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

Class FinalClassCheck

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.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 Details

    • MSG_KEY

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

    • PACKAGE_SEPARATOR

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

    • classes

      private Deque<FinalClassCheck.ClassDesc> classes
      Keeps ClassDesc objects for stack of declared classes.

    • packageName

      private String packageName
      Full qualified name of the package.

  • Constructor Details

    • FinalClassCheck

      public FinalClassCheck()

  • 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:

    • 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

    • 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 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 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 String getQualifiedClassName(String packageName, String outerClassQualifiedName, 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 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(String superClassQualifiedName, 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 String getClassNameFromQualifiedName(String qualifiedName)
      Get class name from qualified name.
      Parameters:
      qualifiedName - qualified class name
      Returns:
      class name