Android tutorial

Android Tutorial
Larry Walters
OOSE Fall 2011

References
 This tutorial is a brief overview of some major
concepts…Android is much richer and more
complex
 Developer’s Guide
 http://developer.android.com/guide/index.html
 API Reference
 http://developer.android.com/reference/packages.html

Tools
 Phone
 Eclipse ( http://www.eclipse.org/downloads/ )
 Android Plugin (ADT)
 Android SDK ( http://developer.android.com/sdk/index.html )
 Install everything except Additional SDK
Platforms, unless you want to
 Windows Users: may need to install Motorola
Driver directly (
http://www.motorola.com/Support/US-EN/Support-Homepage/Software_an
)

Android SDK
 Once installed open the SDK Manager
 Install the desired packages
 Create an Android Virtual Device (AVD)

ADT Plugin (1)
 In Eclipse, go to Help -> Install New Software
 Click ‘Add’ in top right
 Enter:
 Name: ADT Plugin
 Location: https://dl-ssl.google.com/android/eclipse/
 Click OK, then select ‘Developer Tools’, click Next
 Click Next and then Finish
 Afterwards, restart Eclipse
 Specify SDK location (next 3 slides)
 Must do this every time start a new project in a new
location (at least in Windows)

Creating a Project (2)
Need
the
items
circled
Then
click
Finish

Project Components
 src – your source code
 gen – auto-generated code (usually just R.java)
 Included libraries
 Resources
 Drawables (like .png images)
 Layouts
 Values (like strings)
 Manifest file

XML
 Used to define some of the resources
 Layouts (UI)
 Strings
 Manifest file
 Shouldn’t usually have to edit it directly,
Eclipse can do that for you
 Preferred way of creating UIs
 Separates the description of the layout from any
actual code that controls it
 Can easily take a UI from one platform to another

R Class
 Auto-generated: you shouldn’t edit it
 Contains IDs of the project resources
 Enforces good software engineering
 Use findViewById and Resources object to
get access to the resources
 Ex. Button b = (Button)findViewById(R.id.button1)
 Ex. getResources().getString(R.string.hello));

Layouts (1)
 Eclipse has a great UI creator
 Generates the XML for you
 Composed of View objects
 Can be specified for portrait and landscape
mode
 Use same file name, so can make completely
different UIs for the orientations without modifying
any code

Layouts (3)
 Click ‘Create’ to make layout modifications
 When in portrait mode can select ‘Portrait’ to make a
res sub folder for portrait layouts
 Likewise for Landscape layouts while in landscape mode
 Will create folders titled ‘layout-port’ and ‘layout-land’
 Note: these ‘port’ and ‘land’ folders are examples of
‘alternate layouts’, see here for more info
 http://developer.android.com/guide/topics/resources/providing-resources.html
 Avoid errors by making sure components have the
same id in both orientations, and that you’ve tested
each orientation thoroughly

Strings
 In res/values
 strings.xml
 Application wide available strings
 Promotes good software engineering
 UI components made in the UI editor should
have text defined in strings.xml
 Strings are just one kind of ‘Value’ there are
many others

Manifest File (1)
 Contains characteristics about your application
 When have more than one Activity in app, NEED to
specify it in manifest file
 Go to graphical view of the manifest file
 Add an Activity in the bottom right
 Browse for the name of the activity
 Need to specify Services and other components too
 Also important to define permissions and external
libraries, like Google Maps API

Manifest File (2) – Adding an Activity

Android Programming Components
 Activity
 http://developer.android.com/guide/topics/fundamentals/activities.html
 Service
 http://developer.android.com/guide/topics/fundamentals/services.html
 Content Providers
 Broadcast Receivers
 Android in a nutshell:
 http://developer.android.com/guide/topics/fundamentals.html

Activities (1)
 The basis of android applications
 A single Activity defines a single viewable
screen
 the actions, not the layout
 Can have multiple per application
 Each is a separate entity
 They have a structured life cycle
 Different events in their life happen either via the
user touching buttons or programmatically

Services (1)
 Run in the background
 Can continue even if Activity that started it dies
 Should be used if something needs to be done while the user is not
interacting with application
 Otherwise, a thread is probably more applicable
 Should create a new thread in the service to do work in, since the
service runs in the main thread
 Can be bound to an application
 In which case will terminate when all applications bound to it unbind
 Allows multiple applications to communicate with it via a common
interface
 Needs to be declared in manifest file
 Like Activities, has a structured life cycle

Running in Eclipse (1)
 Similar to launching a regular Java app, use
the launch configurations
 Specify an Android Application and create a
new one
 Specify activity to be run
 Can select a manual option, so each time
program is run, you are asked whether you
want to use the actual phone or the emulator
 Otherwise, it should be smart and use whichever
one is available

USB Debugging
 Should be enabled on phone to use
developer features
 In the main apps screen select Settings ->
Applications -> Development -> USB
debugging (it needs to be checked)

