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

Class VisibilityModifierCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.design.VisibilityModifierCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class VisibilityModifierCheck extends AbstractCheck
Checks visibility of class members. Only static final, immutable or annotated by specified annotation members may be public; other class members must be private unless the property protectedAllowed or packageAllowed is set.

Public members are not flagged if the name matches the public member regular expression (contains "^serialVersionUID$" by default).

Note that Checkstyle 2 used to include "^f[A-Z][a-zA-Z0-9]*$" in the default pattern to allow names used in container-managed persistence for Enterprise JavaBeans (EJB) 1.1 with the default settings. With EJB 2.0 it is no longer necessary to have public access for persistent fields, so the default has been changed.

Rationale: Enforce encapsulation.

Check also has options making it less strict:

ignoreAnnotationCanonicalNames - the list of annotations which ignore variables in consideration. If user want to provide short annotation name that type will match to any named the same type without consideration of package.

allowPublicFinalFields - which allows public final fields.

allowPublicImmutableFields - which allows immutable fields to be declared as public if defined in final class.

Field is known to be immutable if:

  • It's declared as final
  • Has either a primitive type or instance of class user defined to be immutable (such as String, ImmutableCollection from Guava, etc.)

Classes known to be immutable are listed in immutableClassCanonicalNames by their canonical names.

Property Rationale: Forcing all fields of class to have private modifier by default is good in most cases, but in some cases it drawbacks in too much boilerplate get/set code. One of such cases are immutable classes.

Restriction: Check doesn't check if class is immutable, there's no checking if accessory methods are missing and all fields are immutable, we only check if current field is immutable or final. Under the flag allowPublicImmutableFields, the enclosing class must also be final, to encourage immutability. Under the flag allowPublicFinalFields, the final modifier on the enclosing class is optional.

Star imports are out of scope of this Check. So if one of type imported via star import collides with user specified one by its short name - there won't be Check's violation.

Since:
3.0

  • Field Details

  • Constructor Details

  • Method Details

    • setIgnoreAnnotationCanonicalNames

      public void setIgnoreAnnotationCanonicalNames(String... annotationNames)
      Setter to specify annotations canonical names which ignore variables in consideration.
      Parameters:
      annotationNames - array of ignore annotations canonical names.
      Since:
      6.5

    • setProtectedAllowed

      public void setProtectedAllowed(boolean protectedAllowed)
      Setter to control whether protected members are allowed.
      Parameters:
      protectedAllowed - whether protected members are allowed
      Since:
      3.0

    • setPackageAllowed

      public void setPackageAllowed(boolean packageAllowed)
      Setter to control whether package visible members are allowed.
      Parameters:
      packageAllowed - whether package visible members are allowed
      Since:
      3.0

    • setPublicMemberPattern

      public void setPublicMemberPattern(Pattern pattern)
      Setter to specify pattern for public members that should be ignored.
      Parameters:
      pattern - pattern for public members to ignore.
      Since:
      3.0

    • setAllowPublicImmutableFields

      public void setAllowPublicImmutableFields(boolean allow)
      Setter to allow immutable fields to be declared as public if defined in final class.
      Parameters:
      allow - user's value.
      Since:
      6.4

    • setAllowPublicFinalFields

      public void setAllowPublicFinalFields(boolean allow)
      Setter to allow final fields to be declared as public.
      Parameters:
      allow - user's value.
      Since:
      7.0

    • setImmutableClassCanonicalNames

      public void setImmutableClassCanonicalNames(String... classNames)
      Setter to specify immutable classes canonical names.
      Parameters:
      classNames - array of immutable types canonical names.
      Since:
      6.4.1

    • 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:

    • beginTree

      public void beginTree(DetailAST rootAst)
      Description copied from class: AbstractCheck
      Called before the starting to process a tree. Ideal place to initialize information that is to be collected whilst processing a tree.
      Overrides:
      beginTree in class AbstractCheck
      Parameters:
      rootAst - the root of the tree

    • visitToken

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

    • isAnonymousClassVariable

      private static boolean isAnonymousClassVariable(DetailAST variableDef)
      Checks if current variable definition is definition of an anonymous class.
      Parameters:
      variableDef - VARIABLE_DEF
      Returns:
      true if current variable definition is definition of an anonymous class.

    • visitVariableDef

      private void visitVariableDef(DetailAST variableDef)
      Checks access modifier of given variable. If it is not proper according to Check - puts violation on it.
      Parameters:
      variableDef - variable to check.

    • hasIgnoreAnnotation

      private boolean hasIgnoreAnnotation(DetailAST variableDef)
      Checks if variable def has ignore annotation.
      Parameters:
      variableDef - VARIABLE_DEF
      Returns:
      true if variable def has ignore annotation.

    • visitImport

      private void visitImport(DetailAST importAst)
      Checks imported type. If type's canonical name was not specified in immutableClassCanonicalNames, but its short name collides with one from immutableClassShortNames - removes it from the last one.
      Parameters:
      importAst - Import

    • isStarImport

      private static boolean isStarImport(DetailAST importAst)
      Checks if current import is star import. E.g.:

      import java.util.*;

      Parameters:
      importAst - Import
      Returns:
      true if it is star import

    • hasProperAccessModifier

      private boolean hasProperAccessModifier(DetailAST variableDef, String variableName)
      Checks if current variable has proper access modifier according to Check's options.
      Parameters:
      variableDef - Variable definition node.
      variableName - Variable's name.
      Returns:
      true if variable has proper access modifier.

