introducing scala in your existing java project

IntroducingScalainyourexistingJavaproject

TimSoethout-INGBank

http://blog.timmybankers.nl

OverviewIntroScala@ING-ContextCompilingScalainMavenMixingJavaandScalasourceCodecoverageCodequalityusingSonarMorecodeanalysisDocumentationforJavaconsumersWrapup

WhoamI?TimSoethout

FunctionalprogrammeratheartScalaevangelist/trainerinsideINGMorerecently:Aquariumenthusiast&WestCoastSwing-dancer

Scala@ING

StateMuchJavawithMavenSomeScalaforrestfulservicesusingAkkaOpensource:CoralDevelopersaregettinginterestedandlookingforpossibilities

ContextMavenprojectwritteninJava6TeamwithmixedScalaexperiencelevels

EagertodoScalaButwithinEnterprise:Compliancy

CompilingScalainMaven

scala-maven-plugin<project> <build> <sourceDirectory>src/main/scala</sourceDirectory> <testSourceDirectory>src/test/scala</testSourceDirectory> <plugins> <plugin> <groupId>net.alchim31.maven</groupId> <artifactId>scala-maven-plugin</artifactId> <version>3.2.2</version> ... </plugin> </plugins> </build></project>

MixingJavaandScalasource

DemoMixedJava&Scala

DemoMultiplemodules

MixingitupSeemstoworkonfirstsightProblemscanarisein:

MultiplemodulesDependenciesfromJavatoScalaDependsoncompileordersbtincrementalcompilertotherescue

scala-maven-plugin:

<configuration> <recompileMode>incremental</recompileMode></configuration>

Anotheroption;runssbtunderneathNotreallymaintainedanymore,buthelpedusalot6monthsago

sbt-compiler-maven-plugin

<plugin> <groupId>com.google.code.sbt-compiler-maven-plugin</groupId> <artifactId>sbt-compiler-maven-plugin</artifactId> <version>1.0.0-beta5</version> <executions> <execution> <goals> <goal>compile</goal> <goal>testCompile</goal> <goal>addScalaSources</goal> </goals> <id>default-sbt-compile</id> </execution> </executions></plugin>

Codecoverage

Cobertura,Jacoco,Clover,EclEmma?!?WorksgoodforJavaLineandbranchcoverage

DemoLet'stryitforScala!

That'sawful!Scalacompilergenerateslotsforyou(i.e.incaseclasses,traitsetc)

CoberturaandJacocoworkonbytecodeergolotsofuncoveredgeneratedcode

Idon'twanttobetestinggeneratedcode,wouldyou?

totherescue!Scalastatementandbranchcoverage!

scoverage-maven-plugin

DemoLet'stryitforScala!

Sowhatdidwedo?!StatementcoverageforScalawithscoverageNormalline/branchcoverageforJavawithCobertura

CodequalityusingSonar

CodeQualityPlatformCodemetrics

CoverageComplexitySizeRules

Spotregression

SonarQube

Tooling

docker-composescriptwithdatacontainer,PostgresdatabaseandSonarQubeContainspluginsneededforScala!(Cobertura,scoverage,Java,etc)

-updatedtousecoberturaonlyforJava

UsedforfilteringScalacoveragefromcobertura.xml

scala-sonarqube-docker

sonar-scala-pluginxml-transform-maven-plugin

DemoJava&ScalacodecoverageinSonar

*.java

cobertura

cobertura.xml

*.scala

scoverage

scoverage.xml

xml-transform-maven-plugin

Sonar Scoverage plugincobertura-without-scala.xml

Sonar Cobertura Plugin

SonarQube

Morecodeanalysis

CompilerflagsJava-Xlint:unchecked-Uncheckedcasts

CompilerflagsScala-unchecked-deprecation-feature-Xlint-Yno-adapted-args-Ywarn-dead-code-Ywarn-numeric-widen-Ywarn-value-discard-Xfuture-Ywarn-unused-import-Ywarn-unused

DemoCompilerflags

FindBugs&FindSecurityBugs

Morechecks-ToimplementAbideWartremover

DocumentationforJavaconsumers

GeneratedoutlineofScalafilesinjavaincludingjavadocannotationsusefultogenerateJavadocforJavaconsumers

genjavadoc

Demogenjavadoc

Wrapup

RecapScalaandJavacodein

singlemodulemultiplemodulescodecoverageonboth

CodeQualitywithSonarQubeScalaStyleFindBugs

Lotstotweak-compilerarguments,lintersDocumentationforJava

ThanksforlisteningQuestions?

/Slides Code

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