IllegalTypeCheck (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.IllegalTypeCheck

All Implemented Interfaces:: Configurable, Contextualizable

public final class IllegalTypeCheck
extends AbstractCheck

Checks that particular classes or interfaces are never used.

Rationale: Helps reduce coupling on concrete classes.

For additional restriction of type usage see also: IllegalInstantiation, IllegalImport

It is possible to set illegal class names via short or canonical name. Specifying illegal type invokes analyzing imports and Check puts violations at corresponding declarations (of variables, methods or parameters). This helps to avoid ambiguous cases, e.g.: java.awt.List was set as illegal class name, then, code like:

 import java.util.List;
 ...
 List list; //No violation here

will be ok.

In most cases it's justified to put following classes to illegalClassNames:

GregorianCalendar
Hashtable
ArrayList
LinkedList
Vector

as methods that are differ from interface methods are rarely used, so in most cases user will benefit from checking for them.

Property validateAbstractClassNames - Control whether to validate abstract class names. Type is boolean. Default value is false.
Property illegalClassNames - Specify classes that should not be used as types in variable declarations, return values or parameters. Type is java.lang.String[]. Default value is HashMap, HashSet, LinkedHashMap, LinkedHashSet, TreeMap, TreeSet, java.util.HashMap, java.util.HashSet, java.util.LinkedHashMap, java.util.LinkedHashSet, java.util.TreeMap, java.util.TreeSet.
Property legalAbstractClassNames - Define abstract classes that may be used as types. Type is java.lang.String[]. Default value is "".
Property ignoredMethodNames - Specify methods that should not be checked. Type is java.lang.String[]. Default value is getEnvironment, getInitialContext.
Property illegalAbstractClassNameFormat - Specify RegExp for illegal abstract class names. Type is java.util.regex.Pattern. Default value is "^(.*[.])?Abstract.*$".
Property memberModifiers - Control whether to check only methods and fields with any of the specified modifiers. This property does not affect method calls nor method references nor record components. Type is java.lang.String[]. Validation type is tokenTypesSet. Default value is "".
Property tokens - tokens to check Type is java.lang.String[]. Validation type is tokenSet. Default value is: ANNOTATION_FIELD_DEF, CLASS_DEF, INTERFACE_DEF, METHOD_CALL, METHOD_DEF, METHOD_REF, PARAMETER_DEF, VARIABLE_DEF, PATTERN_VARIABLE_DEF, RECORD_DEF, RECORD_COMPONENT_DEF.

To configure the default check:

 <module name="IllegalType"/>

 public class Test extends TreeSet { // violation
   public <T extends java.util.HashSet> void method() { // violation

     LinkedHashMap<Integer, String> lhmap =
     new LinkedHashMap<Integer, String>(); // violation
     TreeMap<Integer, String> treemap =
     new TreeMap<Integer, String>(); // violation
     Test t; // OK
     HashMap<String, String> hmap; // violation
     Queue<Integer> intqueue; // OK

     java.lang.IllegalArgumentException illegalex; // OK
     java.util.TreeSet treeset; // violation
   }

 }

To configure the Check so that particular tokens are checked:

 <module name="IllegalType">
   <property name="tokens" value="METHOD_DEF"/>
 </module>

 public class Test extends TreeSet { // OK
   public <T extends java.util.HashSet> void method() { // violation
     LinkedHashMap<Integer, String> lhmap =
     new LinkedHashMap<Integer, String>(); // OK

     java.lang.IllegalArgumentException illegalex; // OK
     java.util.TreeSet treeset; // Ok
   }

   public <T extends java.util.HashSet> void typeParam(T t) {} // violation

   public void fullName(TreeSet a) {} // OK

 }

To configure the Check so that it ignores function() methods:

 <module name="IllegalType">
   <property name="ignoredMethodNames" value="function"/>
 </module>

 public class Test {
   public HashMap<String, String> function() { // OK
     // code
   }

   public HashMap<String, String> function1() { // violation
     // code
   }
 }

To configure the Check so that it validates abstract class names:

  <module name="IllegalType">
    <property name="validateAbstractClassNames" value="true"/>
    <property name="illegalAbstractClassNameFormat" value="Gitt"/>
  </module>

 class Test extends Gitter { // violation
 }

 class Test1 extends Github { // OK
 }

To configure the Check so that it verifies only public, protected or static methods and fields:

