The qcchart2djava and qcrtgraphjava libraries themselves are compatible with Java 1.4. Most all of the example program for the QCRTGraph utilize parametrized collections (Vector), because the use of un-parametrized collections now generates hundreds of warnings in current versions (last 3-4 years) of Eclipse. Parametrized collections are only supported under Java 1.5 and higher. The QCChart2D examples don't use collections and they should all compile and run OK.
Is this just an observation, or is there some reason you need to restrict yourself to Java 1.4?