Question

I do not see gij listed as one of the Java Virtual Machines on http://en.wikipedia.org/wiki/List_of_Java_virtual_machines and I have not found posts here talking about this either. Can anyone tell me whether gij is a JVM and if not, explain what’s the missing in gij or what’s the difference? Thanks.

Answer 1

From The Java Virtual Machine Specification:

However, the Java virtual machine does
not assume any particular
implementation technology, host
hardware, or host operating system. It
is not inherently interpreted, but can
just as well be implemented by
compiling its instruction set to that
of a silicon CPU. It may also be
implemented in microcode or directly
in silicon.

So GCJ can rightfully be called a Java Virtual Machine and GIJ, since it is an interpreter, even more so. The only requirement of a JVM is that it executes Java byte code.

If you look more closely at the Wikipedia page, you see GCJ in the bottom box listed in “Foundation and major implementations” of Java Virtual Machines.