visible to user
• onPause() : save critical data at app data
store

 android:name - specify class name of the Activity
 Other attributes – specify additional information (label, icon,
theme..)
 Intent filter – make your activity available to system or other
applications

basics
 Most important and unique concepts
 Like „message‟to someone
 Can be used to
• Broadcast/Transfer data between application and app components
• Start Activities and Services
• Broadcast that event/action has occurred

 Intent Object  like bundle of information
 Contains
• Component : explicit name of component class to use for intent
• Action : action to be perform
• Data : URI of data to be acted on
• Category : string that indicate kind of a component that should handle
the intent
• Type : indicate Type of intent data
• Extras : key-value pairs of information
• Flags : instruct how to launch activity and how to treat it

Intent object data
 ACTION_VIEW content://contacts/people/1
 ACTOIN_DIAL content://contacts/people/1
 ACTION_VIEW tel:123
 ACTION_DIAL tel:123
 ACTION_EDIT content://contacts/people/1

Intent object category
 Any no of category can be included for intent to categorized

Intent object extras
 Bundle of additional information
 Provide extended information to the component

Intent resolution
 Two groups
• Explicit : used for application-internal messages(b/w activities)
• Delivered to an instance of designated target class
• startActivity(intent)
• Starts new Activity (Data can be passed with intent)
• Parent does not notify when child activity completes
• startActivityForResult(intent, REQUEST_CODE)
• same but parent get notify when child activity completes by OnActivityCompletes()
• Implicit : used to activate components in other applications
• Resolved by intent filters by object‟s (Action – Data - Category)
• System must find best component to handle intent

Intent filter
 Explicit – always deliver to target class
 Activities, Services and Broadcast receivers can have one or more
intent filters
 Filter describes the capability of a component
 Defined in the manifest file

Passing data between activities
 Intent can have addtional data  extras
 Key/value pair
 Send data:
• intent.putExtra(“info”,value);
 Get data:
• Bundle extra = getIntent().getExtras();
• int var = extra.getInt(“info”);

Receiving result from an activity

 Custom Intents
• Customize name in the manifest to receive intent
 Broadcast Intents
• No activity needed
• Listen broadcast intents
• Register in manifest file as Receiver
• Intent-filter used to match with listened intent actions

Fragment Basics
 Fragment represents a behaviour or a portion of user interface in
an Activity
 To build a multi-Pane UI, multiple fragments are combined in a
single activity
 Fragment must be embedded in an activity
 Fragment has its own lifecycle
 It supports more dynamic and flexible UI designs on large screens

 Example of Typical fragment:
• For Tablet: - list in left & content on right
• For Handset: - List & content on different Activity

basic
 Components runs in background (without UI)
 not a separate process or thread
 Can be stand alone process or part of an application
 Started, stopped, controlled by other application cpmponents
 Started services have higher priority than inactive or invisible activities
 Supports
• local services (not accessible outside of application)
• remote services (accessible outside of application)

Service creation
 Create class that extends Service class
 Override needed methods
• onCreate() : Launched on main application thread
• onStartCommand(Intent, int, int) : Create and run new thread
• onBind() : bind Activities to Service
• onDestroy() : do all clean up (stop threads,..)

Service lifcycle
 Context.startService()
• onCreate() : create a Service
• onStart() : start it
• onStartCommand()
• Context.stopService()/stopSelf() : Stops it
 Client.bindService()
• Create if it is not already running
• Doesn‟t call onStartCommand()
• onBind() : client will receive Ibinder object from
Service itself
• Remain running as long as connection is established
• Allows client to call back to Service

Android Workshop_1

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