dagger.multibindings.Multibinds Maven / Gradle / Ivy

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/*
 * Copyright (C) 2015 Google, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package dagger.multibindings;

import dagger.internal.Beta;
import java.lang.annotation.Documented;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;

/**
 * Annotates abstract module methods that declare multibindings.
 *
 * You can declare that a multibound set or map is bound by annotating an abstract module method
 * that returns the set or map you want to declare with {@code @Multibinds}.
 *
 * 
You do not have to use {@code @Multibinds} for sets or maps that have at least one
 * contribution, but you do have to declare them if they may be empty.
 *
 * 

 *   {@literal @Module} abstract class MyModule {
 *     {@literal @Multibinds Set aSet();}
 *     {@literal @Multibinds @MyQualifier Set aQualifiedSet();}
 *     {@literal @Multibinds Map aMap();}
 *     {@literal @Multibinds @MyQualifier Map aQualifiedMap();}
 *
 *     {@literal @Provides}
 *     {@literal static Object usesMultibindings(Set set, @MyQualifier Map map}) {
 *       return …
 *     }
 *   }
 *
 * A given set or map multibinding can be declared any number of times without error. Dagger
 * never implements calls any {@code @Multibinds} methods.
 *
 * @see Multibindings
 */
@Documented
@Target(METHOD)
@Beta
public @interface Multibinds {}