Class JavadocMethodCheck

Checks the Javadoc of a method or constructor. The scope to verify is specified using the Scope class and defaults to Scope.PRIVATE. To verify another scope, set property scope to a different scope.

Violates parameters and type parameters for which no param tags are present can be suppressed by defining property allowMissingParamTags.

Violates methods which return non-void but for which no return tag is present can be suppressed by defining property allowMissingReturnTag.

Violates exceptions which are declared to be thrown (by throws in the method signature or by throw new in the method body), but for which no throws tag is present by activation of property validateThrows. Note that throw new is not checked in the following places:

• Inside a try block (with catch). It is not possible to determine if the thrown exception can be caught by the catch block as there is no knowledge of the inheritance hierarchy, so the try block is ignored entirely. However, catch and finally blocks, as well as try blocks without catch, are still checked.
• Local classes, anonymous classes and lambda expressions. It is not known when the throw statements inside such classes are going to be evaluated, so they are ignored.

ATTENTION: Checkstyle does not have information about hierarchy of exception types so usage of base class is considered as separate exception type. As workaround you need to specify both types in javadoc (parent and exact type).

Javadoc is not required on a method that is tagged with the @Override annotation. However under Java 5 it is not possible to mark a method required for an interface (this was corrected under Java 6). Hence Checkstyle supports using the convention of using a single {@inheritDoc} tag instead of all the other tags.

Note that only inheritable items will allow the {@inheritDoc} tag to be used in place of comments. Static methods at all visibilities, private non-static methods and constructors are not inheritable.

For example, if the following method is implementing a method required by an interface, then the Javadoc could be done as:

 /** {@inheritDoc} */
 public int checkReturnTag(final int aTagIndex,
                           JavadocTag[] aTags,
                           int aLineNo)
 

• Property allowedAnnotations - Specify the list of annotations that allow missed documentation. Type is java.lang.String[]. Default value is Override.
• Property validateThrows - Control whether to validate throws tags. Type is boolean. Default value is false.
• Property scope - Specify the visibility scope where Javadoc comments are checked. Type is com.puppycrawl.tools.checkstyle.api.Scope. Default value is private.
• Property excludeScope - Specify the visibility scope where Javadoc comments are not checked. Type is com.puppycrawl.tools.checkstyle.api.Scope. Default value is null.
• Property allowMissingParamTags - Control whether to ignore violations when a method has parameters but does not have matching param tags in the javadoc. Type is boolean. Default value is false.
• Property allowMissingReturnTag - Control whether to ignore violations when a method returns non-void type and does not have a return tag in the javadoc. Type is boolean. Default value is false.
• Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: METHOD_DEF, CTOR_DEF, ANNOTATION_FIELD_DEF, COMPACT_CTOR_DEF.

To configure the default check:

 <module name="JavadocMethod"/>
 

To configure the check for public scope, ignoring any missing param tags is:

 <module name="JavadocMethod">
   <property name="scope" value="public"/>
   <property name="allowMissingParamTags" value="true"/>
 </module>
 

To configure the check for methods which are in private, but not in protected scope:

 <module name="JavadocMethod">
   <property name="scope" value="private"/>
   <property name="excludeScope" value="protected"/>
 </module>
 

To configure the check to validate throws tags, you can use following config.

 <module name="JavadocMethod">
   <property name="validateThrows" value="true"/>
 </module>
 

 /**
  * Actual exception thrown is child class of class that is declared in throws.
  * It is limitation of checkstyle (as checkstyle does not know type hierarchy).
  * Javadoc is valid not declaring FileNotFoundException
  * BUT checkstyle can not distinguish relationship between exceptions.
  * @param file some file
  * @throws IOException if some problem
  */
 public void doSomething8(File file) throws IOException {
     if (file == null) {
         throw new FileNotFoundException(); // violation
     }
 }

 /**
  * Exact throw type referencing in javadoc even first is parent of second type.
  * It is a limitation of checkstyle (as checkstyle does not know type hierarchy).
  * This javadoc is valid for checkstyle and for javadoc tool.
  * @param file some file
  * @throws IOException if some problem
  * @throws FileNotFoundException if file is not found
  */
 public void doSomething9(File file) throws IOException {
     if (file == null) {
         throw new FileNotFoundException();
     }
 }

 /**
  * Ignore try block, but keep catch and finally blocks.
  *
  * @param s String to parse
  * @return A positive integer
  */
 public int parsePositiveInt(String s) {
     try {
         int value = Integer.parseInt(s);
         if (value <= 0) {
             throw new NumberFormatException(value + " is negative/zero"); // ok, try
         }
         return value;
     } catch (NumberFormatException ex) {
         throw new IllegalArgumentException("Invalid number", ex); // violation, catch
     } finally {
         throw new IllegalStateException("Should never reach here"); // violation, finally
     }
 }

 /**
  * Try block without catch is not ignored.
  *
  * @return a String from standard input, if there is one
  */
 public String readLine() {
     try (Scanner sc = new Scanner(System.in)) {
         if (!sc.hasNext()) {
             throw new IllegalStateException("Empty input"); // violation, not caught
         }
         return sc.next();
     }
 }

 /**
  * Lambda expressions are ignored as we do not know when the exception will be thrown.
  *
  * @param s a String to be printed at some point in the future
  * @return a Runnable to be executed when the string is to be printed
  */
 public Runnable printLater(String s) {
     return () -> {
         if (s == null) {
             throw new NullPointerException(); // ok
         }
         System.out.println(s);
     };
 }
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• javadoc.classInfo
• javadoc.duplicateTag
• javadoc.expectedTag
• javadoc.invalidInheritDoc
• javadoc.return.expected
• javadoc.unusedTag
• javadoc.unusedTagGeneral