Interface ClassToInstanceMap<B>
- Type Parameters:
B
- the common supertype that all entries must share; often this is simplyObject
- All Known Implementing Classes:
ImmutableClassToInstanceMap
,MutableClassToInstanceMap
Map
, the additional type-safe
operations putInstance(java.lang.Class<T>, T)
and getInstance(java.lang.Class<T>)
are available.
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.
This class's support for null
requires some explanation: From release 31.0 onward,
Guava specifies the nullness of its types through annotations. In the case of
ClassToInstanceMap
, it specifies that both the key and value types are restricted to
non-nullable types. This specification is reasonable for keys, which must be non-null
classes. This is in contrast to the specification for values: Null values are
supported by the implementation MutableClassToInstanceMap
, even though that
implementation and this interface specify otherwise. Thus, if you use a nullness checker, you can
safely suppress any warnings it produces when you write null values into a
MutableClassToInstanceMap
. Just be sure to be prepared for null values when reading from it,
since nullness checkers will assume that vaules are non-null then, too.
See the Guava User Guide article on
ClassToInstanceMap
.
To map a generic type to an instance of that type, use TypeToInstanceMap
instead.
- Since:
- 2.0
-
Nested Class Summary
-
Method Summary
Modifier and TypeMethodDescription<T extends B>
TgetInstance
(Class<T> type) Returns the value the specified class is mapped to, ornull
if no entry for this class is present.<T extends B>
TputInstance
(Class<T> type, T value) Maps the specified class to the specified value.Methods inherited from interface java.util.Map
clear, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, equals, forEach, get, getOrDefault, hashCode, isEmpty, keySet, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, replaceAll, size, values
-
Method Details
-
getInstance
Returns the value the specified class is mapped to, ornull
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. -
putInstance
Maps the specified class to the specified value. Does not associate this value with any of the class's supertypes.- Returns:
- the value previously associated with this class (possibly
null
), ornull
if there was no previous entry.
-