Presumably, a design flaw; in any case, one of the reasons many scientists do not program their computations in Java.
Read: http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf and related papers from the same site.
As a bonus, the linked paper serves as a great example of how not to argue a case, namely by pouring endless, hyperbolic invective on the subject of your critique in a bizarrely formated screed that looks like a print-out of a Wiki page.
The same kind of design decisions are also present in C/C++ compilers (the Microsoft ones) and probably many other languages.