OpenJDK 27 · com.sun.beans.TypeResolver · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private static final WeakCache<Type, Map<Type, Type>>	CACHE

Access	Constructor and Description
public	TypeResolver()

Method Summary

Modifier and Type	Method and Description
public static Class<?>	Returns: a corresponding class erase(Type the array of types to convert type) Converts the given `type` to the corresponding class.
public static Class<?>[]	Returns: an array of corresponding classes erase(Type[] the array of types to convert types) Converts all `types` in the given array to the corresponding classes.
private static Type	Returns: a corresponding type for the generic array type, or the same type as `type` fixGenericArray(Type the type to fix type) Replaces a `GenericArrayType` with plain array class where it is possible.
private static Type	Returns: a parameterized type for the class, or the same class as `inClass` getActualType(Class<?> the base class used to resolve inClass) Replaces a `Class` with type parameters with a `ParameterizedType` where every parameter is bound to itself.
private static void	prepare(Map<Type, Type> the mappings of all type variables map, Type the next type in the hierarchy type) Fills the map from type parameters to types as seen by the given `type`.
public static Type	Returns: a resolved type resolve(Type the type that supplies bindings for type variables actual, Type the type where occurrences of the variables in `actual` will be replaced by the corresponding bound values formal) Replaces type variables of the given `formal` type with the types they stand for in the given `actual` type.
public static Type[]	Returns: an array of resolved types resolve(Type the type that supplies bindings for type variables actual, Type[] the array of types to resolve formals) Replaces type variables of all formal types in the given array with the types they stand for in the given `actual` type.
public static Type	Returns: a resolved type resolveInClass(Class<?> the base class used to resolve inClass, Type the type to resolve type) Replaces the given `type` in an inherited method with the actual type it has in the given `inClass`.
public static Type[]	Returns: an array of resolved types resolveInClass(Class<?> the base class used to resolve inClass, Type[] the array of types to resolve types) Replaces all `types` in the given array with the actual types they have in the given `inClass`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

CACHE	back to summary
private static final WeakCache<Type, Map<Type, Type>> CACHE

TypeResolver	back to summary
public TypeResolver()

Method Detail

erase back to summary

erase	back to summary
public static Class<?> erase(Type type) Converts the given `type` to the corresponding class. This method implements the concept of type erasure, that is described in section 4.6 of The Java Language Specification. Parameters type:Type the array of types to convert Returns:Class<?> a corresponding class

public static Class<?> erase(Type type)

Converts the given type to the corresponding class. This method implements the concept of type erasure, that is described in section 4.6 of The Java Language Specification.

Parameters

type:Type: the array of types to convert

Returns:Class<?>

a corresponding class

erase back to summary

erase	back to summary
public static Class<?>[] erase(Type[] types) Converts all `types` in the given array to the corresponding classes. Parameters types:Type[] the array of types to convert Returns:Class<?>[] an array of corresponding classes See Also `erase(Type)`

public static Class<?>[] erase(Type[] types)

Converts all types in the given array to the corresponding classes.

Parameters

types:Type[]: the array of types to convert

Returns:Class<?>[]

an array of corresponding classes

See Also

erase(Type)

fixGenericArray back to summary

fixGenericArray	back to summary
private static Type fixGenericArray(Type type) Replaces a `GenericArrayType` with plain array class where it is possible. Bug 5041784 is that arrays of non-generic type sometimes show up as `GenericArrayType` when using reflection. For example, a `String[]` might show up as a `GenericArrayType` where `getGenericComponentType` is `String.class`. This violates the specification, which says that `GenericArrayType` is used when the component type is a type variable or parameterized type. We fit the specification here. Parameters type:Type the type to fix Returns:Type a corresponding type for the generic array type, or the same type as `type`

private static Type fixGenericArray(Type type)

Replaces a GenericArrayType with plain array class where it is possible. Bug 5041784 is that arrays of non-generic type sometimes show up as GenericArrayType when using reflection. For example, a String[] might show up as a GenericArrayType where getGenericComponentType is String.class. This violates the specification, which says that GenericArrayType is used when the component type is a type variable or parameterized type. We fit the specification here.

