Very interesting to see JPL's coding standards for java. Some obvious requirements: Everything must be compiled with the highest level of warning output, and there must be no warnings or errors; similarly, code must be checked with the most verbose static analysis settings, and there must be no warnings or errors there, either.

Here's one I like: "A nonfinal method should not be called from within a constructor." Rationale: "If such a non-final, non-private method is called in the constructor of the superclass, the call will get dispatched to the sub class, which has not yet been initialized because classes are initialized top down from superclass to sub class, resulting in unpredictable behavior due to access to uninitialized state."

Rehosted from: http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_Java.pdf due to that link being down for a while.