Class MutableExceptionCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Ensures that exception classes (classes with names conforming to some regular expression and explicitly extending classes with names conforming to other regular expression) are immutable, that is, that they have only final fields.
The current algorithm is very simple: it checks that all members of exception are final.
The user can still mutate an exception's instance (e.g. Throwable has a method called
setStackTrace
which changes the exception's stack trace). But, at least, all
information provided by this exception type is unchangeable.
Rationale: Exception instances should represent an error condition. Having non final fields not only allows the state to be modified by accident and therefore mask the original condition but also allows developers to accidentally forget to set the initial state. In both cases, code catching the exception could draw incorrect conclusions based on the state.
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Property
format
- Specify pattern for exception class names. Type isjava.util.regex.Pattern
. Default value is"^.*Exception$|^.*Error$|^.*Throwable$"
. -
Property
extendedClassNameFormat
- Specify pattern for extended class names. Type isjava.util.regex.Pattern
. Default value is"^.*Exception$|^.*Error$|^.*Throwable$"
.
To configure the check:
<module name="MutableException"/>
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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mutable.exception
- Since:
- 3.2
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Nested Class Summary
Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint[]
The configurable token set.int[]
Returns the default token a check is interested in.int[]
The tokens that this check must be registered for.void
leaveToken
(DetailAST ast) Called after all the child nodes have been process.void
setExtendedClassNameFormat
(Pattern extendedClassNameFormat) Setter to specify pattern for extended class names.void
Setter to specify pattern for exception class names.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, log, log, log, 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
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Field Details
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MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
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Constructor Details
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MutableExceptionCheck
public MutableExceptionCheck()
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Method Details
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setExtendedClassNameFormat
Setter to specify pattern for extended class names.- Parameters:
extendedClassNameFormat
- aString
value
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setFormat
Setter to specify pattern for exception class names.- Parameters:
pattern
- the new pattern
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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 classAbstractCheck
- Returns:
- the default tokens
- See Also:
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getRequiredTokens
public int[] getRequiredTokens()Description copied from class:AbstractCheck
The tokens that this check must be registered for.- Specified by:
getRequiredTokens
in classAbstractCheck
- Returns:
- the token set this must be registered for.
- See Also:
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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 classAbstractCheck
- Returns:
- the token set this check is designed for.
- See Also:
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visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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leaveToken
Description copied from class:AbstractCheck
Called after all the child nodes have been process.- Overrides:
leaveToken
in classAbstractCheck
- Parameters:
ast
- the token leaving
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