Java backporting tools
# Java backporting tools

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.

| | 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 | http://retrotranslator.sourceforge.net/ |
| Retroweaver | Java 5 | | 2008-10-14, 2.0.7 | BSD-like | http://retroweaver.sourceforge.net/ |
| Declawer | Java 5 | Java 1.4 | 2007-11-14 | LGPL or MPL | http://www.glazedlists.com/Home/declawer |
| JBossRetro | Java 5 | Java 1.4 | 2008-03-10, 1.1.2 | LGPL | http://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 | Yes | Yes |
| Retrotranslator | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Retroweaver | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | No | No |
| Declawer | No | No | Yes |
| JBossRetro | No | No |
| | Formatted output | Formatted input | Collections framework enhancements | Concurrency utilities | emulate the Java 5.0 memory model | support for JDK1.6 File methods like canExecute | API support for JDK1.4 | API support for JDK1.3 | API support for older release |
| Retrolambda |
| Retrotranslator | Yes | No | Yes | Yes | No | No | extensive | limited | none |
| Retroweaver | No | No | No | No | No |
| Declawer |
| JBossRetro |
