What is the difference between JVM and JRE

hello everyone,
a funny but really confusing question is that how a virtual machine is different from a runtime environment.
some may argue that RE contains the API classes and implementations etc. but i need some real picture of what is the actual difference and anything related to this topic.
thanks,
waiting for your responses :-)

The Java Virtual Machine forms part of a large system, the Java Runtime Environment. Each operating system and CPU architecture requires a different JRE.
The JRE comprises a set of base classes, which are an implementation of the base Java API, as well as a JVM.

Similar Messages

What is the difference between JVM and JRE and JDK?

Hi , I want to know what actually is JVM,JRE and JDK ? and the difference between them?

They should at least try. When it comes to
terminology, if they can find this site, they should
be able to find google, wikipedia, etc. It's
reasonable to expect them to try there first, and
then, if they still have questions, post here,
indicating what they looked at and how it fell short,
what they're still confused about, etc.Perhaps this is a valid point.
I believe physical JVM hardware has also been
manufactured. I wonder what we'd call that? A JPM
(Java Pysical Machine)?No. It is simply a hardware implementation of the abstract Java Virtual Machine.
.class files are executed by software (in fact,the
software that executes the .class files is calledthe
JRE and is short for the Java
Runtime Environment). The JavaRuntime
Environment is a native program (i.e. it is run by
hardware) which provides the ability to executejava
bytecodes (.class files)That's the JVM.No it's not. The JVM is an abstract architecture.
The JRE is the JVM plus native libraries plus core
API Java classes.The JRE is an implementation of the JVM along with some additional facilities. The JVM may be used to describe concrete implementations in industry vernacular, but this is not a technically accurate usage of the term per the specification and is therefore incorrect.
From the preface to the Java Virtual Machine Specification, Second Edition, viewable at http://java.sun.com/docs/books/jvms/second_edition/html/Preface.doc.html:
"The Java virtual machine is an abstract machine."
From Wikipedia (http://en.wikipedia.org/wiki/JVM):
"A Java Virtual Machine (JVM) is a set of computer software programs and data structures which implements a specific virtual machine model."
Perhaps this misconception is the source of the confusion. This is one reason why I answered deepakorsun rather than refer him to somewhere else: anywhere that would be reliable and/or completely accurate would be too dense to readily understand, and anywhere understood easily enough might not be completely accurate.
>
The Java Development Kit (JDK) just provides the
facilities necessary to write programs that willrun
on the Java Virtual Machine. It contains acompiler
It also contains tools such as jar and javap, the API
docs for the core API classes, the source code for
the API classes, probably a few other things, and
generally the JRE (though I'm not sure if that's
officially a required part of the JDK).I never said it didn't contain jar, javap, javac, java, jdb, jconsole, or any of the other programs or resources shipped with jdk. I simply stated affirmatively something it did contain. As I implied before, technical comprehensiveness is exactly what makes resources such as the JVM specification almost unusable for answering questions like this. That is why I omitted such details in my description. And since we're being all technical here, the API documentation does not ship with the Java Development Kit (at least not as of JDK 5.0), it is a separate download. It is the core API source files that ship in a .zip file with the JDK.
Don't get me wrong, I do understand that you have probably seen a lot more people come and go from these forums than I may ever understand and that you have helped more people than you can remember, and I don't mean to disrespect that. I understand that dealing with so many people over such a long period of time and hearing the same questions over and over again can probably start to wear on your patience, but I don't think the right approach is to treat anyone that tries to help them with utter contempt and sarcasm. That's not constructive or useful to anyone. I understand why you would be upset if somebody was purposely trying to be lazy, I probably would be too, but you have no real way of determining whether or not they are being lazy or just don't know something and don't know how to figure it out for themselves so they are asking a question. And if they are honestly just asking a question in good faith and looking up the answer on Wikipedia just did not occur to them (or they couldn't understand what it said), yet they somehow ended up on this site, they have done nothing wrong and there is no reason to get angry at them.
Oh come on, that wasn't nice. Not everybody isable
to answer their own questions. WTF are you talking about?!? Why waste the time to
type something out when they can click on a link and
find 1000 times more information than you can fit
into one post? Either way - they're
STILL going to have to read the
information themselves...
Ridiculous.So I suppose you've either read the Java Virtual Machine Specification, the Java Language Specification, and the Java Native Interface Specification in their entireties, or absolutely nothing about programming in Java. This is because, by your reasoning, these three books contain 1000 times more than anyone can fit on a tutorial, Wikipedia entry, mailing list, forum, blog, or anything else.
Criticizing somebody who isn't doing something the exact way you think it should be done is often quite idiotic and non-constructive. I believe this is this case here. Please post something more useful, meaningful, and/or polite next time. And just for future reference, yelling at a beginner does not help them learn faster or better. It just makes them hate you.
Oh come on, that wasn't nice. Not everybody isable
to answer their own questions. Java terminologycan
be confusing and difficult to understand in part
because of all the acronyms used and all the name
changes undergone by the various development kitsand
platforms.Point taken. You have much more patience than
I, but with lots of intensive therapy and proper
adjustment of my medications, I may get better.Thank you for this post. A display of wisdom and patience. You single handedly caused me to reconsider participating in a flame war.

