Class IllegalInstantiationCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks for illegal instantiations where a factory method is preferred.
Rationale: Depending on the project, for some classes it might be preferable to create instances through factory methods rather than calling the constructor.
A simple example is the java.lang.Boolean
class.
For performance reasons, it is preferable to use the predefined constants
TRUE
and FALSE
.
Constructor invocations should be replaced by calls to Boolean.valueOf()
.
Some extremely performance sensitive projects may require the use of factory methods for other classes as well, to enforce the usage of number caches or object pools.
There is a limitation that it is currently not possible to specify array classes.
-
Property
classes
- Specify fully qualified class names that should not be instantiated. Type isjava.lang.String[]
. Default value is""
. -
Property
tokens
- tokens to check Type isjava.lang.String[]
. Validation type istokenSet
. Default value is: CLASS_DEF.
To configure the check to find instantiations of java.lang.Boolean
:
<module name="IllegalInstantiation"> <property name="classes" value="java.lang.Boolean"/> </module>
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
instantiation.avoid
- Since:
- 3.0
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Nested Class Summary
Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
Called before the starting to process a tree.void
finishTree
(DetailAST rootAST) Called after finished processing a tree.int[]
The configurable token set.int[]
Returns the default token a check is interested in.int[]
The tokens that this check must be registered for.void
setClasses
(String... names) Setter to specify fully qualified class names that should not be instantiated.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearMessages, destroy, getFileContents, getLine, getLines, getMessages, getTabWidth, getTokenNames, init, isCommentNodesRequired, leaveToken, 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
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Field Details
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MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
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Constructor Details
-
IllegalInstantiationCheck
public IllegalInstantiationCheck()
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Method Details
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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:
-
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:
-
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:
-
beginTree
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 classAbstractCheck
- Parameters:
rootAST
- the root of the tree
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visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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finishTree
Description copied from class:AbstractCheck
Called after finished processing a tree. Ideal place to report on information collected whilst processing a tree.- Overrides:
finishTree
in classAbstractCheck
- Parameters:
rootAST
- the root of the tree
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setClasses
Setter to specify fully qualified class names that should not be instantiated.- Parameters:
names
- a comma separate list of class names
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