Available Checks

Checkstyle provides many checks that you can apply to your sourcecode. Below is an alphabetical reference, the site navigation menu provides a reference organized by functionality.

AbstractClassName	Ensures that the names of abstract classes conforming to some regular expression.
AnonInnerLength	Checks for long anonymous inner classes.
ArrayTrailingComma	Checks if array initialization contains optional trailing comma.
ArrayTypeStyle	Checks the style of array type definitions.
AvoidInlineConditionals	Detects inline conditionals.
AvoidNestedBlocks	Finds nested blocks.
AvoidStarImport	Check that finds import statements that use the * notation.
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.
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).
CrossLanguageRegexpHeader	A FileSetCheck similar to
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.
DoubleCheckedLocking	Detect the double-checked locking idiom, a technique that tries to avoid synchronization overhead but is incorrect because of subtle artifacts of the java memory model.
EmptyBlock	Checks for empty blocks.
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.
EmptyStatement	Detects empty statements (standalone ';').
EntityBean	Checks that an EntityBean implementation satisfies EntityBean requirements.
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.
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.
FinalStatic	Checks that all static fields are declared final.
GenericIllegalRegexp	A generic check for code problems, the user can search for any pattern.
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	Class to check the ordering/grouping of imports.
Indentation	Checks correct indentation of Java Code.
InnerAssignment	Checks for assignments in subexpressions, such as in String s = Integer.toString(i = 2);.
InterfaceIsType	Implements Bloch, Effective Java, Item 17 - Use Interfaces only to define types.
JUnitTestCase	Ensures that the setUp(), tearDown()methods are named correctly, have no arguments, return void and are either public or protected.
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.
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.
LocalHomeInterface	Checks the local home interface requirements: every method must not throw the java.rmi.RemoteException Reference: Enterprise JavaBeansTM Specification,Version 2.0, section 9.6.2.
LocalInterface	Checks the methods of a local interface.
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.
MessageBean	Checks that a MessageBean implementation satisfies MessageBean requirements.
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.
MissingCtor	Checks that classes (except abstract one) define a ctor and don't rely on the default one.
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.
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.
NoWhitespaceAfter	Checks that there is no whitespace after a token.
NoWhitespaceBefore	Checks that there is no whitespace before a token.
OperatorWrap	Checks line wrapping for operators.
PackageDeclaration	Ensures there is a package declaration.
PackageHtml	Checks that all packages have a package documentation.
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.
RedundantThrows	Checks for redundant exceptions declared in throws clause such as duplicates, unchecked exceptions or subclasses of another declared exception.
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
RemoteHomeInterface	Checks the methods of a remote home interface.
RemoteInterface	Checks the methods of a remote interface.
RequireThis	Checks that code doesn't rely on the "this" default.
RequiredRegexp	A check that makes sure that a specified pattern exists in the code.
ReturnCount	Restricts return statements to a specified count (default = 2).
RightCurly	Checks the placement of right curly braces.
SessionBean	Checks that a SessionBean implementation satisfies SessionBean requirements.
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.
StrictDuplicateCode	Performs a line-by-line comparison of all code lines and reports duplicate code if a sequence of lines differs only in indentation.
StringLiteralEquality	Checks that string literals are not used with == or !=.
SuperClone	Checks that an overriding clone() method invokes super.clone().
SuperFinalize	Checks that an overriding finalize() method invokes super.finalize().
TabCharacter	Reports tab characters ('\t') in the source code.
ThisParameter	Checks that 'this' is not a parameter of any method calls or constructors for a bean.
ThisReturn	Checks that 'this' is not returned by a bean method.
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.
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.
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.