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

Class FinalClassCheck

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

    Checks that a class which has only private constructors is declared as final. Doesn't check for classes nested in interfaces or annotations, as they are always final there.

    To configure the check: 

     <module name="FinalClass"/>

    Example: 

     final class MyClass {  // OK
   private MyClass() { }
 }

 class MyClass { // violation, class should be declared final
   private MyClass() { }
 }

 class MyClass { // OK, since it has a public constructor
   int field1;
   String field2;
   private MyClass(int value) {
     this.field1 = value;
     this.field2 = " ";
   }
   public MyClass(String value) {
     this.field2 = value;
     this.field1 = 0;
   }
 }

 interface CheckInterface
 {
   class MyClass { // OK, nested class in interface is always final
     private MyClass() {}
   }
 }

 public @interface Test {
   public boolean enabled()
   default true;
   class MyClass { // OK, class nested in an annotation is always final
     private MyClass() { }
   }
 }

 class TestAnonymousInnerClasses { // OK, class has an anonymous inner class.
     public static final TestAnonymousInnerClasses ONE = new TestAnonymousInnerClasses() {

     };

     private TestAnonymousInnerClasses() {
     }
 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • final.class
    Since:
    3.1

    • 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

      • PACKAGE_SEPARATOR

        private static final java.lang.String PACKAGE_SEPARATOR
        Character separate package names in qualified name of java class.
        See Also:
        Constant Field Values

      • packageName

        private java.lang.String packageName
        Full qualified name of the package.

    • Constructor Detail

      • FinalClassCheck

        public FinalClassCheck()

    • Method Detail

      • 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

      • leaveToken

        public void leaveToken​(DetailAST ast)
        Description copied from class: AbstractCheck
        Called after all the child nodes have been process.
        Overrides:
        leaveToken in class AbstractCheck
        Parameters:
        ast - the token leaving

      • extractQualifiedName

        private static java.lang.String extractQualifiedName​(DetailAST ast)
        Get name of class (with qualified package if specified) in ast.
        Parameters:
        ast - ast to extract class name from
        Returns:
        qualified name

      • registerNestedSubclassToOuterSuperClasses

        private void registerNestedSubclassToOuterSuperClasses​(DetailAST classAst)
        Register to outer super classes of given classAst that given classAst is extending them.
        Parameters:
        classAst - class which outer super classes will be informed about nesting subclass

      • doesNameOfClassMatchAnonymousInnerClassName

        private static boolean doesNameOfClassMatchAnonymousInnerClassName​(DetailAST ast,
                                                                   FinalClassCheck.ClassDesc classDesc)
        Check if class name matches with anonymous inner class name.
        Parameters:
        ast - current ast.
        classDesc - class to match.
        Returns:
        true if current class name matches anonymous inner class name.

      • getQualifiedClassName

        private java.lang.String getQualifiedClassName​(DetailAST classAst)
        Get qualified class name from given class Ast.
        Parameters:
        classAst - class to get qualified class name
        Returns:
        qualified class name of a class

      • getQualifiedClassName

        private static java.lang.String getQualifiedClassName​(java.lang.String packageName,
                                                      java.lang.String outerClassQualifiedName,
                                                      java.lang.String className)
        Calculate qualified class name(package + class name) laying inside given outer class.
        Parameters:
        packageName - package name, empty string on default package
        outerClassQualifiedName - qualified name(package + class) of outer class, null if doesn't exist
        className - class name
        Returns:
        qualified class name(package + class name)

      • getSuperClassName

        private static java.lang.String getSuperClassName​(DetailAST classAst)
        Get super class name of given class.
        Parameters:
        classAst - class
        Returns:
        super class name or null if super class is not specified

      • doesNameInExtendMatchSuperClassName

        private static boolean doesNameInExtendMatchSuperClassName​(java.lang.String superClassQualifiedName,
                                                           java.lang.String superClassInExtendClause)
        Checks if given super class name in extend clause match super class qualified name.
        Parameters:
        superClassQualifiedName - super class qualified name (with package)
        superClassInExtendClause - name in extend clause
        Returns:
        true if given super class name in extend clause match super class qualified name, false otherwise

      • getClassNameFromQualifiedName

        private static java.lang.String getClassNameFromQualifiedName​(java.lang.String qualifiedName)
        Get class name from qualified name.
        Parameters:
        qualifiedName - qualified class name
        Returns:
        class name