What is the difference between jdk and jre

what is the difference between jdk and jre
plzz tell me in detail

It's an extremely important skill to learn how to search the web. Not only will it increase your research and development talents, it will also save you from asking questions that have already been answered numerous times before. By doing a little research before you ask a question, you'll show that you're willing to work and learn without needing to have your hand held the entire time; a quality that is seemingly rare but much appreciated by the volunteers who are willing to help you.
If you've done the research, found nothing useful, and decide to post your question, it's a great idea to tell us that you've already searched (and what methodologies you used to do your research). That way, we don't refer you back to something you've already seen.
To get you started, here is an excellent resource: The Java� Glossary

What is the difference between ojvm and client versions?

Changing the java vm from client to ojvm result in the following error:
Errormessage:
java.lang.UnsatisfiedLinkError: no UniqueC in java.library.path
Project Settings -> Configurations -> Development -> Runner -> Virtual Machine -> ojvm FAILS
Project Settings -> Configurations -> Development -> Runner -> Virtual Machine -> ojvm      RUNS OK.
Project Settings -> Configurations -> Development ->Paths ->Additional Classpath:
C:\jars\xerces.jar;C:\jars\UniqueC.dll;C:\jars\log4j-1.2.8.jar
What is the difference between ojvm and client versions? How can I make ojvm to find UniqueC.dll?
Various version info:
Output from program:
java version:1.4.2_01
java home:C:\programfiler\JAVA\2sdk1.4.2_01\jre
java vm version:9.0.3.738 cdov
Taken from JDeveloper Help About:
Oracle IDE     9.0.3.10.35
UML Modelers Version     9.0.3.9.4
Business Components Version     9.0.3.10.7
java.version     1.3.1_02
java.vm.name     OJVM Client VM
java.vm.version     9.0.3.738 o

However, Adobe offers extra paid services to create PDF or to export PDF to other formats. You are not required to buy them, however.

Whatz the difference between jdk and jre

i would like to know the difference between jdk and jre.

Yes JRE is Java Run Time Environment. The java programming language adds the portability by converting the source code to byte code version which can be interpreted by the JRE and gets converted to the platform specific executable ones. Thus for different platforms one has corresponding implementation of JRE. But JRE has to meet the specification JVM (Java Virtual Machine) Concept that serves as a link between the Java libraries and the platform specific implementation of JRE. Thus JVM helps in the abstraction of inner implementation from the programmers who make use of libraries for their programmes.
The JDK(Java Developmental Tool kit) comes along with java libraries and JVM embedded in it. Apart from these it comes along with the utility tools for byte code compilation "javac", Executing the byte codes through java programmes through "java" and many more utilities found in the binary directory of java. Speaking practically JDK is essential for developers, which comes along with library packages to develop Software programmes. While JRE is minimal set of programmes which executes the java class files developed by the software developers.

What is the difference between #variable_name and :variable_name?

