Description

Checks that a specified pattern matches based on file and/or folder path. It can also be used to verify files match specific naming patterns not covered by other checks (Ex: properties, xml, etc.).

When customizing the check, the properties are applied in a specific order. The fileExtensions property first picks only files that match any of the specific extensions supplied. Once files are matched against the fileExtensions, the match property is then used in conjunction with the patterns to determine if the check is looking for a match or mismatch on those files. If the fileNamePattern is supplied, the matching is only applied to the fileNamePattern and not the folderPattern. If no fileNamePattern is supplied, then matching is applied to the folderPattern only and will result in all files in a folder to be reported on violations. If no folderPattern is supplied, then all folders that checkstyle finds are examined for violations. The ignoreFileNameExtensions property drops the file extension and applies the fileNamePattern only to the rest of file name. For example, if the file is named 'test.java' and this property is turned on, the pattern is only applied to 'test'.

If this check is configured with no properties, then the default behavior of this check is to report file names with spaces in them. When at least one pattern property is supplied, the entire check is under the user's control to allow them to fully customize the behavior.

It is recommended that if you create your own pattern, to also specify a custom violation message. This allows the violation message printed to be clear what the violation is, especially if multiple RegexpOnFilename checks are used. Argument 0 for the message populates the check's folderPattern. Argument 1 for the message populates the check's fileNamePattern. The file name is not passed as an argument since it is part of CheckStyle's default violation messages.

Properties

Examples

To configure the check to report file names that contain a space:

<module name="Checker">
  <module name="RegexpOnFilename"/>
</module>
        

Example:

src/xdocs/config_regexp.xml  //OK, contains no whitespace
src/xdocs/"config regexp".xml  //violation, contains whitespace
        

To configure the check to forbid 'gif' files in folders:

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="fileNamePattern" value="\.gif$"/>
  </module>
</module>
        

Example:

src/site/resources/images/favicon.png  //OK
src/site/resources/images/logo.jpg  //OK
src/site/resources/images/groups.gif  //violation, .gif images not allowed
        

To configure the check to forbid 'md' files except 'README.md file' in folders, with custom message:

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="fileNamePattern" value="README"/>
    <property name="fileExtensions" value="md"/>
    <property name="match" value="false"/>
    <message key="regexp.filename.mismatch"
      value="No '*.md' files other then 'README.md'"/>
  </module>
</module>
        

Example:

src/site/resources/README.md  //OK
src/site/resources/Logo.png  //OK
src/site/resources/Text.md  //violation, .md files other than 'README.md' are not allowed
        

To configure the check to only allow property and xml files to be located in the resource folder:

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="folderPattern"
      value="[\\/]src[\\/]\w+[\\/]resources[\\/]"/>
    <property name="match" value="false"/>
    <property name="fileExtensions" value="properties, xml"/>
  </module>
</module>
        

Example:

src/main/resources/sun_checks.xml  //OK
src/main/resources/check_properties.properties  //OK
src/main/resources/JavaClass.java  //violation, xml|property files are allowed in resource folder
        

To configure the check to only allow Java and XML files in your folders use the below.

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="fileNamePattern" value="\.(java|xml)$"/>
    <property name="match" value="false"/>
  </module>
</module>
        

Example:

src/main/java/JavaClass.java  //OK
src/main/MainClass.java  //OK
src/main/java/java_xml.xml  //OK
src/main/main_xml.xml  //OK
src/main/java/image.png  //violation, folders should only contain java or xml files
src/main/check_properties.properties  //violation, folders should only contain java or xml files
        

To configure the check to only allow Java and XML files only in your source folder and ignore any other folders:

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="folderPattern" value="[\\/]src[\\/]"/>
    <property name="fileNamePattern" value="\.(java|xml)$"/>
    <property name="match" value="false"/>
  </module>
</module>
        

Example:

src/SourceClass.java  //OK
src/source_xml.xml  //OK
src/image.png  //violation, only java and xml files are allowed in src folder
src/main/main_properties.properties  //OK, this check only applies to src folder
        

Note: 'folderPattern' must be specified if checkstyle is analyzing more than the normal source folder, like the 'bin' folder where class files can be located.

To configure the check to only allow file names to be camel case:

<module name="Checker">
  <module name="RegexpOnFilename">
    <property name="fileNamePattern" value="^([A-Z][a-z0-9]+\.?)+$"/>
    <property name="match" value="false"/>
    <property name="ignoreFileNameExtensions" value="true"/>
  </module>
</module>
        

Example:

src/main/java/JavaClass.java  //OK
src/main/MainClass.java  //OK
src/main/java/java_class.java  //violation, file names should be in Camel Case
src/main/main_class.java  //violation, file names should be in Camel Case
        

Example of Usage

• Checkstyle Style

Violation Messages

• regexp.filename.match
• regexp.filename.mismatch

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.regexp

Parent Module

Checker