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

Class DefaultComesLastCheck

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

Check that the default is after all the cases in a switch statement.

Rationale: Java allows default anywhere within the switch statement. But it is more readable if it comes after the last case.

  • Property skipIfLastAndSharedWithCase - Control whether to allow default along with case if they are not last. Type is boolean. Default value is false.

To configure the check: 

 <module name="DefaultComesLast"/>

Example:

 switch (i) {
   case 1:
     break;
   case 2:
     break;
   default: // OK
     break;
 }

 switch (i) {
   case 1:
     break;
   case 2:
     break; // OK, no default
 }

 switch (i) {
   case 1:
     break;
   default: // violation, 'default' before 'case'
     break;
   case 2:
     break;
 }

 switch (i) {
   case 1:
   default: // violation, 'default' before 'case'
     break;
   case 2:
     break;
 }

To configure the check to allow default label to be not last if it is shared with case: 

 <module name="DefaultComesLast">
   <property name="skipIfLastAndSharedWithCase" value="true"/>
 </module>

Example:

 switch (i) {
   case 1:
     break;
   case 2:
   default: // OK
     break;
   case 3:
     break;
 }

 switch (i) {
   case 1:
     break;
   default: // violation
   case 2:
     break;
 }

 // Switch rules are not subject to fall through, so this is still a violation:
 switch (i) {
   case 1 -> x = 9;
   default -> x = 10; // violation
   case 2 -> x = 32;
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • default.comes.last
  • default.comes.last.in.casegroup
Since:
3.4

  • 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:

    • MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE

      public static final String MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • skipIfLastAndSharedWithCase

      private boolean skipIfLastAndSharedWithCase
      Control whether to allow default along with case if they are not last.

  • Constructor Details

    • DefaultComesLastCheck

      public DefaultComesLastCheck()

  • Method Details

    • 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:

    • 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:

    • 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:

    • setSkipIfLastAndSharedWithCase

      public void setSkipIfLastAndSharedWithCase(boolean newValue)
      Setter to control whether to allow default along with case if they are not last.
      Parameters:
      newValue - whether to ignore checking.

    • visitToken

      public void visitToken(DetailAST ast)
      Description copied from class: AbstractCheck
      Called to process a token.
      Overrides:
      visitToken in class AbstractCheck
      Parameters:
      ast - the token to process

    • findNextSibling

      private static DetailAST findNextSibling(DetailAST ast, int tokenType)
      Return token type only if passed tokenType in argument is found or returns -1.
      Parameters:
      ast - root node.
      tokenType - tokentype to be processed.
      Returns:
      token if desired token is found or else null.