Google Android Introduction to Mobile Computing

Android is part of the build a better phone process Open Handset Alliance produces Android Comprises handset manufacturers, software firms, mobile operators, and other manufactures and funding companies

Bruce Scharlau, University of Aberdeen, 2009 Android is growing Small, 1% of online web requests Bigger, 10% of online web requests

Android makes mobile Java easier Well, sort of…

Android applications are written in Java package com.google.android.helloactivity; import android.app.Activity; import android.os.Bundle; public class HelloActivity extends Activity { public HelloActivity() { public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.hello_activity); }

Android applications are compiled to Dalvik bytecode Write app in Java Compiled in Java Transformed to Dalvik bytecode Linux OS Loaded into Dalvik VM

The Dalvik runtime is optimized for mobile applications Run multiple VMs efficiently Each app has its own VM Minimal memory footprint

Android has many components

Android has a working emulator

All applications are written in Java and available to each other Android designed to enable reuse of components in other applications Each application can publish its capabilities which other apps can use

Android applications have common structure Views such as lists, grids, text boxes, buttons, and even an embeddable web browser Content Providers that enable applications to access data from other applications (such as Contacts), or to share their own data A Resource Manager, providing access to non- code resources such as localized strings, graphics, and layout files A Notification Manager that enables all apps to display custom alerts in the status bar An Activity Manager that manages the life cycle of applications and provides a common navigation backstack

Android applications have common structure Broadcast receivers can trigger intents that start an application Data storage provide data for your apps, and can be shared between apps – database, file, and shared preferences (hash map) used by group of applications Services run in the background and have no UI for the user – they will update data, and trigger events Intents specify what specific action should be performed Activity is the presentation layer of your app: there will be one per screen, and the Views provide the UI to the activity

There is a common file structure for applications code images files UI layouts constants Auto generated resource list

Standard components form building blocks for Android apps Other applications Has life-cycle screen App to handle content Background app Like music player Views manifest Activity Intents Service Notifications ContentProviders

The AndroidManifest lists application details <manifest xmlns:android=" package="com.my_domain.app.helloactivity">

Bruce Scharlau, University of Aberdeen, 2009 Activity is one thing you can do

Intent provides late running binding to other apps It can be thought of as the glue between activities. It is basically a passive data structure holding an abstract description of an action to be performed. Written as action/data pairs such as: VIEW_ACTION/ACTION content://contacts/1 Written as action/data pairs such as: VIEW_ACTION/ACTION content://contacts/1

Services declared in the manifest and provide support Services run in the background: Music player providing the music playing in an audio application Services run in the background: Music player providing the music playing in an audio application Intensive background apps, might need to spawn their own thread so as to not block the application

Notifications let you know of background events This way you know that an SMS arrived, or that your phone is ringing, and the MP3 player should pause

ContentProviders share data You need one if your application shares data with other applications This way you can share the contact list with the IM application If you dont need to share data, then you can use SQLlite database

UI layouts are in Java and XML setContentView(R.layout.hello_activity); //will load the XML UI file

Security in Android follows standard Linux guidelines Each application runs in its own process Process permissions are enforced at user and group IDs assigned to processes Finer grained permissions are then granted (revoked) per operations <manifest xmlns:android=" package="com.google.android.app.myapp" > <manifest xmlns:android=" package="com.google.android.app.myapp" >

There are lots of sources of information The sdk comes with the API references, sample applications and docs/resources/bootcamp.pdf There are Google news groups There is There is Google search

End of Overview Next, start to build your first app!