Class EmptyLineSeparatorCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks for empty line separators before package, all import declarations, fields, constructors, methods, nested classes, static initializers and instance initializers.
Checks for empty line separators before not only statements but implementation and documentation comments and blocks as well.
ATTENTION: empty line separator is required between token siblings, not after line where token is found. If token does not have same type sibling then empty line is required at its end (for example for CLASS_DEF it is after '}'). Also, trailing comments are skipped.
ATTENTION: violations from multiple empty lines cannot be suppressed via XPath: #8179.
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Property
allowNoEmptyLineBetweenFields
- Allow no empty line between fields. Type isboolean
. Default value isfalse
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Property
allowMultipleEmptyLines
- Allow multiple empty lines between class members. Type isboolean
. Default value istrue
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Property
allowMultipleEmptyLinesInsideClassMembers
- Allow multiple empty lines inside class members. Type isboolean
. Default value istrue
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Property
tokens
- tokens to check Type isjava.lang.String[]
. Validation type istokenSet
. Default value is: PACKAGE_DEF, IMPORT, STATIC_IMPORT, CLASS_DEF, INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF, VARIABLE_DEF, RECORD_DEF, COMPACT_CTOR_DEF.
To configure the default check:
<module name="EmptyLineSeparator"/>
Example of declarations without empty line separator:
/////////////////////////////////////////////////// //HEADER /////////////////////////////////////////////////// package com.whitespace; // violation, 'package' should be separated from previous line. import java.io.Serializable; // violation, 'import' should be separated from previous line. class Foo { // violation, 'CLASS_DEF' should be separated from previous line. public static final int FOO_CONST = 1; public void foo() {} // violation, 'METHOD_DEF' should be separated from previous line. }
Example of declarations with empty line separator that is expected by the Check by default:
/////////////////////////////////////////////////// //HEADER /////////////////////////////////////////////////// package com.puppycrawl.tools.checkstyle.whitespace; import java.io.Serializable; class Foo { public static final int FOO_CONST = 1; public void foo() {} }
To check empty line before VARIABLE_DEF and METHOD_DEF:
<module name="EmptyLineSeparator"> <property name="tokens" value="VARIABLE_DEF, METHOD_DEF"/> </module>
To allow no empty line between fields:
<module name="EmptyLineSeparator"> <property name="allowNoEmptyLineBetweenFields" value="true"/> </module>
Example:
class Foo { int field1; // ok double field2; // ok long field3, field4 = 10L, field5; // ok }
Example of declarations with multiple empty lines between class members (allowed by default):
/////////////////////////////////////////////////// //HEADER /////////////////////////////////////////////////// package com.puppycrawl.tools.checkstyle.whitespace; import java.io.Serializable; class Foo { public static final int FOO_CONST = 1; public void foo() {} // OK }
To disallow multiple empty lines between class members:
<module name="EmptyLineSeparator"> <property name="allowMultipleEmptyLines" value="false"/> </module>
/////////////////////////////////////////////////// //HEADER /////////////////////////////////////////////////// package com.checkstyle.whitespace; // violation, 'package' has more than 1 empty lines before. import java.io.Serializable; // violation, 'import' has more than 1 empty lines before. class Foo { // violation, 'CLASS_DEF' has more than 1 empty lines before. public static final int FOO_CONST = 1; public void foo() {} // violation, 'METHOD_DEF' has more than 1 empty lines before. }
To disallow multiple empty lines inside constructor, initialization block and method:
<module name="EmptyLineSeparator"> <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/> </module>
The check is valid only for statements that have body: CLASS_DEF, INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF.
