Checkstyle provides many checks that you can apply to your source code. Below is an alphabetical reference, the site navigation menu provides a reference organized by functionality.
| AbbreviationAsWordInName | The Check validate abbreviations(consecutive capital letters) length in identifier name, it also allow in enforce camel case naming. |
| AbstractClassName | Ensures that the names of abstract classes conforming to some regular expression. |
| AnnotationLocation | Check location of annotation on language elements. |
| AnnotationUseStyle | This check controls the style with the usage of annotations. |
| AnonInnerLength | Checks for long anonymous inner classes. |
| ArrayTrailingComma | Checks if array initialization contains optional trailing comma. |
| ArrayTypeStyle | Checks the style of array type definitions. |
| AtclauseOrder | Checks the order of at-clauses. |
| AvoidEscapedUnicodeCharacters | Restrict using Unicode escapes. |
| AvoidInlineConditionals | Detects inline conditionals. |
| AvoidNestedBlocks | Finds nested blocks. |
| AvoidStarImport | Check that finds import statements that use the * notation. |
| AvoidStaticImport | Check that finds static imports. |
| BooleanExpressionComplexity | Restricts nested boolean operators (&&, ||, &, | and ^) to a specified depth (default = 3). |
| ClassDataAbstractionCoupling | This metric measures the number of instantiations of other classes within the given class. |
| ClassFanOutComplexity | The number of other classes a given class relies on. |
| ClassTypeParameterName | Checks that class type parameter names conform to a format specified by the format property. |
| ConstantName | Checks that constant names conform to a format specified by the format property. |
| CovariantEquals | Checks that if a class defines a covariant method equals, then it defines method equals(java.lang.Object). |
| CustomImportOrder | Checks that the groups of import declarations appear in the order specified by the user. |
| CyclomaticComplexity | Checks cyclomatic complexity against a specified limit. |
| DeclarationOrder | Checks that the parts of a class or interface declaration appear in the order suggested by the Code Conventions for the Java Programming Language. |
| DefaultComesLast | Check that the default is after all the cases in a switch statement. |
| DescendantToken | Checks for restricted tokens beneath other tokens. |
| DesignForExtension | Checks that classes are designed for inheritance. |
| EmptyBlock | Checks for empty blocks. |
| EmptyCatchBlock | Checks for empty catch blocks with few options to skip violation. |
| EmptyForInitializerPad | Checks the padding of an empty for initializer; that is whether a space is required at an empty for initializer, or such spaces are forbidden. |
| EmptyForIteratorPad | Checks the padding of an empty for iterator; that is whether a space is required at an empty for iterator, or such spaces are forbidden. |
| EmptyLineSeparator | Checks for blank line separators. |
| EmptyStatement | Detects empty statements (standalone ';'). |
| EqualsAvoidNull | Checks that any combination of String literals with optional assignment is on the left side of an equals() comparison. |
| EqualsHashCode | Checks that classes that override equals() also override hashCode(). |
| ExecutableStatementCount | Restricts the number of executable statements to a specified limit (default = 30). |
| ExplicitInitialization | Checks if any class or object member explicitly initialized to default for its type value (null for object references, zero for numeric types and char and false for boolean. |
| FallThrough | Checks for fall through in switch statements Finds locations where a case contains Java code - but lacks a break, return, throw or continue statement. |
| FileLength | Checks for long source files. |
| FileTabCharacter | Checks to see if a file contains a tab character. |
| FinalClass | Checks that class which has only private ctors is declared as final. |
| FinalLocalVariable | Ensures that local variables that never get their values changed, must be declared final. |
| FinalParameters | Check that method/constructor/catch/foreach parameters are final. |
| GenericWhitespace | Checks that the whitespace around the Generic tokens < and > are correct to the typical convention. |
| Header | Checks the header of the source against a fixed header file. |
| HiddenField | Checks that a local variable or a parameter does not shadow a field that is defined in the same class. |
| HideUtilityClassConstructor | Make sure that utility classes (classes that contain only static methods) do not have a public constructor. |
