Class MapBinder<K,​V>

  • Direct Known Subclasses:
    MapBinder.RealMapBinder

    public abstract class MapBinder<K,​V>
    extends java.lang.Object
    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) { ... }
     }

    Creating 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.

    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.

    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).

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  MapBinder.RealMapBinder<K,​V>
      The actual mapbinder plays several roles:
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      abstract LinkedBindingBuilder<V> addBinding​(K key)
      Returns a binding builder used to add a new entry in the map.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, java.lang.Class<K> keyType, java.lang.Class<V> valueType)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with no binding annotation.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, java.lang.Class<K> keyType, java.lang.Class<V> valueType, java.lang.annotation.Annotation annotation)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotation.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, java.lang.Class<K> keyType, java.lang.Class<V> valueType, java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotationType.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, TypeLiteral<K> keyType, TypeLiteral<V> valueType)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with no binding annotation.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, TypeLiteral<K> keyType, TypeLiteral<V> valueType, java.lang.annotation.Annotation annotation)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotation.
      static <K,​V>
      MapBinder<K,​V>
      newMapBinder​(Binder binder, TypeLiteral<K> keyType, TypeLiteral<V> valueType, java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
      Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotationType.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    TypeLiteral<K> keyType,
                                                                    TypeLiteral<V> valueType)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with no binding annotation.
      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    java.lang.Class<K> keyType,
                                                                    java.lang.Class<V> valueType)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with no binding annotation.
      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    TypeLiteral<K> keyType,
                                                                    TypeLiteral<V> valueType,
                                                                    java.lang.annotation.Annotation annotation)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotation.
      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    java.lang.Class<K> keyType,
                                                                    java.lang.Class<V> valueType,
                                                                    java.lang.annotation.Annotation annotation)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotation.
      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    TypeLiteral<K> keyType,
                                                                    TypeLiteral<V> valueType,
                                                                    java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotationType.
      • newMapBinder

        public static <K,​V> MapBinder<K,​V> newMapBinder​(Binder binder,
                                                                    java.lang.Class<K> keyType,
                                                                    java.lang.Class<V> valueType,
                                                                    java.lang.Class<? extends java.lang.annotation.Annotation> annotationType)
        Returns a new mapbinder that collects entries of keyType/valueType in a Map that is itself bound with annotationType.
      • addBinding

        public abstract LinkedBindingBuilder<V> addBinding​(K key)
        Returns a binding builder used to add a new entry in the map. Each key must be distinct (and non-null). Bound providers will be evaluated each time the map is injected.

        It is an error to call this method without also calling one of the to methods on the returned binding builder.

        Scoping elements independently is supported. Use the in method to specify a binding scope.