EmptyLineSeparatorCheck (checkstyle 9.0.1 API)

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.whitespace.EmptyLineSeparatorCheck

All Implemented Interfaces:: Configurable, Contextualizable

public class EmptyLineSeparatorCheck
extends AbstractCheck

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.

Property allowNoEmptyLineBetweenFields - Allow no empty line between fields. Type is boolean. Default value is false.
Property allowMultipleEmptyLines - Allow multiple empty lines between class members. Type is boolean. Default value is true.
Property allowMultipleEmptyLinesInsideClassMembers - Allow multiple empty lines inside class members. Type is boolean. Default value is true.
Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. 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:

empty.line.separator
empty.line.separator.multiple.lines
empty.line.separator.multiple.lines.after
empty.line.separator.multiple.lines.inside

Since:: 5.8

Nested Class Summary
- Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
  AutomaticBean.OutputStreamOptions

Field Summary

Fields
Modifier and Type	Field and Description
`private boolean`	`allowMultipleEmptyLines` Allow multiple empty lines between class members.
`private boolean`	`allowMultipleEmptyLinesInsideClassMembers` Allow multiple empty lines inside class members.
`private boolean`	`allowNoEmptyLineBetweenFields` Allow no empty line between fields.
`static java.lang.String`	`MSG_MULTIPLE_LINES` A key is pointing to the warning message empty.line.separator.multiple.lines in "messages.properties" file.
`static java.lang.String`	`MSG_MULTIPLE_LINES_AFTER` A key is pointing to the warning message empty.line.separator.lines.after in "messages.properties" file.
`static java.lang.String`	`MSG_MULTIPLE_LINES_INSIDE` A key is pointing to the warning message empty.line.separator.multiple.lines.inside in "messages.properties" file.
`static java.lang.String`	`MSG_SHOULD_BE_SEPARATED` A key is pointing to the warning message empty.line.separator in "messages.properties" file.

Constructor Summary

Constructors
Constructor and Description

EmptyLineSeparatorCheck()

Constructors
Constructor and Description
`EmptyLineSeparatorCheck()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`private 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`	`checkCommentsInsideToken(DetailAST token)` 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.
`private static java.util.Optional<DetailAST>`	`findCommentUnder(DetailAST packageDef)` Finds comment in next sibling of given packageDef.
`int[]`	`getAcceptableTokens()` The configurable token set.
`int[]`	`getDefaultTokens()` Returns the default token a check is interested in.
`private java.util.List<java.lang.Integer>`	`getEmptyLines(DetailAST ast)` Get list of empty lines.
`private static java.util.List<java.lang.Integer>`	`getEmptyLinesToLog(java.util.List<java.lang.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.
`private static java.util.Optional<DetailAST>`	`getPostFixNode(DetailAST ast)` Gets postfix Node from AST if present.
`int[]`	`getRequiredTokens()` The tokens that this check must be registered for.
`private static DetailAST`	`getViolationAstForPackage(DetailAST ast)` 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`	`hasMultipleLinesBefore(DetailAST ast)` Whether the token has not allowed multiple empty lines before.
`private boolean`	`hasNotAllowedTwoEmptyLinesBefore(DetailAST token)` 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`	`isCommentNodesRequired()` Whether comment nodes are required or not.
`private static boolean`	`isLineEmptyAfterPackage(DetailAST ast)` 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`	`processMultipleLinesInside(DetailAST ast)` 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.
`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, 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

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - MSG_SHOULD_BE_SEPARATED
```
public static final java.lang.String MSG_SHOULD_BE_SEPARATED
```
    A key is pointing to the warning message empty.line.separator in "messages.properties" file.
    
    See Also:
    
    Constant Field Values
  - MSG_MULTIPLE_LINES
```
public static final java.lang.String MSG_MULTIPLE_LINES
```
    A key is pointing to the warning message empty.line.separator.multiple.lines in "messages.properties" file.
    
    See Also:
    
    Constant Field Values
  - MSG_MULTIPLE_LINES_AFTER
```
public static final java.lang.String MSG_MULTIPLE_LINES_AFTER
```
    A key is pointing to the warning message empty.line.separator.lines.after in "messages.properties" file.
    
    See Also:
    
    Constant Field Values
  - MSG_MULTIPLE_LINES_INSIDE
```
public static final java.lang.String MSG_MULTIPLE_LINES_INSIDE
```
    A key is pointing to the warning message empty.line.separator.multiple.lines.inside in "messages.properties" file.
    
