This document provides an overview and agenda for an Android development course. It covers the basics of the Android platform, development tools, building blocks of Android apps like activities and fragments, and other key topics like resources, intents, lifecycles, and handling different device configurations. The document gives developers an introduction to developing apps for the Android ecosystem.

1. Android Development
- the basics
Tomáš Kypta

2. Agenda
• Android platform and ecosystem
• Android SDK and development tools
• Hello World
• building blocks of Android apps & the
manifest file
• activities, widgets, intents

3. Agenda
• dialogs, toasts, notifications
• fragments

4. Android platform
• Linux-based operating system
• open-source (http://source.android.com/)
• originally phone OS
• tablet support (since Honeycomb, Android
3.0)
• Google TV

5. History
• 2003, Android inc.
• 2005, acquired by Google
• Sep 2008, the first Android phone
• T-Mobile G1
• May 2010, Froyo (Android 2.2)
• Feb 2011, Honeycomb (Android 3.0)

6. History
• Oct 2011, Ice Cream Sandwich (Android
4.0)
• July 2012, Jelly Bean (Android 4.1)
• July 2013, Jelly Bean (Android 4.3)
• Oct 2013, KitKat (Android 4.4)

7. Platform Versions

8. Android ecosystem
• thousands of devices
• the most popular mobile platform
• 1.5 million new devices activated every day
• September 3, 2013, 1 billion Android
devices have been activated
• most devices made by Samsung

9. Google Play
• app can be acquired by app stores
• Google Play, http://play.google.com
• other stores
• > 50 billion apps have been installed from
Google Play
• July 2013, 1 million apps

10. Google Play
• purchasing
• selling
• Play Music, Play Books, ...

11. Google Play
• selling apps
• 15 min return period
• ads
• AdMob, ...
• in-app billing

12. Android “problems”
• fragmentation
• manufacturer/carrier enhancements
• updates & support
• openness - low quality apps in Google Play
• malware
• users

13. Android security
• app can be installed directly
• .apk file
• user accepts app permissions when
installing or updating the app

14. Android security
• Verify Apps (Android 2.3+)
• checks every app install
• Google Play can remotely uninstall harmful
app

17. Development
• programming in “Java”
• native apps possible (C++)
• development tools platform friendly
• Windows, Linux, Mac OS X

18. Development
• IDE support
• Android Studio, IntelliJ IDEA, ADT plugin
for Eclispse, Netbeans
• you can freely develop on any device

19. Android SDK
• android - Android SDK and AVD Manager
• adb - Android Debug Bridge
• monitor - (ddms & hierarchyviewer)
• emulator
• lint, Traceview, ProGuard
• docs, samples

20. Libraries
• compatibility libraries
• v4 - backports lots of newer functionality
to Android 1.6+
• Google Play In-app Billing

21. Libraries
• Google Play Services
• Google Maps
• Games
• Google+
• Authorization

22. Libraries
• AdMob
• Google Analytics, Flurry, Crittercism
• Google Cloud Messaging

24. Hello World

25. Build

28. Android building blocks
• Activity
• Service
• Content provider
• Broadcast receiver
• AndroidManifest.xml

29. Activity
• screen with user interface
• the only visual component
• example - an email app
• list of emails
• details of an email
• email composition

30. Service
• has no UI
• long-running tasks
• examples
• music playback service
• download service
• sync service

31. Content Provider
• managers and shares application data
• data storage doesn’t matter (db, web,
filesystem)
• apps can query and modify data through
content provider
• r/w permissions can be defined
• examples - all system dbs (SMS, contacts, ...)

32. Broadcast Receiver
• responds to broadcasts
• broadcasts are system wide
• can be registered statically or dynamically
• system or custom messages
• examples - incoming SMS, incoming call,
screen turned off, low baterry, removed SD
card, BT device available, ...

33. AndroidManifest.xml
• defines what parts the app have
• defines which endpoints are exposed
• minimum/maximum API level
• permissions
• declare hardware and software features
• require configuration

34. Intent
• asynchronous message
• binds components together (all except
Content Provider)
• starting activities
• starting services and binding to services
• sending broadcasts

35. Activity
• a subclass of android.app.Activity
• app usually has many activities
• activities managed in activity stack
• newly started activity is placed on the top
of the stack

36. Activity Lifecycle
• activity can be in different states during its
lifecycle
• foreground, visible, stopped, killed
• when activity state changes a system
callback is called

37. Activity callbacks
• onCreate() - activity created
• onStart() - activity visible for the user
• onResume() - activity gains user focus
• onPause() - system resuming another
activity
• onStop() - activity becoming invisible to
the user

38. Activity callbacks
• onDestroy() - before activity is
destroyed
• onRestart() - called if activity was
previously stopped, called prior to onStart()

41. Configuration changes
• when configuration changes, activities are
destroyed and recreated
• default behaviour, can be changed
• properly handle config changes
•
onSaveInstanceState(Bundle)

42. Intent & Activity
• starting activity explicitly
•
new Intent(context, MyActivity.class)!
•
new Intent(Intent.ACTION_VIEW, Uri.parse(“http://
developer.android.com”))!
• starting activity implicitly
• starting activity for result

43. User Interface
• defined by a hierarchy of views
• layouts = containers
•
LinearLayout, RelativeLayout, FrameLayout, ...

