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

Class MissingSwitchDefaultCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class MissingSwitchDefaultCheck
extends AbstractCheck

    Checks that switch statement has a default clause.

    Rationale: It's usually a good idea to introduce a default case in every switch statement. Even if the developer is sure that all currently possible cases are covered, this should be expressed in the default branch, e.g. by using an assertion. This way the code is protected against later changes, e.g. introduction of new types in an enumeration type.

    This check does not validate any switch expressions. Rationale: The compiler requires switch expressions to be exhaustive. This means that all possible inputs must be covered.

    This check does not validate switch statements that use pattern or null labels. Rationale: Switch statements that use pattern or null labels are checked by the compiler for exhaustiveness. This means that all possible inputs must be covered.

    See the Java Language Specification for more information about switch statements and expressions.

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • missing.switch.default
    Since:
    3.1

    • Method Detail

      • 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

      • containsDefaultLabel

        private static boolean containsDefaultLabel​(DetailAST detailAst)
        Checks if the case group or its sibling contain the 'default' switch.
        Parameters:
        detailAst - first case group to check.
        Returns:
        true if 'default' switch found.

      • containsPatternCaseLabelElement

        private static boolean containsPatternCaseLabelElement​(DetailAST detailAst)
        Checks if a switch block contains a case label with a pattern variable definition. In this situation, the compiler enforces the given switch block to cover all possible inputs, and we do not need a default label.
        Parameters:
        detailAst - first case group to check.
        Returns:
        true if switch block contains a pattern case label element

      • containsDefaultCaseLabelElement

        private static boolean containsDefaultCaseLabelElement​(DetailAST detailAst)
        Checks if a switch block contains a default case label.
        Parameters:
        detailAst - first case group to check.
        Returns:
        true if switch block contains default case label

      • containsNullCaseLabelElement

        private static boolean containsNullCaseLabelElement​(DetailAST detailAst)
        Checks if a switch block contains a null case label.
        Parameters:
        detailAst - first case group to check.
        Returns:
        true if switch block contains null case label

      • isSwitchExpression

        private static boolean isSwitchExpression​(DetailAST ast)
        Checks if this LITERAL_SWITCH token is part of a switch expression.
        Parameters:
        ast - the switch statement we are checking
        Returns:
        true if part of a switch expression

      • hasNullCaseLabel

        private static boolean hasNullCaseLabel​(DetailAST ast)
        Checks if the case contains null label.
        Parameters:
        ast - the switch statement we are checking
        Returns:
        returnValue the ast of null label