Class IllegalCatchCheck

All Implemented Interfaces:
Configurable, Contextualizable

public final class IllegalCatchCheck extends AbstractCheck

Checks that certain exception types do not appear in a catch statement.

Rationale: catching java.lang.Exception, java.lang.Error or java.lang.RuntimeException is almost never acceptable. Novice developers often simply catch Exception in an attempt to handle multiple exception classes. This unfortunately leads to code that inadvertently catches NullPointerException, OutOfMemoryError, etc.

  • Property illegalClassNames - Specify exception class names to reject. Type is java.lang.String[]. Default value is Error, Exception, RuntimeException, Throwable, java.lang.Error, java.lang.Exception, java.lang.RuntimeException, java.lang.Throwable.

To configure the check:

 <module name="IllegalCatch"/>
 

Example:

 try {
     // some code here
 } catch (Exception e) { // violation

 }

 try {
     // some code here
 } catch (ArithmeticException e) { // OK

 } catch (Exception e) { // violation, catching Exception is illegal
                           and order of catch blocks doesn't matter
 }

 try {
     // some code here
 } catch (ArithmeticException | Exception e) { // violation, catching Exception is illegal

 }

 try {
     // some code here
 } catch (ArithmeticException e) { // OK

 }

 

To configure the check to override the default list with ArithmeticException and OutOfMemoryError:

 <module name="IllegalCatch">
   <property name="illegalClassNames" value="ArithmeticException,
               OutOfMemoryError"/>
 </module>
 

Example:

 try {
     // some code here
 } catch (OutOfMemoryError e) { // violation

 }

 try {
     // some code here
 } catch (ArithmeticException e) { // violation

 }

 try {
     // some code here
 } catch (NullPointerException e) { // OK

 } catch (OutOfMemoryError e) { // violation

 }

 try {
     // some code here
 } catch (ArithmeticException | Exception e) {  // violation

 }

 try {
     // some code here
 } catch (Exception e) { // OK

 }
 

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

  • illegal.catch
Since:
3.2
  • 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:
  • Constructor Details

    • IllegalCatchCheck

      public IllegalCatchCheck()
  • Method Details

    • setIllegalClassNames

      public void setIllegalClassNames(String... classNames)
      Setter to specify exception class names to reject.
      Parameters:
      classNames - array of illegal exception classes
    • 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:
    • 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:
    • visitToken

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