Package com.puppycrawl.tools.checkstyle.checks.coding

Class NestedTryDepthCheck

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.NestedTryDepthCheck
All Implemented Interfaces:
Configurable, Contextualizable
public final class NestedTryDepthCheck extends AbstractCheck

Restricts nested try-catch-finally blocks to a specified depth.

  • Property max - Specify maximum allowed nesting depth. Type is int. Default value is 1.

To configure the check: 

 <module name="NestedTryDepth"/>

case 1: Example of code with violation: 

 try {
     try {
         try { // violation, current depth is 2, default max allowed depth is 1
         } catch (Exception e) {
         }
     } catch (Exception e) {
     }
 } catch (Exception e) {
 }

case 1: Example of compliant code: 

 try {
     try { // OK, current depth is 1, default max allowed depth is also 1
     } catch (Exception e) {
     }
 } catch (Exception e) {
 }

case 2: Example of code for handling unique and general exceptions

 try {
     try { // OK, current depth is 1, default max allowed depth is also 1
             // any more nesting could cause code violation!
             throw ArithmeticException();
     } catch (ArithmeticException e) { // catches arithmetic exceptions
     } catch (NumberFormatException e) { // catches number-format exceptions
     } catch (Exception e) { // catches general exceptions other than stated above
     }
 } catch (
   ArithmeticException
   | NumberFormatException
   | ArrayIndexOutOfBoundsException e) { // catches any of the 3 exception
 } catch (Exception e) { // catches general exception
 } finally { // do something when try-catch block finished execution
 }

To configure the check to allow nesting depth 3: 

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

Example of code with violation: 

 try {
     try {
         try {
             try {
                 try { // violation, current depth is 4, max allowed depth is 3
                 } catch (Exception e) {
                 }
             } catch (Exception e) {
             }
         } catch (Exception e) {
         }
     } catch (Exception e) {
     }
 } catch (Exception e) {
 }

Example of compliant code: 

 try {
     try {
         try {
             try { // OK, current depth is 3, max allowed depth is also 3
             } catch (Exception e) {
             }
         } catch (Exception e) {
         }
     } catch (Exception e) {
     }
 } catch (Exception e) {
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • nested.try.depth
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:

    • max

      private int max
      Specify maximum allowed nesting depth.

    • depth

      private int depth
      Current nesting depth.

  • Constructor Details

    • NestedTryDepthCheck

      public NestedTryDepthCheck()

  • Method Details

    • setMax

      public void setMax(int max)
      Setter to specify maximum allowed nesting depth.
      Parameters:
      max - maximum allowed nesting depth.

    • 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:

    • 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:

    • 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:

    • 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 literalTry)
      Description copied from class: AbstractCheck
      Called to process a token.
      Overrides:
      visitToken in class AbstractCheck
      Parameters:
      literalTry - the token to process

    • leaveToken

      public void leaveToken(DetailAST literalTry)
      Description copied from class: AbstractCheck
      Called after all the child nodes have been process.
      Overrides:
      leaveToken in class AbstractCheck
      Parameters:
      literalTry - the token leaving