We generally try to stick to the official Sun Java Coding Conventions. In addition to that, we apply points number 3, 4 and 5 of the conventions outlined by the Jakarta Turbine project.
The JaxoDraw source code is regularly formatted with jalopy (use the command line:
jalopy -c jalopy-conf.xml PATH_TO_SOURCE_FILES/*.java
with this configuration file), and should be checked with checkstyle (command line:
checkstyle -c checkstyle.xml -o checkstyle.out PATH_TO_SOURCE_FILES/*.java
use this configuration file and this header).
As the Simian report shows, there is quite an awful amount of duplicate code in some files, in particular in the OptionPanels and some Object files (Lines, Arcs, Loops). This should be cleaned up and simplified. For the OptionPanels we should have a hierarchical structure like for objects (OptionPanel - ArcOptionPanel - FArcOptionPanel, etc.).
Another thing to consider is the length of some methods and files (see the checkstyle report). In particular, the JaxoCanvas file is too large, it is difficult to navigate and understand, hence to maintain and debug.