MapBinder

Class Overview

An API to bind multiple map entries separately, only to later inject them as a complete map. MapBinder is intended for use in your application's module:

 public class SnacksModule extends AbstractModule {
   protected void configure() {
     MapBinder<String, Snack> mapbinder
         = MapBinder.newMapBinder(binder(), String.class, Snack.class);
     mapbinder.addBinding("twix").toInstance(new Twix());
     mapbinder.addBinding("snickers").toProvider(SnickersProvider.class);
     mapbinder.addBinding("skittles").to(Skittles.class);
   }
 }

With this binding, a Map<String, Snack> can now be injected:

 class SnackMachine {
   @Inject
   public SnackMachine(Map<String, Snack> snacks) { ... }
 }

In addition to binding Map<K, V>, a mapbinder will also bind Map<K, Provider<V>> for lazy value provision:

 class SnackMachine {
   @Inject
   public SnackMachine(Map<String, Provider<Snack>> snackProviders) { ... }
 }

Contributing mapbindings from different modules is supported. For example, it is okay to have both CandyModule and ChipsModule both create their own MapBinder<String, Snack>, and to each contribute bindings to the snacks map. When that map is injected, it will contain entries from both modules.

The map's iteration order is consistent with the binding order. This is convenient when multiple elements are contributed by the same module because that module can order its bindings appropriately. Avoid relying on the iteration order of elements contributed by different modules, since there is no equivalent mechanism to order modules.

The map is unmodifiable. Elements can only be added to the map by configuring the MapBinder. Elements can never be removed from the map.

Values are resolved at map injection time. If a value is bound to a provider, that provider's get method will be called each time the map is injected (unless the binding is also scoped, or a map of providers is injected).

Annotations are used to create different maps of the same key/value type. Each distinct annotation gets its own independent map.

Keys must be distinct. If the same key is bound more than once, map injection will fail. However, use permitDuplicates() in order to allow duplicate keys; extra bindings to Map<K, Set<V>> and Map<K, Set<Provider<V>> will be added.

Keys must be non-null. addBinding(null) will throw an unchecked exception.

Values must be non-null to use map injection. If any value is null, map injection will fail (although injecting a map of providers will not).

Summary

[Expand] Inherited Methods
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0) final void wait(long arg0, int arg1)