Class MultipleStringLiteralsCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.api.AutomaticBean
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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.MultipleStringLiteralsCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class MultipleStringLiteralsCheck extends AbstractCheck
Checks for multiple occurrences of the same string literal within a single file.
Rationale: Code duplication makes maintenance more difficult, so it can be better to replace the multiple occurrences with a constant.
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Property
allowedDuplicates
- Specify the maximum number of occurrences to allow without generating a warning. Type isint
. Default value is1
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Property
ignoreStringsRegexp
- Specify RegExp for ignored strings (with quotation marks). Type isjava.util.regex.Pattern
. Default value is"^""$"
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Property
ignoreOccurrenceContext
- Specify token type names where duplicate strings are ignored even if they don't match ignoredStringsRegexp. This allows you to exclude syntactical contexts like annotations or static initializers from the check. Type isjava.lang.String[]
. Validation type istokenTypesSet
. Default value isANNOTATION
.
To configure the check:
<module name="MultipleStringLiterals"/>
Example:
public class MyClass { String a = "StringContents"; String a1 = "unchecked"; @SuppressWarnings("unchecked") // OK, duplicate strings are ignored in annotations public void myTest() { String a2 = "StringContents"; // violation, "StringContents" occurs twice String a3 = "DoubleString" + "DoubleString"; // violation, "DoubleString" occurs twice String a4 = "SingleString"; // OK String a5 = ", " + ", " + ", "; // violation, ", " occurs three times } }
To configure the check so that it allows two occurrences of each string:
<module name="MultipleStringLiterals"> <property name="allowedDuplicates" value="2"/> </module>
Example:
public class MyClass { String a = "StringContents"; String a1 = "unchecked"; @SuppressWarnings("unchecked") // OK, duplicate strings are ignored in annotations public void myTest() { String a2 = "StringContents"; // OK, two occurrences are allowed String a3 = "DoubleString" + "DoubleString"; // OK, two occurrences are allowed String a4 = "SingleString"; // OK String a5 = ", " + ", " + ", "; // violation, three occurrences are NOT allowed } }
To configure the check so that it ignores ", " and empty strings:
<module name="MultipleStringLiterals"> <property name="ignoreStringsRegexp" value='^(("")|(", "))$'/> </module>
Example:
public class MyClass { String a = "StringContents"; String a1 = "unchecked"; @SuppressWarnings("unchecked") // OK, duplicate strings are ignored in annotations public void myTest() { String a2 = "StringContents"; // violation, "StringContents" occurs twice String a3 = "DoubleString" + "DoubleString"; // violation, "DoubleString" occurs twice String a4 = "SingleString"; // OK String a5 = ", " + ", " + ", "; // OK, multiple occurrences of ", " are allowed } }
To configure the check so that it flags duplicate strings in all syntactical contexts, even in annotations like
@SuppressWarnings("unchecked")
:<module name="MultipleStringLiterals"> <property name="ignoreOccurrenceContext" value=""/> </module>
Example:
public class MyClass { String a = "StringContents"; String a1 = "unchecked"; @SuppressWarnings("unchecked") // violation, "unchecked" occurs twice public void myTest() { String a2 = "StringContents"; // violation, "StringContents" occurs twice String a3 = "DoubleString" + "DoubleString"; // violation, "DoubleString" occurs twice String a4 = "SingleString"; // OK String a5 = ", " + ", " + ", "; // violation, ", " occurs three times } }
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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multiple.string.literal
- Since:
- 3.5
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Nested Class Summary
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Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
Fields Modifier and Type Field Description private static java.util.regex.Pattern
ALL_NEW_LINES
Compiled pattern for all system newlines.private int
allowedDuplicates
Specify the maximum number of occurrences to allow without generating a warning.private java.util.BitSet
ignoreOccurrenceContext
Specify token type names where duplicate strings are ignored even if they don't match ignoredStringsRegexp.private java.util.regex.Pattern
ignoreStringsRegexp
Specify RegExp for ignored strings (with quotation marks).static java.lang.String
MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.private static java.lang.String
QUOTE
String used to amend TEXT_BLOCK_CONTENT so that it matches STRING_LITERAL.private java.util.Map<java.lang.String,java.util.List<DetailAST>>
stringMap
The found strings and their tokens.
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Constructor Summary
Constructors Constructor Description MultipleStringLiteralsCheck()
Construct an instance with default values.
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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.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.int[]
getRequiredTokens()
The tokens that this check must be registered for.private boolean
isInIgnoreOccurrenceContext(DetailAST ast)
Analyses the path from the AST root to a given AST for occurrences of the token types inignoreOccurrenceContext
.void
setAllowedDuplicates(int allowedDuplicates)
Setter to specify the maximum number of occurrences to allow without generating a warning.void
setIgnoreOccurrenceContext(java.lang.String... strRep)
Setter to specify token type names where duplicate strings are ignored even if they don't match ignoredStringsRegexp.void
setIgnoreStringsRegexp(java.util.regex.Pattern ignoreStringsRegexp)
Setter to specify RegExp for ignored strings (with quotation marks).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.api.AutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Detail
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MSG_KEY
public static final java.lang.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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ALL_NEW_LINES
private static final java.util.regex.Pattern ALL_NEW_LINES
Compiled pattern for all system newlines.
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QUOTE
private static final java.lang.String QUOTE
String used to amend TEXT_BLOCK_CONTENT so that it matches STRING_LITERAL.- See Also:
- Constant Field Values
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stringMap
private final java.util.Map<java.lang.String,java.util.List<DetailAST>> stringMap
The found strings and their tokens.
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ignoreOccurrenceContext
private final java.util.BitSet ignoreOccurrenceContext
Specify token type names where duplicate strings are ignored even if they don't match ignoredStringsRegexp. This allows you to exclude syntactical contexts like annotations or static initializers from the check.
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allowedDuplicates
private int allowedDuplicates
Specify the maximum number of occurrences to allow without generating a warning.
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ignoreStringsRegexp
private java.util.regex.Pattern ignoreStringsRegexp
Specify RegExp for ignored strings (with quotation marks).
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Constructor Detail
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MultipleStringLiteralsCheck
public MultipleStringLiteralsCheck()
Construct an instance with default values.
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Method Detail
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setAllowedDuplicates
public void setAllowedDuplicates(int allowedDuplicates)
Setter to specify the maximum number of occurrences to allow without generating a warning.- Parameters:
allowedDuplicates
- The maximum number of duplicates.
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setIgnoreStringsRegexp
public final void setIgnoreStringsRegexp(java.util.regex.Pattern ignoreStringsRegexp)
Setter to specify RegExp for ignored strings (with quotation marks).- Parameters:
ignoreStringsRegexp
- regular expression pattern for ignored strings
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setIgnoreOccurrenceContext
public final void setIgnoreOccurrenceContext(java.lang.String... strRep)
Setter to specify token type names where duplicate strings are ignored even if they don't match ignoredStringsRegexp. This allows you to exclude syntactical contexts like annotations or static initializers from the check.- Parameters:
strRep
- the string representation of the tokens interested in
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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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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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isInIgnoreOccurrenceContext
private boolean isInIgnoreOccurrenceContext(DetailAST ast)
Analyses the path from the AST root to a given AST for occurrences of the token types inignoreOccurrenceContext
.- Parameters:
ast
- the node from where to start searching towards the root node- Returns:
- whether the path from the root node to ast contains one of the
token type in
ignoreOccurrenceContext
.
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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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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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