xref: /external/guava/guava/src/com/google/common/eventbus/Subscribe.java

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 com.google.common.eventbus;

import com.google.common.annotations.Beta;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Marks a method as an event handler, as used by
 * {@link AnnotatedHandlerFinder} and {@link EventBus}.
 *
 * <p>The type of event will be indicated by the method's first (and only)
 * parameter.  If this annotation is applied to methods with zero parameters,
 * or more than one parameter, the object containing the method will not be able
 * to register for event delivery from the {@link EventBus}.
 *
 * <p>Unless also annotated with @{@link AllowConcurrentEvents}, event handler
 * methods will be invoked serially by each event bus that they are registered
 * with.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Beta
public @interface Subscribe {
}