    See Also:
    
    Constant Field Values
  - allowNoEmptyLineBetweenFields
```
private boolean allowNoEmptyLineBetweenFields
```
    Allow no empty line between fields.
  - allowMultipleEmptyLines
```
private boolean allowMultipleEmptyLines
```
    Allow multiple empty lines between class members.
  - allowMultipleEmptyLinesInsideClassMembers
```
private boolean allowMultipleEmptyLinesInsideClassMembers
```
    Allow multiple empty lines inside class members.
- Constructor Detail
  - EmptyLineSeparatorCheck
```
public EmptyLineSeparatorCheck()
```
- Method Detail
  - setAllowNoEmptyLineBetweenFields
```
public final void setAllowNoEmptyLineBetweenFields(boolean allow)
```
    Setter to allow no empty line between fields.
    
    Parameters:
    
    allow - User's value.
  - setAllowMultipleEmptyLines
```
public void setAllowMultipleEmptyLines(boolean allow)
```
    Setter to allow multiple empty lines between class members.
    
    Parameters:
    
    allow - User's value.
  - setAllowMultipleEmptyLinesInsideClassMembers
```
public void setAllowMultipleEmptyLinesInsideClassMembers(boolean allow)
```
    Setter to allow multiple empty lines inside class members.
    
    Parameters:
    
    allow - User's value.
  - isCommentNodesRequired
```
public boolean isCommentNodesRequired()
```
    Description copied from class: AbstractCheck
    
    Whether comment nodes are required or not.
    
    Overrides:
    
    isCommentNodesRequired in class AbstractCheck
    
    Returns:
    
    false as a default value.
  - 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
  - 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
  - checkToken
```
private void checkToken(DetailAST ast,
                        DetailAST nextToken)
```
    Checks that token and next token are separated.
    
    Parameters:
    
    ast - token to validate
    
    nextToken - next sibling of the token
  - checkCommentInModifiers
```
private void checkCommentInModifiers(DetailAST packageDef)
```
    Checks that packageDef token is separated from comment in modifiers.
    
    Parameters:
    
    packageDef - package def token
  - processMultipleLinesInside
```
private void processMultipleLinesInside(DetailAST ast)
```
    Log violation in case there are multiple empty lines inside constructor, initialization block or method.
    
    Parameters:
    
    ast - the ast to check.
  - getLastElementBeforeEmptyLines
```
private static DetailAST getLastElementBeforeEmptyLines(DetailAST ast,
                                                        int line)
```
    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.
  - getPostFixNode
```
private static java.util.Optional<DetailAST> getPostFixNode(DetailAST ast)
```
    Gets postfix Node from AST if present.
    
    Parameters:
    
    ast - the AST used to get postfix Node.
    
    Returns:
    
    Optional postfix node.
  - 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.
  - getEmptyLines
```
private java.util.List<java.lang.Integer> getEmptyLines(DetailAST ast)
```
    Get list of empty lines.
    
    Parameters:
    
    ast - the ast to check.
    
    Returns:
    
    list of line numbers for empty lines.
  - getEmptyLinesToLog
```
private static java.util.List<java.lang.Integer> getEmptyLinesToLog(java.util.List<java.lang.Integer> emptyLines)
```
    Get list of empty lines to log.
    
    Parameters:
    
    emptyLines - list of empty lines.
    
    Returns:
    
    list of empty lines to log.
  - hasMultipleLinesBefore
```
private boolean hasMultipleLinesBefore(DetailAST ast)
```
    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.
  - processPackage
```
private void processPackage(DetailAST ast,
                            DetailAST nextToken)
```
    Process Package.
    
    Parameters:
    
    ast - token
    
    nextToken - next token
  - isLineEmptyAfterPackage
```
private static boolean isLineEmptyAfterPackage(DetailAST ast)
```
    Checks if there is another element at next line of package declaration.
    
    Parameters:
    
    ast - Package ast.
    
    Returns:
    
    true, if there is an element.
  - getViolationAstForPackage
```
private static DetailAST getViolationAstForPackage(DetailAST ast)
```
    Gets the Ast on which violation is to be given for package declaration.
    
    Parameters:
    
    ast - Package ast.
    
    Returns:
    
    Violation ast.
  - processImport
```
private void processImport(DetailAST ast,
                           DetailAST nextToken)
```
    Process Import.
    
