FinalLocalVariableCheck (checkstyle 9.3 API)

java.lang.Object
- com.puppycrawl.tools.checkstyle.api.AutomaticBean
- - com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
  - - com.puppycrawl.tools.checkstyle.api.AbstractCheck
    - - com.puppycrawl.tools.checkstyle.checks.coding.FinalLocalVariableCheck

All Implemented Interfaces:

Configurable, Contextualizable
```
public class FinalLocalVariableCheck
extends AbstractCheck
```
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 is boolean. Default value is false.
- Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. 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 Classes
Modifier and Type	Class and Description
`private static class`	`FinalLocalVariableCheck.FinalVariableCandidate` Represents information about final local variable candidate.
`private static class`	`FinalLocalVariableCheck.ScopeData` Holder for the scope data.

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions

Field Summary

Fields
Modifier and Type	Field and Description
`private static int[]`	`ASSIGN_OPERATOR_TYPES` Assign operator types.
`private java.util.Deque<java.util.Deque<DetailAST>>`	`currentScopeAssignedVariables` Assigned variables of current scope.
`private static int[]`	`LOOP_TYPES` Loop types.
`static java.lang.String`	`MSG_KEY` A key is pointing to the warning message text in "messages.properties" file.
`private java.util.Deque<java.util.Deque<DetailAST>>`	`prevScopeUninitializedVariables` Uninitialized variables of previous scope.
`private java.util.Deque<FinalLocalVariableCheck.ScopeData>`	`scopeStack` Scope Deque.
`private boolean`	`validateEnhancedForLoopVariable` Control whether to check enhanced for-loop variable.

Constructor Summary

Constructors
Constructor and Description

FinalLocalVariableCheck()

Constructors
Constructor and Description
`FinalLocalVariableCheck()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`private static void`	`determineAssignmentConditions(DetailAST ident, FinalLocalVariableCheck.FinalVariableCandidate candidate)` Determines identifier assignment conditions (assigned or already assigned).
`private static DetailAST`	`findFirstUpperNamedBlock(DetailAST ast)` 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[]`	`getAcceptableTokens()` The configurable token set.
`int[]`	`getDefaultTokens()` Returns the default token a check is interested in.
`private java.util.Optional<FinalLocalVariableCheck.FinalVariableCandidate>`	`getFinalCandidate(DetailAST ast)` Gets final variable candidate for ast.
`int[]`	`getRequiredTokens()` 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`	`isCaseTokenWithAnotherCaseFollowing(DetailAST ast)` If token is CASE_GROUP or SWITCH_RULE and there is another `case` following.
`private static boolean`	`isFirstChild(DetailAST ast)` Whether the ast is the first child of its parent.
`private static boolean`	`isIfTokenWithAnElseFollowing(DetailAST ast)` If token is LITERAL_IF and there is an `else` following.
`private static boolean`	`isInAbstractOrNativeMethod(DetailAST ast)` 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 in `for-loop init`, e.g.:
`void`	`leaveToken(DetailAST ast)` Called after all the child nodes have been process.
`private void`	`removeFinalVariableCandidateFromStack(DetailAST ast)` Removes the final variable candidate from the Stack.
`void`	`setValidateEnhancedForLoopVariable(boolean validateEnhancedForLoopVariable)` Setter to control whether to check enhanced for-loop variable.
`private boolean`	`shouldCheckEnhancedForLoopVariable(DetailAST ast)` Determines whether enhanced for-loop variable should be checked or not.
`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.
`private static boolean`	`shouldUpdateUninitializedVariables(DetailAST ast)` If token is LITERAL_IF and there is an `else` following or token is CASE_GROUP or SWITCH_RULE and there is another `case` following, then update the uninitialized variables.
`private void`	`storePrevScopeUninitializedVariableData()` Store un-initialized variables in a temporary stack for future use.
`private void`	`updateAllUninitializedVariables(java.util.Deque<DetailAST> prevScopeUninitializedVariableData)` Update current scope data uninitialized variable according to the whole scope data.
`private void`	`updateCurrentScopeAssignedVariables()` Update assigned variables in a temporary stack.
`private void`	`updateUninitializedVariables(java.util.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