Parameters

type:Type: the type to fix

Returns:Type

a corresponding type for the generic array type, or the same type as type

getActualType back to summary

getActualType	back to summary
private static Type getActualType(Class<?> inClass) Replaces a `Class` with type parameters with a `ParameterizedType` where every parameter is bound to itself. When calling `resolveInClass` in the context of `inClass`, we can't just pass `inClass` as the `actual` parameter, because if `inClass` has type parameters that would be interpreted as accessing the raw type, so we would get unwanted erasure. This is why we bind each parameter to itself. If `inClass` does have type parameters and has methods where those parameters appear in the return type or argument types, we will correctly leave those types alone. Parameters inClass:Class<?> the base class used to resolve Returns:Type a parameterized type for the class, or the same class as `inClass`

private static Type getActualType(Class<?> inClass)

Replaces a Class with type parameters with a ParameterizedType where every parameter is bound to itself. When calling resolveInClass in the context of inClass, we can't just pass inClass as the actual parameter, because if inClass has type parameters that would be interpreted as accessing the raw type, so we would get unwanted erasure. This is why we bind each parameter to itself. If inClass does have type parameters and has methods where those parameters appear in the return type or argument types, we will correctly leave those types alone.

Parameters

inClass:Class<?>: the base class used to resolve

Returns:Type

a parameterized type for the class, or the same class as inClass

prepare back to summary

prepare	back to summary
private static void prepare(Map<Type, Type> map, Type type) Fills the map from type parameters to types as seen by the given `type`. The method is recursive because the `type` inherits mappings from its parent classes and interfaces. The `type` can be either a `Class` or a `ParameterizedType`. If it is a `Class`, it is either equivalent to a `ParameterizedType` with no parameters, or it represents the erasure of a `ParameterizedType`. Parameters map:Map<Type, Type> the mappings of all type variables type:Type the next type in the hierarchy

private static void prepare(Map<Type, Type> map, Type type)

Fills the map from type parameters to types as seen by the given type. The method is recursive because the type inherits mappings from its parent classes and interfaces. The type can be either a Class or a ParameterizedType. If it is a Class, it is either equivalent to a ParameterizedType with no parameters, or it represents the erasure of a ParameterizedType.

Parameters

map:Map<Type, Type>: the mappings of all type variables
type:Type: the next type in the hierarchy

resolve back to summary

resolve	back to summary
public static Type resolve(Type actual, Type formal) Replaces type variables of the given `formal` type with the types they stand for in the given `actual` type. A ParameterizedType is a class with type parameters, and the values of those parameters. For example, Map<K,V> is a generic class, and a corresponding ParameterizedType might look like Map<K=String,V=Integer>. Given such a ParameterizedType, this method will replace K with String, or List<K> with List<String>, or List<? super K> with List<? super String>. The `actual` argument to this method can also be a Class. In this case, either it is equivalent to a ParameterizedType with no parameters (for example, Integer.class), or it is equivalent to a "raw" ParameterizedType (for example, Map.class). In the latter case, every type parameter declared or inherited by the class is replaced by its "erasure". For a type parameter declared as <T>, the erasure is Object. For a type parameter declared as <T extends Number>, the erasure is Number. Although type parameters are not inherited by subclasses in the Java language, they are effectively inherited when using reflection. For example, if you declare an interface like this... public interface StringToIntMap extends Map<String,Integer> {} ...then StringToIntMap.class.getMethods() will show that it has methods like put(K,V) even though StringToIntMap has no type parameters. The K and V variables are the ones declared by Map, so `TypeVariable#getGenericDeclaration()` will return `Map.class`. For this reason, this method replaces inherited type parameters too. Therefore if this method is called with `actual` being StringToIntMap.class and `formal` being the K from Map, it will return `String.class`. In the case where `actual` is a "raw" ParameterizedType, the inherited type parameters will also be replaced by their erasures. The erasure of a Class is the Class itself, so a "raw" subinterface of StringToIntMap will still show the K from Map as String.class. But in a case like this... public interface StringToIntListMap extends Map<String,List<Integer>> {} public interface RawStringToIntListMap extends StringToIntListMap {} ...the V inherited from Map will show up as List<Integer> in StringToIntListMap, but as plain List in RawStringToIntListMap. Parameters actual:Type the type that supplies bindings for type variables formal:Type the type where occurrences of the variables in `actual` will be replaced by the corresponding bound values Returns:Type a resolved type

public static Type resolve(Type actual, Type formal)

Replaces type variables of the given formal type with the types they stand for in the given actual type.

A ParameterizedType is a class with type parameters, and the values of those parameters. For example, Map<K,V> is a generic class, and a corresponding ParameterizedType might look like Map<K=String,V=Integer>. Given such a ParameterizedType, this method will replace K with String, or List<K> with List<String>, or List<? super K> with List<? super String>.

