layout	title
scalastyle	Scalastyle: Implemented Rules

There are 73 rules which are currently implemented:

Checker	Description
org.scalastyle.file.FileLengthChecker	Check the number of lines in a file.
org.scalastyle.file.FileLineLengthChecker	Check the number of characters in a line.
org.scalastyle.file.FileTabChecker	Check that there are no tabs in a file.
org.scalastyle.file.HeaderMatchesChecker	Check the first lines of each file matches the text.
org.scalastyle.file.IndentationChecker	Checks that lines are indented by a multiple of the tab size.
org.scalastyle.file.NewLineAtEofChecker	Checks that a file ends with a newline character.
org.scalastyle.file.NoNewLineAtEofChecker	Checks that a file does not end with a newline character.
org.scalastyle.file.RegexChecker	Checks that a regular expression cannot be matched, if found reports this.
org.scalastyle.file.WhitespaceEndOfLineChecker	Check that there is no trailing whitespace at the end of lines.
org.scalastyle.scalariform.BlockImportChecker	Checks that block imports are not used.
org.scalastyle.scalariform.CaseBraceChecker	Checks that braces aren't used in case clauses.
org.scalastyle.scalariform.ClassNamesChecker	Check that class names match a regular expression.
org.scalastyle.scalariform.ClassTypeParameterChecker	Checks that type parameter to a class matches a regular expression.
org.scalastyle.scalariform.CovariantEqualsChecker	Check that classes and objects do not define equals without overriding equals(java.lang.Object).
org.scalastyle.scalariform.CurliesImportChecker	Checks that curlies imports are not used.
org.scalastyle.scalariform.CyclomaticComplexityChecker	Checks that the cyclomatic complexity of a method does exceed a value.
org.scalastyle.scalariform.DeprecatedJavaChecker	Checks that Java @Deprecated is not used, Scala @deprecated should be used instead.
org.scalastyle.scalariform.DisallowSpaceAfterTokenChecker	Disallow space after certain token(s).
org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker	Disallow space before certain token(s).
org.scalastyle.scalariform.EmptyClassChecker	If a class/trait has no members, the braces are unnecessary.
org.scalastyle.scalariform.EmptyInterpolatedStringChecker	The interpolation for this string literal is not necessary.
org.scalastyle.scalariform.EnsureSingleSpaceAfterTokenChecker	Ensure single space after certain token(s).
org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker	Ensure single space before certain token(s).
org.scalastyle.scalariform.EqualsHashCodeChecker	Check that if a class implements either equals or hashCode, it should implement the other.
org.scalastyle.scalariform.FieldNamesChecker	Check that field names match a regular expression.
org.scalastyle.scalariform.ForBraceChecker	Checks that braces are used in for comprehensions.
org.scalastyle.scalariform.ForLoopChecker	Checks that parentheses are used in for loops.
org.scalastyle.scalariform.IfBraceChecker	Checks that if statements have braces.
org.scalastyle.scalariform.IllegalImportsChecker	Check that a class does not import certain classes.
org.scalastyle.scalariform.ImportGroupingChecker	Checks that imports are grouped together, not throughout the file.
org.scalastyle.scalariform.ImportOrderChecker	Checks that imports are grouped and ordered according to the style configuration.
org.scalastyle.scalariform.LowercasePatternMatchChecker	Checks that a case statement pattern match is not lower case, as this can cause confusion.
org.scalastyle.scalariform.MagicNumberChecker	Checks for use of magic numbers.
org.scalastyle.scalariform.MethodArgumentNamesChecker	Check that method argument names match a regular expression.
org.scalastyle.scalariform.MethodLengthChecker	Checks that methods do not exceed a maximum length.
