Delivered in Kaunas Technical University as part of NFQ academy (http://www.nfq.lt/atviros-paskaitos/)

1. Intro to programming
with Androids
@MaksimGolivkin
Android dev @Uber

2. Plan
• Brave mobile world
• Daily life-cycle
• Different screens
• Hybrid applications

3. Why “mobile” development?

6. In developing world

7. And in the most posh economies.

8. Smartphones, tablets and more

9. Only an Internet device?

10. What smart devices are made of?

11. Memory Ports Positioning Radios Sensors
Build-­‐in
Audio
Cellular
Mobile
Audio
SD
card
USB
GPS
Wi-­‐Fi
Photo/video
HDMI
Wi-­‐Fi
Bluetooth
Light
A-­‐GPS
NFC
AcceleraBon
MagneBc
Gyroscope
Proximity
… Flash, Stylo, Second Screen

12. Dongle empowering 3 billion $ business

13. Why Android?

14. Android creates
a sweet choice.

15. Open mobile computing platform

16. Android accounts for
64% in smartphones
40% in tablets
of device sales in 2012 Q3

17. GooGPS show-case

18. Two big butts
• App profitability 1/6 of iOS
• Fragmentation

19. Summary
• Dawn of connected devices era.
• HW knowledge creates opportunities.
• Android is leading it.

20. Android OS

21. Designed for fast switching between apps

22. Applications “talk” between each other

23. There is always a Back button

24. Programming Android

25. APIs
• SDK – Java applications
• NDK – mostly games
• Hybrid – everybody should

26. Tools
• Eclipse
• Eclipse ADT plugin
• Android SDK
• USB drivers

27. Learn Android
• d.android.com
• stackoverflow.com
• AppDemo sample application
• youtube for Google I/O
• Android OS source code
• grepcode.com
Books!

28. Script vs. Application

29. uber.com Init
Process
Display Output
Die
PHP script life-cycle

30. Init
Interact
State Process
Display
Die
Application life-cycle

31. Screen
~= Activity

32. In Memory Foreground
Launch Created
Resumed
Interact
Press
Stopped
Home

33. In Memory Visible Foreground
Launch Created
Started
Resumed
Interact
Open
other
Activity Paused
Stopped

34. In Memory Visible Foreground
Re-Launch Started
Resumed
Interact
Press
Home
Paused
Stopped

35. Activities Stack (briefly)

36. 1 st
Screen
1. Resumed

37. 2 nd
Screen
2. Resumed
1. Stopped

38. 3 rd
Screen
3. Resumed
2. Stopped
1. Stopped

39. Closes an application
Delegates responsibility

40. Pressing
Back
3. Resumed
2. Stopped
1. Stopped

41. Destroying
last
activity
2. Resumed
1. Stopped

42. Pressing
Home
3. Resumed
2. Stopped
1. Stopped

43. Stops
everything
3. Stopped
2. Stopped
1. Stopped

44. Returned
to the
app
3. Resumed
2. Stopped
1. Stopped

45. Running
In The
Background?
… not all of them

46. Maintaining state

47. Activity/app life-time
• Parameters
+ Saved Instance State
• Singleton
Singleton is king. Mind the GC!

48. Persistence
• Shared Preferences
• Files
• Server
• SQLite
Do you really need it?

49. Service

50. Use cases
• Long actions in between activities
• Notifications, when app is dead
• Intensive calculations
Consider simply using Threads. Twice!

51. Fragments

53. Fragments enable multi-pane layouts

54. Resources

55. Life
of an image

57. Using resources
Resources r = getResources();
Drawable d =
r.getDrawable(R.drawable.ic_american_express);
ImageView icon =
(ImageView) findViewById(R.layout.card_logo);
icon.setDrawable(d);

58. Drawable vs. View

59. Screen
~= Activity
Everything
else
~= Views

60. Summary (Android OS)
• Android is popular but poor, yet
• Learn life-cycle by heart
• Assess feasibility of Persistence and
Services. Twice.

61. Many screens

63. Different
resolutions
320x480 px 1280x720 px

64. Same
physical size
42 dp

65. Screen density
pixel _ width 2 + pixel _ height 2
screen _ density =
diagonal _ in _ inches

66. Many resolutions
320x426 legacy phones
240x320 legacy phones
320x533 legacy phones
320x576
320x480 phones
320x533 phones
320x568
320x480 new phones
360x640
400x640
640x1067 tweener tablets
640x1138
480x800 tweener tablets
480x854
600x1024
1024x768 tablets
1280x768
1280x800
...

67. Landscape
is yet another
resolution

68. Patterns

69. Stretching

70. Adding margins

71. Multi-pane

72. Switch points

73. Switch points
Home base
240dp 320dp 360dp 400dp 426dp 480dp 533dp 568dp 578dp 640dp
small size portrait small size landscape normal size landscape
normal size portrait large size portrait
resized elements
margins added
switch point (another layout)

74. Expensive way
Boom!
Home base
240dp 320dp 360dp 400dp 426dp 480dp 533dp 568dp 578dp 640dp
small size portrait small size landscape normal size landscape
normal size portrait large size portrait
resized elements
margins added
switch point (another layout)

75. Prepairing graphics

76. Density buckets
ldpi (low) 100 ~ 140 dp
mdpi (medium) 140 ~ 200 dp
hdpi (high) 200 ~ 280 dp
xhdpi (extra high) 280 ~ 340 dp

77. 1 dp = ? px
ldpi 0.75
mdpi 1
hdpi 1.5
xhdpi 2

78. Nine-patch
Resizable area
Content area

79. Nine patch
• Buttons
• Backgrounds

80. Summary (Many screens)
• Needs investment, but little surprise.
• One layout for a start.
• Resolution ignorance is ugly,
but not ineffective.

81. Hybrid apps

82. “Our biggest mistake was betting
too much on HTML5”, - Mark Zuckerberg

83. HTML5 reality in 2012

84. Hybrid champion:
LinkedIn
Native
HTML/CSS
Native

85. Hybrid architecture
Native
JavaScript API
HTML/CSS/
JavaScript

86. Native side
WebView webView = (WebView)
findViewByid(R.id.webview);
webView.addJavascriptInterface(obj, "Android");
final String html = AssetUtil.readAssetsFile(
context, filename);
webView.loadDataWithBaseURL(
"file://", html, "text/html","utf-8", null);

87. JavaScript side
function onClick() {
Android. jsOnNextArticle(this.id);
}

88. “API” glue
public void showArticle(long id, String content) {
webView.loadUrl("javascript: jsShowArticle(" + id
+ ", " + Uri.encode(content) + "");")
}
..
public void jsOnNextArticle(long articleId) {
…
}

89. “API” glue
public void showArticle(long id, String content) {
webView.loadUrl("javascript: jsShowArticle(" + id
+ ", " + Uri.encode(content) + "");")
}
..
public void jsOnNextArticle(long articleId) {
…
}

90. Summary (Hybrid apps)
• Content centered apps
• FAQ, User License, …
• 1-1.5x more effort than native
• Pays of when targeting >= 3 platforms

91. Read ON
- The real problem with Android fragmentation
- Where does Android fragmentation hide?
- The technical adventure building a hybrid app.
- Fast track to Android design.
Interested in Android? @MaksimGolivkin
Care to give feedback? maksim@golivkin.eu