Scalastyle: Implemented Rules

There are 37 rules which are currently implemented:

org.scalastyle.file.FileLengthChecker - Check the number of lines in a file

id - file.size.limit
description - Check the number of lines in a file
class - org.scalastyle.file.FileLengthChecker
default level - WarningLevel

Justification

Files which are too long can be hard to read and understand.

Parameters

Parameter	Description	Type	Default Value
maxFileLength	Maximum file length	integer	1500

Example configuration

<check enabled="true" class="org.scalastyle.file.FileLengthChecker" level="warning">
 <parameters>
  <parameter name="maxFileLength">800</parameter>
 </parameters>
</check>

org.scalastyle.file.FileLineLengthChecker - Check the number of characters in a line

id - line.size.limit
description - Check the number of characters in a line
class - org.scalastyle.file.FileLineLengthChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
maxLineLength	Maximum line length	integer	160
tabSize	Tab size	integer	4

Example configuration

TBD

org.scalastyle.file.FileTabChecker - Check that there are no tabs in a file

id - line.contains.tab
description - Check that there are no tabs in a file
class - org.scalastyle.file.FileTabChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.file.HeaderMatchesChecker - Check the first lines of each file matches the text

id - header.matches
description - Check the first lines of each file matches the text
class - org.scalastyle.file.HeaderMatchesChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
header	Header	string

Example configuration

TBD

org.scalastyle.file.NewLineAtEofChecker - Checks that a file ends with a newline character

id - newline.at.eof
description - Checks that a file ends with a newline character
class - org.scalastyle.file.NewLineAtEofChecker
default level - WarningLevel

Justification

Some version control systems don’t cope well with files which don’t end with a newline character.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.file.NewLineAtEofChecker" level="warning"></check>

org.scalastyle.file.NoNewLineAtEofChecker - Checks that a file does not end with a newline character

id - no.newline.at.eof
description - Checks that a file does not end with a newline character
class - org.scalastyle.file.NoNewLineAtEofChecker
default level - WarningLevel

Justification

Because Mirco Dotta wanted it.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.file.NoNewlineAtEofChecker" level="warning"></check>

org.scalastyle.file.RegexChecker - Checks that a regular expression cannot be matched, if found reports this

id - regex
description - Checks that a regular expression cannot be matched, if found reports this
class - org.scalastyle.file.RegexChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string

Example configuration

<check enabled="true" class="org.scalastyle.file.RegexChecker" level="warning">
 <parameters>
  <parameter name="regex">(?m)^\s*$(\r|)\n^\s*$(\r|)\n</parameter>
 </parameters>
 <customMessage>No double blank lines</customMessage>
</check>

org.scalastyle.file.WhitespaceEndOfLineChecker - Check that there is no trailing whitespace at the end of lines

id - whitespace.end.of.line
description - Check that there is no trailing whitespace at the end of lines
class - org.scalastyle.file.WhitespaceEndOfLineChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.ClassNamesChecker - Check that class names match a regular expression

id - class.name
description - Check that class names match a regular expression
class - org.scalastyle.scalariform.ClassNamesChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[A-Z][A-Za-z]*$

Example configuration

TBD

org.scalastyle.scalariform.CovariantEqualsChecker - Check that classes and objects do not define equals without overriding equals(java.lang.Object).

id - covariant.equals
description - Check that classes and objects do not define equals without overriding equals(java.lang.Object).
class - org.scalastyle.scalariform.CovariantEqualsChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.CyclomaticComplexityChecker - Checks that the cyclomatic complexity of a method does exceed a value

id - cyclomatic.complexity
description - Checks that the cyclomatic complexity of a method does exceed a value
class - org.scalastyle.scalariform.CyclomaticComplexityChecker
default level - WarningLevel

Justification

If the code is too complex, then this can make code hard to read.

Parameters

Parameter	Description	Type	Default Value
maximum	Maximum	integer	10

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.CyclomaticComplexityChecker" level="warning">
 <parameters>
  <parameter name="maximum">10</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.EqualsHashCodeChecker - Check that if a class implements either equals or hashCode, it should implement the other

id - equals.hash.code
description - Check that if a class implements either equals or hashCode, it should implement the other
class - org.scalastyle.scalariform.EqualsHashCodeChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.IfBraceChecker - Checks that if statement have braces

id - if.brace
description - Checks that if statement have braces
class - org.scalastyle.scalariform.IfBraceChecker
default level - WarningLevel

Justification

A lowercase L (l) can look similar to a number 1 with some fonts.

