Class FinalLocalVariableCheck
- All Implemented Interfaces:
Configurable
,Contextualizable
Checks that local variables that never have their values changed are declared final. The check can be configured to also check that unchanged parameters are declared final.
When configured to check parameters, the check ignores parameters of interface methods and abstract methods.
-
Property
validateEnhancedForLoopVariable
- Control whether to check enhanced for-loop variable. Type isboolean
. Default value isfalse
. -
Property
tokens
- tokens to check Type isjava.lang.String[]
. Validation type istokenSet
. Default value is: VARIABLE_DEF.
To configure the check:
<module name="FinalLocalVariable"/>
To configure the check so that it checks local variables and parameters:
<module name="FinalLocalVariable"> <property name="tokens" value="VARIABLE_DEF,PARAMETER_DEF"/> </module>
By default, this Check skip final validation on Enhanced For-Loop.
Option 'validateEnhancedForLoopVariable' could be used to make Check to validate even variable from Enhanced For Loop.
An example of how to configure the check so that it also validates enhanced For Loop Variable is:
<module name="FinalLocalVariable"> <property name="tokens" value="VARIABLE_DEF"/> <property name="validateEnhancedForLoopVariable" value="true"/> </module>
Example:
for (int number : myNumbers) { // violation System.out.println(number); }
An example of how to configure check on local variables and parameters but do not validate loop variables:
<module name="FinalLocalVariable"> <property name="tokens" value="VARIABLE_DEF,PARAMETER_DEF"/> <property name="validateEnhancedForLoopVariable" value="false"/> </module>
Example:
public class MyClass { static int foo(int x, int y) { //violations, parameters should be final return x+y; } public static void main (String []args) { //violation, parameters should be final for (String i : args) { System.out.println(i); } int result=foo(1,2); // violation } }
Parent is com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
-
final.variable
- Since:
- 3.2
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate static class
Represents information about final local variable candidate.private static class
Holder for the scope data.Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final int[]
Assign operator types.Assigned variables of current scope.private static final int[]
Loop types.static final String
A key is pointing to the warning message text in "messages.properties" file.Uninitialized variables of previous scope.private final Deque
<FinalLocalVariableCheck.ScopeData> Scope Deque.private boolean
Control whether to check enhanced for-loop variable. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate static void
determineAssignmentConditions
(DetailAST ident, FinalLocalVariableCheck.FinalVariableCandidate candidate) Determines identifier assignment conditions (assigned or already assigned).private static DetailAST
Find the Class, Constructor, Enum, Method, or Field in which it is defined.private static DetailAST
findLastChildWhichContainsSpecifiedToken
(DetailAST ast, int childType, int containType) Returns the last child token that makes a specified type and contains containType in its branch.int[]
The configurable token set.int[]
Returns the default token a check is interested in.Gets final variable candidate for ast.int[]
The tokens that this check must be registered for.private void
insertParameter
(DetailAST ast) Insert a parameter at the topmost scope stack.private void
insertVariable
(DetailAST ast) Insert a variable at the topmost scope stack.private static boolean
isAssignOperator
(int parentType) Is Arithmetic operator.private static boolean
If token is CASE_GROUP or SWITCH_RULE and there is anothercase
following.private static boolean
isFirstChild
(DetailAST ast) Whether the ast is the first child of its parent.private static boolean
If token is LITERAL_IF and there is anelse
following.private static boolean
Determines whether an AST is a descendant of an abstract or native method.private static boolean
isInitialized
(DetailAST ast) Check if VARIABLE_DEF is initialized or not.private static boolean
isInLambda
(DetailAST paramDef) Check if current param is lambda's param.private static boolean
isInSpecificCodeBlocks
(DetailAST node, int... blockTypes) Checks whether the scope of a node is restricted to a specific code blocks.private static boolean
