Eventbus is tiny library that streamlines the communication between the components without requiring components to explicitly register with one another. This makes data exchange seamless between components like Activites, Fragments, services and any kind of background threads easy.

• decouples event senders and receivers
• avoids complex and error prone dependencies and lifecycle issues
• is tiny(~50k jar)
• supports delivery threads, background threads

GreenRobot

More Info - https://github.com/greenrobot/EventBus