Package com.puppycrawl.tools.checkstyle.checks.naming

Class IllegalIdentifierNameCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.naming.AbstractNameCheck
com.puppycrawl.tools.checkstyle.checks.naming.IllegalIdentifierNameCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class IllegalIdentifierNameCheck extends AbstractNameCheck

Checks identifiers with a pattern for a set of illegal names, such as those that are restricted or contextual keywords. Examples include "yield", "record", "_", and "var". Please read more at Java Language Specification to get to know more about restricted keywords. Since this check uses a pattern to specify valid identifiers, users can also prohibit the usage of certain symbols, such as "$", or any non-ascii character.

To configure the check:

Configuration:

 <module name="IllegalIdentifierName"/>

Example: 

 public class TestClass {
     public static void main(String... args) {
         var var = 4; // violation, "var" should not be used as an identifier.
         int record = 15; // violation, "record" should not be used as an identifier.
         String yield = "yield"; // violation, "yield" should not be used as an identifier.

         record Record // violation, "Record" should not be used as an identifier.
             (Record record) { // violation, "record" should not be used as an identifier.
         }

         String yieldString = "yieldString"; // ok, part of another word
         record MyRecord(){} // ok, part of another word
         var variable = 2; // ok, part of another word
         String _; // violation, underscore should not be used as an identifier.
     }
 }

To configure the check to include "open" and "transitive" in the set of illegal identifiers:

Configuration:

 <module name="IllegalIdentifierName">
     <property name="format" value="(?i)^(?!(record|yield|var
                        |permits|sealed|open|transitive|_)$).+$"/>
 </module>

Example:

 public class TestClass {
     public static void main(String... args) {

         int open = 4; // violation, "open" should not be used as an identifier
         Object transitive = "transitive"; // violation, "transitive" should not
                                                // be used as an identifier

         int openInt = 4; // ok, "open" is part of another word
         Object transitiveObject = "transitiveObject"; // ok, "transitive" is part of another word
     }
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • name.invalidPattern
Since:
8.36

  • Constructor Details

    • IllegalIdentifierNameCheck

      public IllegalIdentifierNameCheck()
      Creates a new IllegalIdentifierNameCheck instance.

  • Method Details

    • getDefaultTokens

      public int[] getDefaultTokens()
      Description copied from class: AbstractCheck
      Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.
      Specified by:
      getDefaultTokens in class AbstractCheck
      Returns:
      the default tokens
      See Also:

    • getAcceptableTokens

      public int[] getAcceptableTokens()
      Description copied from class: AbstractCheck
      The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.
      Specified by:
      getAcceptableTokens in class AbstractCheck
      Returns:
      the token set this check is designed for.
      See Also:

    • getRequiredTokens

      public int[] getRequiredTokens()
      Description copied from class: AbstractCheck
      The tokens that this check must be registered for.
      Specified by:
      getRequiredTokens in class AbstractCheck
      Returns:
      the token set this must be registered for.
      See Also:

    • mustCheckName

      protected boolean mustCheckName(DetailAST ast)
      Description copied from class: AbstractNameCheck
      Decides whether the name of an AST should be checked against the format regexp.
      Specified by:
      mustCheckName in class AbstractNameCheck
      Parameters:
      ast - the AST to check.
      Returns:
      true if the IDENT subnode of ast should be checked against the format regexp.