Hi!
What is the difference between #variable_name and :variable_name?
I have found that if we use alphanumeric variable then :variable_name return value in quotes but #variable_name without quotes.
Why it does not work in the same way for variable default values when variable is used in filter? (It works in mapping)
I use variable in filter like T.OUT_DATE>convert(datetime,:LAST_UPDATE_DATE,121)
When I use my variable in package and do refresh it works fine. But when I try to execute the same interface with variable default value I get error. Seems that variable name has been not changed to the value. It does not work with default value in quotes neither without quotes.
Any ideas how to solve that?
Thank you in advance!
Edited by: user13278245 on Sep 15, 2010 4:34 AM

Question is how to make it work with default value, when I execute interface standalone, not in package? And why it works in mapping but not in filter?
+ I have found that it works if source is Oracle. It doesn't work only for MS SQL source.
Edited by: user13278245 on Sep 15, 2010 6:43 AM

What is the difference between start() and run()

Hi:
what is the difference between start() and the run()???
in my app, i have
Console.debug( "starting thread to listen for clients" );
_server = new Server( this );
_server.start();
_server extends Thread..
why everytime i use server.start(); my app will terminate on it is own, even though in my servr.run() method, i have a while loop
and if i call _server.run() explicitly in my code, that while loop will be in execution
can someone let me know??
thnx

what is the difference between start() and the
run()???start() is a method on Thread that tells it to start.
run() is a method in the object that the thread executes.
why everytime i use _server.start(); my app will
terminate on it is own, Err.... I'm not convinced this is true. It'll throw an IllegalThreadStateException, if you try to restart an existing thread.
If that's what you're saying.
even though in my _servr.run()
method, i have a while loopI don't see the connection. Are you saying that the while loop never terminates, and you don't see why the thread is terminating?
and if i call _server.run() explicitly in my code,
that while loop will be in executionIf you call server.run() explicitly, then run() will be executed in the same thread that you called it in.

What is the difference between exists and in

hi all
if i have these queries
1- select ename from emp where ename in ( select ename from emp where empno=10)
and
2- select ename from emp where exists ( select ename from emp where empno=10)
what is the difference between exists and in is that only when i use in i have to bring the field name or what.... i mean in a complex SQL queries is it will give the same answer
Thanks

You get two entirely different result sets that may be the same. Haah! What do I mean by that.
SQL> select table_name from user_tables;
TABLE_NAME
BAR
FOO
2 rows selected.
SQL> select table_name from user_tables where table_name in (select table_name from user_tables where table_name = 'FOO');
TABLE_NAME
FOO
1 row selected.
SQL> select table_name from user_tables where exists(select table_name from user_tables where table_name = 'FOO');
TABLE_NAME
BAR
FOO
2 rows selected.So, why is this? the WHERE EXISTS means 'if the next is true', much like where 1=1 being always true and 1=2 being always false. In this case, where exists could be TRUE or FALSE, depending on the subquery.
WHERE EXISTS can be useful for something like testing if we have data, without actually having to return columns.
So, if you want to see if an employee exists you might say
SELECT 1 FROM DUAL WHERE EXISTS( select * from emp where empid = 10);
If there is a row in emp for empid=10, then you get back 1 from dual;
This is what I call an 'optimistic' lookup because the WHERE EXISTS ends as soon as there is a hit. It does not care how many - only that at least one exists. It is optimistic because it will continue processing the table lookup until either it hits or reaches the end of the table - for a non-indexed query.

1)Now I use Lightrom 5.7 how to upgrade to 6 or CC? 2) What is the difference between 6 and CC vercion? 3) When I used lightromm 3, I could see inEXIF the distance in meters till the object I took, in the later virsions that function disappeared, it is ve

1)Now I use Lightrom 5.7 how to upgrade to 6 or CC?
2) What is the difference between 6 and CC version?
3) When I used lightromm 3, I could see in EXIF the distance in meters till the object I took, in the later virsions that function disappeared, it is very sad I am stiil waiting and hope that it would be possibble in the new versions. Or this indication may possible by setting?

