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

      • max

        private int max
        Specify maximum allowed nesting depth.
      • depth

        private int depth
        Current nesting depth.
    • Method Detail

      • setMax

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