Great Android apps only include what's needed to achieve the goals of the product, not enhance the resume of the developer. What’s more, the more maintainable an application is, the more likely it will have increased user satisfaction and decreased time to market.

1. Develop
Maintainable Apps
@brwngrldev

2. What’s our job?
A. Make apps
B. Make apps that work
C. Make great apps!
@brwngrldev

3. What’s our job?
Make great apps!
@brwngrldev

4. The tools…
Libraries
1
Domain
Design
2
Code
Quality
3
Testing
4
@brwngrldev

5. Choosing the Right
Library

6. So many options

7. What to consider
Amazing App
!
Documentation
Project Stability
Fulfills a Need
@brwngrldev

8. Example

9. So you need images…
Volley
!
Fresco
!
Glide
!
Picasso
!

10. Documentations
Volley
!

13. Documentations
W Project Stability
Volley
!

15. Documentations
W Project Stability
p Fulfills a need
Volley
!

16. @brwngrldev

17. Rinse & Repeat
Volley
!
Fresco
!
Glide
!
Picasso
!

18. Review…
• Documentation
• Repository Check-ins
• Fulfills a Need
Libraries
1
@brwngrldev

19. Domain Design

20. Doing too much

21. Seen this?

22. Clean
It Up!
How to fix this
MVP
MVVM
OO

23. Foo
What’s involved…
Foo Bar
Baz L
Om

24. Example

25. Remember this?

26. We need tests

28. Extract a Presenter

29. Create an Interface

30. Reference the Interface
public void onEvent (ErrorEvent event)
{
mainView.showVideoUnavailableMessage();
}

31. Implement the Interface
@Override
public void showVideoUnavailableMessage ()
{
Toast.makeText( this,
getString(R.string.video_unavailable),
Toast.LENGTH_LONG )
.show();
}

32. Foo Bar
Baz Lol
Omg
@brwngrldev

33. Review…
• Keep Code Simple
• Use MV* Pattern
• Functional Tests
• Use the Tools
@brwngrldev
Domain
Design
2

34. Code Quality

35. Poor Readability

36. Increase Readability?
“Checkstyle is a development tool to
help programmers write Java code
that adheres to a coding standard.”

37. Source
Files
config.xml
Checkstyle Tool
Modules
Design
Formatting
Code Complexity

38. apply plugin: ‘checkstyle’
task checkstyle(type: Checkstyle) {
description 'Checks if the code passes quality standards'
group 'verification'
configFile file(‘checkstyle.xml')
…
}

39. <module name=“MethodLength">
<property name="max" value=“60"/>
</module>
<module name=“LineLength">
<property name="max" value=“120"/>
</module>
<module name=“CyclomaticComplexity">
<property name="max" value=“8"/>
</module>
…
playerControlConfig.setShowClosedCaptionsButton(a.getBo

40.
<module name=“CyclomaticComplexity">
<property name="max" value=“8"/>
</module>

41. Example

42. public void overlyComplexMethod(Video video) {
if (video != null && video.getStreamUrl() != null) {
switch (video.getCategory()) {
case "CAT1" :
playVideo(video);
if (video.getLargeImageUrl() == null) {
video.setLargeImageUrl("http://www.largeImage.png");
}
updateMetadata(video);
break;
case "CAT2" :
if (video.getLargeImageUrl() == null) {
video.setLargeImageUrl("http://www.smallImage.png");

43. … warning: Cyclomatic Complexity is 9

44. public void overlyComplexMethod(Video video) {
if (video != null && video.getStreamUrl() != null) {
updateVideoBasedOnCategory(video);
}
}
private void updateVideoBasedOnCategory(Video video) {
switch (video.getCategory()) {
case "CAT1" :
playVideo(video);
if (video.getLargeImageUrl() == null) {
video.setLargeImageUrl("http://www.largeImage.png");
}
updateMetadata(video);
break;
7

45. switch (video.getCategory()) {
case "CAT1" :
playVideo(video);
updateMetaDataAndUrl(video, "http://www.largeImage.png");
break;
…
4
@brwngrldev

46. Review…
• Readability Matters
• Use Checkstyle
• Refactor Gradually
@brwngrldev
Code
Quality
3

47. Unit Testing

48. Untested Code

49. “Every single line of code that you
write should be tested. Period.”
— Robert Martin

51. 0
9,000
18,000
27,000
36,000
Lines of Code
Production Tests 90%
2,200
90s
FitNesse

53. JUnit
• Framework for writing repeatable tests
• Assertions for testing expected results
• Features for sharing common test data
• Test suites for organizing tests

54. Mockito
• Enables mock creation and verification
• Mock concrete classes and interfaces
• Simple annotation support

55. Example

56. Test Setup
@Mock
MainView mainView;
@brwngrldev

57. Test Setup
@Mock
MainView mainView;
@Before
public void setUp ()
{
}
@brwngrldev

58. Test Setup
@Mock
MainView mainView;
@Before
public void setUp ()
{
initMocks( this );
mainPresenter = new MainPresenter();
mainPresenter.setMainView( mainView );
}
@brwngrldev

59. Sample Test
@brwngrldev
@Test
public void configurationLoaded_shouldHideSplashScreen ()
{
ConfigurationLoadedEvent event = new ConfigurationLoadedEvent();
mainPresenter.onEvent( event );
}

60. Sample Test
@brwngrldev
@Test
public void configurationLoaded_shouldHideSplashScreen ()
{
ConfigurationLoadedEvent event = new ConfigurationLoadedEvent();
mainPresenter.onEvent( event );
verify( mainView ).hideSplashScreen();
}

61. Test Report
@brwngrldev

62. Continuous Integration
@brwngrldev

63. Code Coverage
@brwngrldev

64. Makes You Powerful

65. Review
• Listen to Robert Martin!
• JUnit + Mockito
• Continuous Integration
• Code Coverage
Testing
4
@brwngrldev

66. Summary
Ensure code quality
Choose the right library
Don’t do too much
Write unit tests
@brwngrldev

67. Thanks!
@brwngrldev
+AnnyceDavis
www.adavis.info

68. Resources
• Clean Code - http://amzn.to/1DJybxH
• Effective Java - http://amzn.to/1Ku8Xel
• Working Effectively with Legacy Code - http://amzn.to/1Jqe1PA
• Unit Testing Idioms - http://goo.gl/Bx1WbL
• Google Code Style - http://goo.gl/8Pf6J3
• Architecting Android - http://goo.gl/UKvmbq
• Conquering Cyclomatic Complexity - http://goo.gl/lRoPXN
@brwngrldev

69. Photo Credits
• Slide 5 - https://www.flickr.com/photos/tshirbert/118250140
• Slide 19 - http://uncompromisedmen.com/2015/02/17/top-10-crazy-beards-
wish-youd-seen-person/
• Slide 34 - https://www.flickr.com/photos/cast_fish/2888442781
• Slide 48 - https://www.flickr.com/photos/desertbusforhope/8207412726/
• Slide 50 - https://www.flickr.com/photos/sokabs/2668975758
• Slide 64 - https://www.flickr.com/photos/pasukaru76/5268559005
@brwngrldev