    Parameters:
    
    ast - token
    
    nextToken - next token
  - processVariableDef
```
private void processVariableDef(DetailAST ast,
                                DetailAST nextToken)
```
    Process Variable.
    
    Parameters:
    
    ast - token
    
    nextToken - next Token
  - isViolatingEmptyLineBetweenFieldsPolicy
```
private boolean isViolatingEmptyLineBetweenFieldsPolicy(DetailAST detailAST)
```
    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
  - hasNotAllowedTwoEmptyLinesBefore
```
private boolean hasNotAllowedTwoEmptyLinesBefore(DetailAST token)
```
    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
  - checkComments
```
private void checkComments(DetailAST token)
```
    Check if group of comments located right before token has more than one previous empty line.
    
    Parameters:
    
    token - DetailAST token
  - checkCommentsInsideToken
```
private void checkCommentsInsideToken(DetailAST token)
```
    Check if group of comments located at the start of token has more than one previous empty line.
    
    Parameters:
    
    token - DetailAST token
  - isPrePreviousLineEmpty
```
private boolean isPrePreviousLineEmpty(DetailAST token)
```
    Checks if a token has empty pre-previous line.
    
    Parameters:
    
    token - DetailAST token.
    
    Returns:
    
    true, if token has empty lines before.
  - hasEmptyLineAfter
```
private boolean hasEmptyLineAfter(DetailAST token)
```
    Checks if token have empty line after.
    
    Parameters:
    
    token - token.
    
    Returns:
    
    true if token have empty line after.
  - findCommentUnder
```
private static java.util.Optional<DetailAST> findCommentUnder(DetailAST packageDef)
```
    Finds comment in next sibling of given packageDef.
    
    Parameters:
    
    packageDef - token to check
    
    Returns:
    
    comment under the token
  - 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 range
    
    endLine - number of the second line in the range
    
    Returns:
    
    true if found any blank line within the range, false otherwise
  - hasEmptyLineBefore
```
private boolean hasEmptyLineBefore(DetailAST token)
```
    Checks if a token has a empty line before.
    
    Parameters:
    
    token - token.
    
    Returns:
    
    true, if token have empty line before.
  - isCommentInBeginningOfLine
```
private boolean isCommentInBeginningOfLine(DetailAST comment)
```
    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.
  - isPrecededByJavadoc
```
private static boolean isPrecededByJavadoc(DetailAST token)
```
    Check if token is preceded by javadoc comment.
    
    Parameters:
    
    token - token for check.
    
    Returns:
    
    true, if token is preceded by javadoc comment.
  - isTypeField
```
private static boolean isTypeField(DetailAST variableDef)
```
    If variable definition is a type field.
    
    Parameters:
    
    variableDef - variable definition.
    
    Returns:
    
    true variable definition is a type field.

Class EmptyLineSeparatorCheck

Nested Class Summary

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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

Methods inherited from class java.lang.Object

Field Detail

MSG_SHOULD_BE_SEPARATED

MSG_MULTIPLE_LINES

MSG_MULTIPLE_LINES_AFTER

MSG_MULTIPLE_LINES_INSIDE

allowNoEmptyLineBetweenFields

allowMultipleEmptyLines

allowMultipleEmptyLinesInsideClassMembers

Constructor Detail

EmptyLineSeparatorCheck

Method Detail

setAllowNoEmptyLineBetweenFields

setAllowMultipleEmptyLines

setAllowMultipleEmptyLinesInsideClassMembers

isCommentNodesRequired

getDefaultTokens

getAcceptableTokens

getRequiredTokens

visitToken

checkToken

checkCommentInModifiers

processMultipleLinesInside

getLastElementBeforeEmptyLines

getPostFixNode

isClassMemberBlock

getEmptyLines

getEmptyLinesToLog

hasMultipleLinesBefore

processPackage

isLineEmptyAfterPackage

getViolationAstForPackage

processImport

processVariableDef

isViolatingEmptyLineBetweenFieldsPolicy

hasNotAllowedTwoEmptyLinesBefore

checkComments

checkCommentsInsideToken

isPrePreviousLineEmpty

hasEmptyLineAfter

findCommentUnder

hasEmptyLine

hasEmptyLineBefore

isCommentInBeginningOfLine

isPrecededByJavadoc

isTypeField