Application Development for Android

Presented by:Anshul Sharma

101225

What is Android?

• Google’s mobile operating system

• A free, open source mobile platform

• A Linux-based, multiprocess, multithreaded OS

• It’s not even limited to phones - you could build

a DVR, a handheld GPS, an MP3 player, etc.

• Offers an SDK and NDK

• Latest SDK version is 4.0/4.1 (Jellybean)

Software development

• Android SDK includes a comprehensive set of development tools.

• The SDK is downloadable on the android developer website.

• The officially supported integrated development environment (IDE) is Eclipse (currently 3.5 or 3.6) using the Android Development Tools (ADT) Plugin

Architecture Overview

Linux Kernel

✓ Security model: The Linux kernel handles security between the

application and the system.

✓ Memory management: The kernel handles memory management for you, leaving you free to develop your app.

✓ Process management: The Linux kernel manages processes well, allocating resources to processes as they need them.

✓ Network stack: The Linux kernel also handles network communication.

✓ Driver model: The goal of Linux is to ensure that everything works. Hardware manufacturers can build their drivers into the Linux build

Native Libraries

✓ Shared libraries all written in C or C++

✓ Compiled for the particular hardware

architecture used by the phone

✓ Preinstalled by the phone vendor

✓ Can be developed using NDK

Android Runtime

✓ Dalvik VM

– Google’s implementation of Java

– Optimized for mobile devices

Every Android application runs in its own process, with its own instance of the Dalvik virtual machine. Dalvik has been written so that a device can run multiple VMs

efficiently.

The Dalvik VM executes files in the Dalvik Executable (.dex)

format which is optimized for minimal memory footprint.

Application framework

✓ Activity manager: Manages the activity life cycle.

✓ Telephony manager: Provides access to telephony services as well as some subscriber information, such as phone numbers.

✓ View system: Handles the views and layouts that make up your user interface (UI).

✓ Location manager: Finds out the device’s geographic location.

Application Lifecycle

Building Blocks

✓ Activities : User Interface

✓ Intent: A mechanism for describing a specific

action

✓ Service: A task that runs in the background

without user interaction

✓ Content providers: is a set of data wrapped up

in a custom API to read and write it

Activities

✓ An activity represents a single screen with a user interface.

✓ An activity is implemented as a subclass of Activity

Activity Lifecycle

Intents ✓ Activities and services — are activated through messages, called intents. ✓ Intent object, is a data structure holding a description of an operation to be performed.

Implicit intents

Explicit intents

Intent intent1 = new Intent(v.getContext(), thirdscreenn.class);

startActivity(intent1);

Services

✓ A service is a component that runs in the background to perform long-running operations or to perform work for remote processes.

✓ For example, a service might play music in the background while the user is in a different application.

✓ A service is implemented as a subclass of Service.

✓ A service does not provide a user interface.

Content providers

✓ A content provider manages a shared set of application data.

✓ You can store the data in the file system, a SQLite database, on the web, or any other persistent storage location your application can access.

✓ Through the content provider, other applications can query or even modify the data (if the content provider allows it).

✓ A content provider is implemented as a subclass of ContentProvider and must implement a standard set of APIs that enable other applications to perform transactions

The AndroidManifest.xml File

✓ Every application must have an AndroidManifest.xml file.

✓ It names the Java package for the application. The package name serves as a unique identifier for the application.

✓ It describes the components of the application — the activities, services, broadcast receivers, and content providers that the application is composed of.

✓ It determines which processes will host application components.

✓ It declares the minimum level of the Android API that the application requires.

AVD (Android Virtual Device)

• An Android Virtual Device (AVD) is an emulator configuration that lets you model an actual device by defining hardware and software options to be emulated by the Android Emulator.

Application Structure

USER INTERFACE

Layouts

• Linear Layout

• Table Layout

• Relative Layout

• Absolute Layout

• Frame Layout

Views

• Views are what your users will see and interact with

Views (cont’d)

Views (cont’d)

Load the XML Resource

Listeners

✓ Tell Android which object to callback when the user touches or clicks the view✓ Use setOnClickListener() method that needs to Be passed an object that implements the OnClickListener Java interface✓ Set android:onClick property with the method name that handles the click action

button.setOnClickListener(new OnClickListener(){

public void onClick(View v) {// TODO Auto-generated method stubIntent j = new Intent(v.getContext(),mediaplayer.class);j.putExtra(mediaconstant.MEDIA_MODE, mediaconstant.MEDIA_PAUSE);startService(j);}} );