Class IllegalInstantiationCheck
- 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.coding.IllegalInstantiationCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class IllegalInstantiationCheck extends AbstractCheck
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 constantsTRUE
andFALSE
. Constructor invocations should be replaced by calls toBoolean.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.
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Property
classes
- Specify fully qualified class names that should not be instantiated. Type isjava.lang.String[]
. Default value is""
.
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
instantiation.avoid
- Since:
- 3.0
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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 Set<String>
classes
Specify fully qualified class names that should not be instantiated.private Set<String>
classNames
The class names defined in the file.private Set<FullIdent>
imports
The imports for the file.private Set<DetailAST>
instantiations
The instantiations in the file.private static String
JAVA_LANG
java.lang
package as string.static String
MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.private String
pkgName
Name of the package.
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Constructor Summary
Constructors Constructor Description IllegalInstantiationCheck()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
beginTree(DetailAST rootAST)
Called before the starting to process a tree.private String
checkImportStatements(String className)
Check import statements.void
finishTree(DetailAST rootAST)
Called after finished processing a tree.int[]
getAcceptableTokens()
The configurable token set.int[]
getDefaultTokens()
Returns the default token a check is interested in.private String
getIllegalInstantiation(String className)
Checks illegal instantiations.int[]
getRequiredTokens()
The tokens that this check must be registered for.private boolean
isSamePackage(String className, int pkgNameLen, String illegal)
Check that type is of the same package.private boolean
isStandardClass(String className, String illegal)
Is Standard Class.private void
postProcessLiteralNew(DetailAST newTokenAst)
Processes one of the collected "new" tokens when walking tree has finished.private void
processClassDef(DetailAST ast)
Collects classes defined in the source file.private void
processImport(DetailAST ast)
Perform processing for an import token.private void
processLiteralNew(DetailAST ast)
Collects a "new" token.private void
processPackageDef(DetailAST ast)
Perform processing for an package token.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
clearViolations, destroy, 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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JAVA_LANG
private static final String JAVA_LANG
java.lang
package as string.- See Also:
- Constant Field Values
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classNames
private final Set<String> classNames
The class names defined in the file.
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instantiations
private final Set<DetailAST> instantiations
The instantiations in the file.
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classes
private Set<String> classes
Specify fully qualified class names that should not be instantiated.
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Constructor Detail
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IllegalInstantiationCheck
public IllegalInstantiationCheck()
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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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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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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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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 classAbstractCheck
- Parameters:
rootAST
- the root of the tree
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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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finishTree
public void finishTree(DetailAST rootAST)
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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processClassDef
private void processClassDef(DetailAST ast)
Collects classes defined in the source file. Required to avoid false alarms for local vs. java.lang classes.- Parameters:
ast
- the class def token.
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processImport
private void processImport(DetailAST ast)
Perform processing for an import token.- Parameters:
ast
- the import token
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processPackageDef
private void processPackageDef(DetailAST ast)
Perform processing for an package token.- Parameters:
ast
- the package token
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processLiteralNew
private void processLiteralNew(DetailAST ast)
Collects a "new" token.- Parameters:
ast
- the "new" token
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postProcessLiteralNew
private void postProcessLiteralNew(DetailAST newTokenAst)
Processes one of the collected "new" tokens when walking tree has finished.- Parameters:
newTokenAst
- the "new" token.
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getIllegalInstantiation
private String getIllegalInstantiation(String className)
Checks illegal instantiations.- Parameters:
className
- instantiated class, may or may not be qualified- Returns:
- the fully qualified class name of className or null if instantiation of className is OK
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checkImportStatements
private String checkImportStatements(String className)
Check import statements.- Parameters:
className
- name of the class- Returns:
- value of illegal instantiated type
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isSamePackage
private boolean isSamePackage(String className, int pkgNameLen, String illegal)
Check that type is of the same package.- Parameters:
className
- class namepkgNameLen
- package nameillegal
- illegal value- Returns:
- true if type of the same package
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isStandardClass
private boolean isStandardClass(String className, String illegal)
Is Standard Class.- Parameters:
className
- class nameillegal
- illegal value- Returns:
- true if type is standard
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setClasses
public void setClasses(String... names)
Setter to specify fully qualified class names that should not be instantiated.- Parameters:
names
- class names- Since:
- 3.0
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