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - 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
  - ASSIGN_OPERATOR_TYPES
```
private static final int[] ASSIGN_OPERATOR_TYPES
```
    Assign operator types.
  - LOOP_TYPES
```
private static final int[] LOOP_TYPES
```
    Loop types.
  - scopeStack
```
private final java.util.Deque<FinalLocalVariableCheck.ScopeData> scopeStack
```
    Scope Deque.
  - prevScopeUninitializedVariables
```
private final java.util.Deque<java.util.Deque<DetailAST>> prevScopeUninitializedVariables
```
    Uninitialized variables of previous scope.
  - currentScopeAssignedVariables
```
private final java.util.Deque<java.util.Deque<DetailAST>> currentScopeAssignedVariables
```
    Assigned variables of current scope.
  - validateEnhancedForLoopVariable
```
private boolean validateEnhancedForLoopVariable
```
    Control whether to check enhanced for-loop variable.
- Constructor Detail
  - FinalLocalVariableCheck
```
public FinalLocalVariableCheck()
```
- Method Detail
  - 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 class AbstractCheck
    
    Returns:
    
    the token set this must be registered for.
    
    See Also:
    
    TokenTypes
  - 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 class AbstractCheck
    
    Returns:
    
    the default tokens
    
    See Also:
    
    TokenTypes
  - 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 class AbstractCheck
    
    Returns:
    
    the token set this check is designed for.
    
    See Also:
    
    TokenTypes
  - visitToken
```
public void visitToken(DetailAST ast)
```
    Description copied from class: AbstractCheck
    
    Called to process a token.
    
    Overrides:
    
    visitToken in class AbstractCheck
    
    Parameters:
    
    ast - the token to process
  - leaveToken
```
public void leaveToken(DetailAST ast)
```
    Description copied from class: AbstractCheck
    
    Called after all the child nodes have been process.
    
    Overrides:
    
    leaveToken in class AbstractCheck
    
    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
```
private static boolean isInSpecificCodeBlocks(DetailAST node,
                                              int... blockTypes)
```
    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
```
private java.util.Optional<FinalLocalVariableCheck.FinalVariableCandidate> getFinalCandidate(DetailAST ast)
```
    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
```
private void updateAllUninitializedVariables(java.util.Deque<DetailAST> prevScopeUninitializedVariableData)
```
    Update current scope data uninitialized variable according to the whole scope data.
    
    Parameters:
    
    prevScopeUninitializedVariableData - variable for previous stack of uninitialized variables
  - updateUninitializedVariables
```
private void updateUninitializedVariables(java.util.Deque<DetailAST> scopeUninitializedVariableData)
```
    Update current scope data uninitialized variable according to the specific scope data.
    
    Parameters:
    
    scopeUninitializedVariableData - variable for specific stack of uninitialized variables
  - shouldUpdateUninitializedVariables
```
private static boolean shouldUpdateUninitializedVariables(DetailAST ast)
```
    If token is LITERAL_IF and there is an else following or token is CASE_GROUP or SWITCH_RULE and there is another case following, then update the uninitialized variables.
    
    Parameters:
    
    ast - token to be checked
    
    Returns:
    
    true if should be updated, else false
  - isIfTokenWithAnElseFollowing
```
private static boolean isIfTokenWithAnElseFollowing(DetailAST ast)
```
    If token is LITERAL_IF and there is an else following.
    
    Parameters:
    
    ast - token to be checked
    
    Returns:
    
    true if token is LITERAL_IF and there is an else following, else false
  - isCaseTokenWithAnotherCaseFollowing
```
private static boolean isCaseTokenWithAnotherCaseFollowing(DetailAST ast)
```
    If token is CASE_GROUP or SWITCH_RULE and there is another case 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 tested
    
    childType - the token type to match
    
    containType - the token type which has to be present in the branch
    
    Returns:
    
    the matching token, or null if no match
  - shouldCheckEnhancedForLoopVariable
```
private boolean shouldCheckEnhancedForLoopVariable(DetailAST ast)
```
    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
```
private void insertParameter(DetailAST ast)
```
    Insert a parameter at the topmost scope stack.
    
