Class OneTopLevelClassCheck

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.design.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 contains 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 Details

    • MSG_KEY

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

  • Constructor Details

    • OneTopLevelClassCheck

      public OneTopLevelClassCheck()

  • 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:

    • visitToken

      public void visitToken(DetailAST compilationUnit)
      Description copied from class: AbstractCheck
      Called to process a token.
      Overrides:
      visitToken in class AbstractCheck
      Parameters:
      compilationUnit - the token to process

    • 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.