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

Class 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. Type is java.lang.String[]. Validation type is tokenTypesSet. Default value is no tokens.
    • 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>>();
   }

 }

    Parent is com.puppycrawl.tools.checkstyle.TreeWalker

    Violation Message Keys:

    • illegal.type
    Since:
    3.2

    • 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

    • 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

      • 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.
        Parameters:
        modifiers - String contains modifiers.