com.google.common.reflect

Interface TypeToInstanceMap<B>

Type Parameters:

B - the common supertype that all entries must share; often this is simply Object

All Superinterfaces:

Map<TypeToken<? extends B>,B>

All Known Implementing Classes:

ImmutableTypeToInstanceMap, MutableTypeToInstanceMap

@Beta
public interface TypeToInstanceMap<B>
extends Map<TypeToken<? extends B>,B>

A map, each entry of which maps a TypeToken to an instance of that type. In addition to implementing Map, the additional type-safe operations putInstance(java.lang.Class<T>, T) and getInstance(java.lang.Class<T>) are available.

Generally, implementations don't support Map.put(K, V) and Map.putAll(java.util.Map<? extends K, ? extends V>) because there is no way to check an object at runtime to be an instance of a TypeToken. Instead, caller should use the type safe putInstance(java.lang.Class<T>, T).

Also, if caller suppresses unchecked warnings and passes in an Iterable<String> for type Iterable<Integer>, the map won't be able to detect and throw type error.

Like any other Map<Class, Object>, this map may contain entries for primitive types, and a primitive type and its corresponding wrapper type may map to different values.

Since:

13.0

Author:

Ben Yu

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Method Summary

Methods

Modifier and Type	Method and Description
<T extends B> T	getInstance(Class<T> type) Returns the value the specified class is mapped to, or null if no entry for this class is present.
<T extends B> T	getInstance(TypeToken<T> type) Returns the value the specified type is mapped to, or null if no entry for this type is present.
<T extends B> T	putInstance(Class<T> type, T value) Maps the specified class to the specified value.
<T extends B> T	putInstance(TypeToken<T> type, T value) Maps the specified type to the specified value.

Methods inherited from interface java.util.Map

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Method Detail

getInstance

@Nullable
<T extends B> T getInstance(Class<T> type)

Returns the value the specified class is mapped to, or null if no entry for this class is present. This will only return a value that was bound to this specific class, not a value that may have been bound to a subtype.

getInstance(Foo.class) is equivalent to getInstance(TypeToken.of(Foo.class)).

putInstance

@Nullable
<T extends B> T putInstance(Class<T> type,
                                   @Nullable
                                   T value)

Maps the specified class to the specified value. Does not associate this value with any of the class's supertypes.

putInstance(Foo.class, foo) is equivalent to putInstance(TypeToken.of(Foo.class), foo).

Returns:

the value previously associated with this class (possibly null), or null if there was no previous entry.

getInstance

@Nullable
<T extends B> T getInstance(TypeToken<T> type)

Returns the value the specified type is mapped to, or null if no entry for this type is present. This will only return a value that was bound to this specific type, not a value that may have been bound to a subtype.

putInstance

@Nullable
<T extends B> T putInstance(TypeToken<T> type,
                                   @Nullable
                                   T value)

Maps the specified type to the specified value. Does not associate this value with any of the type's supertypes.

Returns:

the value previously associated with this type (possibly null), or null if there was no previous entry.