com.puppycrawl.tools.checkstyle.checks.metrics

Class JavaNCSSCheck

java.lang.Object

com.puppycrawl.tools.checkstyle.api.AutomaticBean

com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

com.puppycrawl.tools.checkstyle.api.AbstractCheck

com.puppycrawl.tools.checkstyle.checks.metrics.JavaNCSSCheck

All Implemented Interfaces:

Configurable, Contextualizable

public class JavaNCSSCheck
extends AbstractCheck

Determines complexity of methods, classes and files by counting the Non Commenting Source Statements (NCSS). This check adheres to the specification for the JavaNCSS-Tool written by Chr. Clemens Lee.

Roughly said the NCSS metric is calculated by counting the source lines which are not comments, (nearly) equivalent to counting the semicolons and opening curly braces.

The NCSS for a class is summarized from the NCSS of all its methods, the NCSS of its nested classes and the number of member variable declarations.

The NCSS for a file is summarized from the ncss of all its top level classes, the number of imports and the package declaration.

Rationale: Too large methods and classes are hard to read and costly to maintain. A large NCSS number often means that a method or class has too many responsibilities and/or functionalities which should be decomposed into smaller units.

• Property methodMaximum - Specify the maximum allowed number of non commenting lines in a method. Default value is 50.
• Property classMaximum - Specify the maximum allowed number of non commenting lines in a class. Default value is 1500.
• Property fileMaximum - Specify the maximum allowed number of non commenting lines in a file including all top level and nested classes. Default value is 2000.

To configure the check:

 <module name="JavaNCSS"/>
 

To configure the check with 40 allowed non commenting lines for a method:

 <module name="JavaNCSS">
   <property name="methodMaximum" value="40"/>
 </module>
 

Since:

3.5

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	MSG_CLASS A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_FILE A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_METHOD A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
JavaNCSSCheck()

Method Summary

Modifier and Type	Method and Description
void	beginTree(DetailAST rootAST) Called before the starting to process a tree.
void	finishTree(DetailAST rootAST) Called after finished processing a tree.
int[]	getAcceptableTokens() The configurable token set.
int[]	getDefaultTokens() Returns the default token a check is interested in.
int[]	getRequiredTokens() The tokens that this check must be registered for.
void	leaveToken(DetailAST ast) Called after all the child nodes have been process.
void	setClassMaximum(int classMaximum) Setter to specify the maximum allowed number of non commenting lines in a class.
void	setFileMaximum(int fileMaximum) Setter to specify the maximum allowed number of non commenting lines in a file including all top level and nested classes.
void	setMethodMaximum(int methodMaximum) Setter to specify the maximum allowed number of non commenting lines in a method.
void	visitToken(DetailAST ast) Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

clearMessages, destroy, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MSG_METHOD

public static final java.lang.String MSG_METHOD

A key is pointing to the warning message text in "messages.properties" file.

See Also:

Constant Field Values

MSG_CLASS

public static final java.lang.String MSG_CLASS

A key is pointing to the warning message text in "messages.properties" file.

See Also:

Constant Field Values

MSG_FILE

public static final java.lang.String MSG_FILE

A key is pointing to the warning message text in "messages.properties" file.

See Also:

Constant Field Values

Constructor Detail

JavaNCSSCheck

public JavaNCSSCheck()

Method Detail

getDefaultTokens

public int[] getDefaultTokens()

Description copied from class: AbstractCheck

Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.

Specified by:

getDefaultTokens in class AbstractCheck

Returns:

the default tokens

See Also:

TokenTypes

getRequiredTokens

public int[] getRequiredTokens()

Description copied from class: AbstractCheck

The tokens that this check must be registered for.

Specified by:

getRequiredTokens in class AbstractCheck

Returns:

the token set this must be registered for.

See Also:

TokenTypes

getAcceptableTokens

public int[] getAcceptableTokens()

Description copied from class: AbstractCheck

The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.

Specified by:

getAcceptableTokens in class AbstractCheck

Returns:

the token set this check is designed for.

See Also:

TokenTypes

beginTree

public void beginTree(DetailAST rootAST)

Description copied from class: AbstractCheck

Called before the starting to process a tree. Ideal place to initialize information that is to be collected whilst processing a tree.

Overrides:

beginTree in class AbstractCheck

Parameters:

rootAST - the root of the tree

visitToken

public void visitToken(DetailAST ast)

Description copied from class: AbstractCheck

Called to process a token.

Overrides:

visitToken in class AbstractCheck

Parameters:

ast - the token to process

leaveToken

public void leaveToken(DetailAST ast)

Description copied from class: AbstractCheck

Called after all the child nodes have been process.

Overrides:

leaveToken in class AbstractCheck

Parameters:

ast - the token leaving

finishTree

public void finishTree(DetailAST rootAST)

Description copied from class: AbstractCheck

Called after finished processing a tree. Ideal place to report on information collected whilst processing a tree.

Overrides:

finishTree in class AbstractCheck

Parameters:

rootAST - the root of the tree

setFileMaximum

public void setFileMaximum(int fileMaximum)

Setter to specify the maximum allowed number of non commenting lines in a file including all top level and nested classes.

Parameters:

fileMaximum - the maximum ncss

setClassMaximum

public void setClassMaximum(int classMaximum)

Setter to specify the maximum allowed number of non commenting lines in a class.

Parameters:

classMaximum - the maximum ncss

setMethodMaximum

public void setMethodMaximum(int methodMaximum)

Setter to specify the maximum allowed number of non commenting lines in a method.

Parameters:

methodMaximum - the maximum ncss