com.puppycrawl.tools.checkstyle.checks.coding

Class ReturnCountCheck

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.coding.ReturnCountCheck

All Implemented Interfaces:

Configurable, Contextualizable

public final class ReturnCountCheck
extends AbstractCheck

Restricts the number of return statements in methods, constructors and lambda expressions. Ignores specified methods (equals by default).

max property will only check returns in methods and lambdas that return a specific value (Ex: 'return 1;').

maxForVoid property will only check returns in methods, constructors, and lambdas that have no return type (IE 'return;'). It will only count visible return statements. Return statements not normally written, but implied, at the end of the method/constructor definition will not be taken into account. To disallow "return;" in void return type methods, use a value of 0.

Rationale: Too many return points can mean that code is attempting to do too much or may be difficult to understand.

• Property max - Specify maximum allowed number of return statements in non-void methods/lambdas. Type is int. Default value is 2.
• Property maxForVoid - Specify maximum allowed number of return statements in void methods/constructors/lambdas. Type is int. Default value is 1.
• Property format - Specify method names to ignore. Type is java.util.regex.Pattern. Default value is "^equals$".
• Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: CTOR_DEF, METHOD_DEF, LAMBDA.

To configure the check so that it doesn't allow more than three return statements per method (ignoring the equals() method):

 <module name="ReturnCount">
   <property name="max" value="3"/>
 </module>
 

To configure the check so that it doesn't allow any return statements per void method:

 <module name="ReturnCount">
   <property name="maxForVoid" value="0"/>
 </module>
 

To configure the check so that it doesn't allow more than 2 return statements per method (ignoring the equals() method) and more than 1 return statements per void method:

 <module name="ReturnCount">
   <property name="max" value="2"/>
   <property name="maxForVoid" value="1"/>
 </module>
 

To configure the check so that it doesn't allow more than three return statements per method for all methods:

 <module name="ReturnCount">
   <property name="max" value="3"/>
   <property name="format" value="^$"/>
 </module>
 

To configure the check so that it doesn't allow any return statements in constructors, more than one return statement in all lambda expressions and more than two return statements in methods:

 <module name="ReturnCount">
   <property name="max" value="0"/>
   <property name="tokens" value="CTOR_DEF"/>
 </module>
 <module name="ReturnCount">
   <property name="max" value="1"/>
   <property name="tokens" value="LAMBDA"/>
 </module>
 <module name="ReturnCount">
   <property name="max" value="2"/>
   <property name="tokens" value="METHOD_DEF"/>
 </module>
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

• return.count
• return.countVoid

Since:

3.2

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	ReturnCountCheck.Context Class to encapsulate information about one method.

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

AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
private ReturnCountCheck.Context	context Current method context.
private java.util.Deque<ReturnCountCheck.Context>	contextStack Stack of method contexts.
private java.util.regex.Pattern	format Specify method names to ignore.
private int	max Specify maximum allowed number of return statements in non-void methods/lambdas.
private int	maxForVoid Specify maximum allowed number of return statements in void methods/constructors/lambdas.
static java.lang.String	MSG_KEY A key is pointing to the warning message text in "messages.properties" file.
static java.lang.String	MSG_KEY_VOID A key pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
ReturnCountCheck()

Method Summary

Modifier and Type	Method and Description
void	beginTree(DetailAST rootAST) Called before the starting to process 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.
private void	leave(DetailAST ast) Checks number of return statements and restore previous context.
void	leaveToken(DetailAST ast) Called after all the child nodes have been process.
void	setFormat(java.util.regex.Pattern pattern) Setter to specify method names to ignore.
void	setMax(int max) Setter to specify maximum allowed number of return statements in non-void methods/lambdas.
void	setMaxForVoid(int maxForVoid) Setter to specify maximum allowed number of return statements in void methods/constructors/lambdas.
private void	visitLambda() Creates new lambda context and places old one on the stack.
private void	visitMethodDef(DetailAST ast) Creates new method context and places old one on the stack.
private void	visitReturn(DetailAST ast) Examines the return statement and tells context about it.
void	visitToken(DetailAST ast) Called to process a token.

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

clearViolations, destroy, finishTree, getFileContents, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, 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_KEY

public static final java.lang.String MSG_KEY

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

See Also:

Constant Field Values

MSG_KEY_VOID

public static final java.lang.String MSG_KEY_VOID

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

See Also:

Constant Field Values

contextStack

private final java.util.Deque<ReturnCountCheck.Context> contextStack

Stack of method contexts.

format

private java.util.regex.Pattern format

Specify method names to ignore.

max

private int max

Specify maximum allowed number of return statements in non-void methods/lambdas.

maxForVoid

private int maxForVoid

Specify maximum allowed number of return statements in void methods/constructors/lambdas.

context

private ReturnCountCheck.Context context

Current method context.

Constructor Detail

ReturnCountCheck

public ReturnCountCheck()

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

setFormat

public void setFormat(java.util.regex.Pattern pattern)

Setter to specify method names to ignore.

Parameters:

pattern - a pattern.

setMax

public void setMax(int max)

Setter to specify maximum allowed number of return statements in non-void methods/lambdas.

Parameters:

max - maximum allowed number of return statements.

setMaxForVoid

public void setMaxForVoid(int maxForVoid)

Setter to specify maximum allowed number of return statements in void methods/constructors/lambdas.

Parameters:

maxForVoid - maximum allowed number of return statements for void methods.

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

visitMethodDef

private void visitMethodDef(DetailAST ast)

Creates new method context and places old one on the stack.

Parameters:

ast - method definition for check.

leave

private void leave(DetailAST ast)

Checks number of return statements and restore previous context.

Parameters:

ast - node to leave.

visitLambda

private void visitLambda()

Creates new lambda context and places old one on the stack.

visitReturn

private void visitReturn(DetailAST ast)

Examines the return statement and tells context about it.

Parameters:

ast - return statement to check.