Livebus

Event bus using android architecture components

LiveBus is an event bus for Android which uses LiveData component of the android architecture library to easily manage the lifecycles.

• This library

  • makes it easier to communicate between fragments/activities and view models.

  • helps you to decouple different parts of your application

  • is easy to implement and maintain. There is no additional knowledge needed if you know the android architecture components

  • uses the publish/subscribe pattern

  • is completely written in Kotlin

Add LiveBus to your project

You can add the library through maven

<dependency>
  <groupId>org.insac.core</groupId>
  <artifactId>livebus</artifactId>
  <version>0.3.2</version>
  <type>pom</type>
</dependency>

or through gradle

implementation 'org.insac.core:livebus:0.3.2'

Usage

Publishing an event

There are there different event type on LiveBus: LiveEvent, SingleLiveEvent, StickyLiveEvent

LiveEvent will broadcast the event value passed to it until it doesn't have any observer oberserving the values. Note that this type of event will get unsubscribed and removed from the bus whenever the user closes the app/ turn off the screen, use StickyLiveEvent if you want to keep the subscription to survive app lifecycles.

SingleLiveEvent will send the event value passed to it, to only one of its observer and then the event value will be set to null.

StickyLiveEvent will broadcast the event value passed to it until it is removed from the bus by explicitly calling removeEvent(tag).

Every event on LiveBus is identified by an unique tag. The same tag needs to be used to publish an event and subscribe to an event. Every subscribe/ publish function calls will create an empty event LiveData on the bus if it hasn't been created already.

• setSingleLiveEventValue(tag: String, eventValue: T) : Use this function if you want to publish a SingleLiveEventfrom the UI thread.

• postSingleLiveEventValue(tag: String, eventValue: T) : Use this function if you want to publish a SingleLiveEventfrom a background thread

• setLiveEventValue(tag: String, eventValue: T) : Use this function to publish a LiveEvent from the UI thread.

• postLiveEventValue(tag: String, eventValue: T) : Use this function to publish a LiveEvent from a background thread.

• setStickyLiveEventValue(tag: String, eventValue: T) : Use this function to publish a StickyEvent from the UI thread.

• postStickyLiveEventValue(tag: String, eventValue: T) : Use this function to publish a StickyEvent from a background thread.

Subscribing to an Event

Subscribing to an event is very similar to subscribing to a LiveData on a Activity/Fragment/ViewModel. Pass the tag of the event you want to subscribe to the function depending on the type of the event you want to subscribe and call observe(...) function on the returned LiveData to process the event.

Subscribing to LiveEvent

LiveBus.getInstance().subscribeLiveEvent("EVENT_TAG", EVENT_VALUE_CLASS_TYPE)
                .observe(this, Observer {
                    it?.let {
                        // Process event
                    }
                })

Subscribing to SingleLiveEvent

LiveBus.getInstance().subscribeSingleLiveEvent("EVENT_TAG", EVENT_VALUE_CLASS_TYPE)
                .observe(this, Observer {
                    it?.let {
                        // Process event
                    }
                })

Subscribing to StickyLiveEvent

LiveBus.getInstance().subscribeStickyLiveEvent("EVENT_TAG", EVENT_VALUE_CLASS_TYPE)
                .observe(this, Observer {
                    it?.let {
                        // Process event
                    }
                })

As the object returned by these functions are LiveData objects, no unsubscribe calls are needed, since it'll be automatically handled by the android OS.

Removing an event from the bus

LiveBus.getInstance().removeEvent("EVENT_TAG")

License

Copyright 2018 Cevat Can Undeger

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.