Class EqualsHashCodeCheck
- 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.EqualsHashCodeCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class EqualsHashCodeCheck extends AbstractCheck
Checks that classes that either overrideequals()
orhashCode()
also overrides the other. This check only verifies that the method declarations matchObject.equals(Object)
andObject.hashCode()
exactly to be considered an override. This check does not verify invalid method names, parameters other thanObject
, or anything else.Rationale: The contract of
equals()
andhashCode()
requires that equal objects have the same hashCode. Therefore, whenever you overrideequals()
you must overridehashCode()
to ensure that your class can be used in hash-based collections.Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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equals.noEquals
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equals.noHashCode
- Since:
- 3.0
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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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Field Summary
Fields Modifier and Type Field Description static String
MSG_KEY_EQUALS
A key is pointing to the warning message text in "messages.properties" file.static String
MSG_KEY_HASHCODE
A key is pointing to the warning message text in "messages.properties" file.private Map<DetailAST,DetailAST>
objBlockWithEquals
Maps OBJ_BLOCK to the method definition of equals().private Map<DetailAST,DetailAST>
objBlockWithHashCode
Maps OBJ_BLOCKs to the method definition of hashCode().
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Constructor Summary
Constructors Constructor Description EqualsHashCodeCheck()
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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.void
finishTree(DetailAST rootAST)
Called after finished processing 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
isEqualsMethod(DetailAST ast)
Determines if an AST is a valid Equals method implementation.private static boolean
isHashCodeMethod(DetailAST ast)
Determines if an AST is a valid HashCode method implementation.private static boolean
isObjectParam(DetailAST paramNode)
Determines if an AST is a formal param of type Object.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearViolations, destroy, 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_HASHCODE
public static final String MSG_KEY_HASHCODE
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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MSG_KEY_EQUALS
public static final String MSG_KEY_EQUALS
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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objBlockWithEquals
private final Map<DetailAST,DetailAST> objBlockWithEquals
Maps OBJ_BLOCK to the method definition of equals().
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objBlockWithHashCode
private final Map<DetailAST,DetailAST> objBlockWithHashCode
Maps OBJ_BLOCKs to the method definition of hashCode().
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Constructor Detail
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EqualsHashCodeCheck
public EqualsHashCodeCheck()
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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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isEqualsMethod
private static boolean isEqualsMethod(DetailAST ast)
Determines if an AST is a valid Equals method implementation.- Parameters:
ast
- the AST to check- Returns:
- true if the {code ast} is an Equals method.
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isHashCodeMethod
private static boolean isHashCodeMethod(DetailAST ast)
Determines if an AST is a valid HashCode method implementation.- Parameters:
ast
- the AST to check- Returns:
- true if the {code ast} is a HashCode method.
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isObjectParam
private static boolean isObjectParam(DetailAST paramNode)
Determines if an AST is a formal param of type Object.- Parameters:
paramNode
- the AST to check- Returns:
- true if firstChild is a parameter of an Object type.
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finishTree
public void finishTree(DetailAST rootAST)
Description copied from class:AbstractCheck
Called after finished processing a tree. Ideal place to report on information collected whilst processing a tree.- Overrides:
finishTree
in classAbstractCheck
- Parameters:
rootAST
- the root of the tree
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