Chapter 1. Java Compatibility

jEdit 4.2 runs on Java 1.3 or later, but jEdit 4.3 requires Sun Java 1.5.0 or later. Older versions of Java are not supported.

If you want to use the new LCD Antialiasing feature of Java 1.6, it is supported. From Global Options - Text Area - Antialiased Smooth Text: select Subpixel, and un-check the Fractional Font Metrics checkbox.