org.scalastyle.scalariform.MethodNamesChecker	Check that method names match a regular expression.
org.scalastyle.scalariform.MultipleStringLiteralsChecker	Checks that a string literal does not appear multiple times.
org.scalastyle.scalariform.NamedArgumentChecker	Checks that argument literals are named.
org.scalastyle.scalariform.NoCloneChecker	Check that classes and objects do not define the clone() method.
org.scalastyle.scalariform.NoFinalizeChecker	Check that classes and objects do not define the finalize() method.
org.scalastyle.scalariform.NoWhitespaceAfterLeftBracketChecker	No whitespace after left bracket '['.
org.scalastyle.scalariform.NoWhitespaceBeforeLeftBracketChecker	No whitespace before left bracket '['.
org.scalastyle.scalariform.NoWhitespaceBeforeRightBracketChecker	No whitespace before right bracket '']''.
org.scalastyle.scalariform.NonASCIICharacterChecker	Some editors are unfriendly to non ASCII characters.
org.scalastyle.scalariform.NotImplementedErrorUsage	Checks that the code does not have ??? operators.
org.scalastyle.scalariform.NullChecker	Check that null is not used.
org.scalastyle.scalariform.NumberOfMethodsInTypeChecker	Check that a class / trait / object does not have too many methods.
org.scalastyle.scalariform.NumberOfTypesChecker	Checks that there are not too many types declared in a file.
org.scalastyle.scalariform.ObjectNamesChecker	Check that object names match a regular expression.
org.scalastyle.scalariform.OverrideJavaChecker	Checks that Java @Override is not used.
org.scalastyle.scalariform.PackageNamesChecker	Check that package names match a regular expression.
org.scalastyle.scalariform.PackageObjectNamesChecker	Check that package object names match a regular expression.
org.scalastyle.scalariform.ParameterNumberChecker	Maximum number of parameters for a method.
org.scalastyle.scalariform.PatternMatchAlignChecker	Check that pattern match arrows align.
org.scalastyle.scalariform.ProcedureDeclarationChecker	Use a : Unit = for procedure declarations.
org.scalastyle.scalariform.PublicMethodsHaveTypeChecker	Check that a method has an explicit return type, it is not inferred.
org.scalastyle.scalariform.RedundantIfChecker	Checks that if expressions are not redundant, i.e. easily replaced by a variant of the condition.
org.scalastyle.scalariform.ReturnChecker	Check that return is not used.
org.scalastyle.scalariform.ScalaDocChecker	Checks that the ScalaDoc on documentable members is well-formed.
org.scalastyle.scalariform.SimplifyBooleanExpressionChecker	Boolean expression can be simplified.
org.scalastyle.scalariform.SpaceAfterCommentStartChecker	Checks a space after the start of the comment.
org.scalastyle.scalariform.SpacesAfterPlusChecker	Check that the plus sign is followed by a space.
org.scalastyle.scalariform.SpacesBeforePlusChecker	Check that the plus sign is preceded by a space.
org.scalastyle.scalariform.StructuralTypeChecker	Check that structural types are not used.
org.scalastyle.scalariform.TodoCommentChecker	Check for use of TODO/FIXME single line comments.
org.scalastyle.scalariform.TokenChecker	Checks that a regular expression cannot be matched in a token, if found reports this.
org.scalastyle.scalariform.UnderscoreImportChecker	Avoid wildcard imports.
org.scalastyle.scalariform.UppercaseLChecker	Checks that if a long literal is used, then an uppercase L is used.
org.scalastyle.scalariform.VarFieldChecker	Checks that classes and objects do not define mutable fields.
org.scalastyle.scalariform.VarLocalChecker	Checks that functions do not define mutable variables.
org.scalastyle.scalariform.WhileBraceChecker	Checks that while body have braces.
org.scalastyle.scalariform.WhileChecker	Checks that while is not used.
org.scalastyle.scalariform.XmlLiteralChecker	Check that XML literals are not used.

