Android

1
The Android GUI Framework Android experience
dayDecember 2008
Markus Pilz Peter Wlodarczak
2
Agenda
1. Introduction
2. Anatomy
3. A real word example
4. Life cycle
5. Trends
6. Findings
3
Why Android

• Android was designed as a platform for software
  development

• Android is open

• Android is free

• Community support

• Tool support

4
Android Platform
5
Anatomy I

• Android is Linux based

• GUI is fully written in Java

• Java 1.5 support

• Widget toolkit

• XML based GUI

• Single Touch screen

6
Anatomy II

• Activity

• Intent, IntentFilter, IntertReceiver

• View

• Service

• Content provider

7
Anatomy III

• Storage

• AIDL

• Security

• Life cycle management

• Native calls (not officially)?

• NLS support

8
A real word example I

• A translator for Android

• If you are in a country where no one understands
  your language

• You cannot read anything

• You have your mobile phone always with you

• No additional device needed

9
A real word example II

• Uses the Google translator

• Uses XMPP for data transmission

• Can be extended with new languages

• Adaptive GUI

• GUI fully defined in XML

10
A real word example III
Lets see it
11
A real word example IV

• Used Eclipse for development

• ANT script and make for build

• Uses persistence of user data

• Uses touch screen and keyboard input

12
A real word example V
The AndroidManifest.xml
ltmanifest xmlnsandroid"http//schemas.android.c
om/apk/res/android" package"com.greenliff.tra
nslator"gt ltapplication androidicon"_at_drawable
/logo"gt ltactivity androidlabel"_at_string/s
ettings" androidname"Settings"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/app_name"
androidname"Translate"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
ltcategory androidname"android.intent.
category.LAUNCHER" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/ocr"
androidname"OCR"gt ltintent-filtergt
ltaction androidname"android.intent
.action.MAIN" /gt lt/intent-filtergt
lt/activitygt lt/applicationgt lt/manifestgt
13
A real word example V
The AndroidManifest.xml
ltmanifest xmlnsandroid"http//schemas.android.c
om/apk/res/android" package"com.greenliff.tra
nslator"gt ltapplication androidicon"_at_drawable
/logo"gt ltactivity androidlabel"_at_string/s
ettings" androidname"Settings"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/app_name"
androidname"Translate"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
ltcategory androidname"android.intent.
category.LAUNCHER" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/ocr"
androidname"OCR"gt ltintent-filtergt
ltaction androidname"android.intent
.action.MAIN" /gt lt/intent-filtergt
lt/activitygt lt/applicationgt lt/manifestgt
Activity
14
A real word example V
The AndroidManifest.xml
ltmanifest xmlnsandroid"http//schemas.android.c
om/apk/res/android" package"com.greenliff.tra
nslator"gt ltapplication androidicon"_at_drawable
/logo"gt ltactivity androidlabel"_at_string/s
ettings" androidname"Settings"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/app_name"
androidname"Translate"gt
ltintent-filtergt ltaction
androidname"android.intent.action.MAIN" /gt
ltcategory androidname"android.intent.
category.LAUNCHER" /gt
lt/intent-filtergt lt/activitygt
ltactivity androidlabel"_at_string/ocr"
androidname"OCR"gt ltintent-filtergt
ltaction androidname"android.intent
.action.MAIN" /gt lt/intent-filtergt
lt/activitygt lt/applicationgt lt/manifestgt
Activity
Launch
15
A real word example VI
The AndroidManifest.xml

• Used for security

• Define permissions, e. g.
• ltuses-permission androidname"android.permissio
  n.RECEIVE_SMS" /gt

