Class 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 allowProtected/Package is set.

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

    Rationale: Enforce encapsulation.

    Check also has options making it less strict:

    ignoreAnnotationCanonicalNames - the list of annotations canonical names which ignore variables in consideration, if user will provide short annotation name that type will match to any named the same type without consideration of package, list by default:

    • org.junit.Rule
    • org.junit.ClassRule
    • com.google.common.annotations.VisibleForTesting

    For example such public field will be skipped by default value of list above:

     @org.junit.Rule
     public TemporaryFolder publicJUnitRule = new TemporaryFolder();
     
     

    allowPublicFinalFields - which allows public final fields. Default value is false.

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

    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 and etc)

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

    • java.lang.String
    • java.lang.Integer
    • java.lang.Byte
    • java.lang.Character
    • java.lang.Short
    • java.lang.Boolean
    • java.lang.Long
    • java.lang.Double
    • java.lang.Float
    • java.lang.StackTraceElement
    • java.lang.BigInteger
    • java.lang.BigDecimal
    • java.io.File
    • java.util.Locale
    • java.util.UUID
    • java.net.URL
    • java.net.URI
    • java.net.Inet4Address
    • java.net.Inet6Address
    • java.net.InetSocketAddress

    User can override this list via adding canonical class names to immutableClassCanonicalNames, if user will provide short class name all that type will match to any named the same type without consideration of package.

    Rationale: Forcing all fields of class to have private modified 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 by matching a name to user defined list of immutable classes and defined in final class

    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.

    Examples:

    The check will rise 3 violations if it is run with default configuration against the following code example:

     
     public class ImmutableClass
     {
         public int intValue; // violation
         public java.lang.String notes; // violation
         public BigDecimal value; // violation
    
         public ImmutableClass(int intValue, BigDecimal value, String notes)
         {
             this.intValue = intValue;
             this.value = value;
             this.notes = notes;
         }
     }
     
     

    To configure the Check passing fields of type com.google.common.collect.ImmutableSet and java.util.List:

    <module name="VisibilityModifier"> <property name="allowPublicImmutableFields" value="true"/> <property name="immutableClassCanonicalNames" value="java.util.List, com.google.common.collect.ImmutableSet"/> </module>

     
     public final class ImmutableClass
     {
         public final ImmutableSet&lt;String&gt; includes; // No warning
         public final ImmutableSet&lt;String&gt; excludes; // No warning
         public final BigDecimal value; // Warning here, type BigDecimal isn't specified as immutable
    
         public ImmutableClass(Collection&lt;String&gt; includes, Collection&lt;String&gt; excludes,
                      BigDecimal value)
         {
             this.includes = ImmutableSet.copyOf(includes);
             this.excludes = ImmutableSet.copyOf(excludes);
             this.value = value;
             this.notes = notes;
         }
     }
     
     

    To configure the Check passing fields annotated with

    @com.annotation.CustomAnnotation
    :

    <module name="VisibilityModifier"> <property name="ignoreAnnotationCanonicalNames" value=" com.annotation.CustomAnnotation"/> </module>

     @com.annotation.CustomAnnotation
     String customAnnotated; // No warning
     
     @CustomAnnotation
     String shortCustomAnnotated; // No warning
     
     

    To configure the Check passing fields annotated with short annotation name

    @CustomAnnotation
    :

    <module name="VisibilityModifier"> <property name="ignoreAnnotationCanonicalNames" value="CustomAnnotation"/> </module>

     @CustomAnnotation
     String customAnnotated; // No warning
     
     @com.annotation.CustomAnnotation
     String customAnnotated1; // No warning
     
     @mypackage.annotation.CustomAnnotation
     String customAnnotatedAnotherPackage; // another package but short name matches
                                           // so no violation
     
     
    • 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
      • DEFAULT_IMMUTABLE_TYPES

        private static final java.util.List<java.lang.String> DEFAULT_IMMUTABLE_TYPES
        Default immutable types canonical names.
      • DEFAULT_IGNORE_ANNOTATIONS

        private static final java.util.List<java.lang.String> DEFAULT_IGNORE_ANNOTATIONS
        Default ignore annotations canonical names.
      • PUBLIC_ACCESS_MODIFIER

        private static final java.lang.String PUBLIC_ACCESS_MODIFIER
        Name for 'public' access modifier.
        See Also:
        Constant Field Values
      • PRIVATE_ACCESS_MODIFIER

        private static final java.lang.String PRIVATE_ACCESS_MODIFIER
        Name for 'private' access modifier.
        See Also:
        Constant Field Values
      • PROTECTED_ACCESS_MODIFIER

        private static final java.lang.String PROTECTED_ACCESS_MODIFIER
        Name for 'protected' access modifier.
        See Also:
        Constant Field Values
      • PACKAGE_ACCESS_MODIFIER