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

Justification

Lines that are too long can be hard to read and horizontal scrolling is annoying.

Parameters

Parameter	Description	Type	Default Value
maxLineLength	Maximum line length	integer	160
tabSize	Tab size	integer	4
ignoreImports	Ignore import statements	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.file.FileLineLengthChecker" level="warning">
 <parameters>
  <parameter name="maxLineLength">100</parameter>
  <parameter name="tabSize">2</parameter>
  <parameter name="ignoreImports">true</parameter>
 </parameters>
</check>

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

Justification

Some say that tabs are evil.

Parameters

No parameters

Example configuration

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

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

Justification

A lot of projects require a header with a copyright notice, or they require a license in each file. This does a simple text comparison between the header and the first lines of the file. You can have multiple lines, but make sure you surround the text with a CDATA section. You can also specify a regular expression, as long as you set the regex parameter to true.

Parameters

Parameter	Description	Type	Default Value
header	Header	string
regex	Header Regex	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.file.HeaderMatchesChecker" level="warning">
 <parameters>
  <parameter name="regex">false</parameter>
  <parameter name="header">// Copyright \(C\) 2011-2012 the original author or authors.</parameter>
 </parameters>
</check>

or

<check enabled="true" class="org.scalastyle.file.HeaderMatchesChecker" level="warning">
 <parameters>
  <parameter name="regex">true</parameter>
  <parameter name="header">// Copyright \(C\) (?:\d{4}-)?\d{4} the original author or authors.</parameter>
 </parameters>
</check>

org.scalastyle.file.IndentationChecker - Checks that lines are indented by a multiple of the tab size.

id - indentation
description - Checks that lines are indented by a multiple of the tab size.
class - org.scalastyle.file.IndentationChecker
default level - WarningLevel

Justification

Code that is not indented consistently can be hard to read.

Parameters

Parameter	Description	Type	Default Value
tabSize	Tab size	integer	2
methodParamIndentSize	Multi-line method parameter spacing	integer	2
classParamIndentSize	Multi-line class parameter spacing	integer	4

Example configuration

<check enabled="true" class="org.scalastyle.file.IndentationChecker" level="warning">
 <parameters>
  <parameter name="tabSize">2</parameter>
  <parameter name="methodParamIndentSize">2</parameter>
  <parameter name="classParamIndentSize">4</parameter>
 </parameters>
</check>

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"/>

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"/>

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

Justification

Some checks can be carried out with a regular expression.

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string
line	Line	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.file.RegexChecker" level="warning">
 <parameters>
  <parameter name="regex">(?m)^\s*$(\r|)\n^\s*$(\r|)\n</parameter>
  <parameter name="line">false</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

Justification

Whitespace at the end of a line can cause problems when diffing between files or between versions.

Parameters

Parameter	Description	Type	Default Value
ignoreWhitespaceLines	Ignore lines with just whitespace	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.file.WhitespaceEndOfLineChecker" level="warning">
 <parameters>
  <parameter default="false" type="boolean" name="ignoreWhitespaceLines"/>
 </parameters>
</check>

org.scalastyle.scalariform.BlockImportChecker - Checks that block imports are not used.

id - block.import
description - Checks that block imports are not used.
class - org.scalastyle.scalariform.BlockImportChecker
default level - WarningLevel

Justification

Block imports, e.g. import a.{b, c} can lead to annoying merge errors in large code bases that are maintained by lot of developers. This rule allows to ensure that only single imports are used in order to minimize merge errors in import declarations.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.CaseBraceChecker - Checks that braces aren't used in case clauses.

id - disallow.case.brace
description - Checks that braces aren't used in case clauses.
class - org.scalastyle.scalariform.CaseBraceChecker
default level - WarningLevel

Justification

Braces aren't required in case clauses. They should be omitted according to Scala Style Guide.

Parameters

No parameters

Example configuration

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

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

Justification

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

Parameters

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

Example configuration

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

org.scalastyle.scalariform.ClassTypeParameterChecker - Checks that type parameter to a class matches a regular expression.

id - class.type.parameter.name
description - Checks that type parameter to a class matches a regular expression.
class - org.scalastyle.scalariform.ClassTypeParameterChecker
default level - WarningLevel

Justification

Scala generic type names are generally single upper case letters. This check checks for classes and traits. Note that this check only checks the innermost type parameter, to allow for List[T].

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[A-Z_]$

Example configuration

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

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

Justification

Mistakenly defining a covariant equals() method without overriding method equals(java.lang.Object) can produce unexpected runtime behaviour.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.CurliesImportChecker - Checks that curlies imports are not used.

id - curlies.import
description - Checks that curlies imports are not used.
class - org.scalastyle.scalariform.CurliesImportChecker
default level - WarningLevel

Justification

Curlies imports, e.g. import a.{b, c}, can lead to annoying merge errors in large code bases that are maintained by lot of developers. This rule allows to ensure that only single imports, no renaming and no hiding imports are used in order to minimize merge errors in import declarations.

