RxLifecycle
This library allows one to automatically complete sequences based on a second lifecycle stream.
This capability is useful in Android, where incomplete subscriptions can cause memory leaks.
Usage
You must start with an Observable<T>
representing a lifecycle stream. Then you use RxLifecycle
to bind a sequence to that lifecycle.
You can bind when the lifecycle emits anything:
myObservable
.compose(RxLifecycle.bind(lifecycle))
.subscribe();
Or you can bind to when a specific lifecyle event occurs:
myObservable
.compose(RxLifecycle.bindUntilEvent(lifecycle, ActivityEvent.DESTROY))
.subscribe();
Alternatively, you can let RxLifecycle determine the appropriate time to end the sequence:
myObservable
.compose(RxLifecycleAndroid.bindActivity(lifecycle))
.subscribe();
It assumes you want to end the sequence in the opposing lifecycle event - e.g., if subscribing during START
, it will terminate on STOP
. If you subscribe after PAUSE
, it will terminate at the next destruction event (e.g., PAUSE
will terminate in STOP
).
Providers
Where do lifecycles come from? Generally, they are provided by an appropriate LifecycleProvider<T>
. But where are those implemented?
You have a few options for that:
- Use rxlifecycle-components and subclass the provided
RxActivity
,RxFragment
, etc. classes. - Use Navi + rxlifecycle-navi to generate providers.
- Use Android's lifecycle + rxlifecycle-android-lifecycle to generate providers.
- Write the implementation yourself.
If you use rxlifecycle-components, just extend the appropriate class, then use the built-in bindToLifecycle()
(or bindUntilEvent()
) methods:
public class MyActivity extends RxActivity {
@Override
public void onResume() {
super.onResume();
myObservable
.compose(bindToLifecycle())
.subscribe();
}
}
If you use rxlifecycle-navi, then you just pass your NaviComponent
to NaviLifecycle
to generate a provider:
public class MyActivity extends NaviActivity {
private final LifecycleProvider<ActivityEvent> provider
= NaviLifecycle.createActivityLifecycleProvider(this);
@Override
public void onResume() {
super.onResume();
myObservable
.compose(provider.bindToLifecycle())
.subscribe();
}
}
If you use rxlifecycle-android-lifecycle, then you just pass your LifecycleOwner
to AndroidLifecycle
to generate a provider:
public class MyActivity extends LifecycleActivity {
private final LifecycleProvider<Lifecycle.Event> provider
= AndroidLifecycle.createLifecycleProvider(this);
@Override
public void onResume() {
super.onResume();
myObservable
.compose(provider.bindToLifecycle())
.subscribe();
}
}
Unsubscription
RxLifecycle does not actually unsubscribe the sequence. Instead it terminates the sequence. The way in which it does so varies based on the type:
Observable
,Flowable
andMaybe
- emitsonCompleted()
Single
andCompletable
- emitsonError(CancellationException)
If a sequence requires the Subscription.unsubscribe()
behavior, then it is suggested that you manually handle the Subscription
yourself and call unsubscribe()
when appropriate.
Kotlin
The rxlifecycle-kotlin module provides built-in extensions to the base RxJava types:
myObservable
.bindToLifecycle(myView)
.subscribe {
}
myObservable
.bindUntilEvent(myRxActivity, STOP)
.subscribe {
}
There is an additional rxlifecycle-android-lifecycle-kotlin module to provider extensions to work with LivecycleOwner
's.
myObservable
.bindToLifecycle(myLifecycleActivity, ON_STOP)
.subscribe {
}
Installation
compile 'com.trello.rxlifecycle2:rxlifecycle:2.2.0' // If you want to bind to Android-specific lifecycles compile 'com.trello.rxlifecycle2:rxlifecycle-android:2.2.0' // If you want pre-written Activities and Fragments you can subclass as providers compile 'com.trello.rxlifecycle2:rxlifecycle-components:2.2.0' // If you want pre-written support preference Fragments you can subclass as providers compile 'com.trello.rxlifecycle2:rxlifecycle-components-preference:2.2.0' // If you want to use Navi for providers compile 'com.trello.rxlifecycle2:rxlifecycle-navi:2.2.0' // If you want to use Android Lifecycle for providers compile 'com.trello.rxlifecycle2:rxlifecycle-android-lifecycle:2.2.0' // If you want to use Kotlin syntax compile 'com.trello.rxlifecycle2:rxlifecycle-kotlin:2.2.0' // If you want to use Kotlin syntax with Android Lifecycle compile 'com.trello.rxlifecycle2:rxlifecycle-android-lifecycle-kotlin:2.2.0'
License
Copyright (C) 2016 Trello 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.