isInTheSameLoop
(DetailAST ast1, DetailAST ast2) Check if both the variables are in the same loop.private static boolean
isLoopAst
(int ast) Checks whether the ast is a loop.private static boolean
isMultipleTypeCatch
(DetailAST parameterDefAst) Check if given parameter definition is a multiple type catch.private static boolean
isSameVariables
(DetailAST ast1, DetailAST ast2) Check if both the Variables are same.private static boolean
isUseOfExternalVariableInsideLoop
(DetailAST variable) Checks whether a variable which is declared outside loop is used inside loop.private static boolean
isVariableInForInit
(DetailAST variableDef) Checks if current variable is defined infor-loop init
, e.g.:void
leaveToken
(DetailAST ast) Called after all the child nodes have been process.private void
Removes the final variable candidate from the Stack.final void
setValidateEnhancedForLoopVariable
(boolean validateEnhancedForLoopVariable) Setter to control whether to check enhanced for-loop variable.private boolean
Determines whether enhanced for-loop variable should be checked or not.private static boolean
Whether the final variable candidate should be removed from the list of final local variable candidates.private static boolean
If token is LITERAL_IF and there is anelse
following or token is CASE_GROUP or SWITCH_RULE and there is anothercase
following, then update the uninitialized variables.private void
Store un-initialized variables in a temporary stack for future use.private void
updateAllUninitializedVariables
(Deque<DetailAST> prevScopeUninitializedVariableData) Update current scope data uninitialized variable according to the whole scope data.private void
Update assigned variables in a temporary stack.private void
updateUninitializedVariables
(Deque<DetailAST> scopeUninitializedVariableData) Update current scope data uninitialized variable according to the specific scope data.void
visitToken
(DetailAST ast) Called to process a token.Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearViolations, destroy, finishTree, getFileContents, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, 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
-
Field Details
-
MSG_KEY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
-
ASSIGN_OPERATOR_TYPES
private static final int[] ASSIGN_OPERATOR_TYPESAssign operator types. -
LOOP_TYPES
private static final int[] LOOP_TYPESLoop types. -
scopeStack
Scope Deque. -
prevScopeUninitializedVariables
Uninitialized variables of previous scope. -
currentScopeAssignedVariables
Assigned variables of current scope. -
validateEnhancedForLoopVariable
private boolean validateEnhancedForLoopVariableControl whether to check enhanced for-loop variable.
-
-
Constructor Details
-
FinalLocalVariableCheck
public FinalLocalVariableCheck()
-
-
Method Details
-
setValidateEnhancedForLoopVariable
public final void setValidateEnhancedForLoopVariable(boolean validateEnhancedForLoopVariable) Setter to control whether to check enhanced for-loop variable.- Parameters:
validateEnhancedForLoopVariable
- whether to check for-loop variable
-
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:
-
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:
-
visitToken
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
-
leaveToken
Description copied from class:AbstractCheck
Called after all the child nodes have been process.- Overrides:
leaveToken
in classAbstractCheck
- Parameters:
ast
- the token leaving
-
updateCurrentScopeAssignedVariables
private void updateCurrentScopeAssignedVariables()Update assigned variables in a temporary stack. -
determineAssignmentConditions
private static void determineAssignmentConditions(DetailAST ident, FinalLocalVariableCheck.FinalVariableCandidate candidate) Determines identifier assignment conditions (assigned or already assigned).- Parameters:
ident
- identifier.candidate
- final local variable candidate.
-
isInSpecificCodeBlocks
Checks whether the scope of a node is restricted to a specific code blocks.- Parameters:
node
- node.blockTypes
- int array of all block types to check.- Returns:
- true if the scope of a node is restricted to specific code block types.
-
getFinalCandidate
Gets final variable candidate for ast.- Parameters:
ast
- ast.- Returns:
- Optional of
FinalLocalVariableCheck.FinalVariableCandidate
for ast from scopeStack.
