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Configuration in MegaLinter

Variable Description Default value
JAVA_CHECKSTYLE_ARGUMENTS User custom arguments to add in linter CLI call
Ex: -s --foo "bar"
JAVA_CHECKSTYLE_FILTER_REGEX_INCLUDE Custom regex including filter
Ex: (src\|lib)
Include every file
JAVA_CHECKSTYLE_FILTER_REGEX_EXCLUDE Custom regex excluding filter
Ex: (test\|examples)
Exclude no file
JAVA_CHECKSTYLE_CLI_LINT_MODE Override default CLI lint mode
- file: Calls the linter for each file
- list_of_files: Call the linter with the list of files as argument
- project: Call the linter from the root of the project
JAVA_CHECKSTYLE_FILE_EXTENSIONS Allowed file extensions. "*" matches any extension, "" matches empty extension. Empty list excludes all files
Ex: [".py", ""]
JAVA_CHECKSTYLE_FILE_NAMES_REGEX File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files
Ex: ["Dockerfile(-.+)?", "Jenkinsfile"]
Include every file
JAVA_CHECKSTYLE_PRE_COMMANDS List of bash commands to run before the linter None
JAVA_CHECKSTYLE_POST_COMMANDS List of bash commands to run after the linter None
JAVA_CHECKSTYLE_CONFIG_FILE checkstyle configuration file name
Use LINTER_DEFAULT to let the linter find it
JAVA_CHECKSTYLE_RULES_PATH Path where to find linter configuration file Workspace folder, then MegaLinter default rules
JAVA_CHECKSTYLE_DISABLE_ERRORS Run linter but consider errors as warnings false
JAVA_CHECKSTYLE_DISABLE_ERRORS_IF_LESS_THAN Maximum number of errors allowed 0

IDE Integration

Use checkstyle in your favorite IDE to catch errors before MegaLinter !

IDE Extension Name Install
Eclipse eclipse-cs Visit Web Site
IDEA checkstyle-idea
Visual Studio Code vscode-checkstyle Install in VsCode

MegaLinter Flavours

This linter is available in the following flavours

Flavor Description Embedded linters Info
all Default MegaLinter Flavor 95 Docker Image Size (tag) Docker Pulls
java Optimized for JAVA based projects 42 Docker Image Size (tag) Docker Pulls

Behind the scenes

How are identified applicable files

  • File extensions: .java

How the linting is performed

  • checkstyle is called one time by identified file

Example calls

java -jar /usr/bin/checkstyle
java -jar /usr/bin/checkstyle -c sun_checks.xml

Help content

Usage: java [-options] class [args...]
           (to execute a class)
   or  java [-options] -jar jarfile [args...]
           (to execute a jar file)
where options include:
    -d32    use a 32-bit data model if available
    -d64    use a 64-bit data model if available
    -server    to select the "server" VM
                  The default VM is server,
                  because you are running on a server-class machine.

    -cp <class search path of directories and zip/jar files>
    -classpath <class search path of directories and zip/jar files>
                  A : separated list of directories, JAR archives,
                  and ZIP archives to search for class files.
                  set a system property
                  enable verbose output
    -version      print product version and exit
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  require the specified version to run
    -showversion  print product version and continue
    -jre-restrict-search | -no-jre-restrict-search
                  Warning: this feature is deprecated and will be removed
                  in a future release.
                  include/exclude user private JREs in the version search
    -? -help      print this help message
    -X            print help on non-standard options
                  enable assertions with specified granularity
                  disable assertions with specified granularity
    -esa | -enablesystemassertions
                  enable system assertions
    -dsa | -disablesystemassertions
                  disable system assertions
                  load native agent library <libname>, e.g. -agentlib:hprof
                  see also, -agentlib:jdwp=help and -agentlib:hprof=help
                  load native agent library by full pathname
                  load Java programming language agent, see java.lang.instrument
                  show splash screen with specified image
See for more details.

Installation on mega-linter Docker image

  • Dockerfile commands :
# Parent descriptor install
ENV JAVA_HOME=/usr/lib/jvm/java-1.8-openjdk
# Linter install
        | grep browser_download_url \
        | grep ".jar" \
        | cut -d '"' -f 4) \
    && curl --retry 5 --retry-delay 5 -sSL $CHECKSTYLE_LATEST \
        --output /usr/bin/checkstyle

Example success log

Results of checkstyle linter (version 8.38)
See documentation on

[SUCCESS] .automation/test/java/
    Starting audit...
    Audit done.

Example error log

Results of checkstyle linter (version 8.38)
See documentation on

[ERROR] .automation/test/java/
    Starting audit...
    [ERROR] .automation/test/java/ Utility classes should not have a public or default constructor. [HideUtilityClassConstructor]
    [ERROR] .automation/test/java/ Name 'java_bad_1' must match pattern '^[A-Z][a-zA-Z0-9]*$'. [TypeName]
    [ERROR] .automation/test/java/ '{' at column 1 should be on the previous line. [LeftCurly]
    [ERROR] .automation/test/java/ Parameter args should be final. [FinalParameters]
    [ERROR] .automation/test/java/ Array brackets at illegal position. [ArrayTypeStyle]
    [ERROR] .automation/test/java/ '{' at column 5 should be on the previous line. [LeftCurly]
    Audit done.
    Checkstyle ends with 6 errors.