android handheld systems

ANDROID HANDHELD SYSTEMS

ANDROID

PLATFORM

ANDROID

DEVELOPMENT

ENVIRONMENT

THE ANDROID PLATFORM

A multi-layered software stack for building and running mobile applications

A software stack for mobile devices:OS kernel, system libraries, application frameworks & key apps.Android Software Development Kit (SDK) for creating apps.Libraries & development tools.

SecurityMemory & process managementFile & network I/ODevice drivers

Power managementAndroid shared memoryLow memory killerInter process communicationAnd much more

System C library->Bionic libc

Surface Mgr.->Display management

Media Framework->Audio/ Video

Webkit->browser engine

OpenGL->Graphics engines

SQLite->Relational->database engine

Two main components-> Core Java libraries-> Dalvik Virtual

Machine

basic java classes -- java.*, javax.*app lifecycle -- android.*Internet/Web services -- org. *Unit testing -- junit.*

App written in java compiled to Java byte code files.DX converts java byte code files to a single dex byte code file (CLASSES.DEX).

Dalvik executes DEX byte code file.

Designed for resource-constrainedenvironments

<>Slower CPU<>Less RAM<>Limited battery life

PACKAGE MANAGER

Keeps track of App Packages on Device.

WINDOW MANAGER

Manages the Windows comprising an App.

Sub window

NotificationBar

MainWindow

Tabs

Text View

Buttons

Provides common user interfaceElements.e.g., icons, text entry boxes, buttons and more.

Manages non- compiled resources, e.g. Strings, Graphics, and Layout files.

ACTIVITY MANAGERManages App Lifecycle and Navigation Stack.

Inter Application Data Sharing.

LOCATION MANAGERProvides Location and Movement Information.

NOTIFICATION MANAGERPlace Notification Icons in the Status Bar when

important events occur.

Notification

Standard apps include:Home – main screenContacts – contacts databasePhone – dial phone numbersBrowser – view web pagesEmail reader –compose & read email messages.

ANDROID DEVELOPMENT ENVIRONMENT

Your workbench for writing Android applications

Runs virtual devices

Can emulate many different device/ user characteristics, such as: Network speed/ latencies, Battery power, Location coordinates.

Emulate incoming phone calls & SMS messages

Can interconnect multiple emulators

Doesn’t require an actual phone

Hardware is reconfigurable

Changes are non-destructive

Can be very

slow

Some features

unavailable e.g.,

no support for

blue tooth or

USB connections

Performance /

user experience

can be misleading