The actual argument to this method can also be a Class. In this case, either it is equivalent to a ParameterizedType with no parameters (for example, Integer.class), or it is equivalent to a "raw" ParameterizedType (for example, Map.class). In the latter case, every type parameter declared or inherited by the class is replaced by its "erasure". For a type parameter declared as <T>, the erasure is Object. For a type parameter declared as <T extends Number>, the erasure is Number.

Although type parameters are not inherited by subclasses in the Java language, they are effectively inherited when using reflection. For example, if you declare an interface like this...

public interface StringToIntMap extends Map<String,Integer> {}

...then StringToIntMap.class.getMethods() will show that it has methods like put(K,V) even though StringToIntMap has no type parameters. The K and V variables are the ones declared by Map, so TypeVariable#getGenericDeclaration() will return Map.class.

For this reason, this method replaces inherited type parameters too. Therefore if this method is called with actual being StringToIntMap.class and formal being the K from Map, it will return String.class.

In the case where actual is a "raw" ParameterizedType, the inherited type parameters will also be replaced by their erasures. The erasure of a Class is the Class itself, so a "raw" subinterface of StringToIntMap will still show the K from Map as String.class. But in a case like this...

public interface StringToIntListMap extends Map<String,List<Integer>> {}
public interface RawStringToIntListMap extends StringToIntListMap {}

...the V inherited from Map will show up as List<Integer> in StringToIntListMap, but as plain List in RawStringToIntListMap.

Parameters

actual:Type: the type that supplies bindings for type variables
formal:Type: the type where occurrences of the variables in actual will be replaced by the corresponding bound values

Returns:Type

a resolved type

resolve back to summary

resolve	back to summary
public static Type[] resolve(Type actual, Type[] formals) Replaces type variables of all formal types in the given array with the types they stand for in the given `actual` type. Parameters actual:Type the type that supplies bindings for type variables formals:Type[] the array of types to resolve Returns:Type[] an array of resolved types

public static Type[] resolve(Type actual, Type[] formals)

Replaces type variables of all formal types in the given array with the types they stand for in the given actual type.

Parameters

actual:Type: the type that supplies bindings for type variables
formals:Type[]: the array of types to resolve

Returns:Type[]

an array of resolved types

resolveInClass back to summary

resolveInClass	back to summary
public static Type resolveInClass(Class<?> inClass, Type type) Replaces the given `type` in an inherited method with the actual type it has in the given `inClass`. Although type parameters are not inherited by subclasses in the Java language, they are effectively inherited when using reflection. For example, if you declare an interface like this... public interface StringToIntMap extends Map<String,Integer> {} ...then StringToIntMap.class.getMethods() will show that it has methods like put(K,V) even though StringToIntMap has no type parameters. The K and V variables are the ones declared by Map, so `TypeVariable#getGenericDeclaration()` will return Map.class. The purpose of this method is to take a Type from a possibly-inherited method and replace it with the correct Type for the inheriting class. So given parameters of K and StringToIntMap.class in the above example, this method will return String. Parameters inClass:Class<?> the base class used to resolve type:Type the type to resolve Returns:Type a resolved type See Also `getActualType(Class)`, `resolve(Type, Type)`

public static Type resolveInClass(Class<?> inClass, Type type)

Replaces the given type in an inherited method with the actual type it has in the given inClass.

Although type parameters are not inherited by subclasses in the Java language, they are effectively inherited when using reflection. For example, if you declare an interface like this...

public interface StringToIntMap extends Map<String,Integer> {}

The purpose of this method is to take a Type from a possibly-inherited method and replace it with the correct Type for the inheriting class. So given parameters of K and StringToIntMap.class in the above example, this method will return String.

Parameters

inClass:Class<?>: the base class used to resolve
type:Type: the type to resolve

Returns:Type

a resolved type

resolveInClass back to summary

resolveInClass	back to summary
public static Type[] resolveInClass(Class<?> inClass, Type[] types) Replaces all `types` in the given array with the actual types they have in the given `inClass`. Parameters inClass:Class<?> the base class used to resolve types:Type[] the array of types to resolve Returns:Type[] an array of resolved types See Also `getActualType(Class)`, `resolve(Type, Type[])`

public static Type[] resolveInClass(Class<?> inClass, Type[] types)

Replaces all types in the given array with the actual types they have in the given inClass.

Parameters

inClass:Class<?>: the base class used to resolve
types:Type[]: the array of types to resolve

Returns:Type[]

an array of resolved types

public final Class TypeResolver

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