| IllegalCatch | Catching java.lang.Exception, java.lang.Error or java.lang.RuntimeException is almost never acceptable. |
| IllegalImport | Checks for imports from a set of illegal packages. |
| IllegalInstantiation | Checks for illegal instantiations where a factory method is preferred. |
| IllegalThrows | Throwing java.lang.Error or java.lang.RuntimeException is almost never acceptable. |
| IllegalToken | Checks for illegal tokens. |
| IllegalTokenText | Checks for illegal token text. |
| IllegalType | Checks that particular class are never used as types in variable declarations, return values or parameters. |
| ImportControl | Check that controls what packages can be imported in each package. |
| ImportOrder | Ensures that groups of imports come in a specific order. |
| Indentation | Checks correct indentation of Java Code. |
| InnerAssignment | Checks for assignments in subexpressions, such as in String s = Integer.toString(i = 2);. |
| InnerTypeLast | Check nested (internal) classes/interfaces are declared at the bottom of the class after all method and field declarations. |
| InterfaceIsType | Implements Bloch, Effective Java, Item 17 - Use Interfaces only to define types. |
| InterfaceTypeParameterName | Checks that interface type parameter names conform to a format specified by the format property. |
| JavaNCSS | This check calculates the Non Commenting Source Statements (NCSS) metric for Java source files and methods. |
| JavadocMethod | Checks the Javadoc of a method or constructor. |
| JavadocPackage | Checks that all packages have a package documentation. |
| JavadocTagContinuationIndentation | Checks the indentation of the continuation lines in at-clauses. |
| JavadocParagraph | Checks Javadoc paragraphs. |
| JavadocStyle | Custom Checkstyle Check to validate Javadoc. |
| JavadocType | Checks the Javadoc of a type. |
| JavadocVariable | Checks that a variable has Javadoc comment. |
| LeftCurly | Checks the placement of left curly braces on types, methods and other blocks: |
| LineLength | Checks for long lines. |
| LocalFinalVariableName | Checks that local final variable names conform to a format specified by the format property. |
| LocalVariableName | Checks that local, non-final variable names conform to a format specified by the format property. |
| MagicNumber | Checks for magic numbers. |
| MemberName | Checks that instance variable names conform to a format specified by the format property. |
| MethodCount | Checks the number of methods declared in each type. |
| MethodLength | Checks for long methods. |
| MethodName | Checks that method names conform to a format specified by the format property. |
| MethodParamPad | Checks the padding between the identifier of a method definition, constructor definition, method call, or constructor invocation; and the left parenthesis of the parameter list. |
| MethodTypeParameterName | Checks that class type parameter names conform to a format specified by the format property. |
| MissingCtor | Checks that classes (except abstract one) define a ctor and don't rely on the default one. |
| MissingDeprecated | This class is used to verify that both the |
| MissingOverride | This class is used to verify that the |
| MissingSwitchDefault | Checks that switch statement has "default" clause. |
| ModifiedControlVariable | Check for ensuring that for loop control variables are not modified inside the for block. |
| ModifierOrder | Checks that the order of modifiers conforms to the suggestions in the Java Language specification, sections 8.1.1, 8.3.1 and 8.4.3. |
| MultipleStringLiterals | Checks for multiple occurrences of the same string literal within a single file. |
| MultipleVariableDeclarations | Checks that each variable declaration is in its own statement and on its own line. |
| MutableException | Ensures that exceptions (defined as any class name conforming to some regular expression) are immutable. |
| NPathComplexity | Checks the npath complexity against a specified limit (default = 200). |
| NeedBraces | Checks for braces around code blocks. |
| NestedForDepth | Restricts nested for blocks to a specified depth (default = 1). |
| NestedIfDepth | Restricts nested if-else blocks to a specified depth (default = 1). |
| NestedTryDepth | Restricts nested try-catch-finally blocks to a specified depth (default = 1). |
| NewlineAtEndOfFile | Checks that there is a newline at the end of each file. |
| NoClone | Checks that the clone method is not overridden from the Object class. |
| NoFinalizer | Checks that no method having zero parameters is defined using the name finalize. |
| NonEmptyAtclauseDescription | Checks that the at-clause tag is followed by description . |