Parameters

Parameter	Description	Type	Default Value
singleLineAllowed	Single Line Allowed	boolean	true
doubleLineAllowed	Double Line Allowed	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.IfBraceChecker" level="warning">
 <parameters>
  <parameter name="singleLineAllowed">true</parameter>
  <parameter name="doubleLineAllowed">false</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.IllegalImportsChecker - Check that a class does not import certain classes

id - illegal.imports
description - Check that a class does not import certain classes
class - org.scalastyle.scalariform.IllegalImportsChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
illegalImports	Illegal Imports	string	sun._,java.awt._

Example configuration

TBD

org.scalastyle.scalariform.MagicNumberChecker - Checks for use of magic numbers

id - magic.number
description - Checks for use of magic numbers
class - org.scalastyle.scalariform.MagicNumberChecker
default level - WarningLevel

Justification

Replacing a magic number with a named constant can make code easier to read and understand, and can avoid some subtle bugs.

Description

A simple assignment to a val is not considered to be a magic number, for example:

val foo = 4

is not a magic number, but

var foo = 4

is considered to be a magic number.

Parameters

Parameter	Description	Type	Default Value
ignore	Ignore	string	-1,0,1,2

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MagicNumberChecker" level="warning">
 <parameters>
  <parameter name="ignore">-1,0,1,2,3</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.MethodLengthChecker - Checks that methods do not exceed a maximum length

id - method.length
description - Checks that methods do not exceed a maximum length
class - org.scalastyle.scalariform.MethodLengthChecker
default level - WarningLevel

Justification

Long methods can be hard to read and understand.

Parameters

Parameter	Description	Type	Default Value
maxLength	Maximum length	integer	50

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MethodLengthChecker" level="warning">
 <parameters>
  <parameter name="maxLength">50</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.MethodNamesChecker - Check that method names match a regular expression

id - method.name
description - Check that method names match a regular expression
class - org.scalastyle.scalariform.MethodNamesChecker
default level - WarningLevel

Justification

The Scala style guide recommends that method names conform to certain standards.

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[a-z][A-Za-z0-9]*$

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MethodNamesChecker" level="warning">
 <parameters>
  <parameter name="regex">^[A-Za-z]*$</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.NoCloneChecker - Check that classes and objects do not define the clone() method

id - no.clone
description - Check that classes and objects do not define the clone() method
class - org.scalastyle.scalariform.NoCloneChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.NoFinalizeChecker - Check that classes and objects do not define the finalize() method

id - no.finalize
description - Check that classes and objects do not define the finalize() method
class - org.scalastyle.scalariform.NoFinalizeChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker - No whitespace after left bracket ‘[’

id - no.whitespace.after.left.bracket
description - No whitespace after left bracket ‘[’
class - org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker - No whitespace before left bracket ‘[’

id - no.whitespace.before.left.bracket
description - No whitespace before left bracket ‘[’
class - org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.NullChecker - Check that null is not used

id - null
description - Check that null is not used
class - org.scalastyle.scalariform.NullChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.NumberOfMethodsInTypeChecker - Check that a class / trait / object does not have too many methods

id - number.of.methods
description - Check that a class / trait / object does not have too many methods
class - org.scalastyle.scalariform.NumberOfMethodsInTypeChecker
default level - WarningLevel

Justification

If a type declares too many methods, this can be an indication of bad design.

Parameters

Parameter	Description	Type	Default Value
maxMethods	Maximum methods	integer	30

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.NumberOfMethodsInTypeChecker" level="warning">
 <parameters>
  <parameter name="maxMethods">30</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.NumberOfTypesChecker - Checks that there are not too many types declared in a file

id - number.of.types
description - Checks that there are not too many types declared in a file
class - org.scalastyle.scalariform.NumberOfTypesChecker
default level - WarningLevel

Justification

If there are too many classes/objects defined in a single file, this can cause the code to be difficult to understand.

