com.puppycrawl.tools.checkstyle.checks.blocks

Class EmptyCatchBlockCheck

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.blocks.EmptyCatchBlockCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class EmptyCatchBlockCheck
extends AbstractCheck

Checks for empty catch blocks. There are two options to make validation more precise:

exceptionVariableName - the name of variable associated with exception, if Check meets variable name matching specified value - empty block is suppressed.
default value: "^$"

commentFormat - the format of 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.
default value: ".*"
So, by default Check allows empty catch block with any comment inside.

If both options are specified - they are applied by any of them is matching.

Examples:

To configure the Check to suppress empty catch block if exception's variable name is expected or ignore:

 <module name="EmptyCatchBlock">
    <property name="exceptionVariableName" value="ignore|expected;/>
 </module>
 

Such empty blocks would be both suppressed:

 
 try {
     throw new RuntimeException();
 } catch (RuntimeException expected) {
 }
 
 
 try {
     throw new RuntimeException();
 } catch (RuntimeException ignore) {
 }
 
 

To configure the Check to suppress empty catch block if single-line comment inside is "//This is expected":

 <module name="EmptyCatchBlock">
    <property name="commentFormat" value="This is expected"/>
 </module>
 

Such empty block would be suppressed:

 
 try {
     throw new RuntimeException();
 } catch (RuntimeException ex) {
     //This is expected
 }
 
 

To configure the Check to suppress empty catch block if single-line comment inside is "//This is expected" or exception's variable name is "myException":

 <module name="EmptyCatchBlock">
    <property name="commentFormat" value="This is expected"/>
    <property name="exceptionVariableName" value="myException"/>
 </module>
 

Such empty blocks would be both suppressed:

 
 try {
     throw new RuntimeException();
 } catch (RuntimeException ex) {
     //This is expected
 }
 
 
 try {
     throw new RuntimeException();
 } catch (RuntimeException myException) {

 }
 
 

Author:

Aleksey Nesterenko

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
static String	MSG_KEY_CATCH_BLOCK_EMPTY A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
EmptyCatchBlockCheck()

Method Summary

Modifier and Type	Method and Description
int[]	getAcceptableTokens() The configurable token set.
int[]	getDefaultTokens() Returns the default token a check is interested in.
int[]	getRequiredTokens() The tokens that this check must be registered for.
boolean	isCommentNodesRequired() Whether comment nodes are required or not.
void	setCommentFormat(String commentFormat) Setter for comment format.
void	setExceptionVariableName(String exceptionVariableName) Setter for exception's variable name format.
void	visitToken(DetailAST ast) Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

beginTree, clearMessages, destroy, finishTree, getClassLoader, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, leaveToken, log, log, log, setClassLoader, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

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:

Constant Field Values

Constructor Detail

EmptyCatchBlockCheck

public EmptyCatchBlockCheck()

Method Detail

setExceptionVariableName

public void setExceptionVariableName(String exceptionVariableName)

Setter for exception's variable name format.

Parameters:

exceptionVariableName - format of exception's variable name.

Throws:

org.apache.commons.beanutils.ConversionException - if unable to create Pattern object.

setCommentFormat

public void setCommentFormat(String commentFormat)

Setter for comment format.

Parameters:

commentFormat - format of comment.

Throws:

org.apache.commons.beanutils.ConversionException - if unable to create Pattern object.

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

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