1 /*
2  * Copyright 2018 The Android Open Source Project
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 package androidx.lifecycle
17 
18 /**
19  * Class that can receive any lifecycle change and dispatch it to the receiver.
20  *
21  * If a class implements both this interface and [androidx.lifecycle.DefaultLifecycleObserver], then
22  * methods of `DefaultLifecycleObserver` will be called first, and then followed by the call of
23  * [LifecycleEventObserver.onStateChanged]
24  *
25  * If a class implements this interface and in the same time uses [OnLifecycleEvent], then
26  * annotations will be ignored.
27  */
28 public fun interface LifecycleEventObserver : LifecycleObserver {
29     /**
30      * Called when a state transition event happens.
31      *
32      * @param source The source of the event
33      * @param event The event
34      */
onStateChangednull35     public fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event)
36 }
37