android development, an introduction to development

8/6/2019 Android Development, an introduction to development

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Welcome... to Google IO 11; ooops...sorry,

GTUG welcomes you to the Android launch

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Location: San Francisco, California

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nah!! just Kidding...

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Google Uganda - Android Developer LaunchKampala, Uganda

May, 2011

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Victor Miclovich, Android developer + enthusiasttwitter:@vicmiclovich

An droid A

w

eso meness

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http://cwezi.com/http://storyspaces.org/http://storyspaces.org/http://storyspaces.org/http://storyspaces.org/http://mspoti.com/http://mspoti.com/http://cwezi.com/http://cwezi.com/


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Introducing Android Devices

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Fun and Easy to useCool graphics

lots of power under the hood for

gaming

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Key-lessnesslose the key pad... new devices designed to be touch-

screen compatible; Android takes it a notch higher:

multitouch

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CommunicationGmail

And obviously:Web browser,

Basic BT,etc.

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Online connectivity...

Android OS is designed to enable device

connectivity to the networked world

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A-O-B

Lots of power under the hood >>> in comes Appdevelopment

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Application Development$> Assumptions

$> Framework $> Piecing the UI together$> Basic networking

$> Services (RESTful web service intro)

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Assumptions

Youve read thehandout or have itclose by to guide you...

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About Android }-*->F-work

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What is a mobile app?

a set of user interfaces arranged to form a pattern

these patterns tend to accomplish tasks!!!

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How to design an app?

Start with an idea

Research the idea (ask around: UCD )

Concept it (use storyboards, write! write!)

Prototype it

Start codingIterate (repeat step 1 or 2)

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Isnt that easy?

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How?????

?how?

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Android UIs

2 ways of working magic with apps-->>

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One way is...

through a declarative approach...

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Declarative user interface

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http://schemas.android.com/apk/res/androidhttp://schemas.android.com/apk/res/androidhttp://schemas.android.com/apk/res/androidhttp://schemas.android.com/apk/res/android


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another way is to...

use a programmatic approach...

Google advises programmers to choose option 1)why?

->It is cleaner + keeps your code easy to maintain->In case you make app changes, it is easy to do

examples:*swing*gwt

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what to do?

Youll use both approaches

Declarative approach to describe how somethinglooks or appears such what a button should look like

Programmatic approach to give life to the UI

component such as a button

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user interface design...

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Android UID

Views

Layouts

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Views

Everything you see through your screen is a view

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Examples of Views

TextView (text)

ButtonView (buttons)

ListView (lists)

EditView (text boxes)

ImageView (image)

MapView (to viewmaps)

WebView (embeddedweb + webkitrendering)

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Layouts

Organize views

group view components together

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Examples Layouts

LinearLayouts

TableLayouts

FrameLayout

RelativeLayout

AbsoluteLayout (using (x,y) coord. system)

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Notes

Layouts are resizable (expand with content)expand with the different device sizes (bettergraphics rendering that supports)

Layouts are customizable

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What else in Android?

Services that will run in the background

Intents and broadcasting (that support in-appnotication and instructions)

lots of crazy cool stuff... just need to dig deeper than45 minutes! lol!

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Prerequisites

Java programming

Read the handout

watch out for things like the application life cycle, etc.

Ask questions at the end

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Code

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Layout parameters

Specify the way layouts appear

Basically in your xml les:

android:layout_height =

android:layout_width =

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analogous to a screen

respond to broadcast intents/ msgs

tasks that run in the backgroundapps can share data

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Activities

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Intents

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Intents

Intents help describe what you want done (verb words+ objects)

Pick photo from album

Delete music

Make a call

Android matches Intent with Activity (object) that canbest provide a service

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NoteActivities and BroadcastReceivers describe what intents

they can service in their IntentFilters through theAndroidManifest.xml le

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BroadcastReceivers

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BroadcastReceivers

components designed to respond to Broadcast Intents

also, apps can create and broadcast their own Intents

as well.

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Servers

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Services

These are components that run in the background...

A music player keeps running even when you chooseto start looking through your gallery

You can type a message while listening to music

Download a pdf while browsing Youtubeetc.

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ContentProviders

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ContentProviders

A ContentProvider enables sharing of data acrossdifferent apps

some apps can poll the address book an app could use your gallery photos, etc.

Provides a single unied API for

CRUD operations

Content is represented by a URI and MIME type

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Other issues of great importance...

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Persisting data

Some apps need to cache or store data inside of thephone (email, messages, attachments via bluetooth,etc.)

Android provides a couple of ways to store your data

as a at le

in a database (SQLite)

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Note

There are lots of useful APIs to interact with thedatabase, le system, etc.

Android is powerful and quite large

Look around to see what you can do with it...

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Going forward...

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Packaging

Android apps are packaged in .apk les

Everything needed to run your app is found in the apk

It also includes your application manifest le (wherepermissions for activities and other predened settingsare saved up) {look at handout for more info in app}

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Android denes resources an app uses in the res/ folderres/layout (contains layout rules)

res/drawable (for drawing)

res/anim (for animations your app might need)

res/values (externalized values for strings, colors, styles and lots more)

res/xml (general xml les that are needed at run time such as a settings.xml le, etc.)

res/raw (binary les like sound are dened in there)

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Assets

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Assets

A lot similar to resources (from slides before)

Any kind of le can be stored (make sure it doesntcomplete the SD card memory or other)

Differences are:

assets are read onlyInputStream class (methods) access assets

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The Networked world...

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so much to say...

Trending way of development

use an API to expose a service your mobile app canuse

Your app can persist data in a database if network isunavailable

Apps are so much fun when connected to theInternet

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The End...More might come in the future,

(coming soon)

vicmiclovich{at}gmail.com
http://cwezi.com/trainingshttp://cwezi.com/trainings

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