        private static final java.lang.String PACKAGE_ACCESS_MODIFIER
        Name for implicit 'package' access modifier.
        See Also:
        Constant Field Values
      • STATIC_KEYWORD

        private static final java.lang.String STATIC_KEYWORD
        Name for 'static' keyword.
        See Also:
        Constant Field Values
      • FINAL_KEYWORD

        private static final java.lang.String FINAL_KEYWORD
        Name for 'final' keyword.
        See Also:
        Constant Field Values
      • EXPLICIT_MODS

        private static final java.lang.String[] EXPLICIT_MODS
        Contains explicit access modifiers.
      • publicMemberPattern

        private java.util.regex.Pattern publicMemberPattern
        Regexp for public members that should be ignored. Note: Earlier versions of checkstyle used ^f[A-Z][a-zA-Z0-9]*$ as the default to allow CMP for EJB 1.1 with the default settings. With EJB 2.0 it is not longer necessary to have public access for persistent fields.
      • ignoreAnnotationShortNames

        private final java.util.List<java.lang.String> ignoreAnnotationShortNames
        List of ignore annotations short names.
      • immutableClassShortNames

        private final java.util.List<java.lang.String> immutableClassShortNames
        List of immutable classes short names.
      • ignoreAnnotationCanonicalNames

        private java.util.List<java.lang.String> ignoreAnnotationCanonicalNames
        List of ignore annotations canonical names.
      • protectedAllowed

        private boolean protectedAllowed
        Whether protected members are allowed.
      • packageAllowed

        private boolean packageAllowed
        Whether package visible members are allowed.
      • allowPublicImmutableFields

        private boolean allowPublicImmutableFields
        Allows immutable fields of final classes to be declared as public.
      • allowPublicFinalFields

        private boolean allowPublicFinalFields
        Allows final fields to be declared as public.
      • immutableClassCanonicalNames

        private java.util.List<java.lang.String> immutableClassCanonicalNames
        List of immutable classes canonical names.
    • Constructor Detail

      • VisibilityModifierCheck

        public VisibilityModifierCheck()
    • Method Detail

      • setIgnoreAnnotationCanonicalNames

        public void setIgnoreAnnotationCanonicalNames​(java.lang.String... annotationNames)
        Set the list of ignore annotations.
        Parameters:
        annotationNames - array of ignore annotations canonical names.
      • setProtectedAllowed

        public void setProtectedAllowed​(boolean protectedAllowed)
        Set whether protected members are allowed.
        Parameters:
        protectedAllowed - whether protected members are allowed
      • setPackageAllowed

        public void setPackageAllowed​(boolean packageAllowed)
        Set whether package visible members are allowed.
        Parameters:
        packageAllowed - whether package visible members are allowed
      • setPublicMemberPattern

        public void setPublicMemberPattern​(java.util.regex.Pattern pattern)
        Set the pattern for public members to ignore.
        Parameters:
        pattern - pattern for public members to ignore.
      • setAllowPublicImmutableFields

        public void setAllowPublicImmutableFields​(boolean allow)
        Sets whether public immutable fields are allowed.
        Parameters:
        allow - user's value.
      • setAllowPublicFinalFields

        public void setAllowPublicFinalFields​(boolean allow)
        Sets whether public final fields are allowed.
        Parameters:
        allow - user's value.
      • setImmutableClassCanonicalNames

        public void setImmutableClassCanonicalNames​(java.lang.String... classNames)
        Set the list of immutable classes types names.
        Parameters:
        classNames - array of immutable types canonical names.
      • 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
      • 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
      • 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 it's 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,
                                                java.lang.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​(java.lang.String variableName,
                                              java.lang.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 java.util.Set<java.lang.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 java.lang.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 and 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 java.util.List<java.lang.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​(java.util.List<java.lang.String> typeArgsClassNames)
        Checks whether all of 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 of 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.
      • getTypeName

        private static java.lang.String getTypeName​(DetailAST type,
                                                    boolean isCanonicalName)
        Gets the name of type from given ast TYPE node. If type is specified via its canonical name - canonical name will be returned, else - short type's name.
        Parameters:
        type - TYPE node.
        isCanonicalName - is given name canonical.
        Returns:
        String representation of given type's name.
      • 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 java.lang.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 java.util.List<java.lang.String> getClassShortNames​(java.util.List<java.lang.String> canonicalClassNames)
        Gets the list with short names classes. These names are taken from array of classes canonical names.
        Parameters:
        canonicalClassNames - canonical class names.
        Returns:
        the list of short names of classes.
      • getClassShortName

        private static java.lang.String getClassShortName​(java.lang.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