static code analysis
TRANSCRIPT
Static Code Analysis
@brwngrldev +AnnyceDavis
“I’ll be learning something new on my deathbed.”
Checking your program for errors without executing it
What is it?
@brwngrldev
Testing
What it’s not
@brwngrldev
1 / 7 - 10@brwngrldev
1 / 10@brwngrldev
1000
The tools…
Checkstyle
1
FindBugs
2
PMD
3
Lint
4
@brwngrldev
@brwngrldev
Lint
Checkstyle
FindBugs
PMD
Checkstyle
“… a development tool to help programmers write Java code that
adheres to a coding standard.”
Source
Files
config.xml
Checkstyle Tool
Modules
Design
Formatting
Code Complexity
apply plugin: ‘checkstyle’
task checkstyle(type: Checkstyle) { description 'Checks if the code passes quality standards' group 'verification' configFile file(‘checkstyle.xml') …}
<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.getBoolean(R.styleable.WapoVideoView_showClosedCaptionsButton, false)); playerControlConfig.setShowClosedCaptionsButton(a.getBoolean(R.styleable.WapoVideoView_showClosedCaptionsButton, false));
<module name=“CyclomaticComplexity"> <property name="max" value=“8"/> </module>
Example
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"); }
… warning: Cyclomatic Complexity is 9
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
switch (video.getCategory()) { case "CAT1" : playVideo(video); updateMetaDataAndUrl(video, "http://www.largeImage.png"); break; …
4
@brwngrldev
Review…
• Formatting
• Code Complexity
• Refactor Gradually
@brwngrldev
Checkstyle
1
FindBugs
But this…
“…inspect Java bytecode for occurrences of bug
patterns”
apply plugin: ‘findbugs’
task findbugs(type: FindBugs) { description 'Run findbugs' group 'verification'
effort 'max' excludeFilter file('findbugs-exclude.xml') …}
<FindBugsFilter> <Match> <Class name="~.*R\$.*"/> </Match> <Match> <Bug pattern="HE_EQUALS_NO_HASHCODE"/> </Match>
…</FindBugsFilter>
Example
gradle findbugs
Review…
• Bug Patterns
• Not Always Right
• Use the Filters
FindBugs
2
@brwngrldev
PMD
“…finds common programming flaws like unused variables, empty catch blocks…”
apply plugin: ‘pmd’
task pmd(type: Pmd) { description 'Run pmd' group 'verification'
ruleSetFiles = files("./qa-checks/pmd-ruleset.xml") …}
<ruleset> <rule ref="rulesets/java/braces.xml" />
<rule ref="rulesets/java/strings.xml" />
<rule ref="rulesets/java/basic.xml" /> …</ruleset>
Braces Ruleset
Example
gradle pmd
Find out why
Fix it…
Review…
• Possible Bugs
• Wasteful Usage
• Duplicate Code
@brwngrldev
PMD
3
Ewww!!!
“…checks for structural code problems that could affect the quality and performance of
your application.”
Lint
Lintian
JSLintAndroid Lint SplintPC-Lint
PyLint
cpplint
Example
Android Lint<lint> <issue id="IconColors" severity="ignore" /> <issue id="IconMissingDensityFolder" severity="ignore" /> <issue id="UnusedResources"> <ignore path="**/config.xml" /> </issue> …</lint>
Continous Integration
Review
• Structural Issues
• Exclude Checks
• Continuous Integration
Lint
4
@brwngrldev
Summary
PMD
Checkstyle
FindBugs
Lint
@brwngrldev
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
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