    • isStaticFinalVariable

      private static boolean isStaticFinalVariable(DetailAST variableDef)
      Checks whether variable has static final modifiers.
      Parameters:
      variableDef - Variable definition node.
      Returns:
      true of variable has static final modifiers.

    • isIgnoredPublicMember

      private boolean isIgnoredPublicMember(String variableName, String variableScope)
      Checks whether variable belongs to public members that should be ignored.
      Parameters:
      variableName - Variable's name.
      variableScope - Variable's scope.
      Returns:
      true if variable belongs to public members that should be ignored.

    • isAllowedPublicField

      private boolean isAllowedPublicField(DetailAST variableDef)
      Checks whether the variable satisfies the public field check.
      Parameters:
      variableDef - Variable definition node.
      Returns:
      true if allowed.

    • isImmutableFieldDefinedInFinalClass

      private boolean isImmutableFieldDefinedInFinalClass(DetailAST variableDef)
      Checks whether immutable field is defined in final class.
      Parameters:
      variableDef - Variable definition node.
      Returns:
      true if immutable field is defined in final class.

    • getModifiers

      private static Set<String> getModifiers(DetailAST defAST)
      Returns the set of modifier Strings for a VARIABLE_DEF or CLASS_DEF AST.
      Parameters:
      defAST - AST for a variable or class definition.
      Returns:
      the set of modifier Strings for defAST.

    • getVisibilityScope

      private static String getVisibilityScope(DetailAST variableDef)
      Returns the visibility scope for the variable.
      Parameters:
      variableDef - Variable definition node.
      Returns:
      one of "public", "private", "protected", "package"

    • isImmutableField

      private boolean isImmutableField(DetailAST variableDef)
      Checks if current field is immutable: has final modifier and either a primitive type or instance of class known to be immutable (such as String, ImmutableCollection from Guava, etc.). Classes known to be immutable are listed in immutableClassCanonicalNames
      Parameters:
      variableDef - Field in consideration.
      Returns:
      true if field is immutable.

    • isCanonicalName

      private static boolean isCanonicalName(DetailAST type)
      Checks whether type definition is in canonical form.
      Parameters:
      type - type definition token.
      Returns:
      true if type definition is in canonical form.

    • getGenericTypeArgs

      private static DetailAST getGenericTypeArgs(DetailAST type, boolean isCanonicalName)
      Returns generic type arguments token.
      Parameters:
      type - type token.
      isCanonicalName - whether type name is in canonical form.
      Returns:
      generic type arguments token.

    • getTypeArgsClassNames

      private static List<String> getTypeArgsClassNames(DetailAST typeArgs)
      Returns a list of type parameters class names.
      Parameters:
      typeArgs - type arguments token.
      Returns:
      a list of type parameters class names.

    • areImmutableTypeArguments

      private boolean areImmutableTypeArguments(Collection<String> typeArgsClassNames)
      Checks whether all generic type arguments are immutable. If at least one argument is mutable, we assume that the whole list of type arguments is mutable.
      Parameters:
      typeArgsClassNames - type arguments class names.
      Returns:
      true if all generic type arguments are immutable.

    • isFinalField

      private static boolean isFinalField(DetailAST variableDef)
      Checks whether current field is final.
      Parameters:
      variableDef - field in consideration.
      Returns:
      true if current field is final.

    • isPrimitive

      private static boolean isPrimitive(DetailAST type)
      Checks if current type is primitive type (int, short, float, boolean, double, etc.). As primitive types have special tokens for each one, such as: LITERAL_INT, LITERAL_BOOLEAN, etc. So, if type's identifier differs from IDENT token - it's a primitive type.
      Parameters:
      type - Ast TYPE node.
      Returns:
      true if current type is primitive type.

    • getCanonicalName

      private static String getCanonicalName(DetailAST type)
      Gets canonical type's name from given TYPE node.
      Parameters:
      type - DetailAST TYPE node.
      Returns:
      canonical type's name

    • getNextSubTreeNode

      private static DetailAST getNextSubTreeNode(DetailAST currentNodeAst, DetailAST subTreeRootAst)
      Gets the next node of a syntactical tree (child of a current node or sibling of a current node, or sibling of a parent of a current node).
      Parameters:
      currentNodeAst - Current node in considering
      subTreeRootAst - SubTree root
      Returns:
      Current node after bypassing, if current node reached the root of a subtree method returns null

    • getClassShortNames

      private static Set<String> getClassShortNames(Set<String> canonicalClassNames)
      Converts canonical class names to short names.
      Parameters:
      canonicalClassNames - the set of canonical class names.
      Returns:
      the set of short names of classes.

    • getClassShortName

      private static String getClassShortName(String canonicalClassName)
      Gets the short class name from given canonical name.
      Parameters:
      canonicalClassName - canonical class name.
      Returns:
      short name of class.

    • findMatchingAnnotation

      private DetailAST findMatchingAnnotation(DetailAST variableDef)
      Checks whether the AST is annotated with an annotation containing the passed in regular expression and return the AST representing that annotation.

      This method will not look for imports or package statements to detect the passed in annotation.

      To check if an AST contains a passed in annotation taking into account fully-qualified names (ex: java.lang.Override, Override) this method will need to be called twice. Once for each name given.

      Parameters:
      variableDef - variable def node.
      Returns:
      the AST representing the first such annotation or null if no such annotation was found