org.jdbi.v3.core.generic

Class GenericTypes

java.lang.Object

org.jdbi.v3.core.generic.GenericTypes

public class GenericTypes
extends Object

Utilities for working with generic types.

Method Summary

Modifier and Type	Method and Description
static Type	box(Type type) Perform boxing conversion on a Type, if it is a primitive type.
static Optional<Type>	findGenericParameter(Type type, Class<?> parameterizedSupertype) Same as findGenericParameter(Type, Class, int) with n = 0.
static Optional<Type>	findGenericParameter(Type type, Class<?> parameterizedSupertype, int n) For the given type which extends parameterizedSupertype, returns the nth generic parameter for the parameterized supertype, if concretely expressed.
static Class<?>	getErasedType(Type type) Returns the erased class for the given type.
static boolean	isArray(Type type)
static Type	parameterizeClass(Class<?> clazz, Type... arguments) Creates a type of class clazz with arguments as type arguments.
static Type	resolveMapEntryType(Type mapType) Given a subtype of Map<K,V>, returns the corresponding map entry type Map.Entry<K,V>.
static Type	resolveMapEntryType(Type keyType, Type valueType) Given a key and value type, returns the map entry type Map.Entry<keyType,valueType>.
static Type	resolveType(Type type, Type contextType) Resolves the type parameter in the context of contextType.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

box

public static Type box(Type type)

Perform boxing conversion on a Type, if it is a primitive type. Otherwise return the input argument.

Parameters:

type - the type to box

Returns:

the boxed type, or the input type if it is not a primitive

findGenericParameter

public static Optional<Type> findGenericParameter(Type type,
                                                  Class<?> parameterizedSupertype)

Same as findGenericParameter(Type, Class, int) with n = 0.

Parameters:

type - the type

parameterizedSupertype - the parameterized supertype

Returns:

the first parameter type

See Also:

findGenericParameter(Type, Class, int)

findGenericParameter

public static Optional<Type> findGenericParameter(Type type,
                                                  Class<?> parameterizedSupertype,
                                                  int n)

For the given type which extends parameterizedSupertype, returns the nth generic parameter for the parameterized supertype, if concretely expressed.

Example:

• if type is ArrayList<String>, parameterizedSuperType is List.class, and n is 0, returns Optional.of(String.class).
• if type is Map<String, Integer>, parameterizedSuperType is Map.class, and n is 1, returns Optional.of(Integer.class).
• if type is ArrayList.class (raw), parameterizedSuperType is List.class, and n is 0, returns Optional.empty().

Parameters:

type - the subtype of parameterizedSupertype

parameterizedSupertype - the parameterized supertype from which we want the generic parameter

n - the index in Foo<X, Y, Z, ...>

Returns:

the parameter on the supertype, if it is concretely defined.

Throws:

ArrayIndexOutOfBoundsException - if n > the number of type variables the type has

getErasedType

public static Class<?> getErasedType(Type type)

Returns the erased class for the given type.

Example: if type is List<String>, returns List.class

parameter

Parameters:

type - the type

Returns:

the erased class

isArray

public static boolean isArray(Type type)

Parameters:

type - a type

Returns:

whether the given Type is an Array type.

parameterizeClass

public static Type parameterizeClass(Class<?> clazz,
                                     Type... arguments)

Creates a type of class clazz with arguments as type arguments.

For example: parameterizedClass(Map.class, Integer.class, String.class) returns the type Map<Integer, String>.

Parameters:

clazz - Type class of the type to create

arguments - Type arguments for the variables of clazz, or null if these are not known.

Returns:

A ParameterizedType, or simply clazz if arguments is null or empty.

resolveMapEntryType

public static Type resolveMapEntryType(Type mapType)

Given a subtype of Map<K,V>, returns the corresponding map entry type Map.Entry<K,V>.

Parameters:

mapType - the map subtype

Returns:

the map entry type

resolveMapEntryType

public static Type resolveMapEntryType(Type keyType,
                                       Type valueType)

Given a key and value type, returns the map entry type Map.Entry<keyType,valueType>.

Parameters:

keyType - the key type

valueType - the value type

Returns:

the map entry type

resolveType

public static Type resolveType(Type type,
                               Type contextType)

Resolves the type parameter in the context of contextType. For example, if type is List.class.getMethod("get", int.class).getGenericReturnType(), and contextType is List<String>, this method returns String.class

Parameters:

type - the type to be resolved in the scope of contextType

contextType - the context type in which type is interpreted to resolve the type.

Returns:

the resolved type.