Parameters

No parameters

Example configuration

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

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
countCases	Count Cases	boolean	true

Example configuration

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

org.scalastyle.scalariform.DeprecatedJavaChecker - Checks that Java @Deprecated is not used, Scala @deprecated should be used instead.

id - deprecated.java
description - Checks that Java @Deprecated is not used, Scala @deprecated should be used instead.
class - org.scalastyle.scalariform.DeprecatedJavaChecker
default level - WarningLevel

Justification

You should be using the Scala @deprecated instead.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.DisallowSpaceAfterTokenChecker - Disallow space after certain token(s).

id - disallow.space.after.token
description - Disallow space after certain token(s).
class - org.scalastyle.scalariform.DisallowSpaceAfterTokenChecker
default level - WarningLevel

Justification

Correct formatting can help readability.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.DisallowSpaceAfterTokenChecker" level="warning">
 <parameters>
  <parameter name="tokens">LPAREN</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker - Disallow space before certain token(s).

id - disallow.space.before.token
description - Disallow space before certain token(s).
class - org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker
default level - WarningLevel

Justification

Correct formatting can help readability.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker" level="warning">
 <parameters>
  <parameter name="tokens">COLON, COMMA, RPAREN</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.EmptyClassChecker - If a class/trait has no members, the braces are unnecessary.

id - empty.class
description - If a class/trait has no members, the braces are unnecessary.
class - org.scalastyle.scalariform.EmptyClassChecker
default level - WarningLevel

Justification

If a class / trait has no members, then braces are unnecessary, and can be removed.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.EmptyInterpolatedStringChecker - The interpolation for this string literal is not necessary.

id - empty.interpolated.strings
description - The interpolation for this string literal is not necessary.
class - org.scalastyle.scalariform.EmptyInterpolatedStringChecker
default level - WarningLevel

Justification

Empty interpolated strings are harder to read and not necessary.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.EnsureSingleSpaceAfterTokenChecker - Ensure single space after certain token(s).

id - ensure.single.space.after.token
description - Ensure single space after certain token(s).
class - org.scalastyle.scalariform.EnsureSingleSpaceAfterTokenChecker
default level - WarningLevel

Justification

Correct formatting can help readability.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.EnsureSingleSpaceAfterTokenChecker" level="warning">
 <parameters>
  <parameter name="tokens">COLON, IF</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker - Ensure single space before certain token(s).

id - ensure.single.space.before.token
description - Ensure single space before certain token(s).
class - org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker
default level - WarningLevel

Justification

Correct formatting can help readability.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.EnsureSingleSpaceBeforeTokenChecker" level="warning">
 <parameters>
  <parameter name="tokens">LPAREN</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

Justification

Defining either equals or hashCode in a class without defining the is a known source of bugs. Usually, when you define one, you should also define the other.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.FieldNamesChecker - Check that field names match a regular expression.

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

Justification

A consistent naming convention for field names can make code easier to read and understand.

Parameters

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

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.FieldNamesChecker" level="warning">
 <parameters>
  <parameter name="regex">^[a-z][A-Za-z0-9]*$</parameter>
  <parameter name="objectFieldRegex">^[A-Z][A-Za-z0-9]*$</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.ForBraceChecker - Checks that braces are used in for comprehensions.

id - for.brace
description - Checks that braces are used in for comprehensions.
class - org.scalastyle.scalariform.ForBraceChecker
default level - WarningLevel

Justification

Usage of braces (rather than parentheses) within a for comprehension mean that you don't have to specify a semi-colon at the end of every line:

for { // braces
  t <- List(1,2,3)
  if (t % 2 == 0)
} yield t

is preferred to

for ( // parentheses
  t <- List(1,2,3);
  if (t % 2 == 0)
) yield t

To fix it, replace the () with {}. And then remove the ; at the end of the lines.

Description

The singleLineAllowed property allows for constructions of the type:

for (i <- List(1,2,3)) yield i

Parameters

Parameter	Description	Type	Default Value
singleLineAllowed	Allow parentheses for single-line for	boolean	false

Example configuration

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

org.scalastyle.scalariform.ForLoopChecker - Checks that parentheses are used in for loops.

id - for.loop
description - Checks that parentheses are used in for loops.
class - org.scalastyle.scalariform.ForLoopChecker
default level - WarningLevel

Justification

For-comprehensions which lack a yield clause is actually a loop rather than a functional comprehension and it is usually more readable to string the generators together between parentheses rather than using the syntactically-confusing } { construct:

for (x <- board.rows; y <- board.files) {
  printf("(%d, %d)", x, y)
}

is preferred to

for {
  x <- board.rows
  y <- board.files
} {
  printf("(%d, %d)", x, y)
}

Parameters

No parameters

Example configuration

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

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

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

Justification

Some people find if clauses with braces easier to read.

