Java backporting tools explained

Java backporting tools are programs (usually written in Java) that convert Java classes bytecodes from one version of the Java Platform to an older one (for example Java 5.0 backported to 1.4).

Java backporting tools comparison

Main information

The JVM has evolved a lot for the past years. However, most language features that were added are simply a syntactic sugar. They do not require new byte-code, hence can be compiled to the Java 8. But, since the Java language was always bound to the JVM development, new language features require the same target as the JVM because they get released all together.^[1]


	Source version	Target version	Last release	License	Website
Retrolambda	Java 8	Java 7, 6, 5	2015-12-19, 2.1.0	Apache License 2.0	https://github.com/orfjackal/retrolambda
Retrotranslator	Java 5		2009-08-09, 1.2.9	BSD-like	https://retrotranslator.sourceforge.net/
Retroweaver	Java 5		2008-10-14, 2.0.7	BSD-like	https://retroweaver.sourceforge.net/
Declawer	Java 5	Java 1.4	2007-11-14	LGPL or MPL	https://www.glazedlists.com/Home/declawer
JBossRetro	Java 5	Java 1.4	2008-03-10, 1.1.2	LGPL	https://www.jboss.org/community/docs/DOC-10738
Jabel	Java 9–14	Java 1.8	2021-10-20, 0.4.2	Apache License 2.0	https://github.com/bsideup/jabel

Features

	lambda expressions	default methods	generics	enhanced for loops	annotations	autoboxing and unboxing	static imports	varargs	enumerations	reflection on generics and annotations	covariant return types
Retrolambda
Retrotranslator
Retroweaver
Declawer
JBossRetro

	concurrency utilities	API support for JDK 1.4	API support for JDK 1.3	API support for older release
Retrolambda
Retrotranslator	^[2]	extensive	limited	none
Retroweaver
Declawer
JBossRetro

References

Web site: Jabel – use modern Java 9–14 syntax when targeting Java 8 . . 17 June 2022 .
It uses the backport of the Java 5.0 concurrency utilities.

External links

How to use Java 5 language features in earlier JDKs