Description

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 a sibling of the same type, then empty line is required at its end (for example for CLASS_DEF it is after '}'). Also, trailing comments are skipped.

Properties

Examples

To configure the default check:

<module name="Checker">
  <module name="TreeWalker">
    <module name="EmptyLineSeparator"/>
  </module>
</module>
        

Example of declarations without empty line separator:

///////////////////////////////////////////////////
//HEADER
///////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.whitespace.emptylineseparator;
import java.io.Serializable;
// violation 2 lines above ''package' should be separated from previous line'
// violation 2 lines above ''import' should be separated from previous line'

class Example1 {

  int var1 = 1;
  int var2 = 2; // violation ''VARIABLE_DEF' should be separated from previous line'


  int var3 = 3;


  void method1() {}
  void method2() { // violation ''METHOD_DEF' should be separated from previous line'
    int var4 = 4;


    int var5 = 5;
  }
}
        

To check empty line before VARIABLE_DEF and METHOD_DEF:

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

Example:

///////////////////////////////////////////////////
//HEADER
///////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.whitespace.emptylineseparator;
import java.io.Serializable;

class Example2 {

  int var1 = 1;
  int var2 = 2; // violation ''VARIABLE_DEF' should be separated from previous line'


  int var3 = 3;


  void method1() {}
  void method2() { // violation ''METHOD_DEF' should be separated from previous line'
    int var4 = 4;


    int var5 = 5;
  }
}
        

To allow no empty line between fields:

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

Example:

///////////////////////////////////////////////////
//HEADER
///////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.whitespace.emptylineseparator;
import java.io.Serializable;
// violation 2 lines above ''package' should be separated from previous line'
// violation 2 lines above ''import' should be separated from previous line'

class Example3 {

  int var1 = 1;
  int var2 = 2;


  int var3 = 3;


  void method1() {}
  void method2() { // violation ''METHOD_DEF' should be separated from previous line'
    int var4 = 4;


    int var5 = 5;
  }
}
        

To disallow multiple empty lines between class members:

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

Example:

///////////////////////////////////////////////////
//HEADER
///////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.whitespace.emptylineseparator;
import java.io.Serializable;
// violation 2 lines above ''package' should be separated from previous line'
// violation 2 lines above ''import' should be separated from previous line'

class Example4 {

  int var1 = 1;
  int var2 = 2; // violation ''VARIABLE_DEF' should be separated from previous line'


  int var3 = 3; // violation ''VARIABLE_DEF' has more than 1 empty lines before'


  void method1() {} // violation ''METHOD_DEF' has more than 1 empty lines before'
  void method2() { // violation ''METHOD_DEF' should be separated from previous line'
    int var4 = 4;


    int var5 = 5;
  }
}
        

To disallow multiple empty lines inside constructor, initialization block and method:

<module name="Checker">
  <module name="TreeWalker">
    <module name="EmptyLineSeparator">
      <property name="allowMultipleEmptyLinesInsideClassMembers"
                value="false"/>
    </module>
  </module>
</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.checks.whitespace.emptylineseparator;
import java.io.Serializable;
// violation 2 lines above ''package' should be separated from previous line'
// violation 2 lines above ''import' should be separated from previous line'

class Example5 {

  int var1 = 1;
  int var2 = 2; // violation ''VARIABLE_DEF' should be separated from previous line'


  int var3 = 3;


  void method1() {}
  void method2() { // violation ''METHOD_DEF' should be separated from previous line'
    int var4 = 4; // violation 'There is more than 1 empty line after this line'


    int var5 = 5;
  }
}
        

Example of Usage

• Google Style
• Checkstyle Style

Violation Messages

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

All messages can be customized if the default message doesn't suit you. Please see the documentation to learn how to.

Package

com.puppycrawl.tools.checkstyle.checks.whitespace

Parent Module

TreeWalker