Class UnusedCatchParameterShouldBeUnnamedCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
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- com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
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- com.puppycrawl.tools.checkstyle.api.AbstractCheck
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- com.puppycrawl.tools.checkstyle.checks.coding.UnusedCatchParameterShouldBeUnnamedCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class UnusedCatchParameterShouldBeUnnamedCheck extends AbstractCheck
Ensures that catch parameters that are not used are declared as an unnamed variable.Rationale:
- Improves code readability by clearly indicating which parameters are unused.
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Follows Java conventions for denoting unused parameters with an underscore (
_
).
See the Java Language Specification for more information about unnamed variables.
Attention: This check should be activated only on source code that is compiled by jdk21 or higher; unnamed catch parameters came out as the first preview in Java 21.
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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unused.catch.parameter
- Since:
- 10.18.0
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Nested Class Summary
Nested Classes Modifier and Type Class Description private static class
UnusedCatchParameterShouldBeUnnamedCheck.CatchParameterDetails
Maintains information about the catch parameter.-
Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
AbstractAutomaticBean.OutputStreamOptions
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Field Summary
Fields Modifier and Type Field Description private Deque<UnusedCatchParameterShouldBeUnnamedCheck.CatchParameterDetails>
catchParameters
Keeps track of the catch parameters in a block.private static int[]
INVALID_CATCH_PARAM_IDENT_PARENTS
Invalid parents of the catch parameter identifier.static String
MSG_UNUSED_CATCH_PARAMETER
A key is pointing to the warning message text in "messages.properties" file.
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Constructor Summary
Constructors Constructor Description UnusedCatchParameterShouldBeUnnamedCheck()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
beginTree(DetailAST rootAST)
Called before the starting to process a tree.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.private static boolean
isCatchParameterIdentifierCandidate(DetailAST identifierAst)
Visit ast of typeTokenTypes.IDENT
and check if it is a candidate for a catch parameter identifier.private static boolean
isLeftHandOfAssignment(DetailAST identAst)
Check if the givenTokenTypes.IDENT
is a left hand side value.private static boolean
isMethodInvocation(DetailAST identAst)
Check if the givenTokenTypes.IDENT
is a child of a dot operator and is a candidate for catch parameter.void
leaveToken(DetailAST ast)
Called after all the child nodes have been process.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearViolations, destroy, finishTree, getFileContents, getFilePath, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, log, log, log, setFileContents, setTabWidth, setTokens
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity
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Methods inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Detail
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MSG_UNUSED_CATCH_PARAMETER
public static final String MSG_UNUSED_CATCH_PARAMETER
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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INVALID_CATCH_PARAM_IDENT_PARENTS
private static final int[] INVALID_CATCH_PARAM_IDENT_PARENTS
Invalid parents of the catch parameter identifier.
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catchParameters
private final Deque<UnusedCatchParameterShouldBeUnnamedCheck.CatchParameterDetails> catchParameters
Keeps track of the catch parameters in a block.
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Constructor Detail
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UnusedCatchParameterShouldBeUnnamedCheck
public UnusedCatchParameterShouldBeUnnamedCheck()
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Method Detail
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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:
TokenTypes
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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:
TokenTypes
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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:
TokenTypes
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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 classAbstractCheck
- Parameters:
rootAST
- the root of the tree
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visitToken
public void visitToken(DetailAST ast)
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
public void leaveToken(DetailAST ast)
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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isCatchParameterIdentifierCandidate
private static boolean isCatchParameterIdentifierCandidate(DetailAST identifierAst)
Visit ast of typeTokenTypes.IDENT
and check if it is a candidate for a catch parameter identifier.- Parameters:
identifierAst
- token representingTokenTypes.IDENT
- Returns:
- true if the given
TokenTypes.IDENT
could be a catch parameter identifier
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isMethodInvocation
private static boolean isMethodInvocation(DetailAST identAst)
Check if the givenTokenTypes.IDENT
is a child of a dot operator and is a candidate for catch parameter.- Parameters:
identAst
- token representingTokenTypes.IDENT
- Returns:
- true if the given
TokenTypes.IDENT
is a child of a dot operator and a candidate for catch parameter.
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isLeftHandOfAssignment
private static boolean isLeftHandOfAssignment(DetailAST identAst)
Check if the givenTokenTypes.IDENT
is a left hand side value.- Parameters:
identAst
- token representingTokenTypes.IDENT
- Returns:
- true if the given
TokenTypes.IDENT
is a left hand side value.
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