# greenrobot/EventBus

Event bus for Android and Java that simplifies communication between Activities, Fragments, Threads, Services, etc. Less code, better quality.

Repository: https://github.com/greenrobot/EventBus
Canonical: https://ross.abutalabs.com/products/eventbus
Homepage: http://greenrobot.org/eventbus/
Language: Java
License: Apache-2.0
License Family: permissive
Last push: 2024-02-21T18:18:34+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5161, "days_push": 924, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 24718, forks 4640 (observed 2026-08-28T04:11:37.619715+00:00)

## What it is
EventBus is a publish/subscribe event bus library for Android and Java that decouples event senders and receivers with a simple annotation-based API. It supports thread-mode delivery, sticky events, subscriber priorities, and build-time subscriber indexing for high performance.

## Use cases
- communicate between Android activities and fragments without tight coupling
- deliver events from background threads to the Android main thread
- replace complex listener interfaces and callbacks with a decoupled event bus
- share state updates across services, threads, and UI components in an Android app
- cache the latest event value for late subscribers using sticky events
- use a lightweight pub/sub event bus in plain Java applications

## When to choose
- you are building an Android app and want simple, battle-tested decoupled component communication
- you need thread-aware event delivery (main thread, background, async) with minimal boilerplate
- you want a tiny, fast, zero-configuration library proven in apps with billions of installs

## When to avoid
- you prefer reactive streams with rich operators like filtering and combining (consider RxJava or Kotlin Flow)
- you need distributed or inter-process messaging rather than in-process events
- you are using modern Android architecture patterns that favor shared flows, LiveData, or state holders over event buses

## Facets
- artifact type: library
- maturity: stable
- function: middleware, concurrency, developer-tools
- domain: mobile-development, android-tools, developer-tools, cross-platform
- platform: jvm, cross-platform
- tags: event-bus, publish-subscribe, decoupling, annotation-processing, thread-modes, sticky-events, android

## Member repositories
- greenrobot/EventBus (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:37.619715+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T16:56:10.165601+00:00, confidence not recorded.
  - readme: https://github.com/greenrobot/EventBus (fetched 2026-08-28T04:11:37.619715+00:00, sha f3a817bef53a)
  - homepage: http://greenrobot.org/eventbus/ (fetched 2026-08-29T07:53:42.155344+00:00, sha 18a5e69962cd)
  - site_page: https://greenrobot.org/eventbus/features (fetched 2026-08-29T07:53:42.164818+00:00, sha 4fa06b05822b)
  - site_page: https://greenrobot.org/eventbus/documentation (fetched 2026-08-29T07:53:42.166906+00:00, sha ce9b1a155589)
  - site_page: https://greenrobot.org/eventbus/documentation/how-to-get-started (fetched 2026-08-29T07:53:42.168751+00:00, sha 4edddab93803)
  - site_page: https://greenrobot.org/eventbus/documentation/delivery-threads-threadmode (fetched 2026-08-29T07:53:42.170441+00:00, sha 7ba65dc1fa7c)
  - site_page: https://greenrobot.org/eventbus/documentation/configuration (fetched 2026-08-29T07:53:42.172204+00:00, sha d3e960eab436)
  - site_page: https://greenrobot.org/eventbus/documentation/configuration/sticky-events (fetched 2026-08-29T07:53:42.173814+00:00, sha 685e2caa0e2d)
  - site_page: https://greenrobot.org/eventbus/documentation/priorities-and-event-cancellation (fetched 2026-08-29T07:53:42.175390+00:00, sha a30f8bcf0c67)
  - site_page: https://greenrobot.org/eventbus/documentation/subscriber-index (fetched 2026-08-29T07:53:42.176949+00:00, sha 7fa93e023717)
- Data as of 2026-08-30T08:39:29.467469+00:00.