Class NoWhitespaceBeforeCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks that there is no whitespace before a token.
More specifically, it checks that it is not preceded with whitespace,
or (if linebreaks are allowed) all characters on the line before are
whitespace. To allow linebreaks before a token, set property
allowLineBreaks
to true
. No check occurs before semi-colons in empty
for loop initializers or conditions.
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Property
allowLineBreaks
- Control whether whitespace is allowed if the token is at a linebreak. Type isboolean
. Default value isfalse
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Property
tokens
- tokens to check Type isjava.lang.String[]
. Validation type istokenSet
. Default value is: COMMA, SEMI, POST_INC, POST_DEC, ELLIPSIS, LABELED_STAT.
To configure the check:
<module name="NoWhitespaceBefore"/>
Example:
int foo; foo ++; // violation, whitespace before '++' is not allowed foo++; // OK for (int i = 0 ; i < 5; i++) {} // violation // ^ whitespace before ';' is not allowed for (int i = 0; i < 5; i++) {} // OK int[][] array = { { 1, 2 } , { 3, 4 } }; // violation, whitespace before ',' is not allowed int[][] array2 = { { 1, 2 }, { 3, 4 } }; // OK Lists.charactersOf("foo").listIterator() .forEachRemaining(System.out::print) ; // violation, whitespace before ';' is not allowed { label1 : // violation, whitespace before ':' is not allowed for (int i = 0; i < 10; i++) {} } { label2: // OK while (true) {} }
To configure the check to allow linebreaks before default tokens:
<module name="NoWhitespaceBefore"> <property name="allowLineBreaks" value="true"/> </module>
Example:
int[][] array = { { 1, 2 } , { 3, 4 } }; // OK, linebreak is allowed before ',' int[][] array2 = { { 1, 2 }, { 3, 4 } }; // OK, ideal code void ellipsisExample(String ...params) {}; // violation, whitespace before '...' is not allowed void ellipsisExample2(String ...params) {}; //OK, linebreak is allowed before '...' Lists.charactersOf("foo") .listIterator() .forEachRemaining(System.out::print); // OK
To Configure the check to restrict the use of whitespace before METHOD_REF and DOT tokens:
<module name="NoWhitespaceBefore"> <property name="tokens" value="METHOD_REF"/> <property name="tokens" value="DOT"/> </module>
Example:
Lists.charactersOf("foo").listIterator() .forEachRemaining(System.out::print); // violation, whitespace before '.' is not allowed Lists.charactersOf("foo").listIterator().forEachRemaining(System.out ::print); // violation, // whitespace before '::' is not allowed ^ Lists.charactersOf("foo").listIterator().forEachRemaining(System.out::print); // OK
To configure the check to allow linebreak before METHOD_REF and DOT tokens:
<module name="NoWhitespaceBefore"> <property name="tokens" value="METHOD_REF"/> <property name="tokens" value="DOT"/> <property name="allowLineBreaks" value="true"/> </module>
Example:
Lists .charactersOf("foo") //violation, whitespace before '.' is not allowed .listIterator() .forEachRemaining(System.out ::print); // violation, // ^ whitespace before '::' is not allowed Lists.charactersOf("foo") .listIterator() .forEachRemaining(System.out::print); // OK
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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ws.preceded
- Since:
- 3.0
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Nested Class Summary
Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate boolean
Control whether whitespace is allowed if the token is at a linebreak.static final String
A key is pointing to the warning message text in "messages.properties" file. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint[]
The configurable token set.int[]
Returns the default token a check is interested in.int[]
The tokens that this check must be registered for.private static boolean
isInEmptyForInitializerOrCondition
(DetailAST semicolonAst) Checks that semicolon is in empty for initializer or condition.void
setAllowLineBreaks
(boolean allowLineBreaks) Setter to control whether whitespace is allowed if the token is at a linebreak.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearViolations, destroy, finishTree, getFileContents, 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.api.AutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Details
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MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
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allowLineBreaks
private boolean allowLineBreaksControl whether whitespace is allowed if the token is at a linebreak.
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Constructor Details
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NoWhitespaceBeforeCheck
public NoWhitespaceBeforeCheck()
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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:
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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:
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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:
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visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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isInEmptyForInitializerOrCondition
Checks that semicolon is in empty for initializer or condition.- Parameters:
semicolonAst
- DetailAST of semicolon.- Returns:
- true if semicolon is in empty for initializer or condition.
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setAllowLineBreaks
public void setAllowLineBreaks(boolean allowLineBreaks) Setter to control whether whitespace is allowed if the token is at a linebreak.- Parameters:
allowLineBreaks
- whether whitespace should be flagged at line breaks.
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