Package com.puppycrawl.tools.checkstyle.checks.design

Class OneTopLevelClassCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class OneTopLevelClassCheck
extends AbstractCheck

    Checks that each top-level class, interface, enum or annotation resides in a source file of its own. Official description of a 'top-level' term: 7.6. Top Level Type Declarations. If file doesn't contain public class, interface, enum or annotation, top-level type is the first type in file.

    To configure the check: 

     <module name="OneTopLevelClass"/>

    ATTENTION: This Check does not support customization of validated tokens, so do not use the "tokens" property.

    An example of code with violations: 

     public class Foo { // OK, first top-level class
   // methods
 }

 class Foo2 { // violation, second top-level class
   // methods
 }

 record Foo3 { // violation, third top-level "class"
     // methods
 }

    An example of code without public top-level type: 

     class Foo { // OK, first top-level class
   // methods
 }

 class Foo2 { // violation, second top-level class
   // methods
 }

    An example of code without violations: 

     public class Foo { // OK, only one top-level class
   // methods
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • one.top.level.class
    Since:
    5.8

    • Field Detail

      • MSG_KEY

        public static final java.lang.String MSG_KEY
        A key is pointing to the warning message text in "messages.properties" file.
        See Also:
        Constant Field Values

    • Method Detail

      • 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

      • isTypeDef

        private static boolean isTypeDef​(DetailAST node)
        Checks if an AST node is a type definition.
        Parameters:
        node - AST node to check.
        Returns:
        true if the node is a type (class, enum, interface, annotation) definition.

      • isPublic

        private static boolean isPublic​(DetailAST typeDef)
        Checks if a type is public.
        Parameters:
        typeDef - type definition node.
        Returns:
        true if a type has a public access level modifier.