• Give other Activities access

16
A real word example VII
An XML snipped of the main Activity
ltScrollView xmlnsandroid"http//schemas.android.
com/apk/res/android" androidlayout_width"fil
l_parent" androidlayout_height"wrap_content"
androidscrollbars"vertical"gt
ltLinearLayout xmlnsandroid"http//schemas.androi
d.com/apk/res/android" androidid"_at_id/li
nLayout" androidorientation"vertical"
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"gt ltTextView
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"
androidbackground"_at_drawable/blue"
androidtext"_at_string/translate_to_1"/gt ltEditTex
t androidid"_at_id/toTranslate"
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"
androidbackground"_at_androiddrawable/editbox
_background" androidlayout_below"_at_id/l
inLayout androidhint"Type here..." /gt .....
Text reference
17
A real word example VII
An XML snipped of the main Activity
ltScrollView xmlnsandroid"http//schemas.android.
com/apk/res/android" androidlayout_width"fil
l_parent" androidlayout_height"wrap_content"
androidscrollbars"vertical"gt
ltLinearLayout xmlnsandroid"http//schemas.androi
d.com/apk/res/android" androidid"_at_id/li
nLayout" androidorientation"vertical"
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"gt ltTextView
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"
androidbackground"_at_drawable/blue"
androidtext"_at_string/translate_to_1"/gt ltEditTex
t androidid"_at_id/toTranslate"
androidlayout_width"fill_parent"
androidlayout_height"wrap_content"
androidbackground"_at_androiddrawable/editbox
_background" androidlayout_below"_at_id/l
inLayout androidhint"Type here..." /gt .....
Id
Text reference
18
A real word example VIII