 <module name="IllegalType">
   <property name="memberModifiers" value="LITERAL_PUBLIC,
    LITERAL_PROTECTED, LITERAL_STATIC"/>
 </module>

 public class Test {
   public HashMap<String, String> function1() { // violation
     // code
   }

   private HashMap<String, String> function2() { // OK
     // code
   }

   protected HashMap<Integer, String> function3() { // violation
     // code
   }

   public static TreeMap<Integer, String> function4() { // violation
     // code
   }

 }

To configure the check so that it verifies usage of types Boolean and Foo:

 <module name="IllegalType">
           <property name="illegalClassNames" value="Boolean, Foo"/>
 </module>

 public class Test {

   public Set<Boolean> set; // violation
   public java.util.List<Map<Boolean, Foo>> list; // violation

   private void method(List<Foo> list, Boolean value) { // violation
     SomeType.<Boolean>foo(); // violation
     final Consumer<Foo> consumer = Foo<Boolean>::foo; // violation
   }

   public <T extends Boolean, U extends Serializable> void typeParam(T a) {} // violation

   public void fullName(java.util.ArrayList<? super Boolean> a) {} // violation

   public abstract Set<Boolean> shortName(Set<? super Boolean> a); // violation

   public Set<? extends Foo> typeArgument() { // violation
     return new TreeSet<Foo<Boolean>>();
   }

 }

To configure the check to target fields types only:

 <module name="IllegalType">
   <property name="illegalClassNames" value="java.util.Optional"/>
   <property name="tokens" value="VARIABLE_DEF"/>
   <property name="id" value="IllegalTypeOptionalAsField"/>
 </module>
 <module name="SuppressionXpathSingleFilter">
   <property name="query" value="//METHOD_DEF//*"/>
   <property name="id" value="IllegalTypeOptionalAsField"/>
 </module>

 import java.util.Optional;

 public class Main {

   static int field1 = 4; // OK
   public Optional<String> field2; // violation, usage of type 'Optional' is not allowed
   protected String field3; // OK
   Optional<String> field4; // violation, usage of type 'Optional' is not allowed
   private Optional<String> field5; // violation, usage of type 'Optional' is not allowed

   void foo() {
     Optional<String> i; // OK
   }
   public <T extends java.util.Optional> void method(T t) { // OK
     Optional<T> i; // OK
   }
 }

Parent is com.puppycrawl.tools.checkstyle.TreeWalker

Violation Message Keys:

illegal.type

Since:: 3.2

Nested Class Summary
- 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 java.lang.String[]`	`DEFAULT_IGNORED_METHOD_NAMES` Default ignored method names.
`private static java.lang.String[]`	`DEFAULT_ILLEGAL_TYPES` Types illegal by default.
`private java.util.Set<java.lang.String>`	`ignoredMethodNames` Specify methods that should not be checked.
`private java.util.regex.Pattern`	`illegalAbstractClassNameFormat` Specify RegExp for illegal abstract class names.
`private java.util.Set<java.lang.String>`	`illegalClassNames` Specify classes that should not be used as types in variable declarations, return values or parameters.
`private java.util.Set<java.lang.String>`	`illegalShortClassNames` Illegal short classes.
`private java.util.Set<java.lang.String>`	`legalAbstractClassNames` Define abstract classes that may be used as types.
`private java.util.List<java.lang.Integer>`	`memberModifiers` Control whether to check only methods and fields with any of the specified modifiers.
`static java.lang.String`	`MSG_KEY` A key is pointing to the warning message text in "messages.properties" file.
`private boolean`	`validateAbstractClassNames` Control whether to validate abstract class names.

Constructor Summary

Constructors
Constructor and Description

IllegalTypeCheck()
Creates new instance of the check.

Constructors
Constructor and Description
`IllegalTypeCheck()` Creates new instance of the check.

