CheckStyle

Checkstyle is a tool for checking Code Standards Violations. It can be used different environments:

• Standalone (not covered here)
• Ant
• Maven
• IDE

Installation in Ant

To set CheckStyle in Ant add the following line of code to the build.xml. <syntaxhighlight lang="xml" line>

  <property name = "checkstyle.home.dir" location = "." />
  ...
  <taskdef resource  = "com/puppycrawl/tools/checkstyle/ant/checkstyle-ant-task.properties" classpath = "checkstyle-6.8.1-all.jar" />
  ...
  <property name="checkstyle.sourcepath"    value="src"                      />
  <property name="checkstyle.report.path"   value="."                        />
  <property name="checkstyle.report.style"  value="checkstyle-simple.xsl"    />
  <property name="checkstyle.report.xml"    value="checkstyle-report.xml"    />
  <property name="checkstyle.report.html"   value="checkstyle-report.html"   />
  ...
  <target name        = "check"
          description = "Generates a report of code convention violations.">

     <mkdir dir   = "${checkstyle.report.path}" />

     <checkstyle config          = "${checkstyle.report.config}"
                 failureProperty = "checkstyle.failure"
                 failOnViolation = "false">
        <formatter type   = "xml"
                   tofile = "${checkstyle.report.xml}"/>
        <fileset dir      = "${checkstyle.sourcepath}"
                 includes = "**/*.java, **/*.xml, **/*.properties"
                 excludes = "checkstyle/" />
     </checkstyle>
     <xslt basedir = "${checkstyle.report.path}"
           destdir = "${checkstyle.report.path}"
           style   = "${checkstyle.report.style}" />
  </target>

</syntaxhighlight>

Line	Description	Default	Global
1-2	Property for the location of all the checkstyle-jar files.	Current Directory	/usr/local/bin/checkstyle-6.8.1
4-5	Reference to the checkstyle properties	checkstyle-6.8.1-all.jar
7-12
14-36

Installation in Maven

To set CheckStyle in Maven or Maven 2 add the following lines of code to the settings of the project.xml, project.properties.

Project.xml

<syntaxhighlight lang="xml">

 <reports>
    ...
    <report>maven-checkstyle-plugin</report>
    ...
 </reports>

</syntaxhighlight>

Project.properties

Add the name of the file containing the checkstyle settings: <syntaxhighlight lang="bash">

1. Checkstyle settings #

maven.checkstyle.excludes=**/*generated*/** maven.checkstyle.properties=${basedir}/AAB_checks.xml </syntaxhighlight>

Configuration

The default CheckStyle is highly configurable. The installation come with sample configuration files:

• Apache Avalon (avalon_checks.xml)
• Sun coding conventions (sun_checks.xml)
• Apache Turbine Framework (turbine_checks.xml), this is the base of Frame

The AAB uses its own CheckStyle convention (AAB_checks.xml), which is configured for each project separately. The format of the configuration file: <syntaxhighlight lang="xml"> <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE module PUBLIC "-//Puppy Crawl//DTD Check Configuration 1.1//EN" "http://www.puppycrawl.com/dtds/configuration_1_1.dtd"> <module name="Checker">

   <module name="TreeWalker">
       <module name="com.puppycrawl.tools.checkstyle.checks.GenericIllegalRegexpCheck">
           <property name="format" value="System.err"/>
           <property name="ignoreCase" value="false"/>
           <property name="ignoreComments" value="false"/>
           <property name="message" value="Do not use System.err"/>
           <property name="severity" value="warning"/>
       </module>
       ...
       <module name="com.puppycrawl.tools.checkstyle.checks.sizes.LineLengthCheck">
           <property name="ignorePattern" value="^$"/>
           <property name="max" value="110"/>
           <property name="severity" value="warning"/>
           <property name="tabWidth" value="4"/>
       </module>
       ...
  </module>

</module> </syntaxhighlight>

Problem

The CheckStyle report becomes very long and difficult to handel. There are a few checks which delivers very much lines of report lines. A comparison of the size of checkstyle-report.html file for the different checkstyles

CheckStyle HTML-Size Kb HTML Reduction % HTML-Lines K Line Reduction % Description All 3,881  0 90,142 0,00% Default checks No LineLength 3,545  336 82,104 8.66% No com.puppycrawl.tools.checkstyle.checks.sizes.LineLengthCheck (AAB_1_checks.xml) No indentation 1,563 1,982 37,411 51.07% No com.puppycrawl.tools.checkstyle.checks.indentation.IndentationCheck (AAB_1_checks.xml) No whitespace Param Pad 1,561  2 37,378 0.05% No com.puppycrawl.tools.checkstyle.checks.whitespace.MethodParamPadCheck tokens: CTOR_DEF, LITERAL_NEW, METHOD_CALL, METHOD_DEF, SUPER_CTOR_CALL No whitespace After 1,537  24 36,795 0.62% No com.puppycrawl.tools.checkstyle.checks.whitespace.NoWhitespaceAfterCheck tokens: ARRAY_INIT, BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS, UNARY_PLUS No whitespace Before 1,536  1 36.773 0.03% No com.puppycrawl.tools.checkstyle.checks.whitespace.WhitespaceAfterCheck tokens: SEMI, POST_DEC, POST_INC No whitespace After 1,058 478 25,286 12.32% No com.puppycrawl.tools.checkstyle.checks.whitespace.NoWhitespaceAfterCheck tokens: COMMA, SEMI, TYPECAST No whitespace Around 643 415 15,276 10.69% No com.puppycrawl.tools.checkstyle.checks.whitespace.WhitespaceAroundCheck tokens: ASSIGN, BAND, BAND_ASSIGN, BOR, BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN, EQUAL, GE, GT, LAND, LCURLY, LE, LITERAL_ASSERT, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE, LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN, LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS, MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION, RCURLY, SL, SLIST, SL_ASSIGN, SR, SR_ASSIGN, STAR, STAR_ASSIGN