Description

The singleLineAllowed property allows if constructions of the type:

if (bool_expression) expression1 else expression2

The doubleLineAllowed property allows if constructions of the type:

if (bool_expression) expression1 else expression2

Note: If you intend to enable only if expressions in the format below, disable the IfBraceChecker altogether.

if (bool_expression) expression1 else expression2

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

Justification

Use of some classes can be discouraged for a project. For instance, use of sun._ is generally discouraged because they are internal to the JDK and can be changed.

Parameters

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

Example configuration

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

org.scalastyle.scalariform.ImportGroupingChecker - Checks that imports are grouped together, not throughout the file.

id - import.grouping
description - Checks that imports are grouped together, not throughout the file.
class - org.scalastyle.scalariform.ImportGroupingChecker
default level - WarningLevel

Justification

If imports are spread throughout the file, knowing what is in scope at any one place can be difficult to work out.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.ImportOrderChecker - Checks that imports are grouped and ordered according to the style configuration.

id - import.ordering
description - Checks that imports are grouped and ordered according to the style configuration.
class - org.scalastyle.scalariform.ImportOrderChecker
default level - WarningLevel

Justification

Consistent import ordering improves code readability and reduces unrelated changes in patches.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.ImportOrderChecker" level="warning">
 <parameters>
  <parameter name="groups">java,scala,others</parameter>
  <parameter name="group.java">javax?\..+</parameter>
  <parameter name="group.scala">scala\..+</parameter>
  <parameter name="group.others">.+</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.LowercasePatternMatchChecker - Checks that a case statement pattern match is not lower case, as this can cause confusion.

id - lowercase.pattern.match
description - Checks that a case statement pattern match is not lower case, as this can cause confusion.
class - org.scalastyle.scalariform.LowercasePatternMatchChecker
default level - WarningLevel

Justification

A lower case pattern match clause with no other tokens is the same as _; this is not true for patterns which start with an upper case letter. This can cause confusion, and may not be what was intended:

val foo = "foo"
val Bar = "bar"
"bar" match { case Bar => "we got bar" } // result = "we got bar"
"bar" match { case foo => "we got foo" } // result = "we got foo"
"bar" match { case `foo` => "we got foo" } // result = MatchError

This checker raises a warning with the second match. To fix it, use an identifier which starts with an upper case letter (best), use case _ or, if you wish to refer to the value, add a type : Any, e.g.:

val lc = "lc"
"something" match { case lc: Any => "lc" } // result = "lc"
"something" match { case _ => "lc" } // result = "lc"

Parameters

No parameters

Example configuration

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

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.MethodArgumentNamesChecker - Check that method argument names match a regular expression.

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

Justification

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

Parameters

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

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MethodArgumentNamesChecker" level="warning">
 <parameters>
  <parameter name="regex">^[a-z][A-Za-z0-9]*$</parameter>
  <parameter name="ignoreRegex">^$</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
ignoreComments	Ignore comments	boolean	false
ignoreEmpty	Ignore empty lines	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MethodLengthChecker" level="warning">
 <parameters>
  <parameter name="maxLength">50</parameter>
  <parameter name="ignoreComments">false</parameter>
  <parameter name="ignoreEmpty">false</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. If the methods are overriding another method, and the overridden method cannot be changed, then use the ignoreOverride parameter.

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^[a-z][A-Za-z0-9]*(_=)?$
ignoreRegex	Regular expression to ignore	string	^$
ignoreOverride	Ignore override	boolean	false

Example configuration

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

org.scalastyle.scalariform.MultipleStringLiteralsChecker - Checks that a string literal does not appear multiple times.

id - multiple.string.literals
description - Checks that a string literal does not appear multiple times.
class - org.scalastyle.scalariform.MultipleStringLiteralsChecker
default level - WarningLevel

Justification

Code duplication makes maintenance more difficult, so it can be better to replace the multiple occurrences with a constant.

