HiddenFieldCheck (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.HiddenFieldCheck

All Implemented Interfaces:: Configurable, Contextualizable

public class HiddenFieldCheck
extends AbstractCheck

Checks that a local variable or a parameter does not shadow a field that is defined in the same class.

It is possible to configure the check to ignore all property setter methods.

A method is recognized as a setter if it is in the following form

 ${returnType} set${Name}(${anyType} ${name}) { ... }

where ${anyType} is any primitive type, class or interface name; ${name} is name of the variable that is being set and ${Name} its capitalized form that appears in the method name. By default it is expected that setter returns void, i.e. ${returnType} is 'void'. For example

 void setTime(long time) { ... }

Any other return types will not let method match a setter pattern. However, by setting setterCanReturnItsClass property to true definition of a setter is expanded, so that setter return type can also be a class in which setter is declared. For example

 class PageBuilder {
   PageBuilder setName(String name) { ... }
 }

Such methods are known as chain-setters and a common when Builder-pattern is used. Property setterCanReturnItsClass has effect only if ignoreSetter is set to true.

Property ignoreFormat - Define the RegExp for names of variables and parameters to ignore. Type is java.util.regex.Pattern. Default value is null.
Property ignoreConstructorParameter - Control whether to ignore constructor parameters. Type is boolean. Default value is false.
Property ignoreSetter - Allow to ignore the parameter of a property setter method. Type is boolean. Default value is false.
Property setterCanReturnItsClass - Allow to expand the definition of a setter method to include methods that return the class' instance. Type is boolean. Default value is false.
Property ignoreAbstractMethods - Control whether to ignore parameters of abstract methods. 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, PARAMETER_DEF, PATTERN_VARIABLE_DEF, LAMBDA, RECORD_COMPONENT_DEF.

To configure the check:

  <module name="HiddenField"/>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // violation, 'testField' param hides 'testField' field
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // violation, 'testField' param
                                                // hides 'testField' field
       this.field = field;
   }
   public SomeClass setField(String field) { // violation, 'field' param hides 'field' field
       this.field = field;
   }
 }

To configure the check so that it checks local variables but not parameters:

 <module name="HiddenField">
   <property name="tokens" value="VARIABLE_DEF"/>
 </module>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // OK, 'testField' param doesn't hide any field
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // OK, 'testField' param doesn't hide any field
       this.field = field;
   }
   public SomeClass setField(String field) { // OK, 'field' param doesn't hide any field
       this.field = field;
   }
 }

To configure the check so that it ignores the variables and parameters named "test":

 <module name="HiddenField">
   <property name="ignoreFormat" value="^testField"/>
 </module>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // OK, because it match ignoreFormat
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // OK, because it match ignoreFormat
       this.field = field;
   }
   public SomeClass setField(String field) { // violation, 'field' param hides 'field' field
       this.field = field;
   }
 }

To configure the check so that it ignores constructor parameters:

 <module name="HiddenField">
   <property name="ignoreConstructorParameter" value="true"/>
 </module>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // OK, 'testField' param doesn't hide any field
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // violation, 'testField' variable
                                                // hides 'testField' field
       this.field = field;
   }
   public SomeClass setField(String field) { // violation, 'field' param hides 'field' field
       this.field = field;
   }
 }

To configure the check so that it ignores the parameter of setter methods:

 <module name="HiddenField">
   <property name="ignoreSetter" value="true"/>
 </module>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // violation, 'testField' param hides 'testField' field
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // OK, 'testField' param doesn't hide any field
       this.field = field;
   }
   public SomeClass setField(String field) { // violation, 'field' param hides 'field' field
       this.field = field;
   }
 }

To configure the check so that it ignores the parameter of setter methods recognizing setter as returning either void or a class in which it is declared:

