Swixml.org says that 2.2.0 requires java 1.6, but is compiled with target 1.7

[thiagokronig]

Excert from swixml.org:

Version 2.2 Build 220 of the SwiXml library (incl. Java source code as well as TAG and API documentation.) Requires Java 6.0 or later and supports JGoodie FormLayout.

build.xml from http://www.swixml.org/swixml_220.zip defines:
<property name="ant.build.javac.target" value="1.7"/>

[jlpoolen]

I had the same problem, fortunately I just changed the value="1.6" (verified Ant was running under 1.6 and had to reset Eclipse default to 1.6) and successfully built the project. Until I did that, I was getting that incompatible version error 51.