44. User Interface
• widgets
• UI objects
• Button, TextView, EditText,
RadioButton, ...
• WebView

45. User Interface
• list widgets
• subclasses of AdapterView
• display a list of items
• use adapter to bind list do data
•
ListView, GridView, Spinner, ...

46. Resources
• drawables
• bitmaps
• 9-patch png
• state lists
• layer lists
• shape drawables

47. Resources
• layout
• strings
• colors
• menus
• dimensions
• animations

48. Resources
• arrays
• ids
• raw
• xml
• ...

49. Screen sizes and
densities

50. Screen sizes and
densities
• How to handle different screen sizes and
densities?

51. Resources
• resources can be created in several
versions
• the best version is selected according to
current device configuration in runtime
• resource units
• dp - density-independent pixel
• sp - scale-independent pixel (for fonts)

52. Resource qualifiers
• suffixes for resource folders
• drawables, drawable-mdpi, ...
• values, values-cs
• layout, layout-sw640dp
• drawable-hdpi-v11

53. Resource qualifiers
• screen density - ldpi, mdpi, hdpi, xhdpi, ...
• screen size - small, normal, large, xlarge
• screen orientation - port, land
• language - en, cs, sk, ...
• version - v11, v14, ...

54. Resource qualifiers
• since Android 3.2
• w<N>dp - available screen width, w600dp
• h<N>dp - available screen heights, h720dp
• sw<N>dp - smallest width (does not
change with orientation)

55. Resources
• accessed from code via generated R.java file
and resource ids
• view.findViewById(R.id.txt_name)!
• txtName.setText(R.string.txt_name_label)

56. Android version
fragmentation
• How to handle different API levels available
on different devices?

57. Android version
fragmentation
• build target
• API level the app is compiled against
• AndroidManifest.xml
•
<uses-sdk android:minSdkVersion="8"
android:targetSdkVersion="16" />

58. Android version
fragmentation
• handling versions in code
if (Build.VERSION.SDK_INT <
Build.VERSION_CODES.GINGERBREAD) {!
// code for Android < 2.3!
}

59. Android version
fragmentation
private boolean functionalitySupported = false;!
!
static {!
try {!
checkFunctionalitySupported();!
} catch (NoClassDefFoundError e) {!
!
functionalitySupported = false;!
}!
}!
!
private static void checkFunctionalitySupported() throws !
!
!
!
!
!
!
NoClassDefFoundError {!
!
functionalitySupported = android.app.Fragment.class != null;!
}!

60. Fragments
• a piece of application UI
• introduced to support more flexible UI
• phones and tablets together in one app
• fragment != activity
• fragments are used within activities

61. Fragments
• since Android 3.0
• support library v4 backports them to
Android 1.6+

62. Threads
• main thread = UI thread
• do not ever block the UI thread!!!
• use worker threads for time consuming
operations
• UI toolkit not thread safe - never
manipulate UI from a worker thread

63. Menu
• menu resource
• Android < 3.0 the whole menu hidden
under menu button
• ActionBar since Android 3.0
• items can be displayed in the action bar

64. Menu
• behaviour for items that don’t fit in the
action bar
• hidden under menu button (if the device
has one)
• system overflow icon in the action bar

65. Dialogs
• floating window screen

66. Dialogs
• standard dialogs
• custom dialogs
• activity with dialog style
• since fragments used via DialogFragment

67. Dialogs
• might be tedious to create
• difficult to style
• StyledDialogs
•
https://github.com/inmite/android-styled-dialogs
• the library makes styling and using dialogs
a piece of cake

68. Toast
• simple non-modal information
• displayed for a short period of time
• doesn’t have user focus

69. Notifications
• a message that can be displayed to the user
outside your normal UI
• displayed in notification area

70. Notifications
• user can open notification drawer to see
the details
• app can define UI and click action
•
NotificationCompat.Builder

71. Preferences
SharedPreferences prefs = PreferenceManager!
.getDefaultSharedPreferences(context);!
!
SharedPreferences prefs =
!
config.getSharedPreferences(PREFS_FILE_NAME,!
Activity.MODE_PRIVATE);!
!
int storedValue = prefs.getInt(SOME_KEY, defaultValue);!
!
SharedPreferences.Editor editor = prefs.edit();!
editor.putInt(SOME_KEY, storedValue);!
editor.commit();

72. Sources
• developer.android.com
• android-developers.blogspot.com
• source.android.com
• stackoverflow.com
• youtube.com/androiddevelopers
• svetandroida.cz

73. THE END