    Parameters:
    
    ast - the variable to insert.
  - insertVariable
```
private void insertVariable(DetailAST ast)
```
    Insert a variable at the topmost scope stack.
    
    Parameters:
    
    ast - the variable to insert.
  - isInitialized
```
private static boolean isInitialized(DetailAST ast)
```
    Check if VARIABLE_DEF is initialized or not.
    
    Parameters:
    
    ast - VARIABLE_DEF to be checked
    
    Returns:
    
    true if initialized
  - isFirstChild
```
private static boolean isFirstChild(DetailAST ast)
```
    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
```
private void removeFinalVariableCandidateFromStack(DetailAST ast)
```
    Removes the final variable candidate from the Stack.
    
    Parameters:
    
    ast - variable to remove.
  - isMultipleTypeCatch
```
private static boolean isMultipleTypeCatch(DetailAST parameterDefAst)
```
    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
```
private static boolean isUseOfExternalVariableInsideLoop(DetailAST variable)
```
    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
```
private static boolean isVariableInForInit(DetailAST variableDef)
```
    Checks if current variable is defined in for-loop init, e.g.:
    for (int i = 0, j = 0; i < j; i++) { . . . }
    i, j are defined in for-loop init
    
    Parameters:
    
    variableDef - variable definition node.
    
    Returns:
    
    true if variable is defined in for-loop init
  - isInAbstractOrNativeMethod
```
private static boolean isInAbstractOrNativeMethod(DetailAST ast)
```
    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
```
private static boolean isInLambda(DetailAST paramDef)
```
    Check if current param is lambda's param.
    
    Parameters:
    
    paramDef - parameter def.
    
    Returns:
    
    true if current param is lambda's param.
  - findFirstUpperNamedBlock
```
private static DetailAST findFirstUpperNamedBlock(DetailAST ast)
```
    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
```
private static boolean isSameVariables(DetailAST ast1,
                                       DetailAST ast2)
```
    Check if both the Variables are same.
    
    Parameters:
    
    ast1 - Variable to compare
    
    ast2 - Variable to compare
    
    Returns:
    
    true if both the variables are same, otherwise false
  - isInTheSameLoop
```
private static boolean isInTheSameLoop(DetailAST ast1,
                                       DetailAST ast2)
```
    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.

Class FinalLocalVariableCheck

Nested Class Summary

Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

Field Summary

Constructor Summary

Method Summary

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean

Methods inherited from class java.lang.Object

Field Detail

MSG_KEY

ASSIGN_OPERATOR_TYPES

LOOP_TYPES

scopeStack

prevScopeUninitializedVariables

currentScopeAssignedVariables

validateEnhancedForLoopVariable

Constructor Detail

FinalLocalVariableCheck

Method Detail

setValidateEnhancedForLoopVariable

getRequiredTokens

getDefaultTokens

getAcceptableTokens

visitToken

leaveToken

updateCurrentScopeAssignedVariables

determineAssignmentConditions

isInSpecificCodeBlocks

getFinalCandidate

storePrevScopeUninitializedVariableData

updateAllUninitializedVariables

updateUninitializedVariables

shouldUpdateUninitializedVariables

isIfTokenWithAnElseFollowing

isCaseTokenWithAnotherCaseFollowing

findLastChildWhichContainsSpecifiedToken

shouldCheckEnhancedForLoopVariable

insertParameter

insertVariable

isInitialized

isFirstChild

removeFinalVariableCandidateFromStack

isMultipleTypeCatch

shouldRemoveFinalVariableCandidate

isUseOfExternalVariableInsideLoop

isAssignOperator

isVariableInForInit

isInAbstractOrNativeMethod

isInLambda

findFirstUpperNamedBlock

isSameVariables

isInTheSameLoop

isLoopAst