Parameters

Parameter	Description	Type	Default Value
maxTypes	Maximum Number	integer	20

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.NumberOfTypesChecker" level="warning">
 <parameters>
  <parameter name="maxTypes">20</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.ObjectNamesChecker - Check that object names match a regular expression

id - object.name
description - Check that object names match a regular expression
class - org.scalastyle.scalariform.ObjectNamesChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[A-Z][A-Za-z]*$

Example configuration

TBD

org.scalastyle.scalariform.PackageObjectNamesChecker - Check that package object names match a regular expression

id - package.object.name
description - Check that package object names match a regular expression
class - org.scalastyle.scalariform.PackageObjectNamesChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[a-z][A-Za-z]*$

Example configuration

TBD

org.scalastyle.scalariform.ParameterNumberChecker - Maximum number of parameters for a method

id - parameter.number
description - Maximum number of parameters for a method
class - org.scalastyle.scalariform.ParameterNumberChecker
default level - WarningLevel

Parameters

Parameter	Description	Type	Default Value
maxParameters	Maximum Number	integer	8

Example configuration

TBD

org.scalastyle.scalariform.PublicMethodsHaveTypeChecker - Check that a method has an explicit return type, it is not inferred

id - public.methods.have.type
description - Check that a method has an explicit return type, it is not inferred
class - org.scalastyle.scalariform.PublicMethodsHaveTypeChecker
default level - WarningLevel

Justification

A public method declared on a type is effectively an API declaration. Explicitly declaring a return type means that other code which depends on that type won’t break unexpectedly.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker" level="warning"></check>

org.scalastyle.scalariform.ReturnChecker - Check that return is not used

id - return
description - Check that return is not used
class - org.scalastyle.scalariform.ReturnChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.SimplifyBooleanExpressionChecker - Boolean expression can be simplified

id - simplify.boolean.expression
description - Boolean expression can be simplified
class - org.scalastyle.scalariform.SimplifyBooleanExpressionChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.SpacesAfterPlusChecker - Check that the plus sign is followed by a space

id - spaces.after.plus
description - Check that the plus sign is followed by a space
class - org.scalastyle.scalariform.SpacesAfterPlusChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.SpacesBeforePlusChecker - Check that the plus sign is preceded by a space

id - spaces.before.plus
description - Check that the plus sign is preceded by a space
class - org.scalastyle.scalariform.SpacesBeforePlusChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.StructuralTypeChecker - Check that structural types are not used.

id - structural.type
description - Check that structural types are not used.
class - org.scalastyle.scalariform.StructuralTypeChecker
default level - WarningLevel

Parameters

No parameters

Example configuration

TBD

org.scalastyle.scalariform.UppercaseLChecker - Checks that if a long literal is used, then an uppercase L is used

id - uppercase.l
description - Checks that if a long literal is used, then an uppercase L is used
class - org.scalastyle.scalariform.UppercaseLChecker
default level - WarningLevel

Justification

A lowercase L (l) can look similar to a number 1 with some fonts.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.UppercaseLChecker" level="warning"></check>

org.scalastyle.scalariform.VarFieldChecker - Checks that classes and objects do not define mutable fields

id - var.field
description - Checks that classes and objects do not define mutable fields
class - org.scalastyle.scalariform.VarFieldChecker
default level - WarningLevel

Justification

var (mutable fields) are deprecated if you’re using a strict functional style

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.VarFieldChecker" level="warning"></check>

org.scalastyle.scalariform.VarLocalChecker - Checks that functions do not define mutable variables

id - var.local
description - Checks that functions do not define mutable variables
class - org.scalastyle.scalariform.VarLocalChecker
default level - WarningLevel

Justification

vars (mutable local variables) loops are deprecated if you’re using a strict functional style

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.VarLocalChecker" level="warning"></check>

org.scalastyle.scalariform.WhileChecker - Checks that while is not used

id - while
description - Checks that while is not used
class - org.scalastyle.scalariform.WhileChecker
default level - WarningLevel

Justification

while loops are deprecated if you’re using a strict functional style

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.WhileChecker" level="warning"></check>