com.google.inject

Interface Provider<T>

Type Parameters:

T - the type of object this provides

All Superinterfaces:

Provider<T>

All Known Subinterfaces:

ProviderWithDependencies<T>, ProviderWithExtensionVisitor<T>

public interface Provider<T>
extends Provider<T>

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 Injector.getProvider(com.google.inject.Key<T>) methods.

Method Summary

Modifier and Type	Method and Description
T	get() Provides an instance of T.

Method Detail

get

T get()

Provides an instance of T. Must never return null.

Specified by:

get in interface Provider<T>

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.