 | 1 Introduction | -- | |
| | 1.1 Terminology notes | -- | |
| | 1.2 Guide notes | -- | |
| | 2 Source file basics | ↓ | |
| | 2.1 File name |  OuterTypeFilename ( config) | samples |
| | 2.2 File encoding: UTF-8 |  explanation | |
| | 2.3 Special characters | ↓ | |
| | 2.3.1 Whitespace characters | FileTabCharacter ( config) | samples |
| | 2.3.2 Special escape sequences | IllegalTokenText ( config) | samples |
| | 2.3.3 Non-ASCII characters | AvoidEscapedUnicodeCharacters ( config) | samples |
| | 3 Source file structure |  EmptyLineSeparator ( config)
Rule is not enforced in package-info.java file. It will be addressed at: #17541
Rule for module-info.java file is not covered because of lack of support for Java modules Grammar, see details at: #8240 | samples |
| | 3.1 License or copyright information, if present | -- | |
| | 3.2 Package statement | LineLength ( config)
NoLineWrap ( config) | samples |
| | 3.3 Import statements | ↓ | |
| | 3.3.1 No wildcard imports | AvoidStarImport ( config) | samples |
| | 3.3.2 No line-wrapping | LineLength ( config)
NoLineWrap ( config) | samples |
| | 3.3.3 Ordering and spacing | CustomImportOrder ( config) | samples |
| | 3.3.4 No static import for classes | Violations of this guideline cannot be detected by Checkstyle due to its limitation, multiple file checking is not supported. | |
| | 3.4 Class declaration | ↓ | |
| | 3.4.1 Exactly one top-level class declaration | OneTopLevelClass ( config) | samples |
| | 3.4.2 Class member ordering | -- | |
| | 3.4.2.1 Overloads: never split | OverloadMethodsDeclarationOrder ( config)
ConstructorsDeclarationGrouping ( config) | samples |
| | 3.5 Module declaration | ↓ | |
| | 3.5.1 Ordering and spacing of module directives | Checkstyle currently does not have a Parser to support module-info.java file Grammar. For more information, see the discussion at: #17170 | |
| | 4 Formatting | -- | |
| | 4.1 Braces | ↓ | |
| | 4.1.1 Use of optional braces | NeedBraces ( config) | samples |
| | 4.1.2 Nonempty blocks: K & R style | LeftCurly ( config)
RightCurly ( config)
There are some false-negatives regarding ELSE and DEFAULT blocks, they will be addressed at: #15791 and #14782 | samples |
| | 4.1.3 Empty blocks: may be concise | RegexpSinglelineJava ( config)
There are some false-negatives regarding K & R style brackets for empty blocks, they're addressed at: #15791 | samples |
| | 4.2 Block indentation: +2 spaces | Indentation ( config) | samples |
| | 4.3 One statement per line | OneStatementPerLine ( config) | samples |
| | 4.4 Column limit: 100 | LineLength ( config)
We can detect URL with protocol type as http://, https:// etc.
However, there are some cases we cannot cover, for example: JSNI(see reason at: #14938), detecting command lines, long identifiers and so on.
To disable this rule for above cases, please use SuppressWithNearbyTextFilter . Check out Suppressions section to learn how to use this suppression.
| samples |
| | 4.5 Line-wrapping | -- | |
| | 4.5.1 Where to break | OperatorWrap ( config)
SeparatorWrap ( config)
MethodParamPad ( config)
Line break before and after the lambda(->) is not covered. It will be addressed at: #17253 | samples |
| | 4.5.2 Indent continuation lines at least +4 spaces | Indentation ( config) | samples |
| | 4.6 Whitespace | ↓ | |
| | 4.6.1 Vertical Whitespace | EmptyLineSeparator ( config)
Blank lines between two consecutive fields are optional. This exception is not satisfied | samples |
| | 4.6.2 Horizontal whitespace | WhitespaceAround ( config)
GenericWhitespace ( config)
MethodParamPad ( config)
ParenPad ( config)
WhitespaceAfter ( config)
NoWhitespaceBefore ( config)
NoWhitespaceBeforeCaseDefaultColon ( config)
MatchXpath ( config)
A single whitespace before the empty block({}) of a class, method, interface, static, loops(while, do, for), and record is not covered. It will be addressed at: #17715 | samples |
| | 4.6.3 Horizontal alignment: never required | -- | |
| | 4.7 Grouping parentheses: recommended | -- | |
| | 4.8 Specific constructs | ↓ | |
| | 4.8.1 Enum classes | -- | |
| | 4.8.2 Variable declarations | ↓ | |
| | 4.8.2.1 One variable per declaration | MultipleVariableDeclarations ( config) | samples |
| | 4.8.2.2 Declared when needed | VariableDeclarationUsageDistance ( config)
| samples |
| | 4.8.3 Arrays | ↓ | |
| | 4.8.3.1 Array initializers: can be "block-like" | -- | |
| | 4.8.3.2 No C-style array declarations | ArrayTypeStyle ( config) | samples |
| | 4.8.4 Switch statements and expressions | -- | |
| | 4.8.4.1 Indentation | Indentation ( config)
Line break after { of non-empty block in switch-rule is not covered. It will be addressed at: #17565 | samples |
| | 4.8.4.2 Fall-through: commented | FallThrough ( config) | samples |
| | 4.8.4.3 Exhaustiveness and presence of the default label | MissingSwitchDefault ( config)
"Exception: enum type may omit the default statement group" requirement can not be covered as we can not distinguish types, enum values may look the same as static final String constants. | samples |
| | 4.8.4.4 Switch expressions | -- | |
| | 4.8.5 Annotations | ↓ | |