Android Debug Bridge
 Used for a wide variety of developer tasks
 Read from the log file
 Show what android devices are available
 Install android applications (.apk files)
 In the ‘platform-tools’ directory of the main
android sdk directory
 Recommend putting this directory and the ‘tools’
directory on the system path
 adb.exe

Debugging
 Instead of using traditional System.out.println, use the Log class
 Imported with android.util.Log
 Multiple types of output (debug, warning, error, …)
 Log.d(<tag>,<string>)
 Can be read using logcat.
 Print out the whole log, which auto-updates
 adb logcat
 Erase log
 adb logcat –c
 Filter output via tags
 adb logcat <tag>:<msg type> *:S
 can have multiple <tag>:<msg type> filters
 <msg type> corresponds to debug, warning, error, etc.
 If use Log.d(), then <msg type> = D
 Reference
 http://developer.android.com/guide/developing/debugging/debugging-log.html

Screen Shots
 Some say you need to root the phone – that
is not true
 One option: Android Screen Capture
 http://www.mightypocket.com/2010/08/android-screens
 It’s slow, but fine for screenshots of applications
whose screens aren’t changing fast
 Read their installation help, following the extra
steps if need be (I had to copy adb.exe and some
dll files, as they explain)

Maps Example (1)
 Using Google Maps in your app
 Setup project to use ‘Google API’ version
 Edit Manifest file
 To indicate the app will use maps and the internet
 Get a maps API key
 Note: Google Maps API can display a map and draw overlays,
but is not the full Google Maps experience you enjoy on the web
 For example, there does not seem to be inherent support for
drawing routes between points (if you find it let me know)…
however, you can draw lines between points and almost any type
of overlay, but that’s different than street routes
 The directions API is a web service, which is different, among
several other Google web services
 Read the Google API terms of use

Maps Example (3) – Manifest (1)
 Open Manifest file
 Add map library tag
 Add the ‘Uses Library’ com.google.android.maps
 Indicate the app will access the internet
 Add the ‘Permission’ android.permission.lNTERNET
 End goal is to add the following two lines to XML file,
under the <manifest> and <application tags>,
respectively
 Under the <manifest> tag
 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
 Under the <application> tag
 <uses-library android:name="com.google.android.maps"></uses-library>
 Following is GUI way to add them

1
2

 Select ‘Add’ under ‘Uses Library’ (last slide)
 Then select ‘Uses Library at this prompt
 Set name as: com.google.android.maps (next
slide) and save

2
1

 Select ‘Permissions’ and then ‘Add’ (last slide)
 Select ‘Uses Permissions’ at this prompt
 Set name to: android.permission.INTERNET
and save (next slide)

Maps Example (10) – Maps API Key (1)
 All Android applications need to be signed
 The debug mode signs for you with special debug
certificate
 All MapView elements in map applications
need to have an API key associated with
them
 That key must be registered with the certificate
used to sign the app
 When releasing app, need to sign with a
release certificate and get a new API Key

Maps Example (11) – Maps API Key (2)
 For debug mode, get the MD5 fingerprint of the debug certificate
 Locate the ‘keystore’
 Windows Vista: C:Users<user>.androiddebug.keystore
 Windows XP: C:Documents and Settings<user>.androiddebug.keystore
 OS X and Linux: ~/.android/debug.keystore
 Use Keytool (comes with Java, in the bin directory with the other
Java tools, should put that dir on system PATH) to get fingerprint
 keytool -list –v -alias androiddebugkey -keystore
“<path_to_debug_keystore>” -storepass android -keypass android
 If don’t include –v option, then will probably get only 1 fingerprint, and if it’s
not MD5, then need –v (Java 7 needs –v)
 Extract the MD5 fingerprint, SHA will not work unfortunately
 Go to https://code.google. com/android/maps-api-signup.html ,
agree to terms and paste MD5 fingerprint, you will then be given
an API Key

Maps Example (12)
 Need to put MapView tag in XML
 com.google.android.maps.MapView
 MapView is the basic view that represents a Google Map
display
 Must include API Key in XML, inside a layout
 <com.google.android.maps.MapView
android:id="@+id/mapview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:clickable="true"
android:apiKey=“<api key>”/>
 Maps API Reference
 http://code.google.com/android/add-ons/google-apis/reference/index.html

Acknowledgements
 Android Developer’s Website
 Activity and Service life-cycle flow charts
 Tons of other Android info
 Google Maps API external library
 http://code.google.com/android/add-ons/google-apis/maps-overview.html
 MightyPocket
 http://www.mightypocket.com/2010/08/android-screenshots-screen-capture-screen-cast/
 Numerous Forums & other developer sites, including:
 http://www.javacodegeeks.com/2011/02/android-google-maps-tutorial.html
 http://efreedom.com/Question/1-6070968/Google-Maps-Api-Directions
 http://www.mail-archive.com/android-developers@googlegroups.com/msg28487.html
 http://android.bigresource.com/ threads
 http://groups.google.com/group/android-developers threads
 Many http://stackoverflow.com threads
 http://www.anddev.org/google_driving_directions_-_mapview_overlayed-t826.html
 Zainan Victor Zhou – for advice and his own tutorial

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