com.datastax.oss.driver.api.core.type.reflect

Class GenericType<T>

java.lang.Object

com.datastax.oss.driver.api.core.type.reflect.GenericType<T>

@Immutable
public class GenericType<T>
extends Object

Runtime representation of a generic Java type.

This is used by type codecs to indicate which Java types they accept (TypeCodec.accepts(GenericType)), and by generic getters and setters (such as GettableByIndex.get(int, GenericType) in the driver's query API.

There are various ways to build instances of this class:

By using one of the static factory methods:

 GenericType<List<String>> stringListType = GenericType.listOf(String.class);
 

By using an anonymous class:

 GenericType<Foo<Bar>> fooBarType = new GenericType<Foo<Bar>>(){};
 

In a generic method, by using where(GenericTypeParameter, GenericType) to substitute free type variables with runtime types:

 <T> GenericType<Optional<T>> optionalOf(GenericType<T> elementType) {
   return new GenericType<Optional<T>>() {}
     .where(new GenericTypeParameter<T>() {}, elementType);
 }
 ...
 GenericType<Optional<List<String>>> optionalStringListType = optionalOf(GenericType.listOf(String.class));
 

You are encouraged to store and reuse these instances.

Note that this class is a thin wrapper around Guava's TypeToken. The only reason why TypeToken is not used directly is because Guava is not exposed in the driver's public API (it's used internally, but shaded).

Field Summary

Fields

Modifier and Type	Field and Description
static GenericType<BigDecimal>	BIG_DECIMAL
static GenericType<BigInteger>	BIG_INTEGER
static GenericType<Boolean>	BOOLEAN
static GenericType<Byte>	BYTE
static GenericType<ByteBuffer>	BYTE_BUFFER
static GenericType<CqlDuration>	CQL_DURATION
static GenericType<Double>	DOUBLE
static GenericType<Duration>	DURATION
static GenericType<Float>	FLOAT
static GenericType<InetAddress>	INET_ADDRESS
static GenericType<Instant>	INSTANT
static GenericType<Integer>	INTEGER
static GenericType<LocalDate>	LOCAL_DATE
static GenericType<LocalTime>	LOCAL_TIME
static GenericType<Long>	LONG
static GenericType<Short>	SHORT
static GenericType<String>	STRING
static GenericType<TupleValue>	TUPLE_VALUE
static GenericType<UdtValue>	UDT_VALUE
static GenericType<UUID>	UUID
static GenericType<ZonedDateTime>	ZONED_DATE_TIME

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	GenericType()

Method Summary

Modifier and Type	Method and Description
com.datastax.oss.driver.shaded.guava.common.reflect.TypeToken<T>	__getToken() This method is for internal use, DO NOT use it from client code.
boolean	equals(Object other)
GenericType<?>	getComponentType() Returns the array component type if this type represents an array (int[], T[], <? extends Map<String, Integer>[]> etc.), or else null is returned.
Class<? super T>	getRawType() Returns the raw type of T.
GenericType<? extends T>	getSubtype(Class<?> subclass) Returns subtype of this with subclass as the raw class.
GenericType<? super T>	getSupertype(Class<? super T> superclass) Returns the generic form of superclass.
Type	getType() Returns the represented type.
int	hashCode()
boolean	isArray() Returns true if this type is known to be an array type, such as int[], T[], <? extends Map<String, Integer>[]> etc.
boolean	isPrimitive() Returns true if this type is one of the nine primitive types (including void).
boolean	isSubtypeOf(GenericType<?> type) Returns true if this type is a subtype of the given type.
boolean	isSupertypeOf(GenericType<?> type) Returns true if this type is a supertype of the given type.
static <T> GenericType<List<T>>	listOf(Class<T> elementType)
static <T> GenericType<List<T>>	listOf(GenericType<T> elementType)
static <K,V> GenericType<Map<K,V>>	mapOf(Class<K> keyType, Class<V> valueType)
static <K,V> GenericType<Map<K,V>>	mapOf(GenericType<K> keyType, GenericType<V> valueType)
static <T> GenericType<T>	of(Class<T> type)
static GenericType<?>	of(Type type)
static <T> GenericType<Set<T>>	setOf(Class<T> elementType)
static <T> GenericType<Set<T>>	setOf(GenericType<T> elementType)
String	toString()
GenericType<T>	unwrap() Returns the corresponding primitive type if this is a wrapper type; otherwise returns this itself.
<X> GenericType<T>	where(GenericTypeParameter<X> freeVariable, Class<X> actualType) Substitutes a free type variable with an actual type.
<X> GenericType<T>	where(GenericTypeParameter<X> freeVariable, GenericType<X> actualType) Substitutes a free type variable with an actual type.
GenericType<T>	wrap() Returns the corresponding wrapper type if this is a primitive type; otherwise returns this itself.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

