Android Application Development (Daniel Switkin)

Android applications

• Introduce major Android application concepts

• Walk you through a sample application in the

development environment

Agenda

•System architecture

•Hello World!

•Application components

•Practical matters

•Toolchain

What is Android?

• A free, open source mobile platform

• A Linux-based, multiprocess, multithreaded OS

• Android is not a device or a product

• It’s not even limited to phones - you could build a DVR, a handheld GPS, an MP3 player, etc.

The History of GUIs

• Hardcoded to the screen

• Hardcoded to the window

• Hardcoded within a view hierarchy

• Dynamic layout within a view hierarchy

Generating GUIs

• Two ways to create GUIs: in XML or in code

• Declarative route via XML has advantages

• A lot of your GUI-related work will take place in:

•res/layout

•res/values

•@id/name_for_component gives you handle for referencing XML declarations in code

Views

• Views are building blocks

• Examples:

• Can be as basic as: TextView, EditText, or

ListView

• Fancier views: ImageView, MapView, WebView

Layouts

• Controls how Views are laid out

• FrameLayout : each child a layer

• LinearLayout : single row or column

• RelativeLayout : relative to other Views

• TableLayout : rows and columns

• AbsoluteLayout : <x,y> coordinates

Layouts are resizable

Layouts are customizable

Layout Parameters

• Specify many aspects of what’s being rendered

• Examples: android:layoutheight, android:layout_width

• Tip: start with documentation for a specific View or Layout and then look at what’s inherited from

parent class

Activities

• Typically correspond to one screen in a UI

• But, they can:

• be faceless

• be in a floating window

• return a value

Intents

• Think of Intents as a verb and object; a description of what you want done

• Examples: VIEW, CALL, PLAY, etc.

• System matches Intent with Activity that can best provide that service

• Activities and BroadcastReceivers describe what Intents they can service in their IntentFilters (via

AndroidManifest.xml)

BroadcastReceivers

• Components designed to respond to broadcast Intents

• Think of them as a way to respond to external notifications or alarms

• Applications can invent and broadcast their own Intents as well

Services

• Faceless components that run in the background

• Example: music player, network downlaod, etc.

• Bind your code to a running service via a remote-able interface defined in an IDL

• Can run in your own process or separateprocess

ContentProviders

• Enables sharing of data across applications

• Examples: address book, photo gallery, etc.

• Provides uniform APIs for:

• querying (returns a Cursor)

• delete, update, and insert rows

• Content is represented by URI and MIME type

Practical matters

Storage and Persistence

• A couple of different options:

• Preferences

• Flat file

• SQLite

• ContentProvider

Packaging

• Think of .apk files as Android packages

• Everything needed for an application is bundled up therein

• Basically a glorified ZIP file

Resources

• res/layout: declarative layout files

• res/drawable: intended for drawing

• res/anim: bitmaps, animations for transitions

• res/values: externalized values for things likestrings, colors, styles, etc.

• res/xml: general XML files used at runtime

• res/raw: binary files (e.g. sound)

Assets

• Similar to Resources

• Differences:

• Read-only

• InputStream access to assets

• Any kind of file

• Be mindful of file sizes

Application Lifecycle

• Application lifecycle is managed by the system

• Application start/stop is transparent to the user

• End-user only sees that they are moving between

Eclipse Plugin

Debugging