 <module name="HiddenField">
   <property name="ignoreSetter" value="true"/>
   <property name="setterCanReturnItsClass" value="true"/>
 </module>

 public class SomeClass {

   private String field;
   private String testField;

   public SomeClass(String testField) { // violation, 'testField' param hides 'testField' field
   }
   public void method(String param) { // OK
       String field = param; // violation, 'field' variable hides 'field' field
   }
   public void setTestField(String testField) { // OK, 'testField' param doesn't hide any field
       this.field = field;
   }
   public SomeClass setField(String field) { // OK, 'field' param doesn't hide any field
       this.field = field;
   }
 }

To configure the check so that it ignores parameters of abstract methods:

 <module name="HiddenField">
   <property name="ignoreAbstractMethods" value="true"/>
 </module>

 abstract class SomeClass {

   private String field;

   public SomeClass(int field) { // violation, 'field' param hides a 'field' field
     float field; // violation, 'field' variable hides a 'field' field
   }
   public abstract int method(String field); // OK
 }

 public class Demo extends SomeClass {

   public int method(String param){
     return param;
   }
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

hidden.field

Since:: 3.0

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private static class HiddenFieldCheck.FieldFrame
Holds the names of static and instance fields of a type.
- Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
  AutomaticBean.OutputStreamOptions

Nested Classes
Modifier and Type	Class and Description
`private static class`	`HiddenFieldCheck.FieldFrame` Holds the names of static and instance fields of a type.

Field Summary

Fields
Modifier and Type	Field and Description
`private HiddenFieldCheck.FieldFrame`	`frame` Stack of sets of field names, one for each class of a set of nested classes.
`private boolean`	`ignoreAbstractMethods` Control whether to ignore parameters of abstract methods.
`private boolean`	`ignoreConstructorParameter` Control whether to ignore constructor parameters.
`private java.util.regex.Pattern`	`ignoreFormat` Define the RegExp for names of variables and parameters to ignore.
`private boolean`	`ignoreSetter` Allow to ignore the parameter of a property setter method.
`static java.lang.String`	`MSG_KEY` A key is pointing to the warning message text in "messages.properties" file.
`private boolean`	`setterCanReturnItsClass` Allow to expand the definition of a setter method to include methods that return the class' instance.

Constructor Summary

Constructors
Constructor and Description

HiddenFieldCheck()

Constructors
Constructor and Description
`HiddenFieldCheck()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`beginTree(DetailAST rootAST)` Called before the starting to process a tree.
`private static java.lang.String`	`capitalize(java.lang.String name)` Capitalizes a given property name the way we expect to see it in a setter name.
`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`	`isIgnoredConstructorParam(DetailAST ast)` Decides whether to ignore an AST node that is the parameter of a constructor.
`private boolean`	`isIgnoredParam(DetailAST ast, java.lang.String name)` Checks whether method or constructor parameter is ignored.
`private boolean`	`isIgnoredParamOfAbstractMethod(DetailAST ast)` Decides whether to ignore an AST node that is the parameter of an abstract method.
`private boolean`	`isIgnoredSetterParam(DetailAST ast, java.lang.String name)` Decides whether to ignore an AST node that is the parameter of a setter method, where the property setter method for field 'xyz' has name 'setXyz', one parameter named 'xyz', and return type void (default behavior) or return type is name of the class in which such method is declared (allowed only if `setSetterCanReturnItsClass(boolean)` is called with value true).
`private boolean`	`isInstanceField(DetailAST ast, java.lang.String name)` Check for instance field.
`private static boolean`	`isInStatic(DetailAST ast)` Determines whether an AST node is in a static method or static initializer.
`private boolean`	`isMatchingRegexp(java.lang.String name)` Check name by regExp.
`private boolean`	`isSetterMethod(DetailAST aMethodAST, java.lang.String aName)` Determine if a specific method identified by methodAST and a single variable name aName is a setter.
`void`	`leaveToken(DetailAST ast)` Called after all the child nodes have been process.
`private void`	`processLambda(DetailAST ast)` Process a lambda token.
`private void`	`processVariable(DetailAST ast)` Process a variable token.
`void`	`setIgnoreAbstractMethods(boolean ignoreAbstractMethods)` Setter to control whether to ignore parameters of abstract methods.
`void`	`setIgnoreConstructorParameter(boolean ignoreConstructorParameter)` Setter to control whether to ignore constructor parameters.
`void`	`setIgnoreFormat(java.util.regex.Pattern pattern)` Setter to define the RegExp for names of variables and parameters to ignore.
`void`	`setIgnoreSetter(boolean ignoreSetter)` Setter to allow to ignore the parameter of a property setter method.
`void`	`setSetterCanReturnItsClass(boolean aSetterCanReturnItsClass)` Setter to allow to expand the definition of a setter method to include methods that return the class' instance.
`private void`	`visitOtherTokens(DetailAST ast, int type)` Called to process tokens other than `TokenTypes.VARIABLE_DEF` and `TokenTypes.PARAMETER_DEF`.
`void`	`visitToken(DetailAST ast)` Called to process a token.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
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
  - frame
```
private HiddenFieldCheck.FieldFrame frame
```
    Stack of sets of field names, one for each class of a set of nested classes.
  - ignoreFormat
```
private java.util.regex.Pattern ignoreFormat
```
    Define the RegExp for names of variables and parameters to ignore.
  - ignoreSetter
```
private boolean ignoreSetter
```
    Allow to ignore the parameter of a property setter method.
  - setterCanReturnItsClass
```
private boolean setterCanReturnItsClass
```
    Allow to expand the definition of a setter method to include methods that return the class' instance.
  - ignoreConstructorParameter
```
private boolean ignoreConstructorParameter
```
    Control whether to ignore constructor parameters.
  - ignoreAbstractMethods
```
private boolean ignoreAbstractMethods
```
    Control whether to ignore parameters of abstract methods.
- Constructor Detail
  - HiddenFieldCheck
```
public HiddenFieldCheck()
```
- Method Detail
  - 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
  - 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
  - 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 class AbstractCheck
    