1)Now I use Lightrom 5.7 how to upgrade to 6 or CC?
Purchase the standalone upgrade from here: Products
Download CC version from here: Explore Adobe desktop apps | Adobe Creative Cloud
2) What is the difference between 6 and CC version?
See this comparison chart: Compare Lightroom versions | Adobe Photoshop Lightroom CC
3) When I used lightromm 3, I could see in EXIF the distance in meters till the object I took, in the later virsions that function disappeared, it is very sad I am stiil waiting and hope that it would be possibble in the new versions. Or this indication may possible by setting?
Rob Cole's ExifMeta plugin displays the Subject Distance field (and much more). Unfortunately, his Web site appears to be down again. He used to be very active here, but he hasn't posted in several months.

What's the difference between thunderbolt and mini displayport?

I'm trying to connect my Macbook with a monitor and I'm thinking of what cable to get. I will have to connect using a (Thunderbolt to HDMI cable) or a (mini displayport to HDMI cable).
I was wondering what's the difference between Thunderbolt and mini displayport
Thanks

@bontistic: it is not true that only the Macbook Air supports Thunderbolt. All models(!) support thunderbolt: also the Macbook Pro's and Mini's. Eg.: http://www.apple.com/nl/macbookpro/features.html#thunderbolt
My Macbook Pro from 2011 already supported Thunderbolt...

What is the difference between, DSO and DTP in BI 7.0

Hi Guru's
what is the difference between, DSO and DTP in BI 7.0 , how it will come the data from r/3 to BI 7.0, can u discribe?
points will be assined?
Thanks & Regards,
Reddy.

Hi,
The data will be replicated in the same way as we do in 3.5.
Activating, and Transporting the same DS in BW, and Replicating them in BW from R/3.
First you need to know Diff b/w 3.5 nd 7.0, for that check the below doc's:
http://help.sap.com/saphelp_nw04s/helpdata/en/a4/1be541f321c717e10000000a155106/content.htm
blogs:
/people/sap.user72/blog/2004/11/01/sap-bi-versus-sap-bw-what146s-in-a-name
Re: How to identify Header, Item and Schedule item level data sources?
For Transformations in BI:
http://help.sap.com/saphelp_nw70/helpdata/en/33/045741c0c28447e10000000a1550b0/frameset.htm
http://help.sap.com/saphelp_nw70/helpdata/en/f8/7913426e48db2ce10000000a1550b0/frameset.htm
http://help.sap.com/saphelp_nw70/helpdata/en/a9/497f42d540d665e10000000a155106/frameset.htm
For DTP:
DTP:
http://help.sap.com/saphelp_nw70/helpdata/en/20/a894ed07e75648ba5cf7c876430589/frameset.htm
For DSO:
Data Store Objects:
http://help.sap.com/saphelp_nw70/helpdata/en/f9/45503c242b4a67e10000000a114084/frameset.htm
Reg
Pra

What is the difference between TO_CHAR and TO_DATE()?

Hi everybody,
i am facing a problem in my system.It is quite urgent, can you explain me "What is the difference between TO_CHAR and TO_DATE()?".
According to user's requirement, they need to generate a code with format "YYMRRR".
YY = year of current year
M = month of current month (IF M >=10 'A' ,M >=11 'B' , M >=10 'C')
RRR = sequence number
Example: we have table USER(USER_ID , USER_NAME , USER_CODE)
EX: SYSDATE = "05-29-2012" MM-DD-YYYY
IF 10
ROW USER_ID , USER_NAME , USER_CODE
1- UID01 , AAAAA , 125001
2- UID02 , AAAAA , 125002
10- UID010 , AAAAA , 12A010
This is the original Script code. But This script runs very well at my Local. Right format. But it just happens wrong format on production.
12A010 (Right) => 11C010 (Wrong).
SELECT TO_CHAR(SYSDATE, 'YY') || DECODE( TO_CHAR(SYSDATE, 'MM'),'01','1', '02','2', '03','3', '04','4', '05','5', '06','6', '07','7', '08','8','09','9', '10','A', '11','B', '12','C') ||     NVL(SUBSTR(MAX(USER_CODE), 4, 3), '000') USER_CODE FROM TVC_VSL_SCH
     WHERE TO_CHAR(SYSDATE,'YY') = SUBSTR(USER_CODE,0,2)
     AND TO_CHAR(SYSDATE,'MM') = DECODE(SUBSTR(USER_CODE,3,1),'1','01',
          '2','02', '3','03', '4','04', '5','05',
          '6','06', '7','07', '8','08', '9','09',
          'A','10', 'B','11', 'C','12')
I want to know "What is the difference between TO_CHAR and TO_DATE()?".

