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

Class 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 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

    • Constructor Detail

      • NestedTryDepthCheck

        public NestedTryDepthCheck()

    • Method Detail

      • 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:
        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

      • 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

      • 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