Example of declarations with multiple empty lines inside method:
/////////////////////////////////////////////////// //HEADER /////////////////////////////////////////////////// package com.puppycrawl.tools.checkstyle.whitespace; class Foo { public void foo() { System.out.println(1); // violation, There is more than 1 empty line one after another // in previous line. } }
To disallow multiple empty lines between class members:
<module name="EmptyLineSeparator"> <property name="allowMultipleEmptyLines" value="false"/> </module>
Example:
package com.puppycrawl.tools.checkstyle.whitespace; class Test { private int k; private static void foo() {} // violation, 'METHOD_DEF' has more than 1 empty lines before. }
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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empty.line.separator
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empty.line.separator.multiple.lines
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empty.line.separator.multiple.lines.after
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empty.line.separator.multiple.lines.inside
- Since:
- 5.8
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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
Allow multiple empty lines between class members.private boolean
Allow multiple empty lines inside class members.private boolean
Allow no empty line between fields.static final String
A key is pointing to the warning message empty.line.separator.multiple.lines in "messages.properties" file.static final String
A key is pointing to the warning message empty.line.separator.lines.after in "messages.properties" file.static final String
A key is pointing to the warning message empty.line.separator.multiple.lines.inside in "messages.properties" file.static final String
A key is pointing to the warning message empty.line.separator in "messages.properties" file. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate void
checkCommentInModifiers
(DetailAST packageDef) Checks that packageDef token is separated from comment in modifiers.private void
checkComments
(DetailAST token) Check if group of comments located right before token has more than one previous empty line.private void
Check if group of comments located at the start of token has more than one previous empty line.private void
checkToken
(DetailAST ast, DetailAST nextToken) Checks that token and next token are separated.findCommentUnder
(DetailAST packageDef) Finds comment in next sibling of given packageDef.int[]
The configurable token set.int[]
Returns the default token a check is interested in.getEmptyLines
(DetailAST ast) Get list of empty lines.getEmptyLinesToLog
(List<Integer> emptyLines) Get list of empty lines to log.private static DetailAST
getLastElementBeforeEmptyLines
(DetailAST ast, int line) Returns the element after which empty lines exist.getPostFixNode
(DetailAST ast) Gets postfix Node from AST if present.int[]
The tokens that this check must be registered for.private static DetailAST
Gets the Ast on which violation is to be given for package declaration.private boolean
hasEmptyLine
(int startLine, int endLine) Checks, whether there are empty lines within the specified line range.private boolean
hasEmptyLineAfter
(DetailAST token) Checks if token have empty line after.private boolean
hasEmptyLineBefore
(DetailAST token) Checks if a token has a empty line before.private boolean
Whether the token has not allowed multiple empty lines before.private boolean
Checks if a token has empty two previous lines and multiple empty lines is not allowed.private static boolean
isClassMemberBlock
(int astType) Whether the AST is a class member block.private boolean
isCommentInBeginningOfLine
(DetailAST comment) Check if token is comment, which starting in beginning of line.boolean
Whether comment nodes are required or not.private static boolean
Checks if there is another element at next line of package declaration.private static boolean
isPrecededByJavadoc
(DetailAST token) Check if token is preceded by javadoc comment.private boolean
isPrePreviousLineEmpty
(DetailAST token) Checks if a token has empty pre-previous line.private static boolean
isTypeField
(DetailAST variableDef) If variable definition is a type field.private boolean
isViolatingEmptyLineBetweenFieldsPolicy
(DetailAST detailAST) Checks whether token placement violates policy of empty line between fields.private void
processImport
(DetailAST ast, DetailAST nextToken) Process Import.private void
Log violation in case there are multiple empty lines inside constructor, initialization block or method.private void
processPackage
(DetailAST ast, DetailAST nextToken) Process Package.private void
processVariableDef
(DetailAST ast, DetailAST nextToken) Process Variable.void
setAllowMultipleEmptyLines
(boolean allow) Setter to allow multiple empty lines between class members.void
setAllowMultipleEmptyLinesInsideClassMembers
(boolean allow) Setter to allow multiple empty lines inside class members.final void
setAllowNoEmptyLineBetweenFields
(boolean allow) Setter to allow no empty line between fields.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, 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_SHOULD_BE_SEPARATED
A key is pointing to the warning message empty.line.separator in "messages.properties" file.- See Also:
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MSG_MULTIPLE_LINES
A key is pointing to the warning message empty.line.separator.multiple.lines in "messages.properties" file.- See Also:
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MSG_MULTIPLE_LINES_AFTER
A key is pointing to the warning message empty.line.separator.lines.after in "messages.properties" file.- See Also:
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MSG_MULTIPLE_LINES_INSIDE
A key is pointing to the warning message empty.line.separator.multiple.lines.inside in "messages.properties" file.- See Also:
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allowNoEmptyLineBetweenFields
private boolean allowNoEmptyLineBetweenFieldsAllow no empty line between fields. -
allowMultipleEmptyLines
private boolean allowMultipleEmptyLinesAllow multiple empty lines between class members. -
allowMultipleEmptyLinesInsideClassMembers
private boolean allowMultipleEmptyLinesInsideClassMembersAllow multiple empty lines inside class members.
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Constructor Details
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EmptyLineSeparatorCheck
public EmptyLineSeparatorCheck()
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Method Details
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setAllowNoEmptyLineBetweenFields
public final void setAllowNoEmptyLineBetweenFields(boolean allow) Setter to allow no empty line between fields.- Parameters:
allow
- User's value.
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setAllowMultipleEmptyLines
public void setAllowMultipleEmptyLines(boolean allow) Setter to allow multiple empty lines between class members.- Parameters:
allow
- User's value.
