I am researching large file support for Java. I need to know what the largest file that a 32-bit and 64-bit JRE(1.5) can handle. I would think it would be 2GB for a 32-bit JRE and 2^64 for a 64-bit JRE. I understand that the OS must have alot of memory to keep up with the JRE, which is not a problem. But should a 64-bit JRE be able to handle files in the >10 GB range?
I don't think memory availability has anything to do with it. Your question seems to be more about how large a file can a particular operating system handle. And that question really has nothing to do with the number of bits in a typical number, but more to do with the design of the low-level APIs for handling files in that operating system.
However, the File class has a length() method that returns a long value, which cannot exceed 2^63-1. So files larger than that many bytes would not be handled correctly by Java regardless of the underlying operating system.