Class EqualsAvoidNullCheck
java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractCheck
com.puppycrawl.tools.checkstyle.checks.coding.EqualsAvoidNullCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks that any combination of String literals
is on the left side of an equals()
comparison.
Also checks for String literals assigned to some field
(such as someString.equals(anotherString = "text")
).
Rationale: Calling the equals()
method on String literals
will avoid a potential NullPointerException
. Also, it is
pretty common to see null checks right before equals comparisons,
which is not necessary in the example below.
For example, this code:
String nullString = null; nullString.equals("My_Sweet_String");
should be refactored to:
String nullString = null; "My_Sweet_String".equals(nullString);
-
Property
ignoreEqualsIgnoreCase
- Control whether to ignoreString.equalsIgnoreCase(String)
invocations. Type isboolean
. Default value isfalse
.
To configure the check:
<module name="EqualsAvoidNull"/>
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
equals.avoid.null
-
equalsIgnoreCase.avoid.null
- Since:
- 5.0
-
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 TypeMethodDescriptionvoid
Called before the starting to process a tree.void
finishTree
(DetailAST ast) Called after finished processing a tree.int[]
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
setIgnoreEqualsIgnoreCase
(boolean newValue) Setter to control whether to ignoreString.equalsIgnoreCase(String)
invocations.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearMessages, destroy, 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
-
MSG_EQUALS_AVOID_NULL
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
MSG_EQUALS_IGNORE_CASE_AVOID_NULL
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
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Constructor Details
-
EqualsAvoidNullCheck
public EqualsAvoidNullCheck()
-
-
Method Details
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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:
-
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:
-
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:
-
setIgnoreEqualsIgnoreCase
public void setIgnoreEqualsIgnoreCase(boolean newValue) Setter to control whether to ignoreString.equalsIgnoreCase(String)
invocations.- Parameters:
newValue
- whether to ignore checkingString.equalsIgnoreCase(String)
.
-
beginTree
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
-
visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
-
leaveToken
Description copied from class:AbstractCheck
Called after all the child nodes have been process.- Overrides:
leaveToken
in classAbstractCheck
- Parameters:
ast
- the token leaving
-
finishTree
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:
ast
- the root of the tree
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