-
storePrevScopeUninitializedVariableData
private void storePrevScopeUninitializedVariableData()Store un-initialized variables in a temporary stack for future use. -
updateAllUninitializedVariables
Update current scope data uninitialized variable according to the whole scope data.- Parameters:
prevScopeUninitializedVariableData
- variable for previous stack of uninitialized variables
-
updateUninitializedVariables
Update current scope data uninitialized variable according to the specific scope data.- Parameters:
scopeUninitializedVariableData
- variable for specific stack of uninitialized variables
-
shouldUpdateUninitializedVariables
If token is LITERAL_IF and there is anelse
following or token is CASE_GROUP or SWITCH_RULE and there is anothercase
following, then update the uninitialized variables.- Parameters:
ast
- token to be checked- Returns:
- true if should be updated, else false
-
isIfTokenWithAnElseFollowing
If token is LITERAL_IF and there is anelse
following.- Parameters:
ast
- token to be checked- Returns:
- true if token is LITERAL_IF and there is an
else
following, else false
-
isCaseTokenWithAnotherCaseFollowing
If token is CASE_GROUP or SWITCH_RULE and there is anothercase
following.- Parameters:
ast
- token to be checked- Returns:
- true if token is CASE_GROUP or SWITCH_RULE and there is another
case
following, else false
-
findLastChildWhichContainsSpecifiedToken
private static DetailAST findLastChildWhichContainsSpecifiedToken(DetailAST ast, int childType, int containType) Returns the last child token that makes a specified type and contains containType in its branch.- Parameters:
ast
- token to be testedchildType
- the token type to matchcontainType
- the token type which has to be present in the branch- Returns:
- the matching token, or null if no match
-
shouldCheckEnhancedForLoopVariable
Determines whether enhanced for-loop variable should be checked or not.- Parameters:
ast
- The ast to compare.- Returns:
- true if enhanced for-loop variable should be checked.
-
insertParameter
Insert a parameter at the topmost scope stack.- Parameters:
ast
- the variable to insert.
-
insertVariable
Insert a variable at the topmost scope stack.- Parameters:
ast
- the variable to insert.
-
isInitialized
Check if VARIABLE_DEF is initialized or not.- Parameters:
ast
- VARIABLE_DEF to be checked- Returns:
- true if initialized
-
isFirstChild
Whether the ast is the first child of its parent.- Parameters:
ast
- the ast to check.- Returns:
- true if the ast is the first child of its parent.
-
removeFinalVariableCandidateFromStack
Removes the final variable candidate from the Stack.- Parameters:
ast
- variable to remove.
-
isMultipleTypeCatch
Check if given parameter definition is a multiple type catch.- Parameters:
parameterDefAst
- parameter definition- Returns:
- true if it is a multiple type catch, false otherwise
-
shouldRemoveFinalVariableCandidate
private static boolean shouldRemoveFinalVariableCandidate(FinalLocalVariableCheck.ScopeData scopeData, DetailAST ast) Whether the final variable candidate should be removed from the list of final local variable candidates.- Parameters:
scopeData
- the scope data of the variable.ast
- the variable ast.- Returns:
- true, if the variable should be removed.
-
isUseOfExternalVariableInsideLoop
Checks whether a variable which is declared outside loop is used inside loop. For example:int x; for (int i = 0, j = 0; i < j; i++) { x = 5; }
- Parameters:
variable
- variable.- Returns:
- true if a variable which is declared outside loop is used inside loop.
-
isAssignOperator
private static boolean isAssignOperator(int parentType) Is Arithmetic operator.- Parameters:
parentType
- token AST- Returns:
- true is token type is in arithmetic operator
-
isVariableInForInit
Checks if current variable is defined infor-loop init
, e.g.:for (int i = 0, j = 0; i < j; i++) { . . . }
i, j
are defined infor-loop init
- Parameters:
variableDef
- variable definition node.- Returns:
- true if variable is defined in
for-loop init
-
isInAbstractOrNativeMethod
Determines whether an AST is a descendant of an abstract or native method.- Parameters:
ast
- the AST to check.- Returns:
- true if ast is a descendant of an abstract or native method.
-
isInLambda
Check if current param is lambda's param.- Parameters:
paramDef
-parameter def
.- Returns:
- true if current param is lambda's param.
-
findFirstUpperNamedBlock
Find the Class, Constructor, Enum, Method, or Field in which it is defined.- Parameters:
ast
- Variable for which we want to find the scope in which it is defined- Returns:
- ast The Class or Constructor or Method in which it is defined.
-
isSameVariables
Check if both the Variables are same.- Parameters:
ast1
- Variable to compareast2
- Variable to compare- Returns:
- true if both the variables are same, otherwise false
-
isInTheSameLoop
Check if both the variables are in the same loop.- Parameters:
ast1
- variable to compare.ast2
- variable to compare.- Returns:
- true if both the variables are in the same loop.
-
isLoopAst
private static boolean isLoopAst(int ast) Checks whether the ast is a loop.- Parameters:
ast
- the ast to check.- Returns:
- true if the ast is a loop.
-