Parameters

Parameter	Description	Type	Default Value
allowed	Maximum occurences allowed	integer	1
ignoreRegex	Ignore regular expression	string	^""$

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.MultipleStringLiteralsChecker" level="warning">
 <parameters>
  <parameter name="allowed">1</parameter>
  <parameter name="ignoreRegex">^\&quot;\&quot;$</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.NamedArgumentChecker - Checks that argument literals are named.

id - named.argument
description - Checks that argument literals are named.
class - org.scalastyle.scalariform.NamedArgumentChecker
default level - WarningLevel

Justification

Nameless literals make code harder to understand (consider updateEntity(1, true) and updateEntity(id = 1, enabled = true)).

Parameters

Parameter	Description	Type	Default Value
checkString	Check string literals	boolean	false
ignoreMethod	Ignore methods by pattern	string	^set.+$

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.NamedArgumentChecker" level="warning">
 <parameters>
  <parameter name="checkString">false</parameter>
  <parameter name="ignoreMethod">^set.+$</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

Justification

The clone method is difficult to get right. You can use the copy constructor of case classes rather than implementing clone. For more information on clone(), see Effective Java by Joshua Bloch pages.

Parameters

No parameters

Example configuration

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

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

Justification

finalize() is called when the object is garbage collected, and garbage collection is not guaranteed to happen. It is therefore unwise to rely on code in finalize() method.

Parameters

No parameters

Example configuration

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

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

Justification

If there is whitespace after a left bracket, this can be confusing to the reader.

Parameters

No parameters

Example configuration

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

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

Justification

If there is whitespace before a left bracket, this can be confusing to the reader.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.NoWhitespaceBeforeRightBracketChecker - No whitespace before right bracket '']''.

id - no.whitespace.before.right.bracket
description - No whitespace before right bracket '']''.
class - org.scalastyle.scalariform.NoWhitespaceBeforeRightBracketChecker
default level - WarningLevel

Justification

If there is whitespace before a right bracket, this can be confusing to the reader.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.NonASCIICharacterChecker - Some editors are unfriendly to non ASCII characters.

id - non.ascii.character.disallowed
description - Some editors are unfriendly to non ASCII characters.
class - org.scalastyle.scalariform.NonASCIICharacterChecker
default level - WarningLevel

Justification

Scala allows unicode characters as operators and some editors misbehave when they see non-ascii character. In a project collaborated by a community of developers. This check can be helpful in such situations.

"value" match {
  case "value" => println("matched")
  ...
}

is preferred to

"value" match {
  case "value" ⇒ println("matched")
  ...
}

To fix it, replace the (unicode operator) ⇒ with =>.

Parameters

Parameter	Description	Type	Default Value
allowStringLiterals	Allow non-ASCII scripts in string literals.	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.NonASCIICharacterChecker" level="warning">
 <parameters>
  <parameter name="allowStringLiterals">true</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.NotImplementedErrorUsage - Checks that the code does not have ??? operators.

id - not.implemented.error.usage
description - Checks that the code does not have ??? operators.
class - org.scalastyle.scalariform.NotImplementedErrorUsage
default level - WarningLevel

Justification

The ??? operator denotes that an implementation is missing. This rule helps to avoid potential runtime errors because of not implemented code.

Parameters

No parameters

Example configuration

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

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

Justification

Scala discourages use of null, preferring Option.

Parameters

Parameter	Description	Type	Default Value
allowNullChecks	Allow null checks	boolean	true

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.NullChecker" level="warning">
 <parameters>
  <parameter name="allowNullChecks">true</parameter>
 </parameters>
</check>

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

Justification

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

Parameters

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

Example configuration

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

org.scalastyle.scalariform.OverrideJavaChecker - Checks that Java @Override is not used.

id - override.java
description - Checks that Java @Override is not used.
class - org.scalastyle.scalariform.OverrideJavaChecker
default level - WarningLevel

Justification

You should be using the Scala override keyword instead.

Parameters

No parameters

Example configuration

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

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

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

Justification

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

Parameters

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

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.PackageNamesChecker" level="warning">
 <parameters>
  <parameter name="regex">^[a-z]+$</parameter>
 </parameters>
</check>

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

Justification

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

Parameters

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

Example configuration

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

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

Justification

A method which has more than a certain number of parameters can be hard to understand.