try to use following select
with t as
(select TO_CHAR(SYSDATE, 'YY') ||
         DECODE(TO_CHAR(SYSDATE, 'MM'),
                '01', '1',
                '02', '2',
                '03', '3',
                '04', '4',
                '05', '5',
                '06', '6',
                '07', '7',
                '08', '8',
                '09', '9',
                '10', 'A',
                '11', 'B',
                '12', 'C') as code
    from dual)
SELECT t.code || NVL(SUBSTR(MAX(USER_CODE), 4, 3), '000') USER_CODE
FROM TVC_VSL_SCH
WHERE SUBSTR(USER_CODE, 1, 3) = t.codeand yes you need check time on your prodaction server
good luck
Edited by: Galbarad on May 29, 2012 3:56 AM

What is the difference between upgradation and migration.

Hi Guru's
what is the difference between upgradation and migration.
actuallly i involved in upgradation project, here my role is
1. first i check the query's in 3.5 save the query and transport the query. and check the query in bex analyzer also.
2. go to BI .7 find the query;s ,give the query name and save the query ,
3. once save the query, again will come to 3.5 open the query , it will not open. this is my job here,
come to 7.0 check the query in analyzer also.
i am having littile bit confusion, how it will comes query in 7.0, why are u saving the query's in 3.5 and 7.0
query's already available in 7.0 why are u doing this work?
can i know the upgrades those objects, is it neccessary, if necessary how can i upgrade.
infoobje , transferrules, transferstructure ,infosoure, datasoure,updaterules, ods, cubes.
Points will be Assingned ,
Thanks & Regards
prabhavathi

Hi,
I was talking in a general sense not on a query level.
If your taling about migration in that level meaning as a part of larger upgradation (in your case 3.x to 7) there may be many places where you need to do this kind of activities.
Fr eg migration into new data flow, Migration of Web templates from BW 3.x to Netweaver 2004s, etc
Hope this helps.
Thanks,
JituK

What is the difference between ws_upload and gui_upload

what is the difference between ws_upload and gui_upload
what is the difference between ws_download and gui_down load
pls tell briefly

Hi Kuamr,
UPLOAD and DOWNLOAD, the function modules used until now are not part of the standard set of ABAP commands. They are used to display the file interface on the presentation server. UPLOAD and DOWNLOAD are not compatible with USs and have been replaced by GUI_UPLOAD and GUI_DOWNLOAD.
The new function modules, GUI_UPLOAD and GUI_DOWNLOAD, have an interface that also allows you to write Unicode format to the local hard drive. For a description of these interfaces, refer to the documentation for each function module, available under SAP Easy Access " Development " Function Builder " Goto " Documentation.
Instead of using the function modules, you can use the static methods GUI_UPLOAD and GUI_DOWNLOAD of the global class CL_GUI_FRONTEND_SERVICES.
Hope this resolves your query.
Reward all the helpful answers.
Regards

What is the difference between count(*) and count(1)

what is the difference between count(*) and count(1)

Hi,
903830 wrote:
some say count(1) is faster and some say count(*), i am confused about count function?In the link provided by Prakash :
prakash wrote:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1156159920245
You can read :
Followup August 31, 2001 :
I'll have to guess, since you don't say, that you are using 7.x and before when count(*) and count(1) were different (and count(1) was slower). In all releases of the databases for the last 4-5 years, they are the same.
Don't waste your time on that.
;-)

What is the difference between JVM and JRE

Similar Messages

Maybe you are looking for