Package com.puppycrawl.tools.checkstyle.checks.coding

Class EqualsHashCodeCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.AbstractAutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.puppycrawl.tools.checkstyle.checks.coding.EqualsHashCodeCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class EqualsHashCodeCheck
extends AbstractCheck

Checks that classes that either override equals() or hashCode() also overrides the other. This check only verifies that the method declarations match Object.equals(Object) and Object.hashCode() exactly to be considered an override. This check does not verify invalid method names, parameters other than Object, or anything else.

Rationale: The contract of equals() and hashCode() requires that equal objects have the same hashCode. Therefore, whenever you override equals() you must override hashCode() to ensure that your class can be used in hash-based collections.

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• equals.noEquals
• equals.noHashCode

Since:

3.0

Nested Class Summary

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

AbstractAutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field	Description
static final String	MSG_KEY_EQUALS	A key is pointing to the warning message text in "messages.properties" file.
static final String	MSG_KEY_HASHCODE	A key is pointing to the warning message text in "messages.properties" file.
private final Map<DetailAST,DetailAST>	objBlockWithEquals	Maps OBJ_BLOCK to the method definition of equals().
private final Map<DetailAST,DetailAST>	objBlockWithHashCode	Maps OBJ_BLOCKs to the method definition of hashCode().

Constructor Summary

Constructors

Constructor	Description
EqualsHashCodeCheck()

Method Summary

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

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.AbstractAutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

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

Field Details

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

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

objBlockWithEquals

private final Map<DetailAST,DetailAST> objBlockWithEquals

Maps OBJ_BLOCK to the method definition of equals().

objBlockWithHashCode

private final Map<DetailAST,DetailAST> objBlockWithHashCode

Maps OBJ_BLOCKs to the method definition of hashCode().

Constructor Details

EqualsHashCodeCheck

public EqualsHashCodeCheck()

Method Details

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

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 class AbstractCheck

Parameters:

rootAST - the root of the tree

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

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.

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.

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.

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 class AbstractCheck

Parameters:

rootAST - the root of the tree