Hello Android - Pune GTUG

Agenda Brief history of Android Android phones Android experiments What is Android? What's in new SDK? Android architecture in detail Application fundamentals User interface Resources and assets Data storage Content providers Security and permissions Developing with Eclipse First Android application Copyright © 2008 Wissen Systems. All rights reserved

Brief history of Android Developed by a small unknown company, Android Inc Google acquired this company in 2005 Later Google opened up to form, Open handset alliance (OHA) OHA consists of Google HTC T-mobile Sprint China mobile, Telecom Italia etc Vodafone, LG, Samsung, Motorola ARM, Intel Many others Copyright © 2008 Wissen Systems. All rights reserved

What is Android? Software stack, not an operating system Linux is the operating system under Android Provides application programming interface through Java/Dalvik virtual machine (DVM) Dalvik hides OS complexities from app programmer, who can write apps in (best programming language :-) ) Java Jxyz can be ported, or already ported, to run on DVM Provides utilities and libraries like modern web browser, media support, GSM telephony and lot of other things like OpenGL, Location support. My thoughts – Android is Linux based platform, customized to run on mobile/handheld devices which have limited processing power and memory. These devices will run many apps/utilities, one of them being GSM telephony. Ideal target for Netbooks Copyright © 2008 Wissen Systems. All rights reserved

What's new SDK? Latest version available is 1.5, known as cupcake. Rumours already loud about donut release ie 2.0, with which LOT of new handsets are expected to come Features for programmer - Locale support Media framework api changes Application defined hardware requirements Speech recognition Lot of other smaller changes Copyright © 2008 Wissen Systems. All rights reserved

Android architecture details Linux kernel Version 2.6, currently used Provides abstraction layer between hardware and rest of the stack Security, memory management, process management, network stack, driver model Libraries Libc port variants Media libraries for audio, video, images Surface manager for touch screen LibWebCore, modern web browser SGL, 2D graphics engine FreeType, bitmap and vector fonts SQLite Copyright © 2008 Wissen Systems. All rights reserved

Android architecture details... Android runtime DVM and core libraries Every android process runs its own process and VM instance DVM optimized to run multiple Vms efficiently .dex format for minimal memory footprint Depends on kernel for threading, low level memory management etc Application framework Typical framework, which makes writing apps easier Applications All applications including, apps packaged with android platform All apps are equal Copyright © 2008 Wissen Systems. All rights reserved

Application fundamentals AndroidManifest.xml Written as Java applications Applications live in their own world, separate process, VM, userId Ways to share userId Folder structure Components Activities Services Broadcast receivers Content providers Again all applications are equal Copyright © 2008 Wissen Systems. All rights reserved

Activity Presents visual interface Each user interface is separate activity. Implemented by subclassing Activity class Modal dialogs and floating activities Activity state Droiddraw and hierarchyviewer Copyright © 2008 Wissen Systems. All rights reserved

Service Background processes Works when user is using some other app. Long living component Implemented by subclassing Service class Requires intent to activate Registered in androidmanifest.xml Bound services, not long living, lives through the context only Communication with bound services through serviceconnection Services run in app process, can be setup to run in their own process Communication with remote process through AIDL. (Corba/RMI like) Permissions can be setup in manifest file Copyright © 2008 Wissen Systems. All rights reserved

Broadcast Receiver Event handling, also known as intent receiver All communication is managed through intents Extends BroadcastReceiver class to implement Entry in manifest or dynamically registered through context class Broadcast intent with sendBroadCast or sendOrderedBroadCast Permissions very important, specially for platform developers. Copyright © 2008 Wissen Systems. All rights reserved

Content providers Way of sharing data between processes/apps Remember – each app data is stored separately and lost after app is uninstalled. A content provider class implements standard set of methods to expose its app data to be used/consumed/created by other apps Supports CRUD operations Standard content providers, like contacts, files, media library provided in platform through core applications REST like implementation where every data object is a URI Copyright © 2008 Wissen Systems. All rights reserved

User Interface Built using View and ViewGroup Activities UI is constricted using nodes of View and ViewGroup object Widget – A View object which serves as interaction with user. Buttons etc UI Events are handled using EventListners like onTouchListner, onClickListner Menu – are also defined using View hierarchy, but programmer doesn't define own structure. Menu also have their own event handling callbacks Copyright © 2008 Wissen Systems. All rights reserved

Resources and Assets Resources and assets are external elements that you want use and reference in your application Examples – Audio, Video, Images etc Resources are available through R class, compiled by Android Assets are accessible through AssetManager as byte streams Standard set of resources are available to reference in your application Copyright © 2008 Wissen Systems. All rights reserved

Hello Android - Pune GTUG

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Hello Android - Pune GTUG