    Parameters:
    
    rootAST - the root of the tree
  - 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
  - processLambda
```
private void processLambda(DetailAST ast)
```
    Process a lambda token. Checks whether a lambda parameter shadows a field. Note, that when parameter of lambda expression is untyped, ANTLR parses the parameter as an identifier.
    
    Parameters:
    
    ast - the lambda token.
  - visitOtherTokens
```
private void visitOtherTokens(DetailAST ast,
                              int type)
```
    Called to process tokens other than TokenTypes.VARIABLE_DEF and TokenTypes.PARAMETER_DEF.
    
    Parameters:
    
    ast - token to process
    
    type - type of the token
  - 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
  - processVariable
```
private void processVariable(DetailAST ast)
```
    Process a variable token. Check whether a local variable or parameter shadows a field. Store a field for later comparison with local variables and parameters.
    
    Parameters:
    
    ast - the variable token.
  - isIgnoredParam
```
private boolean isIgnoredParam(DetailAST ast,
                               java.lang.String name)
```
    Checks whether method or constructor parameter is ignored.
    
    Parameters:
    
    ast - the parameter token.
    
    name - the parameter name.
    
    Returns:
    
    true if parameter is ignored.
  - isInstanceField
```
private boolean isInstanceField(DetailAST ast,
                                java.lang.String name)
```
    Check for instance field.
    
    Parameters:
    
    ast - token
    
    name - identifier of token
    
    Returns:
    
    true if instance field
  - isMatchingRegexp
```
private boolean isMatchingRegexp(java.lang.String name)
```
    Check name by regExp.
    
    Parameters:
    
    name - string value to check
    
    Returns:
    
    true is regexp is matching
  - isInStatic
```
private static boolean isInStatic(DetailAST ast)
```
    Determines whether an AST node is in a static method or static initializer.
    
    Parameters:
    
    ast - the node to check.
    
    Returns:
    
    true if ast is in a static method or a static block;
  - isIgnoredSetterParam
```
private boolean isIgnoredSetterParam(DetailAST ast,
                                     java.lang.String name)
```
    Decides whether to ignore an AST node that is the parameter of a setter method, where the property setter method for field 'xyz' has name 'setXyz', one parameter named 'xyz', and return type void (default behavior) or return type is name of the class in which such method is declared (allowed only if setSetterCanReturnItsClass(boolean) is called with value true).
    
