# eclipse-collections/eclipse-collections

Eclipse Collections is a collections framework for Java with optimized data structures and a rich, functional and fluent API.

Repository: https://github.com/eclipse-collections/eclipse-collections
Canonical: https://ross.abutalabs.com/products/eclipse-collections
Homepage: https://eclipse.dev/collections/
Language: Java
License Family: other
Topics: java, eclipse-collections, java-collections, collections, data-structures, functional, object-oriented, immutable-collections, primitive-collections
Last push: 2026-08-22T01:57:20+00:00

## Health v2 (maintenance only)
Score: 78/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 40, longevity 100
- inputs: {"age_days": 3935, "days_push": 12, "days_rel": 400, "gap_med": 0, "n_releases_24m": 2}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2648, forks 690 (observed 2026-08-28T04:07:06.851600+00:00)

## What it is
Eclipse Collections is a comprehensive collections framework for Java offering optimized data structures like Bag and primitive collections, plus a rich, fluent, functional API inspired by Smalltalk. It is compatible with the standard Java Collection Framework and supports eager, lazy, serial, and parallel iteration.

## Use cases
- replace Java streams with more expressive collection APIs
- use immutable collections in Java
- work with primitive collections without boxing
- count elements with a Bag data structure
- perform lazy and parallel iteration over collections
- write fluent functional code over lists and sets in Java

## When to choose
- you want richer, more fluent collection APIs than the JDK or Streams
- you need memory-efficient primitive collections or Bags
- you want immutable collection types with a mature, well-tested library

## When to avoid
- your project must avoid extra dependencies and JDK collections suffice
- you are not on the JVM or using Java
- you need collections interoperable with non-JVM languages

## Facets
- artifact type: library
- maturity: stable
- function: serialization
- domain: developer-tools, performance
- platform: jvm
- tags: collections, data-structures, functional-programming, immutable-collections, primitive-collections, java, algorithms

## Member repositories
- eclipse-collections/eclipse-collections (main) score 78

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:06.851600+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 2026-08-30T02:18:56.300552+00:00, confidence not recorded.
  - readme: https://github.com/eclipse-collections/eclipse-collections (fetched 2026-08-28T04:07:06.851600+00:00, sha ed87dc3b614a)
  - homepage: https://eclipse.dev/collections/ (fetched 2026-08-29T10:01:41.424568+00:00, sha af4d4a2bec4b)
- Data as of 2026-08-30T08:39:29.467469+00:00.