| NoLineWrap | Checks that chosen statements are not line-wrapped. |
| NoWhitespaceAfter | Checks that there is no whitespace after a token. |
| NoWhitespaceBefore | Checks that there is no whitespace before a token. |
| OneStatementPerLine | Checks there is only one statement per line. |
| OneTopLevelClass | Checks that each top-level class, interfaces or enum resides in a source file of its own. |
| OperatorWrap | Checks line wrapping for operators. |
| OuterTypeFilename | Checks that the outer type name and the file name match. |
| OuterTypeNumber | Checks for the number of defined types at the "outer" level. |
| PackageAnnotation | This check makes sure that all package annotations are in the package-info.java file. |
| PackageDeclaration | Ensures there is a package declaration and (optionally) in the correct directory. |
| PackageName | Checks that package names conform to a format specified by the format property. |
| ParameterAssignment | Disallow assignment of parameters. |
| ParameterName | Checks that parameter names conform to a format specified by the format property. |
| ParameterNumber | Checks the number of parameters that a method or constructor has. |
| ParenPad | Checks the padding of parentheses; that is whether a space is required after a left parenthesis and before a right parenthesis, or such spaces are forbidden, with the exception that it does not check for padding of the right parenthesis at an empty for iterator. |
| RedundantImport | Checks for imports that are redundant. |
| RedundantModifier | Checks for redundant modifiers in interface and annotation definitions. |
| Regexp | A check that makes sure that a specified pattern exists (or not) in the file. |
| RegexpHeader | Checks the header of the source against a header file that contains a |
| RegexpMultiline | Implementation of a check that looks that matches across multiple lines in any file type. |
| RegexpSingleline | Implementation of a check that looks for a single line in any file type. |
| RegexpSinglelineJava | Implementation of a check that looks for a single line in Java files. |
| RequireThis | Checks that code doesn't rely on the "this" default. |
| ReturnCount | Restricts return statements to a specified count (default = 2). |
| RightCurly | Checks the placement of right curly braces. |
| SeparatorWrap | Checks line wrapping with separators. |
| SingleLineJavadoc | Checks that a JavaDoc block which can fit on a single line and doesn't contain at-clauses |
| SimplifyBooleanExpression | Checks for overly complicated boolean expressions. |
| SimplifyBooleanReturn | Checks for overly complicated boolean return statements. |
| StaticVariableName | Checks that static, non-final variable names conform to a format specified by the format property. |
| StringLiteralEquality | Checks that string literals are not used with == or !=. |
| SummaryJavadoc | Checks that Javadoc summary sentence does not contain phrases that are not recommended to use. |
| SuperClone | Checks that an overriding clone() method invokes super.clone(). |
| SuperFinalize | Checks that an overriding finalize() method invokes super.finalize(). |
| SuppressWarnings | This check allows you to specify what warnings that |
| SuppressWarningsHolder | This check allows for finding code that should not be reported by Checkstyle |
| ThrowsCount | Restricts throws statements to a specified count (default = 1). |
| TodoComment | A check for TODO comments. |
| TrailingComment | The check to ensure that requires that comments be the only thing on a line. |
| Translation | The TranslationCheck class helps to ensure the correct translation of code by checking property files for consistency regarding their keys. |
| TypeName | Checks that type names conform to a format specified by the format property. |
| TypecastParenPad | Checks the padding of parentheses for typecasts. |
| UncommentedMain | Detects uncommented main methods. |
| UniqueProperties | Detects duplicated keys in properties files. |
| UnnecessaryParentheses | Checks if unnecessary parentheses are used in a statement or expression. |
| UnusedImports | Checks for unused import statements. |
| UpperEll | Checks that long constants are defined with an upper ell. |
| VariableDeclarationUsageDistance | Checks the distance between declaration of variable and its first usage. |
| VisibilityModifier | Checks visibility of class members. |
| WhitespaceAfter | Checks that a token is followed by whitespace, with the exception that it does not check for whitespace after the semicolon of an empty for iterator. |
| WhitespaceAround | Checks that a token is surrounded by whitespace. |
| WriteTag | Outputs a JavaDoc tag as information. |