# luontola/retrolambda

Backport of Java 8's lambda expressions to Java 7, 6 and 5

Repository: https://github.com/luontola/retrolambda
Canonical: https://ross.abutalabs.com/products/retrolambda
Language: Java
License: Apache-2.0
License Family: permissive
Last push: 2023-09-26T15:12:04+00:00

## Health v2 (maintenance only)
Score: 32/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 4792, "days_push": 1072, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3514, forks 226 (observed 2026-08-28T04:08:07.785571+00:00)

## What it is
Retrolambda is a Java bytecode transformation tool that backports Java 8 lambda expressions, method references, and try-with-resources to Java 7, 6, or 5 runtimes. It can be run as a Maven plugin, Gradle plugin, or command-line application, producing plain .class files with no runtime dependencies.

## Use cases
- run java 8 lambdas on java 7
- backport lambda expressions to older jvm
- use method references on java 6
- make java 8 code run on android
- transform compiled bytecode for legacy java runtimes
- backport try-with-resources to java 5

## When to choose
- you must target old Java 5-7 runtimes but want modern Java 8 syntax
- you maintain legacy Android projects without built-in Java 8 desugaring
- you need zero runtime dependencies after transformation

## When to avoid
- you target Java 8+ runtimes where lambdas work natively
- you use Android Studio, which has built-in Java 8 support
- you need backported Java 8 APIs like streams or java.time (use streamsupport or ThreeTen instead)

## Facets
- artifact type: library
- maturity: maintenance
- function: compiler, build-tool, developer-tools
- domain: programming-languages, compilers, developer-tools, mobile-development
- platform: jvm, cli
- tags: bytecode-transformation, java-8-backport, lambdas, maven-plugin, gradle-plugin, android

## Member repositories
- luontola/retrolambda (main) score 32

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:07.785571+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 2026-08-29T18:35:36.271575+00:00, confidence not recorded.
  - readme: https://github.com/luontola/retrolambda (fetched 2026-08-28T04:08:07.785571+00:00, sha 93125d5c3df6)
- Data as of 2026-08-30T08:39:29.467469+00:00.