com.puppycrawl.tools.checkstyle.checks.coding

Class NestedTryDepthCheck

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.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

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

AutomaticBean.OutputStreamOptions

Field Summary

Fields

Modifier and Type	Field and Description
static String	MSG_KEY A key is pointing to the warning message text in "messages.properties" file.

Constructor Summary

Constructors

Constructor and Description
NestedTryDepthCheck()

Method Summary

Modifier and Type	Method and Description
void	beginTree(DetailAST rootAST) Called before the starting to process a tree.
int[]	getAcceptableTokens() The configurable token set.
int[]	getDefaultTokens() Returns the default token a check is interested in.
int[]	getRequiredTokens() The tokens that this check must be registered for.
void	leaveToken(DetailAST literalTry) Called after all the child nodes have been process.
void	setMax(int max) Setter to specify maximum allowed nesting depth.
void	visitToken(DetailAST literalTry) Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

clearMessages, destroy, finishTree, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, log, log, log, setFileContents, setTabWidth, setTokens

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

configure, contextualize, getConfiguration, setupChild

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MSG_KEY

public static final String MSG_KEY

A key is pointing to the warning message text in "messages.properties" file.

See Also:

Constant Field Values

Constructor Detail

NestedTryDepthCheck

public NestedTryDepthCheck()

Method Detail

setMax

public void setMax(int max)

Setter to specify maximum allowed nesting depth.

Parameters:

max - maximum allowed nesting depth.

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:

TokenTypes

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

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:

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

visitToken

public void visitToken(DetailAST literalTry)

Description copied from class: AbstractCheck

Called to process a token.

Overrides:

visitToken in class AbstractCheck

Parameters:

literalTry - the token to process

leaveToken

public void leaveToken(DetailAST literalTry)

Description copied from class: AbstractCheck

Called after all the child nodes have been process.

Overrides:

leaveToken in class AbstractCheck

Parameters:

literalTry - the token leaving