Parameters

Parameter	Description	Type	Default Value
maxParameters	Maximum Number	integer	8

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.ParameterNumberChecker" level="warning">
 <parameters>
  <parameter name="maxParameters">8</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.PatternMatchAlignChecker - Check that pattern match arrows align.

id - pattern.match.align
description - Check that pattern match arrows align.
class - org.scalastyle.scalariform.PatternMatchAlignChecker
default level - WarningLevel

Justification

Correct formatting can help readability.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.ProcedureDeclarationChecker - Use a : Unit = for procedure declarations.

id - procedure.declaration
description - Use a : Unit = for procedure declarations.
class - org.scalastyle.scalariform.ProcedureDeclarationChecker
default level - WarningLevel

Justification

A procedure style declaration can cause confusion - the developer may have simply forgotten to add a =, and now their method returns Unit rather than the inferred type:

def foo() { println("hello"); 5 }

This checker raises a warning with the first line. To fix it, use an explicit return type, or add a = before the body.

def foo() = { println("hello"); 5 }

Parameters

No parameters

Example configuration

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

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

Parameter	Description	Type	Default Value
ignoreOverride	Ignore overridden methods	boolean	false

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker" level="warning">
 <parameters>
  <parameter name="ignoreOverride">false</parameter>
 </parameters>
</check>

org.scalastyle.scalariform.RedundantIfChecker - Checks that if expressions are not redundant, i.e. easily replaced by a variant of the condition.

id - if.redundant
description - Checks that if expressions are not redundant, i.e. easily replaced by a variant of the condition.
class - org.scalastyle.scalariform.RedundantIfChecker
default level - WarningLevel

Justification

If expressions with boolean constants in both branches can be eliminated without affecting readability. Prefer simply cond to if (cond) true else false and !cond to if (cond) false else true.

Parameters

No parameters

Example configuration

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

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

Justification

Use of return is not usually necessary in Scala. In fact, use of return can discourage a functional style of programming.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.ScalaDocChecker - Checks that the ScalaDoc on documentable members is well-formed.

id - scaladoc
description - Checks that the ScalaDoc on documentable members is well-formed.
class - org.scalastyle.scalariform.ScalaDocChecker
default level - WarningLevel

Justification

Scaladoc is generally considered a good thing. Within reason.

Description

Ignore tokens is a comma separated string that may include the following: PatDefOrDcl (variables), TmplDef (classes, traits), TypeDefOrDcl (type definitions), FunDefOrDcl (functions). Supported indentation styles are "scaladoc" (for ScalaDoc-style comments, with two spaces before the asterisk), "javadoc" (for JavaDoc-style comments, with a single space before the asterisk) or "anydoc" to support any style (any number of spaces before the asterisk). For backwards compatibility, if left empty, "anydoc" will be assumed.

Parameters

Parameter	Description	Type	Default Value
ignoreRegex	Regular expression	string	^$
ignoreTokenTypes	Comma Separated String	string	^$
ignoreOverride	Ignore override	boolean	false
indentStyle	Force indent style	string	anydoc

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.ScalaDocChecker" level="warning">
 <parameters>
  <parameter name="ignoreRegex">(.*Spec$)|(.*SpecIT$)</parameter>
  <parameter name="ignoreTokenTypes">PatDefOrDcl,TypeDefOrDcl,FunDefOrDcl,TmplDef</parameter>
  <parameter name="ignoreOverride">false</parameter>
  <parameter name="indentStyle">anydoc</parameter>
 </parameters>
</check>

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

Justification

A boolean expression which can be simplified can make code easier to read.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.SpaceAfterCommentStartChecker - Checks a space after the start of the comment.

id - space.after.comment.start
description - Checks a space after the start of the comment.
class - org.scalastyle.scalariform.SpaceAfterCommentStartChecker
default level - WarningLevel

Justification

To bring consistency with how comments should be formatted, leave a space right after the beginning of the comment.

package foobar

object Foobar {
  /**WRONG
    *
    */
  /** Correct
    *
    */
  val d = 2 /*Wrong*/ //Wrong
  /**
    * Correct
    */
  val e = 3 /** Correct*/ // Correct
}

Parameters

No parameters

Example configuration

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

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

Justification

An expression with spaces around + can be easier to read.

