Package com.puppycrawl.tools.checkstyle.checks.blocks

Class EmptyCatchBlockCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.blocks.EmptyCatchBlockCheck
All Implemented Interfaces:
Configurable, Contextualizable
public class EmptyCatchBlockCheck extends AbstractCheck
Checks for empty catch blocks. By default, check allows empty catch block with any comment inside.

There are two options to make validation more precise: exceptionVariableName and commentFormat. If both options are specified - they are applied by any of them is matching.

  • Property commentFormat - Specify the RegExp for the first comment inside empty catch block. If check meets comment inside empty catch block matching specified format - empty block is suppressed. If it is multi-line comment - only its first line is analyzed. Type is java.util.regex.Pattern. Default value is ".*".
  • Property exceptionVariableName - Specify the RegExp for the name of the variable associated with exception. If check meets variable name matching specified value - empty block is suppressed. Type is java.util.regex.Pattern. Default value is "^$".

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • catch.block.empty
Since:
6.4

  • Field Details

    • MSG_KEY_CATCH_BLOCK_EMPTY

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

    • LINE_END_PATTERN

      private static final Pattern LINE_END_PATTERN
      A pattern to split on line ends.

    • exceptionVariableName

      private Pattern exceptionVariableName
      Specify the RegExp for the name of the variable associated with exception. If check meets variable name matching specified value - empty block is suppressed.

    • commentFormat

      private Pattern commentFormat
      Specify the RegExp for the first comment inside empty catch block. If check meets comment inside empty catch block matching specified format - empty block is suppressed. If it is multi-line comment - only its first line is analyzed.

  • Constructor Details

  • Method Details

    • setExceptionVariableName

      public void setExceptionVariableName(Pattern exceptionVariablePattern)
      Setter to specify the RegExp for the name of the variable associated with exception. If check meets variable name matching specified value - empty block is suppressed.
      Parameters:
      exceptionVariablePattern - pattern of exception's variable name.
      Since:
      6.4

    • setCommentFormat

      public void setCommentFormat(Pattern commentPattern)
      Setter to specify the RegExp for the first comment inside empty catch block. If check meets comment inside empty catch block matching specified format - empty block is suppressed. If it is multi-line comment - only its first line is analyzed.
      Parameters:
      commentPattern - pattern of comment.
      Since:
      6.4

    • 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:

    • isCommentNodesRequired

      public boolean isCommentNodesRequired()
      Description copied from class: AbstractCheck
      Whether comment nodes are required or not.
      Overrides:
      isCommentNodesRequired in class AbstractCheck
      Returns:
      false as a default value.

    • 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

    • visitCatchBlock

      private void visitCatchBlock(DetailAST catchAst)
      Visits catch ast node, if it is empty catch block - checks it according to Check's options. If exception's variable name or comment inside block are matching specified regexp - skips from consideration, else - puts violation.
      Parameters:
      catchAst - LITERAL_CATCH

    • getCommentFirstLine

      private static String getCommentFirstLine(DetailAST catchAst)
      Gets the first line of comment in catch block. If comment is single-line - returns it fully, else if comment is multi-line - returns the first line.
      Parameters:
      catchAst - LITERAL_CATCH
      Returns:
      the first line of comment in catch block, "" if no comment was found.

    • isVerifiable

      private boolean isVerifiable(DetailAST emptyCatchAst, String commentContent)
      Checks if current empty catch block is verifiable according to Check's options (exception's variable name and comment format are both in consideration).
      Parameters:
      emptyCatchAst - empty catch LITERAL_CATCH block.
      commentContent - text of comment.
      Returns:
      true if empty catch block is verifiable by Check.

    • isEmptyCatchBlock

      private static boolean isEmptyCatchBlock(DetailAST catchAst)
      Checks if catch block is empty or contains only comments.
      Parameters:
      catchAst - LITERAL_CATCH
      Returns:
      true if catch block is empty.

    • getExceptionVariableName

      private static String getExceptionVariableName(DetailAST catchAst)
      Gets variable's name associated with exception.
      Parameters:
      catchAst - LITERAL_CATCH
      Returns:
      Variable's name associated with exception.