RxLifecycle
The utilities provided here allow for automatic completion of sequences based on Activity
or Fragment
lifecycle events. This capability is useful in Android, where incomplete subscriptions can cause memory leaks.
Usage
You must provide an Observable<ActivityEvent>
or Observable<FragmentEvent>
that gives
RxLifecycle the information needed to complete the sequence at the correct time.
You can then end the sequence explicitly when an event occurs:
myObservable
.compose(RxLifecycle.bindUntilActivityEvent(lifecycle, ActivityEvent.DESTROY))
.subscribe();
Alternatively, you can let RxLifecycle determine the appropriate time to end the sequence:
myObservable
.compose(RxLifecycle.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
).
Components
Where do the sequences of ActivityEvent
or FragmentEvent
come from? You can either write it yourself, or you can
include rxlifecycle-components, which comes with pre-built Activity
and Fragment
implementations with lifecycles.
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();
}
}
In addition, these components come with lifecycle()
, which allows you to do your own logic based on the Activity
or Fragment
lifecycle.
Unsubscription
RxLifecycle does not actually unsubscribe the sequence. It terminates it by emitting onCompleted()
, which ends the
sequence. This differs from Subscription.unsubscribe()
, which causes the sequence to simply end.
In most cases this works out fine (since onCompleted()
is not often used). In cases where you do not want
onCompleted()
called during early termination, then it is suggested that you manually handle the Subscription
yourself and call unsubscribe()
when appropriate.
(To understand why RxLifecycle has this behavior, read this)
Installation
compile 'com.trello:rxlifecycle:0.3.0'
compile 'com.trello:rxlifecycle-components:0.3.0'
License
Copyright (C) 2015 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.