| | 4.8.5.1 Type-use annotations | Violations of this guideline cannot be detected by Checkstyle due to its limitation, multiple file checking is not supported. | |
| | 4.8.5.2 Class, package, and module annotations | AnnotationLocation ( config)
InvalidJavadocPosition ( config)
Annotation rule for modules is not covered because of lack of support for Java modules Grammar, see details at: #8240 | samples |
| | 4.8.5.3 Methods And Constructors Annotations | AnnotationLocation ( config)
InvalidJavadocPosition ( config) | samples |
| | 4.8.5.4 Field Annotations | AnnotationLocation ( config)
InvalidJavadocPosition ( config) | samples |
| | 4.8.5.5 Parameter and local variable annotations | --
For type-use annotations see 4.8.5.1 Type-use annotations | |
| | 4.8.6 Comments | ↓ | |
| | 4.8.6.1 Block comment style | CommentsIndentation ( config) | samples | |
| | 4.8.6.2 TODO comments | TodoComment ( config) | samples | |
| | 4.8.7 Modifiers | ModifierOrder ( config)
Rule for Modifiers on requires module directives is not covered because of lack of support for Java modules Grammar, see details at: #8240 | samples |
| | 4.8.8 Numeric Literals | UpperEll ( config) | samples |
| | 4.8.9 Text Blocks | Opening and closing quotes of text blocks are always on new line is not covered. It will be addressed at: #17159 | |
| | 5 Naming | ↓ | |
| | 5.1 Rules common to all identifiers | CatchParameterName ( config)
All other types of identifiers are covered in special sections below | samples | |
| | 5.2 Rules by identifier type | ↓ | |
| | 5.2.1 Package and module names | PackageName ( config)
Modules name validation is not covered because of lack of support for Java modules Grammar, see details at: #8240 | samples |
| | 5.2.2 Class names | TypeName () config
Checkstyle is a Static analysis tool and cannot determine whether a name is a noun, an adjective, or any other grammatical category. | samples |
| | 5.2.3 Method names | MethodName ( config)
There are some false-negatives regarding the use of underscores in the method names. They will be addressed at: #17841
Checkstyle is a Static analysis tool and cannot determine whether a name is a noun, an adjective, or any other grammatical category. | samples |
| | 5.2.4 Constant names | Every constant is a static final field, but not all static final fields are constants - impossible to check such rule. | |
| | 5.2.5 Non-constant field names | MemberName ( config)
There are some false-negatives regarding the use of underscore in the member names. They will be addressed at: #17842 | samples |
| | 5.2.6 Parameter names | ParameterName () config
CatchParameterName ( config)
LambdaParameterName ( config)
RecordComponentName ( config) | samples |
| | 5.2.7 Local variable names | LocalVariableName ( config)
PatternVariableName ( config) | samples |
| | 5.2.8 Type variable names | MethodTypeParameterName ( config)
ClassTypeParameterName ( config)
InterfaceTypeParameterName ( config)
RecordTypeParameterName ( config)
| samples
|
| | 5.3 Camel case: defined | AbbreviationAsWordInName ( config)
Non covered:
1. Some words are ambiguously hyphenated in the English language. No way to distinguish "YouTubeImporter" or "YoutubeImporter".
2. There are some false-negatives regarding the use of underscores in method and member names. They will be addressed at: #17841 and #17842 respectively. | samples |
| | 6 Programming Practices | ↓ | |
| | 6.1 @Override: always used | Violations of this guideline cannot be detected by Checkstyle due to its limitation, multiple file checking is not supported.
Coverage is missing for explicitly declared accessor method for a record component. It will be addressed at: #17561 | |
| | 6.2 Caught exceptions: not ignored | EmptyCatchBlock ( config) | samples |
| | 6.3 Static members: qualified using class | Violations of this guideline cannot be detected by Checkstyle due to its limitation, multiple file checking is not supported. | |
| | 6.4 Finalizers: not used | NoFinalizer ( config) | samples |
| | 7 Javadoc | ↓ | |
| | 7.1 Formatting | ↓ | |
| | 7.1.1 General form | SingleLineJavadoc ( config)
JavadocLeadingAsteriskAlign ( config)
InvalidJavadocPosition ( config) | samples |
| | 7.1.2 Paragraphs | JavadocParagraph ( config)
RequireEmptyLineBeforeBlockTagGroup ( config) | samples |
| | 7.1.3 Block tags | AtclauseOrder ( config)
JavadocTagContinuationIndentation ( config)
NonEmptyAtclauseDescription ( config) | samples |
| | 7.2 The summary fragment | SummaryJavadoc ( config) | samples |
| | 7.3 Where Javadoc is used | MissingJavadocType ( config)
MissingJavadocMethod ( config)
JavadocMethod ( config) | samples |
| | 7.3.1 Exception: self-explanatory members | MissingJavadocMethod ( config)
Optional javadoc for "simple, obvious" members is only valid for getters/setters, but they should follow certain rules mentioned at Check's Description section.
JavadocMethod ( config) | samples |
| | 7.3.2 Exception: overrides | MissingJavadocMethod ( config)
Overrides are checked by presence of "@Override" annotation on method.
JavadocMethod ( config) | samples |
| | 7.3.4 Non-required Javadoc | InvalidJavadocPosition ( config) | samples |
