com.google.inject

Interface Provider<T>

  • Type Parameters:
    T - the type of object this provides
    All Superinterfaces:
    javax.inject.Provider<T>
    All Known Subinterfaces:
    ProviderWithDependencies<T>, ProviderWithExtensionVisitor<T>
    All Known Implementing Classes:
    ProviderMethod

    public interface Provider<T>
extends javax.inject.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.
    Author:
    crazybob@google.com (Bob Lee)

    • Method Detail

      • get

        T get()
        Provides an instance of T.
        Specified by:
        get in interface javax.inject.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.

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