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setAllowMultipleEmptyLinesInsideClassMembers
public void setAllowMultipleEmptyLinesInsideClassMembers(boolean allow) Setter to allow multiple empty lines inside class members.- Parameters:
allow
- User's value.
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isCommentNodesRequired
public boolean isCommentNodesRequired()Description copied from class:AbstractCheck
Whether comment nodes are required or not.- Overrides:
isCommentNodesRequired
in classAbstractCheck
- Returns:
- false as a default value.
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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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checkToken
Checks that token and next token are separated.- Parameters:
ast
- token to validatenextToken
- next sibling of the token
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checkCommentInModifiers
Checks that packageDef token is separated from comment in modifiers.- Parameters:
packageDef
- package def token
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processMultipleLinesInside
Log violation in case there are multiple empty lines inside constructor, initialization block or method.- Parameters:
ast
- the ast to check.
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getLastElementBeforeEmptyLines
Returns the element after which empty lines exist.- Parameters:
ast
- the ast to check.line
- the empty line which gives violation.- Returns:
- The DetailAST after which empty lines are present.
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getPostFixNode
Gets postfix Node from AST if present.- Parameters:
ast
- the AST used to get postfix Node.- Returns:
- Optional postfix node.
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isClassMemberBlock
private static boolean isClassMemberBlock(int astType) Whether the AST is a class member block.- Parameters:
astType
- the AST to check.- Returns:
- true if the AST is a class member block.
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getEmptyLines
Get list of empty lines.- Parameters:
ast
- the ast to check.- Returns:
- list of line numbers for empty lines.
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getEmptyLinesToLog
Get list of empty lines to log.- Parameters:
emptyLines
- list of empty lines.- Returns:
- list of empty lines to log.
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hasMultipleLinesBefore
Whether the token has not allowed multiple empty lines before.- Parameters:
ast
- the ast to check.- Returns:
- true if the token has not allowed multiple empty lines before.
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processPackage
Process Package.- Parameters:
ast
- tokennextToken
- next token
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isLineEmptyAfterPackage
Checks if there is another element at next line of package declaration.- Parameters:
ast
- Package ast.- Returns:
- true, if there is an element.
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getViolationAstForPackage
Gets the Ast on which violation is to be given for package declaration.- Parameters:
ast
- Package ast.- Returns:
- Violation ast.
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processImport
Process Import.- Parameters:
ast
- tokennextToken
- next token
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processVariableDef
Process Variable.- Parameters:
ast
- tokennextToken
- next Token
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isViolatingEmptyLineBetweenFieldsPolicy
Checks whether token placement violates policy of empty line between fields.- Parameters:
detailAST
- token to be analyzed- Returns:
- true if policy is violated and warning should be raised; false otherwise
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hasNotAllowedTwoEmptyLinesBefore
Checks if a token has empty two previous lines and multiple empty lines is not allowed.- Parameters:
token
- DetailAST token- Returns:
- true, if token has empty two lines before and allowMultipleEmptyLines is false
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checkComments
Check if group of comments located right before token has more than one previous empty line.- Parameters:
token
- DetailAST token
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checkCommentsInsideToken
Check if group of comments located at the start of token has more than one previous empty line.- Parameters:
token
- DetailAST token
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isPrePreviousLineEmpty
Checks if a token has empty pre-previous line.- Parameters:
token
- DetailAST token.- Returns:
- true, if token has empty lines before.
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hasEmptyLineAfter
Checks if token have empty line after.- Parameters:
token
- token.- Returns:
- true if token have empty line after.
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findCommentUnder
Finds comment in next sibling of given packageDef.- Parameters:
packageDef
- token to check- Returns:
- comment under the token
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hasEmptyLine
private boolean hasEmptyLine(int startLine, int endLine) Checks, whether there are empty lines within the specified line range. Line numbering is started from 1 for parameter values- Parameters:
startLine
- number of the first line in the rangeendLine
- number of the second line in the range- Returns:
true
if found any blank line within the range,false
otherwise
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hasEmptyLineBefore
Checks if a token has a empty line before.- Parameters:
token
- token.- Returns:
- true, if token have empty line before.
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isCommentInBeginningOfLine
Check if token is comment, which starting in beginning of line.- Parameters:
comment
- comment token for check.- Returns:
- true, if token is comment, which starting in beginning of line.
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isPrecededByJavadoc
Check if token is preceded by javadoc comment.- Parameters:
token
- token for check.- Returns:
- true, if token is preceded by javadoc comment.
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isTypeField
If variable definition is a type field.- Parameters:
variableDef
- variable definition.- Returns:
- true variable definition is a type field.
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