Package com.puppycrawl.tools.checkstyle.checks.coding

Class FinalLocalVariableCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable
    public class FinalLocalVariableCheck
extends AbstractCheck

    Ensures that local variables that never get their values changed, must be declared final.

    An example of how to configure the check to validate variable definition is: 

     <module name="FinalLocalVariable">
     <property name="tokens" value="VARIABLE_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); }

    • 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.

      • 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
        Controls whether to check enhanced for-loop variable.

    • Constructor Detail

      • FinalLocalVariableCheck

        public FinalLocalVariableCheck()

    • Method Detail

      • setValidateEnhancedForLoopVariable

        public final void setValidateEnhancedForLoopVariable​(boolean validateEnhancedForLoopVariable)
        Whether to check enhanced for-loop variable or not.
        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

      • 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.

      • isInSpecificCodeBlock

        private static boolean isInSpecificCodeBlock​(DetailAST node,
                                             int blockType)
        Checks whether the scope of a node is restricted to a specific code block.
        Parameters:
        node - node.
        blockType - block type.
        Returns:
        true if the scope of a node is restricted to a specific code block.

      • storePrevScopeUninitializedVariableData

        private void storePrevScopeUninitializedVariableData()
        Store un-initialized variables in a temporary stack for future use.

      • updateAllUninitializedVariables

        private void updateAllUninitializedVariables​(java.util.Deque<DetailAST> prevScopeUnitializedVariableData)
        Update current scope data uninitialized variable according to the whole scope data.
        Parameters:
        prevScopeUnitializedVariableData - variable for previous stack of uninitialized variables

      • updateUninitializedVariables

        private void updateUninitializedVariables​(java.util.Deque<DetailAST> scopeUnitializedVariableData)
        Update current scope data uninitialized variable according to the specific scope data.
        Parameters:
        scopeUnitializedVariableData - 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 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 and there is another case following.
        Parameters:
        ast - token to be checked
        Returns:
        true if token is CASE_GROUP 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 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.