1   /*
2    * Copyright (C) 2007 The Guava Authors
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    * http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package com.google.common.eventbus;
18  
19  import com.google.common.annotations.Beta;
20  
21  import java.lang.annotation.ElementType;
22  import java.lang.annotation.Retention;
23  import java.lang.annotation.RetentionPolicy;
24  import java.lang.annotation.Target;
25  
26  /**
27   * Marks a method as an event subscriber.
28   *
29   * <p>The type of event will be indicated by the method's first (and only)
30   * parameter.  If this annotation is applied to methods with zero parameters,
31   * or more than one parameter, the object containing the method will not be able
32   * to register for event delivery from the {@link EventBus}.
33   *
34   * <p>Unless also annotated with @{@link AllowConcurrentEvents}, event subscriber
35   * methods will be invoked serially by each event bus that they are registered
36   * with.
37   *
38   * @author Cliff Biffle
39   * @since 10.0
40   */
41  @Retention(RetentionPolicy.RUNTIME)
42  @Target(ElementType.METHOD)
43  @Beta
44  public @interface Subscribe {
45  }