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

Class IllegalIdentifierNameCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class IllegalIdentifierNameCheck
extends AbstractNameCheck

    Checks identifiers with a regular expression 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 regular expression 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 Detail

      • IllegalIdentifierNameCheck

        public IllegalIdentifierNameCheck()
        Creates a new IllegalIdentifierNameCheck instance.

    • Method Detail

      • 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:
        TokenTypes

      • 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:
        TokenTypes

      • 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:
        TokenTypes

      • 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.