File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
The moose likes Beginning Java and the fly likes A question about JIT(just-in-time) Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "A question about JIT(just-in-time)" Watch "A question about JIT(just-in-time)" New topic

A question about JIT(just-in-time)

Michael Keisu
Ranch Hand

Joined: Oct 08, 2009
Posts: 30
So I am taking notes in order to better learn Java, however I have come across something which confused me a bit(JIT). I'm not sure if it is a beginner subject exactly as the book
I used for the Java course I took didn't mention it, but another one I'm on did, and this is how I interpreted it, in my own words:

When running a program the Java Virtual Machine interprets java bytecode in combination with using the just-in-time compiler to translate
the heavy/frequently used instructions/java bytecode into machine code at runtime, to achieve better speed. In the early Java days,
when JIT didn't exist, Java programs ran more slowly. Of course, that also had to do with computers being slower.

So I'm basically asking if I got it right? What more is there to it? I would like to learn all the details

thanks in advance.
Ulf Dittmer

Joined: Mar 22, 2005
Posts: 42965
Welcome to JavaRanch.

Basically, your interpretation is correct. JITs have improved a LOT since they first appeared, though, so that's another factor of the speedup. Search for "HotSpot" to find information about Sun's runtime environment and JIT.
Michael Keisu
Ranch Hand

Joined: Oct 08, 2009
Posts: 30
Thank you

I think I got pointed in the right direciton
this is what I found ->
I believe that's the latest on the subject
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 46378
No, that page is over 6 years old. Try here for something more recent.
I agree. Here's the link:
subject: A question about JIT(just-in-time)
It's not a secret anymore!