    Parameters:
    
    ast - the AST to check.
    
    name - the name of ast.
    
    Returns:
    
    true if ast should be ignored because check property ignoreSetter is true and ast is the parameter of a setter method.
  - isSetterMethod
```
private boolean isSetterMethod(DetailAST aMethodAST,
                               java.lang.String aName)
```
    Determine if a specific method identified by methodAST and a single variable name aName is a setter. This recognition partially depends on mSetterCanReturnItsClass property.
    
    Parameters:
    
    aMethodAST - AST corresponding to a method call
    
    aName - name of single parameter of this method.
    
    Returns:
    
    true of false indicating of method is a setter or not.
  - capitalize
```
private static java.lang.String capitalize(java.lang.String name)
```
    Capitalizes a given property name the way we expect to see it in a setter name.
    
    Parameters:
    
    name - a property name
    
    Returns:
    
    capitalized property name
  - isIgnoredConstructorParam
```
private boolean isIgnoredConstructorParam(DetailAST ast)
```
    Decides whether to ignore an AST node that is the parameter of a constructor.
    
    Parameters:
    
    ast - the AST to check.
    
    Returns:
    
    true if ast should be ignored because check property ignoreConstructorParameter is true and ast is a constructor parameter.
  - isIgnoredParamOfAbstractMethod
```
private boolean isIgnoredParamOfAbstractMethod(DetailAST ast)
```
    Decides whether to ignore an AST node that is the parameter of an abstract method.
    
    Parameters:
    
    ast - the AST to check.
    
    Returns:
    
    true if ast should be ignored because check property ignoreAbstractMethods is true and ast is a parameter of abstract methods.
  - setIgnoreFormat
```
public void setIgnoreFormat(java.util.regex.Pattern pattern)
```
    Setter to define the RegExp for names of variables and parameters to ignore.
    
    Parameters:
    
    pattern - a pattern.
  - setIgnoreSetter
```
public void setIgnoreSetter(boolean ignoreSetter)
```
    Setter to allow to ignore the parameter of a property setter method.
    
    Parameters:
    
    ignoreSetter - decide whether to ignore the parameter of a property setter method.
  - setSetterCanReturnItsClass
```
public void setSetterCanReturnItsClass(boolean aSetterCanReturnItsClass)
```
    Setter to allow to expand the definition of a setter method to include methods that return the class' instance.
    
    Parameters:
    
    aSetterCanReturnItsClass - if true then setter can return either void or class in which it is declared. If false then in order to be recognized as setter method (otherwise already recognized as a setter) must return void. Later is the default behavior.
  - setIgnoreConstructorParameter
```
public void setIgnoreConstructorParameter(boolean ignoreConstructorParameter)
```
    Setter to control whether to ignore constructor parameters.
    
    Parameters:
    
    ignoreConstructorParameter - decide whether to ignore constructor parameters.
  - setIgnoreAbstractMethods
```
public void setIgnoreAbstractMethods(boolean ignoreAbstractMethods)
```
    Setter to control whether to ignore parameters of abstract methods.
    
    Parameters:
    
    ignoreAbstractMethods - decide whether to ignore parameters of abstract methods.

Class HiddenFieldCheck

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

frame

ignoreFormat

ignoreSetter

setterCanReturnItsClass

ignoreConstructorParameter

ignoreAbstractMethods

Constructor Detail

HiddenFieldCheck

Method Detail

getDefaultTokens

getAcceptableTokens

getRequiredTokens

beginTree

visitToken

processLambda

visitOtherTokens

leaveToken

processVariable

isIgnoredParam

isInstanceField

isMatchingRegexp

isInStatic

isIgnoredSetterParam

isSetterMethod

capitalize

isIgnoredConstructorParam

isIgnoredParamOfAbstractMethod

setIgnoreFormat

setIgnoreSetter

setSetterCanReturnItsClass

setIgnoreConstructorParameter

setIgnoreAbstractMethods