BOOLEAN

public static final GenericType<Boolean> BOOLEAN

BYTE

public static final GenericType<Byte> BYTE

DOUBLE

public static final GenericType<Double> DOUBLE

FLOAT

public static final GenericType<Float> FLOAT

INTEGER

public static final GenericType<Integer> INTEGER

LONG

public static final GenericType<Long> LONG

SHORT

public static final GenericType<Short> SHORT

INSTANT

public static final GenericType<Instant> INSTANT

ZONED_DATE_TIME

public static final GenericType<ZonedDateTime> ZONED_DATE_TIME

LOCAL_DATE

public static final GenericType<LocalDate> LOCAL_DATE

LOCAL_TIME

public static final GenericType<LocalTime> LOCAL_TIME

BYTE_BUFFER

public static final GenericType<ByteBuffer> BYTE_BUFFER

STRING

public static final GenericType<String> STRING

BIG_INTEGER

public static final GenericType<BigInteger> BIG_INTEGER

BIG_DECIMAL

public static final GenericType<BigDecimal> BIG_DECIMAL

UUID

public static final GenericType<UUID> UUID

INET_ADDRESS

public static final GenericType<InetAddress> INET_ADDRESS

CQL_DURATION

public static final GenericType<CqlDuration> CQL_DURATION

TUPLE_VALUE

public static final GenericType<TupleValue> TUPLE_VALUE

UDT_VALUE

public static final GenericType<UdtValue> UDT_VALUE

DURATION

public static final GenericType<Duration> DURATION

Constructor Detail

GenericType

protected GenericType()

Method Detail

of

@NonNull
public static <T> GenericType<T> of(@NonNull
                                             Class<T> type)

of

@NonNull
public static GenericType<?> of(@NonNull
                                         Type type)

listOf

@NonNull
public static <T> GenericType<List<T>> listOf(@NonNull
                                                       Class<T> elementType)

listOf

@NonNull
public static <T> GenericType<List<T>> listOf(@NonNull
                                                       GenericType<T> elementType)

setOf

@NonNull
public static <T> GenericType<Set<T>> setOf(@NonNull
                                                     Class<T> elementType)

setOf

@NonNull
public static <T> GenericType<Set<T>> setOf(@NonNull
                                                     GenericType<T> elementType)

mapOf

@NonNull
public static <K,V> GenericType<Map<K,V>> mapOf(@NonNull
                                                         Class<K> keyType,
                                                         @NonNull
                                                         Class<V> valueType)

mapOf

@NonNull
public static <K,V> GenericType<Map<K,V>> mapOf(@NonNull
                                                         GenericType<K> keyType,
                                                         @NonNull
                                                         GenericType<V> valueType)

isSupertypeOf

public final boolean isSupertypeOf(@NonNull
                                   GenericType<?> type)

Returns true if this type is a supertype of the given type. "Supertype" is defined according to the rules for type arguments introduced with Java generics.

isSubtypeOf

public final boolean isSubtypeOf(@NonNull
                                 GenericType<?> type)

Returns true if this type is a subtype of the given type. "Subtype" is defined according to the rules for type arguments introduced with Java generics.

isArray

public final boolean isArray()

Returns true if this type is known to be an array type, such as int[], T[], <? extends Map<String, Integer>[]> etc.

isPrimitive

public final boolean isPrimitive()

Returns true if this type is one of the nine primitive types (including void).

wrap

@NonNull
public final GenericType<T> wrap()

Returns the corresponding wrapper type if this is a primitive type; otherwise returns this itself. Idempotent.

unwrap

@NonNull
public final GenericType<T> unwrap()

Returns the corresponding primitive type if this is a wrapper type; otherwise returns this itself. Idempotent.

where

@NonNull
public final <X> GenericType<T> where(@NonNull
                                               GenericTypeParameter<X> freeVariable,
                                               @NonNull
                                               GenericType<X> actualType)

Substitutes a free type variable with an actual type. See this class's javadoc for an example.

where

@NonNull
public final <X> GenericType<T> where(@NonNull
                                               GenericTypeParameter<X> freeVariable,
                                               @NonNull
                                               Class<X> actualType)

Substitutes a free type variable with an actual type. See this class's javadoc for an example.

getComponentType

@Nullable
public final GenericType<?> getComponentType()

Returns the array component type if this type represents an array (int[], T[], <? extends Map<String, Integer>[]> etc.), or else null is returned.

getRawType

@NonNull
public Class<? super T> getRawType()

Returns the raw type of T. Formally speaking, if T is returned by Method.getGenericReturnType(), the raw type is what's returned by Method.getReturnType() of the same method object. Specifically:

• If T is a Class itself, T itself is returned.
• If T is a parameterized type, the raw type of the parameterized type is returned.
• If T is an array type , the returned type is the corresponding array class. For example: List<Integer>[] => List[].
• If T is a type variable or a wildcard type, the raw type of the first upper bound is returned. For example: <X extends Foo> => Foo.

getSupertype

@NonNull
public final GenericType<? super T> getSupertype(@NonNull
                                                          Class<? super T> superclass)

Returns the generic form of superclass. For example, if this is ArrayList<String>, Iterable<String> is returned given the input Iterable.class.

getSubtype

@NonNull
public final GenericType<? extends T> getSubtype(@NonNull
                                                          Class<?> subclass)

Returns subtype of this with subclass as the raw class. For example, if this is Iterable<String> and subclass is List, List<String> is returned.

getType

@NonNull
public final Type getType()

Returns the represented type.

__getToken

@NonNull
public com.datastax.oss.driver.shaded.guava.common.reflect.TypeToken<T> __getToken()

This method is for internal use, DO NOT use it from client code.

It leaks a shaded type. This should be part of the internal API, but due to internal implementation details it has to be exposed here.

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object