com.google.inject.Provider Maven / Gradle / Ivy
package com.google.inject;
/**
* An object capable of providing instances of type {@code 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 {@code Provider}
* instead, to control exactly how Guice creates or obtains instances for the binding.
*
*
- An implementation class may always choose to have a {@code Provider
} instance injected,
* rather than having a {@code 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 {@code @RequestScoped} object from within a {@code @SessionScoped} object), or
* instances that will be initialized lazily.
*
* - A custom {@link Scope} is implemented as a decorator of {@code Provider
}, which decides
* when to delegate to the backing provider and when to provide the instance some other way.
*
* - The {@link Injector} offers access to the {@code Provider
} it uses to fulfill requests
* for a given key, via the {@link Injector#getProvider} methods.
*
*
* @param the type of object this provides
*/
public interface Provider extends javax.inject.Provider {
/**
* Provides an instance of {@code T}. Must never return {@code null}.
*
* @throws ProvisionException if an instance cannot be provided. Such exceptions include messages
* and throwables to describe why provision failed.
*/
@Override
T get();
}