Take  a look at

http://java.sun.com/docs/books/vmspec/2nd-edition/html/VMSpecTOC.doc.html

start with
http://java.sun.com/docs/books/vmspec/2nd-edition/html/Overview.doc.html#1963

and move on to

http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#1513

and
http://java.sun.com/docs/books/vmspec/2nd-edition/html/Compiling.doc.html#14787

Jim

It's implementation dependent (actually it's implementation dependent in C++
too).  The only way you can find out is to read the source for the /particular/
JVM implementation you are interested in.

In point of fact, and as far as I can tell, Sun's current range of JVMs use a
small inline cache at the point-of-call (a type-test and unconditional jump if
the test passes) with a fallback to the horrendously inefficient vtable-based
dispatch if that fails.  (That's for optimised code, I have no idea how "eager"
the implementation is to use that optimisation).

Static method dispatch (invokestatic), interface method dispatch
(invokeinterface), and invocation of private methods and super-sends can be,
and have to be, handled differently.

   -- chris