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 void`	`checkBaseTypes(DetailAST clause)` Checks the `extends` or `implements` statement.
`private void`	`checkClassName(DetailAST ast)` Checks type and type arguments/parameters of given method, parameter, variable or method call/reference.
`private void`	`checkIdent(DetailAST type)` Checks the identifier of the given type.
`private void`	`checkType(DetailAST type)` Checks the given type, its arguments and parameters.
`private void`	`checkTypeArguments(DetailAST node)` Checks the type arguments of the node.
`private void`	`checkTypeBounds(DetailAST type)` Checks the upper and lower bounds for the given type.
`private void`	`checkTypeParameters(DetailAST node)` Checks the type parameters of the node.
`private void`	`extendIllegalClassNamesWithShortName(java.lang.String canonicalName)` Extends illegal class names set via imported short type name.
`int[]`	`getAcceptableTokens()` The configurable token set.
`int[]`	`getDefaultTokens()` Returns the default token a check is interested in.
`private static java.lang.String`	`getImportedTypeCanonicalName(DetailAST importAst)` Gets imported type's canonical name.
`private static DetailAST`	`getNextSubTreeNode(DetailAST currentNodeAst, DetailAST subTreeRootAst)` Gets the next node of a syntactical tree (child of a current node or sibling of a current node, or sibling of a parent of a current node).
`int[]`	`getRequiredTokens()` The tokens that this check must be registered for.
`private boolean`	`isCheckedMethod(DetailAST ast)` Returns true if method has to be checked or false.
`private boolean`	`isContainVerifiableType(DetailAST modifiers)` Checks is modifiers contain verifiable type.
`private boolean`	`isMatchingClassName(java.lang.String className)` Returns true if given class name is one of illegal classes or else false.
`private static boolean`	`isStarImport(DetailAST importAst)` Checks if current import is star import.
`private boolean`	`isVerifiable(DetailAST methodOrVariableDef)` Checks if current method's return type or variable's type is verifiable according to memberModifiers option.
`void`	`setIgnoredMethodNames(java.lang.String... methodNames)` Setter to specify methods that should not be checked.
`void`	`setIllegalAbstractClassNameFormat(java.util.regex.Pattern pattern)` Setter to specify RegExp for illegal abstract class names.
`void`	`setIllegalClassNames(java.lang.String... classNames)` Setter to specify classes that should not be used as types in variable declarations, return values or parameters.
`void`	`setLegalAbstractClassNames(java.lang.String... classNames)` Setter to define abstract classes that may be used as types.
`void`	`setMemberModifiers(java.lang.String modifiers)` Setter to control whether to check only methods and fields with any of the specified modifiers.
`void`	`setValidateAbstractClassNames(boolean validateAbstractClassNames)` Setter to control whether to validate abstract class names.
`private void`	`visitImport(DetailAST importAst)` Checks imported type (as static and star imports are not supported by Check, only type is in the consideration). If this type is illegal due to Check's options - puts violation on it.
`private void`	`visitMethodCallOrRef(DetailAST methodCallOrRef)` Checks the type arguments of given method call/reference.
`private void`	`visitMethodDef(DetailAST methodDef)` Checks return type of a given method.
`private void`	`visitParameterDef(DetailAST parameterDef)` Checks type of parameters.
`void`	`visitToken(DetailAST ast)` Called to process a token.
`private void`	`visitTypeDef(DetailAST typeDef)` Checks the super type and implemented interfaces of a given type.
`private void`	`visitVariableDef(DetailAST variableDef)` Checks type of given variable.

Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
clearViolations, destroy, finishTree, getFileContents, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, 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
  - DEFAULT_ILLEGAL_TYPES
```
private static final java.lang.String[] DEFAULT_ILLEGAL_TYPES
```
    Types illegal by default.
  - DEFAULT_IGNORED_METHOD_NAMES
```
private static final java.lang.String[] DEFAULT_IGNORED_METHOD_NAMES
```
    Default ignored method names.
  - illegalClassNames
```
private final java.util.Set<java.lang.String> illegalClassNames
```
    Specify classes that should not be used as types in variable declarations, return values or parameters.
  - illegalShortClassNames
```
private final java.util.Set<java.lang.String> illegalShortClassNames
```
    Illegal short classes.
  - legalAbstractClassNames
```
private final java.util.Set<java.lang.String> legalAbstractClassNames
```
    Define abstract classes that may be used as types.
  - ignoredMethodNames
```
private final java.util.Set<java.lang.String> ignoredMethodNames
```
    Specify methods that should not be checked.
  - memberModifiers
```
private java.util.List<java.lang.Integer> memberModifiers
```
    Control whether to check only methods and fields with any of the specified modifiers. This property does not affect method calls nor method references nor record components.
  - illegalAbstractClassNameFormat
```
private java.util.regex.Pattern illegalAbstractClassNameFormat
```
    Specify RegExp for illegal abstract class names.
  - validateAbstractClassNames
```
private boolean validateAbstractClassNames
```
    Control whether to validate abstract class names.
- Constructor Detail
  - IllegalTypeCheck
```
public IllegalTypeCheck()
```
    Creates new instance of the check.
- Method Detail
  - setIllegalAbstractClassNameFormat
```
public void setIllegalAbstractClassNameFormat(java.util.regex.Pattern pattern)
```
    Setter to specify RegExp for illegal abstract class names.
    
    Parameters:
    
    pattern - a pattern.
  - setValidateAbstractClassNames
```
public void setValidateAbstractClassNames(boolean validateAbstractClassNames)
```
    Setter to control whether to validate abstract class names.
    
    Parameters:
    
    validateAbstractClassNames - whether abstract class names must be ignored.
  - 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
  - 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
  - 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
  - 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
  - isVerifiable
```
private boolean isVerifiable(DetailAST methodOrVariableDef)
```
    Checks if current method's return type or variable's type is verifiable according to memberModifiers option.
    
    Parameters:
    
    methodOrVariableDef - METHOD_DEF or VARIABLE_DEF ast node.
    
    Returns:
    
    true if member is verifiable according to memberModifiers option.
  - isContainVerifiableType
```
private boolean isContainVerifiableType(DetailAST modifiers)
```
    Checks is modifiers contain verifiable type.
    
    Parameters:
    
    modifiers - parent node for all modifiers
    
    Returns:
    
    true if method or variable can be verified
  - visitTypeDef
```
private void visitTypeDef(DetailAST typeDef)
```
    Checks the super type and implemented interfaces of a given type.
    
    Parameters:
    
    typeDef - class or interface for check.
  - visitMethodDef
```
private void visitMethodDef(DetailAST methodDef)
```
    Checks return type of a given method.
    
    Parameters:
    
    methodDef - method for check.
  - visitParameterDef
```
private void visitParameterDef(DetailAST parameterDef)
```
    Checks type of parameters.
    
    Parameters:
    
    parameterDef - parameter list for check.
  - visitVariableDef
```
private void visitVariableDef(DetailAST variableDef)
```
    Checks type of given variable.
    
    Parameters:
    
    variableDef - variable to check.
  - visitMethodCallOrRef
```
private void visitMethodCallOrRef(DetailAST methodCallOrRef)
```
    Checks the type arguments of given method call/reference.
    
    Parameters:
    
    methodCallOrRef - method call/reference to check.
  - visitImport
```
private void visitImport(DetailAST importAst)
```
    Checks imported type (as static and star imports are not supported by Check, only type is in the consideration).
    If this type is illegal due to Check's options - puts violation on it.
    
    Parameters:
    
    importAst - Import
  - isStarImport
```
private static boolean isStarImport(DetailAST importAst)
```
    Checks if current import is star import. E.g.:
    import java.util.*;
    
    Parameters:
    
    importAst - Import
    
    Returns:
    
    true if it is star import
  - checkClassName
```
private void checkClassName(DetailAST ast)
```
    Checks type and type arguments/parameters of given method, parameter, variable or method call/reference.
    
    Parameters:
    
    ast - node to check.
  - checkIdent
```
private void checkIdent(DetailAST type)
```
    Checks the identifier of the given type.
    
    Parameters:
    
    type - node to check.
  - checkBaseTypes
```
private void checkBaseTypes(DetailAST clause)
```
    Checks the extends or implements statement.
    
    Parameters:
    
    clause - DetailAST for either TokenTypes.EXTENDS_CLAUSE or TokenTypes.IMPLEMENTS_CLAUSE
  - checkType
```
private void checkType(DetailAST type)
```
    Checks the given type, its arguments and parameters.
    
