Class WhenShouldBeUsedCheck
- 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.WhenShouldBeUsedCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class WhenShouldBeUsedCheck extends AbstractCheck
Ensures thatwhen
is used instead of a singleif
statement inside a case block.Rationale: Java 21 has introduced enhancements for switch statements and expressions that allow the use of patterns in case labels. The
when
keyword is used to specify condition for a case label, also called as guarded case labels. This syntax is more readable and concise than the singleif
statement inside the pattern match block.See the Java Language Specification for more information about guarded case labels.
See the Java Language Specification for more information about patterns.
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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when.should.be.used
- Since:
- 10.18.0
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Nested Class Summary
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Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
AbstractAutomaticBean.OutputStreamOptions
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Constructor Summary
Constructors Constructor Description WhenShouldBeUsedCheck()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description int[]
getAcceptableTokens()
The configurable token set.private static List<DetailAST>
getBlockStatements(DetailAST statementList)
Get all statements inside the case block.int[]
getDefaultTokens()
Returns the default token a check is interested in.int[]
getRequiredTokens()
The tokens that this check must be registered for.private static DetailAST
getStatementList(DetailAST caseAST)
Get the statement list token of the case block.private static boolean
hasPatternLabel(DetailAST caseAST)
Check if the case block has a pattern variable definition or a record pattern definition.private static boolean
isAcceptableStatement(DetailAST ast)
Check if the statement is an acceptable statement inside the case block.private static boolean
isSingleIfWithNoElse(DetailAST statement)
Check if the case block statement is a single if statement with no else branch.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearViolations, destroy, finishTree, getFileContents, getFilePath, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, 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_KEY
public static final String MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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Constructor Detail
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WhenShouldBeUsedCheck
public WhenShouldBeUsedCheck()
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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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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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getStatementList
private static DetailAST getStatementList(DetailAST caseAST)
Get the statement list token of the case block.- Parameters:
caseAST
- the AST node representingLITERAL_CASE
- Returns:
- the AST node representing
SLIST
of the current case
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getBlockStatements
private static List<DetailAST> getBlockStatements(DetailAST statementList)
Get all statements inside the case block.- Parameters:
statementList
- the AST node representingSLIST
of the current case- Returns:
- statements inside the current case block
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isAcceptableStatement
private static boolean isAcceptableStatement(DetailAST ast)
Check if the statement is an acceptable statement inside the case block. If these statements are the only ones in the case block, this case can be considered a violation. If at least one of the statements is not acceptable, this case can not be a violation.- Parameters:
ast
- the AST node representing the statement- Returns:
- true if the statement is an acceptable statement, false otherwise
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hasPatternLabel
private static boolean hasPatternLabel(DetailAST caseAST)
Check if the case block has a pattern variable definition or a record pattern definition.- Parameters:
caseAST
- the AST node representingLITERAL_CASE
- Returns:
- true if the case block has a pattern label, false otherwise
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isSingleIfWithNoElse
private static boolean isSingleIfWithNoElse(DetailAST statement)
Check if the case block statement is a single if statement with no else branch.- Parameters:
statement
- statement to check inside the current case block- Returns:
- true if the statement is a single if statement with no else branch, false otherwise
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