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 String MSG_KEY
        A key is pointing to the warning message text in "messages.properties" file.
        See Also:
        Constant Field Values
    • Constructor Detail

      • VisibilityModifierCheck

        public VisibilityModifierCheck()
    • Method Detail

      • setIgnoreAnnotationCanonicalNames

        public void setIgnoreAnnotationCanonicalNames​(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​(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​(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