Package com.puppycrawl.tools.checkstyle.checks.whitespace

Class EmptyLineSeparatorCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class EmptyLineSeparatorCheck
extends AbstractCheck
    Checks for empty line separators after header, package, all import declarations, fields, constructors, methods, nested classes, static initializers and instance initializers.

    By default the check will check the following statements: PACKAGE_DEF, IMPORT, CLASS_DEF, INTERFACE_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF, CTOR_DEF, VARIABLE_DEF.

    Example of declarations without empty line separator: 

     ///////////////////////////////////////////////////
 //HEADER
 ///////////////////////////////////////////////////
 package com.puppycrawl.tools.checkstyle.whitespace;
 import java.io.Serializable;
 class Foo
 {
     public static final int FOO_CONST = 1;
     public void foo() {} //should be separated from previous statement.
 }

    An example of how to configure the check with default parameters is: 

     <module name="EmptyLineSeparator"/>

    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() {}
 }

    An example how to check empty line after VARIABLE_DEF and METHOD_DEF: 

     <module name="EmptyLineSeparator">
    <property name="tokens" value="VARIABLE_DEF, METHOD_DEF"/>
 </module>

    An example how to allow no empty line between fields: 

     <module name="EmptyLineSeparator">
    <property name="allowNoEmptyLineBetweenFields" value="true"/>
 </module>

    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() {}
 }

    An example how to disallow multiple empty lines between class members: 

     <module name="EmptyLineSeparator">
    <property name="allowMultipleEmptyLines" value="false"/>
 </module>

    An example how to disallow multiple empty line inside methods, constructors, etc.: 

     <module name="EmptyLineSeparator">
    <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
 </module>

    The check is valid only for statements that have body: TokenTypes.CLASS_DEF, TokenTypes.INTERFACE_DEF, TokenTypes.ENUM_DEF, TokenTypes.STATIC_INIT, TokenTypes.INSTANCE_INIT, TokenTypes.METHOD_DEF, TokenTypes.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 since method has 2 empty lines subsequently
     }
 }

    • 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
        Allows no empty line between fields.

      • allowMultipleEmptyLines

        private boolean allowMultipleEmptyLines
        Allows multiple empty lines between class members.

      • allowMultipleEmptyLinesInsideClassMembers

        private boolean allowMultipleEmptyLinesInsideClassMembers
        Allows multiple empty lines inside class members.

    • Constructor Detail

      • EmptyLineSeparatorCheck

        public EmptyLineSeparatorCheck()

    • Method Detail

      • setAllowNoEmptyLineBetweenFields

        public final void setAllowNoEmptyLineBetweenFields​(boolean allow)
        Allow no empty line between fields.
        Parameters:
        allow - User's value.

      • setAllowMultipleEmptyLines

        public void setAllowMultipleEmptyLines​(boolean allow)
        Allow multiple empty lines between class members.
        Parameters:
        allow - User's value.

      • setAllowMultipleEmptyLinesInsideClassMembers

        public void setAllowMultipleEmptyLinesInsideClassMembers​(boolean allow)
        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

      • 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.

      • 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

      • processImport

        private void processImport​(DetailAST ast,
                           DetailAST nextToken,
                           int astType)
        Process Import.
        Parameters:
        ast - token
        nextToken - next token
        astType - token Type

      • 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

      • 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.

      • 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.

      • 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.

      • isComment

        private static boolean isComment​(DetailAST ast)
        Check if token is a comment.
        Parameters:
        ast - ast node
        Returns:
        true, if given ast is 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.