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Sun Java 6 hotspot JVM
Apple Supplied JVM 1.6
the Iced Tea JVM
Apple Supplied JVM 1.5
Related
I read a few posts about JVM at Stack Overflow and would like to download a binary copy of the Hotspot JVM, yet I am not able to find it on http://www.java.net.
Beside that, what is the difference between Hotspot JVM and JVMs found at Oracle
Is Oracle JVM good for a production website?
Overview:
This SO question may clear up your questions regarding "What is JVM, Hotspot and OpenJDK".
Basically:
JVM means Java Virtual Machine. The JVM is the underlying runtime that executes java bytecode. There are multiple different implementations out there, all implementing the Java Virtual Machine Specification
HotSpot is the most used implementation of the JVM concept. It is used in both, Oracle JDK and OpenJDK. Oracle's JDK can be downloaded on oracle's website, currently http://www.oracle.com/technetwork/java/javase/downloads/index.html. This is "the typical JVM you will find on a normal user's windows machine".
OpenJDK is the open source project maintaining and impelmenting the HotSpot JVM, but also many other projects beside the JVM such as Graal or VisualVM. On Ubuntu for example you can install this OpenJDK (current version 8) by running sudo apt-get install openjdk8.
Conclusion:
While this explaination is not really perfect, it may be good enough to understand that there is no big difference between Oracle JDK and OpenJDK. If you are interested in a little more info on this, have a look at the SO question Differences between Oracle JDK and Open JDK
JDK / JVM sourcecode:
If you are interested in the source code, OpenJDK is the way to go. Here you can find the current OpenJDK 8 (which includes the HotSpot JVM). Its source code can be found here. It also states how to download the source code:
The jdk8u-dev forest for ongoing development can be cloned using this command: hg clone http://hg.openjdk.java.net/jdk8u/jdk8u-dev;cd jdk8u-dev;sh get_source.sh .
The corresponding master forest jdk8u can be cloned using this command: hg clone http://hg.openjdk.java.net/jdk8u/jdk8u;cd jdk8u;sh get_source.sh .
In addition, the source code for the last release, 8u66, is available by cloning the 8u master forest : http://hg.openjdk.java.net/jdk8u/jdk8u and using the 'jdk8u66-b17' mercurial tag.
There are many articles/webpages stating that JRockit will be merged into new version of JVM or JDK 8:
https://en.wikipedia.org/wiki/JRockit
http://www.mythics.com/about/blog/answers-to-common-questions-on-java-versions-editions
Where to download JRockit for Java 7?
But I cannot find any articles/webpages stating that JRockit is really merged into JDK 8. Is there are any updated news for that? Or there is only part of the features of JRockit is implemented in JDK 8 so that the real-time performance of JDK 8 is not as good as JRockit? Thanks!
From JDK 7 itself, JRockit and HotSpot has been merged into single JVM, incorporating the best features from both.
https://blogs.oracle.com/henrik/entry/oracles_jvm_strategy
I understand that the Oracle Java SE contains closed source extensions and tools that are not part of the OpenJDK however is the Oracle Java SE JVM identical to the OpenJDK JVM or does Oracle make changes to the OpenJDK JVM before releasing it as a Java SE JVM?
Update 1:
I found some info from the JDK7 updates projects: http://openjdk.java.net/projects/jdk7u/qanda.html
Will the 7 Update Project receive security fixes from Oracle?
Yes.
As with OpenJDK 6, security fixes are first kept confidential and applied to a private forest before being pushed to the public forest as part of the general synchronized publication of the fix to effected JDK release trains. In addition, they will not go through the public code review and putback approval process, and their corresponding issues in the Project's issue tracker will not be publicly visible.
OpenJDK is the reference implementation of Java as of version 7.
OpenJDK 7 is the starting point for the version that Oracle distributes as Oracle JDK. Other vendors (e.g. RedHat for IcedTea) may also use OpenJDK as their starting point.
In terms of the differences between OpenJDK and a vendor VM, there may be patches which a vendor wants to apply but which the overall OpenJDK community has not accepted into mainline.
Vendor VMs must, of course, be able to prove that they are in conformance with the TCK if they want to use the Java trademarks to describe their product.
Oracle JDK is also not open-source. This is possible because of Java's dual licensing arrangements, and the fact that Oracle own Java overall.
Do you have more specific questions - as posed, your question is a bit vague. What specific aspects are you interested in?
As i know java programs are able to run on any Operating System.
and there are JVM's for any kind of machines.
I need a JVM that runs on my PC stand alone, and not on my OS (windows or any thing else).
I mean a JVM that acts like a boot, instead of the OS boot
i searched for all versions of JVM on "www.java.com/en/download/manual.jsp", but i did not get the suitable JVM.
the following link helped me a little but that was not enough
http://java-virtual-machine.net/other.html#jvm
my PC CPU is AMD Athlon(tm) 64X2 Dual Core Processor 5200 + 2.69 GHz
any body can help me to find the suitable jvm version ?!
Sure, have a look at JRockit Virtual Edition. As I understand it it's basically a micro kernel especially tailored for the JRockit VM.
From this page:
Java without the OS: JRockit Virtual Edition (VE)
Am I the only one that's never heard of this before? The Oracle JRockit team is looking at eliminating the OS from the stack required to run Java. This product will be called JRockit VE (not out yet)
JavaOS
Good lucking getting hold of it, though, it's nothing more than a historical curiosity.
There are two JVMs that I am aware of, which have this property:
The Fiji WM: http://www.fiji-systems.com/index.html
According to http://rtjava.blogspot.com/2009/11/new-real-time-vm-was-born-fiji-vm.html it also runs on bare metal.
The next possibility is JNode: an open source operating system where most parts are written in Java (the rest in assembly): http://www.jnode.org/
JNode is still beta, though.
No.
There was an idea of making a machine that could run a JVM as an actual machine (non virtualized), similiar to LISP machines, but that idea never took off...
You need a host OS to run a JVM.
Googling "java real machine" might give you some interesting articles.
I've found two: one from 2004, talking about how such a machine could be built and another one, talking about how JVM runs as a real machine on hardware such as mobile devices.
Still, no dice with a plain PC.
I'm looking at developing an application that takes advantage of the Pulse smart pen.
I would rather do it in python than java. Its not clear what version of the jvm runs on the pen, as evidence here in the tech specs
Are there limitations on whether or not jython and jruby will run on mobile version of the jvm?
The Livescribe Java API is based on Java ME; Jython and JRuby require a lot of functionality that isn't in Java ME. Also, I can't imagine the pen would have enough free RAM to run either.
Maybe in a few years.