Package 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

  • Field Details

    • MSG_KEY

      public static final String MSG_KEY
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • MSG_KEY_VOID

      public static final String MSG_KEY_VOID
      A key pointing to the warning message text in "messages.properties" file.
      See Also:

    • contextStack

      private final Deque<ReturnCountCheck.Context> contextStack
      Stack of method contexts.

    • format

      private 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 Details

    • ReturnCountCheck

      public ReturnCountCheck()

  • Method Details

    • 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:

    • 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:

    • 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:

    • setFormat

      public void setFormat(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.