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

Class 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