Package com.puppycrawl.tools.checkstyle.checks.metrics

Class CyclomaticComplexityCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class CyclomaticComplexityCheck
extends AbstractCheck
    Checks cyclomatic complexity against a specified limit. It is a measure of the minimum number of possible paths through the source and therefore the number of required tests, it is not about quality of code! It is only applied to methods, c-tors, static initializers and instance initializers.

    The complexity is equal to the number of decision points + 1. Decision points:

    • if, while, do, for, ?:, catch, switch, case statements.
    • Operators && and || in the body of target.
    • when expression in case labels, also known as guards.

    By pure theory level 1-4 is considered easy to test, 5-7 OK, 8-10 consider re-factoring to ease testing, and 11+ re-factor now as testing will be painful.

    When it comes to code quality measurement by this metric level 10 is very good level as a ultimate target (that is hard to archive). Do not be ashamed to have complexity level 15 or even higher, but keep it below 20 to catch really bad-designed code automatically.

    Please use Suppression to avoid violations on cases that could not be split in few methods without damaging readability of code or encapsulation.

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • cyclomaticComplexity
    Since:
    3.2

    • Method Detail

      • setSwitchBlockAsSingleDecisionPoint

        public void setSwitchBlockAsSingleDecisionPoint​(boolean switchBlockAsSingleDecisionPoint)
        Setter to control whether to treat the whole switch block as a single decision point.
        Parameters:
        switchBlockAsSingleDecisionPoint - whether to treat the whole switch block as a single decision point.
        Since:
        6.11

      • setMax

        public final void setMax​(int max)
        Setter to specify the maximum threshold allowed.
        Parameters:
        max - the maximum threshold
        Since:
        3.2

      • 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

      • visitTokenHook

        private void visitTokenHook​(DetailAST ast)
        Hook called when visiting a token. Will not be called the method definition tokens.
        Parameters:
        ast - the token being visited

      • leaveMethodDef

        private void leaveMethodDef​(DetailAST ast)
        Process the end of a method definition.
        Parameters:
        ast - the token representing the method definition

      • incrementCurrentValue

        private void incrementCurrentValue​(BigInteger amount)
        Increments the current value by a specified amount.
        Parameters:
        amount - the amount to increment by

      • pushValue

        private void pushValue()
        Push the current value on the stack.

      • popValue

        private void popValue()
        Pops a value off the stack and makes it the current value.

      • visitMethodDef

        private void visitMethodDef()
        Process the start of the method definition.