Studies show that for every 7 to 10 lines of code we write, we introduce one defect. Now often times we can spot these errors before they ever see the light of day, however that is not true in all cases. So what can we use to assist us in leveling the playing field? Well, we can take advantage of Static Code Analysis tools! In this talk, learn how you can incorporate the following tools into your development process: Checkstyle, PMD, FindBugs, and Lint.

1. Static Code Analysis

3. @brwngrldev
+AnnyceDavis
“I’ll be learning
something new
on my deathbed.”

4. Checking your program for errors
without executing it
What is it?
@brwngrldev

5. Testing
What it’s not
@brwngrldev

6. 1 / 7 - 10
@brwngrldev

8. 1 / 10
@brwngrldev
1000

9. The tools…
Checkstyle
1
FindBugs
2
PMD
3
Lint
4
@brwngrldev

10. @brwngrldev
Lint
Checkstyle
FindBugs
PMD

11. Checkstyle
“… a development tool to help
programmers write Java code that
adheres to a coding standard.”

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

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

14. <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

15.
<module name=“CyclomaticComplexity">
<property name="max" value=“8"/>
</module>

16. Example

17. 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");

18. … warning: Cyclomatic Complexity is 9

19. 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

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

21. Review…
• Formatting
• Code Complexity
• Refactor Gradually
@brwngrldev
Checkstyle
1

22. FindBugs

23. But this…
“…inspect Java bytecode
for occurrences of bug
patterns”

24. apply plugin: ‘findbugs’
task findbugs(type: FindBugs) {
description 'Run findbugs'
group 'verification'
effort 'max'
excludeFilter file('findbugs-exclude.xml')
…
}

25. <FindBugsFilter>
<Match>
<Class name="~.*R$.*"/>
</Match>
<Match>
<Bug pattern="HE_EQUALS_NO_HASHCODE"/>
</Match>
…
</FindBugsFilter>

26. Example

27. gradle findbugs

30. Review…
• Bug Patterns
• Not Always Right
• Use the Filters
FindBugs
2
@brwngrldev

32. PMD
“…finds common programming flaws like
unused variables, empty catch blocks…”

33. apply plugin: ‘pmd’
task pmd(type: Pmd) {
description 'Run pmd'
group 'verification'
ruleSetFiles = files("./qa-checks/pmd-ruleset.xml")
…
}

34. <ruleset>
<rule ref="rulesets/java/braces.xml" />
<rule ref="rulesets/java/strings.xml" />
<rule ref="rulesets/java/basic.xml" />
…
</ruleset>

35. Braces Ruleset

36. Example

37. gradle pmd

38. Find out why

39. Fix it…

40. Review…
• Possible Bugs
• Wasteful Usage
• Duplicate Code
@brwngrldev
PMD
3

41. Ewww!!!

42. “…checks for structural code problems that
could affect the quality and performance of
your application.”
Lint

43. Lintian
JSLintAndroid Lint Splint
PC-Lint
PyLint
cpplint

44. Example

45. Android Lint
<lint>
<issue id="IconColors" severity="ignore" />
<issue id="IconMissingDensityFolder" severity="ignore" />
<issue id="UnusedResources">
<ignore path="**/config.xml" />
</issue>
…
</lint>

48. Continous Integration

49. Review
• Structural Issues
• Exclude Checks
• Continuous Integration
Lint
4
@brwngrldev

50. Summary
PMD
Checkstyle
FindBugs
Lint
@brwngrldev

51. Resources
• Clean Code - http://amzn.to/1DJybxH
• Effective Java - http://amzn.to/1Ku8Xel
• Google Code Style - http://goo.gl/8Pf6J3
• QA Checks - http://git.io/vCMwc
• Conquering Cyclomatic Complexity - http://goo.gl/lRoPXN
• Using Android Lint - http://goo.gl/Zl2BPx
• Static Code Analysis Tools - https://goo.gl/0Hczxn
@brwngrldev

52. Photo Credits
• Slide 7 - https://www.flickr.com/photos/orinrobertjohn/13068719
• Slide 20 - https://www.flickr.com/photos/oakleyoriginals/2750185692
• Slide 41 - https://commons.wikimedia.org/wiki/File:Navel_lint_ball.jpg
• Slide 50 - https://pixabay.com/en/thumb-success-successful-fan-
faust-328420/
@brwngrldev

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