    Parameters:
    
    type - node to check.
  - checkTypeBounds
```
private void checkTypeBounds(DetailAST type)
```
    Checks the upper and lower bounds for the given type.
    
    Parameters:
    
    type - node to check.
  - checkTypeParameters
```
private void checkTypeParameters(DetailAST node)
```
    Checks the type parameters of the node.
    
    Parameters:
    
    node - node to check.
  - checkTypeArguments
```
private void checkTypeArguments(DetailAST node)
```
    Checks the type arguments of the node.
    
    Parameters:
    
    node - node to check.
  - isMatchingClassName
```
private boolean isMatchingClassName(java.lang.String className)
```
    Returns true if given class name is one of illegal classes or else false.
    
    Parameters:
    
    className - class name to check.
    
    Returns:
    
    true if given class name is one of illegal classes or if it matches to abstract class names pattern.
  - extendIllegalClassNamesWithShortName
```
private void extendIllegalClassNamesWithShortName(java.lang.String canonicalName)
```
    Extends illegal class names set via imported short type name.
    
    Parameters:
    
    canonicalName - Canonical name of imported type.
  - getImportedTypeCanonicalName
```
private static java.lang.String getImportedTypeCanonicalName(DetailAST importAst)
```
    Gets imported type's canonical name.
    
    Parameters:
    
    importAst - Import
    
    Returns:
    
    Imported canonical type's name.
  - getNextSubTreeNode
```
private static DetailAST getNextSubTreeNode(DetailAST currentNodeAst,
                                            DetailAST subTreeRootAst)
```
    Gets the next node of a syntactical tree (child of a current node or sibling of a current node, or sibling of a parent of a current node).
    
    Parameters:
    
    currentNodeAst - Current node in considering
    
    subTreeRootAst - SubTree root
    
    Returns:
    
    Current node after bypassing, if current node reached the root of a subtree method returns null
  - isCheckedMethod
```
private boolean isCheckedMethod(DetailAST ast)
```
    Returns true if method has to be checked or false.
    
    Parameters:
    
    ast - method def to check.
    
    Returns:
    
    true if we should check this method.
  - setIllegalClassNames
```
public void setIllegalClassNames(java.lang.String... classNames)
```
    Setter to specify classes that should not be used as types in variable declarations, return values or parameters.
    
    Parameters:
    
    classNames - array of illegal variable types
  - setIgnoredMethodNames
```
public void setIgnoredMethodNames(java.lang.String... methodNames)
```
    Setter to specify methods that should not be checked.
    
    Parameters:
    
    methodNames - array of ignored method names
  - setLegalAbstractClassNames
```
public void setLegalAbstractClassNames(java.lang.String... classNames)
```
    Setter to define abstract classes that may be used as types.
    
    Parameters:
    
    classNames - array of legal abstract class names
  - setMemberModifiers
```
public void setMemberModifiers(java.lang.String modifiers)
```
    Setter to control whether to check only methods and fields with any of the specified modifiers. This property does not affect method calls nor method references nor record components.
    
    Parameters:
    
    modifiers - String contains modifiers.

Class IllegalTypeCheck

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

DEFAULT_ILLEGAL_TYPES

DEFAULT_IGNORED_METHOD_NAMES

illegalClassNames

illegalShortClassNames

legalAbstractClassNames

ignoredMethodNames

memberModifiers

illegalAbstractClassNameFormat

validateAbstractClassNames

Constructor Detail

IllegalTypeCheck

Method Detail

setIllegalAbstractClassNameFormat

setValidateAbstractClassNames

getDefaultTokens

getAcceptableTokens

beginTree

getRequiredTokens

visitToken

isVerifiable

isContainVerifiableType

visitTypeDef

visitMethodDef

visitParameterDef

visitVariableDef

visitMethodCallOrRef

visitImport

isStarImport

checkClassName

checkIdent

checkBaseTypes

checkType

checkTypeBounds

checkTypeParameters

checkTypeArguments

isMatchingClassName

extendIllegalClassNamesWithShortName

getImportedTypeCanonicalName

getNextSubTreeNode

isCheckedMethod

setIllegalClassNames

setIgnoredMethodNames

setLegalAbstractClassNames

setMemberModifiers