Class ThrowsCountCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
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- com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
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- com.puppycrawl.tools.checkstyle.api.AbstractCheck
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- com.puppycrawl.tools.checkstyle.checks.design.ThrowsCountCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public final class ThrowsCountCheck extends AbstractCheck
Restricts throws statements to a specified count. Methods with "Override" or "java.lang.Override" annotation are skipped from validation as current class cannot change signature of these methods.Rationale: Exceptions form part of a method's interface. Declaring a method to throw too many differently rooted exceptions makes exception handling onerous and leads to poor programming practices such as writing code like
catch(Exception ex)
. 4 is the empirical value which is based on reports that we had for the ThrowsCountCheck over big projects such as OpenJDK. This check also forces developers to put exceptions into a hierarchy such that in the simplest case, only one type of exception need be checked for by a caller but any subclasses can be caught specifically if necessary. For more information on rules for the exceptions and their issues, see Effective Java: Programming Language Guide Second Edition by Joshua Bloch pages 264-273.ignorePrivateMethods - allows to skip private methods as they do not cause problems for other classes.
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Property
ignorePrivateMethods
- Allow private methods to be ignored. Type isboolean
. Default value istrue
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Property
max
- Specify maximum allowed number of throws statements. Type isint
. Default value is4
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Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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throws.count
- Since:
- 3.2
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Nested Class Summary
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Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
AbstractAutomaticBean.OutputStreamOptions
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Field Summary
Fields Modifier and Type Field Description private static int
DEFAULT_MAX
Default value of max property.private boolean
ignorePrivateMethods
Allow private methods to be ignored.private int
max
Specify maximum allowed number of throws statements.static String
MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.
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Constructor Summary
Constructors Constructor Description ThrowsCountCheck()
Creates new instance of the check.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description int[]
getAcceptableTokens()
The configurable token set.private static String
getAnnotationName(DetailAST annotation)
Gets name of an annotation.int[]
getDefaultTokens()
Returns the default token a check is interested in.int[]
getRequiredTokens()
The tokens that this check must be registered for.private static boolean
isInPrivateMethod(DetailAST ast)
Checks if method, which throws an exception is private.private static boolean
isOverriding(DetailAST ast)
Check if a method has annotation @Override.void
setIgnorePrivateMethods(boolean ignorePrivateMethods)
Setter to allow private methods to be ignored.void
setMax(int max)
Setter to specify maximum allowed number of throws statements.private void
visitLiteralThrows(DetailAST ast)
Checks number of throws statements.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearViolations, destroy, finishTree, getFileContents, getFilePath, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity
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Methods inherited from class com.puppycrawl.tools.checkstyle.AbstractAutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Detail
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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
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DEFAULT_MAX
private static final int DEFAULT_MAX
Default value of max property.- See Also:
- Constant Field Values
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ignorePrivateMethods
private boolean ignorePrivateMethods
Allow private methods to be ignored.
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max
private int max
Specify maximum allowed number of throws statements.
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Constructor Detail
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ThrowsCountCheck
public ThrowsCountCheck()
Creates new instance of the check.
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Method Detail
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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 classAbstractCheck
- Returns:
- the default tokens
- See Also:
TokenTypes
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getRequiredTokens
public int[] getRequiredTokens()
Description copied from class:AbstractCheck
The tokens that this check must be registered for.- Specified by:
getRequiredTokens
in classAbstractCheck
- Returns:
- the token set this must be registered for.
- See Also:
TokenTypes
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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 classAbstractCheck
- Returns:
- the token set this check is designed for.
- See Also:
TokenTypes
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setIgnorePrivateMethods
public void setIgnorePrivateMethods(boolean ignorePrivateMethods)
Setter to allow private methods to be ignored.- Parameters:
ignorePrivateMethods
- whether private methods must be ignored.- Since:
- 6.7
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setMax
public void setMax(int max)
Setter to specify maximum allowed number of throws statements.- Parameters:
max
- maximum allowed throws statements.- Since:
- 3.2
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visitToken
public void visitToken(DetailAST ast)
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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visitLiteralThrows
private void visitLiteralThrows(DetailAST ast)
Checks number of throws statements.- Parameters:
ast
- throws for check.
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isOverriding
private static boolean isOverriding(DetailAST ast)
Check if a method has annotation @Override.- Parameters:
ast
- throws, which is being checked.- Returns:
- true, if a method has annotation @Override.
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getAnnotationName
private static String getAnnotationName(DetailAST annotation)
Gets name of an annotation.- Parameters:
annotation
- to get name of.- Returns:
- name of an annotation.
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isInPrivateMethod
private static boolean isInPrivateMethod(DetailAST ast)
Checks if method, which throws an exception is private.- Parameters:
ast
- throws, which is being checked.- Returns:
- true, if method, which throws an exception is private.
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