com.google.inject.Provider<T> |
Known Indirect Subclasses
|
Class Overview
An object capable of providing instances of type T
. Providers are used in numerous ways
by Guice:
- When the default means for obtaining instances (an injectable or parameterless constructor)
is insufficient for a particular binding, the module can specify a custom
Provider
instead, to control exactly how Guice creates or obtains instances for the binding.
- An implementation class may always choose to have a
Provider<T>
instance injected,
rather than having a T
injected directly. This may give you access to multiple
instances, instances you wish to safely mutate and discard, instances which are out of scope
(e.g. using a @RequestScoped
object from within a @SessionScoped
object), or
instances that will be initialized lazily.
- A custom
Scope
is implemented as a decorator of Provider<T>
, which decides
when to delegate to the backing provider and when to provide the instance some other way.
- The
Injector
offers access to the Provider<T>
it uses to fulfill requests
for a given key, via the getProvider(Key)
methods.
Summary
Public Methods |
abstract
T
|
get()
Provides an instance of T .
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[Expand]
Inherited Methods |
From interface
javax.inject.Provider
|
Public Methods
public
abstract
T
get
()
Provides an instance of T
. Must never return null
.
Throws
OutOfScopeException
| when an attempt is made to access a scoped object while the scope
in question is not currently active |
ProvisionException
| if an instance cannot be provided. Such exceptions include messages
and throwables to describe why provision failed.
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