• Could also be developed purely in Java

• XML cannot be debugged

• Not all the attributes can be defined in XML

19
A real word example IX
A code snipped of the Translate Activity
_at_Override public void onCreate(Bundle
icicle) super.onCreate(icicle)
Window wp getWindow() mContext
wp.getContext() setTheme(android.R.style.
Theme_Light) setContentView(R.layout.main
) mLayout (LinearLayout)
this.findViewById(R.id.linLayout)
mToTranslate (EditText) this.findViewById(R.id.t
oTranslate) setShowLanguages()
mEnge (LinearLayout) this.findViewById(R.id
.enge) LANGUAGE_LAYOUT0 mEnge
de2en (Button) this.findViewById(R.id.de2en)
de2en.setOnClickListener(new
View.OnClickListener() public void
onClick(View view)
if(!connect())
notLoggedInAlert() else
doConnect("de2en_at_bot.talk.google.com"
) rearrange(mEnge)
) ....
20
A real word example IX
A code snipped of the Translate Activity
_at_Override public void onCreate(Bundle
icicle) super.onCreate(icicle)
Window wp getWindow() mContext
wp.getContext() setTheme(android.R.style.
Theme_Light) setContentView(R.layout.main
) mLayout (LinearLayout)
this.findViewById(R.id.linLayout)
mToTranslate (EditText) this.findViewById(R.id.t
oTranslate) setShowLanguages()
mEnge (LinearLayout) this.findViewById(R.id
.enge) LANGUAGE_LAYOUT0 mEnge
de2en (Button) this.findViewById(R.id.de2en)
de2en.setOnClickListener(new
View.OnClickListener() public void
onClick(View view)
if(!connect())
notLoggedInAlert() else
doConnect("de2en_at_bot.talk.google.com"
) rearrange(mEnge)
) ....
Set layout
21
A real word example IX
A code snipped of the Translate Activity
_at_Override public void onCreate(Bundle
icicle) super.onCreate(icicle)
Window wp getWindow() mContext
wp.getContext() setTheme(android.R.style.
Theme_Light) setContentView(R.layout.main
) mLayout (LinearLayout)
this.findViewById(R.id.linLayout)
mToTranslate (EditText) this.findViewById(R.id.t
oTranslate) setShowLanguages()
mEnge (LinearLayout) this.findViewById(R.id
.enge) LANGUAGE_LAYOUT0 mEnge
de2en (Button) this.findViewById(R.id.de2en)
de2en.setOnClickListener(new
View.OnClickListener() public void
onClick(View view)
if(!connect())
notLoggedInAlert() else
doConnect("de2en_at_bot.talk.google.com"
) rearrange(mEnge)
) ....
Find elements
Set layout
22
A real word example IX
A code snipped of the Translate Activity
_at_Override public void onCreate(Bundle
icicle) super.onCreate(icicle)
Window wp getWindow() mContext
wp.getContext() setTheme(android.R.style.
Theme_Light) setContentView(R.layout.main
) mLayout (LinearLayout)
this.findViewById(R.id.linLayout)
mToTranslate (EditText) this.findViewById(R.id.t
oTranslate) setShowLanguages()
mEnge (LinearLayout) this.findViewById(R.id
.enge) LANGUAGE_LAYOUT0 mEnge
de2en (Button) this.findViewById(R.id.de2en)
de2en.setOnClickListener(new
View.OnClickListener() public void
onClick(View view)
if(!connect())
notLoggedInAlert() else
doConnect("de2en_at_bot.talk.google.com"
) rearrange(mEnge)
) ....
Find elements
Set layout
Add behavior
23
A real word example X
Call an other Activity
_at_Override public boolean
onOptionsItemSelected(Menu.Item item)
switch (item.getId()) case 0
showLogin() break
case 1 Intent intent new
Intent(Translate.this, Settings.class)
intent.putExtras(mShownLanguages)
startSubActivity(intent, SETTINGS)
break // switch return
true
24
A real word example X
Call an other Activity
_at_Override public boolean
onOptionsItemSelected(Menu.Item item)
switch (item.getId()) case 0
showLogin() break
case 1 Intent intent new
Intent(Translate.this, Settings.class)
intent.putExtras(mShownLanguages)
startSubActivity(intent, SETTINGS)
break // switch return
true
Start an Activity
25
A real word example X
Call an other Activity
_at_Override public boolean
onOptionsItemSelected(Menu.Item item)
switch (item.getId()) case 0
showLogin() break
case 1 Intent intent new
Intent(Translate.this, Settings.class)
intent.putExtras(mShownLanguages)
startSubActivity(intent, SETTINGS)
break // switch return
true
Start an Activity
Pass data to new Activity
26
A real word example XI
Store user data
_at_Override protected void onPause()
super.onPause() SharedPreferences.Editor
ed mPrefs.edit() for(int i 0 i lt
SUPPORTED_LANGUAGES.length i)
ed.putBoolean(SUPPORTED_LANGUAGESi,
mShownLanguages.getBoolean(SUPPORTED_LANGUAGESi
)) ed.commit()
Persistent store
27
A real word example XII
Store user data

• Preferences

• Database

• Files

• Content provider

• Network

28
Life cycle

• Life cycle not directly controlled by application

• System can kill an application to free up memory

• Controll through onCreate(), onPause(), onStop()
  ... methods

• Android has different types of processes,
  visible processes, service processes, background
  processes ...

• Services can be used for long-lived background
  processes

29
Trends I

• Eyes-free user interfaces

• Other user interfaces like tones, vibrant alarm,
  sensors, actuators

• Leverage hearing and touch

• Camera input

• Ubiquitous computing technologies

30
Trends II

• Speech recognition

• Accelerometer

• Magnetic compass

• Location self-awareness

• Locating others

• Sensing the environment

31
Findings

• Android uses proven technology like Java, XML
  and Linux

• It offers a rich API for application development

• There is an initial learning effort

• Android doesnt have many of the limitations
  other mobile platforms have

• Trend towards eyes-free user interfaces

32
Some figures

• Q4 2007 more than 3 billion mobile subscribers
  (world population 6.7 billion)?

• 1.14 billion handsets delivered in 2007
  (computers 271.2 million)?

• 118 million where smart phones

• Currently more than 30 mobile platforms

• Symbian leads with 65 share, ahead of Microsoft
  on 12, RIM on 11, Apple on 7, and Linux at 5

33
Thank you for the attention
Questions?
Find out more at http//code.google.com/android