Parameters

No parameters

Example configuration

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

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

Justification

An expression with spaces around + can be easier to read.

Parameters

No parameters

Example configuration

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

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

Justification

Structural types in Scala can use reflection - this can have unexpected performance consequences. Warning: This check can also wrongly pick up type lamdbas and other such constructs. This checker should be used with care. You always have the alternative of the scalac checking for structural types.

Parameters

No parameters

Example configuration

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

org.scalastyle.scalariform.TodoCommentChecker - Check for use of TODO/FIXME single line comments.

id - todo.comment
description - Check for use of TODO/FIXME single line comments.
class - org.scalastyle.scalariform.TodoCommentChecker
default level - WarningLevel

Justification

Some projects may consider TODO or FIXME comments in a code bad style. They would rather you fix the problem.

Parameters

Parameter	Description	Type	Default Value
words	Word list	string	TODO\|FIXME

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.TodoCommentChecker" level="warning">
 <parameters>
  <parameter default="TODO|FIXME" type="string" name="words"/>
 </parameters>
</check>

org.scalastyle.scalariform.TokenChecker - Checks that a regular expression cannot be matched in a token, if found reports this.

id - token
description - Checks that a regular expression cannot be matched in a token, if found reports this.
class - org.scalastyle.scalariform.TokenChecker
default level - WarningLevel

Justification

Some checks can be carried by just the presence of a particular token.

Parameters

Parameter	Description	Type	Default Value
regex	Regular expression	string	^$

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.TokenChecker" level="warning">
 <parameters>
  <parameter name="regex">^[ai]sInstanceOf$</parameter>
 </parameters>
 <customMessage>Avoid casting.</customMessage>
</check>

org.scalastyle.scalariform.UnderscoreImportChecker - Avoid wildcard imports.

id - underscore.import
description - Avoid wildcard imports.
class - org.scalastyle.scalariform.UnderscoreImportChecker
default level - WarningLevel

Justification

Importing all classes from a package or static members from a class leads to tight coupling between packages or classes and might lead to problems when a new version of a library introduces name clashes.

Parameters

No parameters

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.UnderscoreImportChecker" level="warning">
 <parameters>
  <parameter name="ignoreRegex">collection\.JavaConverters\._|scala\.concurrent\.duration\._</parameter>
 </parameters>
</check>

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"/>

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"/>

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

var (mutable local variables) 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"/>

org.scalastyle.scalariform.WhileBraceChecker - Checks that while body have braces.

id - while.brace
description - Checks that while body have braces.
class - org.scalastyle.scalariform.WhileBraceChecker
default level - WarningLevel

Justification

While cannot be used in a pure-functional manner, that's why it's recommended to never omit braces according to Scala Style Guide.

Parameters

No parameters

Example configuration

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

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"/>

org.scalastyle.scalariform.XmlLiteralChecker - Check that XML literals are not used.

id - xml.literal
description - Check that XML literals are not used.
class - org.scalastyle.scalariform.XmlLiteralChecker
default level - WarningLevel

Justification

Some projects prefer not to have XML literals. They could use a templating engine instead.

Parameters

No parameters

Example configuration

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

Files

rules-1.4.0.md

Latest commit

History

rules-1.4.0.md

File metadata and controls

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

org.scalastyle.file.IndentationChecker - Checks that lines are indented by a multiple of the tab size.

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

org.scalastyle.scalariform.BlockImportChecker - Checks that block imports are not used.

Justification

Parameters

Example configuration

org.scalastyle.scalariform.CaseBraceChecker - Checks that braces aren't used in case clauses.

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

org.scalastyle.scalariform.ClassTypeParameterChecker - Checks that type parameter to a class matches a regular expression.

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

org.scalastyle.scalariform.CurliesImportChecker - Checks that curlies imports are not used.

Justification

Parameters

Example configuration

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

Justification

Parameters

Example configuration

org.scalastyle.scalariform.DeprecatedJavaChecker - Checks that Java @Deprecated is not used, Scala @deprecated should be used instead.

Justification

Parameters

Example configuration

org.scalastyle.scalariform.DisallowSpaceAfterTokenChecker - Disallow space after certain token(s).

Justification

Parameters

Example configuration

org.scalastyle.scalariform.DisallowSpaceBeforeTokenChecker - Disallow space before certain token(s).

Justification