JVM, J2SE & J2EE - Confused!

Hi,
I was reading specs somewhere on a java application. It says:
- Development: JDK� 1.3.1
- Deployment: JDK 1.1.8 or higher (JDK 1.3.1 recommended)
1) So does this mean that any J2SE 1.3.1 code you write will run on JDK 1.1.8 or above?
2) So could I code for J2SE 1.4 and have it run on basically any Application Server? (WebLogic, WebSphere, Oracle, etc.) ? Or do I have to decide between using J2SE 1.3 and J2SE 1.4 ?
I want to use J2SE 1.4 but am afraid that it might not run on some application servers.

any J2SE 1.3.1 code you write will run on JDK 1.1.8 or aboveOf course generally speaking not (though it might hold for some well-defined environment like a given IDE). That is generally not even true for 1.2; it has for example the soft/weak references, the collections, swing etc. that are incompatible with java 1.1; 1.3 has besides the Proxy etc.

Similar Messages

Design Patterns that are used in standard j2se/j2ee classes/interfaces

Hi All,
I am understanding following design patterns (used within standard j2se/j2ee):
Adapter
Facade
Composite
Bridge
Singleton
Observer
Mediator
Proxy
Chain of Responsibility
Flyweight
Builder
Factory Method
Abstract Factory
Prototype
Memento
Template Method
State
Strategy
Command
Interpreter
Decorator
Iterator
Visitor
I want to see if/where these design patterns are used in j2se/j2ee classes/interfaces. i am looking for few examples of standard java classes/interfaces/cases where these design patterns are used by jdk developers.
for e.g.
WindowAdapter class is an example of Adapter DP.
JOptionPane is an exmple of Facade DP.
MouseListener is an example of Observer DP.
Similarly, where can find examples of jdk classes/interfaces of the remaining DPs.
I searched a lot of books, but they explain the DPs by creating their own classes/interfaces.
I would like to see where these DPs are already utilised in std j2se/j2ee
thanks,
Madhu_1980

877316 wrote:
I searched a lot of books, but they explain the DPs by creating their own classes/interfaces.
I would like to see where these DPs are already utilised in std j2se/j2eeWell, you can go through the javadocs first, they sometimes mention the pattern used.
Then you can get the sources for the jdk and go through the classes yourself, identifying the patterns.

What are the diffrences among J2SE,J2EE, and J2ME ?

Could one explain me..what are these terms and terms like JDK,SDK and what are the diffrences and similarities.I have installed J2sdk1.4.1 in my computer.I have written some programs and run them.Applets too.What are the extra benifits that I can take if I install J2EE.In other words what are the things that J2SDK is lacking when compared to J2EE?
Please explain..I am quite new to java.
Regards..Saman

J2ME - Java 2, Micro Edition.
This is a specification, a developement platform for Java enable device, it is mostly for mobile devices,such as PDA, handphone.
J2SE - Java 2, Standard Edition
This is a specification, a developement platform for developing standard service, which is software. Such as graphic user interface, input output device, applet and more.
J2EE - Java 2 Enterprise Edition.
This is a specification, a developement platform for enterprise system, server side program. and examnple is Java Server Page, Java Servlet, Enterprise Java Bean and more.

Directory structure for a J2SE+J2EE project: suggestions are very welcome

Hi, I have to start coding and organizing the CVS tree of an already mature project which is J2SE. This J2SE project can be described as a "core engine" for something else, and is a quite large project, and up to now has only a command line User Interface. I organized the dir structure as this:
/build.xml
/src/
/src/java/<package>/...../*.java
/src/demo/<package/...../*.java
/src/test/<package>/....../*.java
when I ant compile, all the .classes will be done in the "build" directory (reflecting the structure in the "src" dir):
/build/
/build/java/<package>/....../*.class
/build/demo/<package/...../*.class
/build/test/<package>/..../*.class
I am happy with this, but now comes the issue: a web interface to use this core engine (it will have the same package namespace) is in developing progess, so I have to put somewhere the *.jsp, the WEB-INF dir with web.xml and servlet sources: how would you do this? And where would you let Ant put the compiled servlet classes?
I can modify the previous directory structure to accomodate the J2EE part, this is really not a problem!
Thanks to who can suggest me a clean solution
Alessio

Create a web-inf folder at the same level of src and
jsp folder inside src
i mean
/build.xml
/src/
/src/java/<package>/...../*.java
/src/demo/<package/...../*.java
/src/test/<package>/....../*.java
/src/jsp
/web-infSo, would you put in /src/jsp only the *.jsp?
And what in /WEB-INF ? What woud you put there? Would you do something like:
/WEB-INF/web.xml
/WEB-INF/src/<package>/..../<my_servlets_and_j2ee_stuff>.java
/WEB-INF/classes/<package>/..../<my_servlets_and_j2ee_stuff>.java
In this manner sources and classes are in the same tree, it does not seem very clean to me, expecially if you consider that probably I must have a "test" directory to unit test some j2ee stuff (as for the j2se stuff in "src"): how would you do that?
Is this directory structure anyway what you meant or not?
alessio

J2SE/J2EE

What's the difference between the Standard Edition and Enterprise Edition? Any advantages or disadvantages? I just wanna know which one I should download. Tnx!

What's the difference between the Standard Edition and
Enterprise Edition? Any advantages or disadvantages? I
just wanna know which one I should download. Tnx!Learn The Standard Edition First.
http://java.sun.com/j2se/
Learn This Later. It depends on the Standard Edition.
http://java.sun.com/j2ee/
(Yes, I need the Duke Dollars) ;)

J2EE confusion in EJB Docu example!

I installed the j2ee beta and following the track in the documentation to learn EJB. the sample works fine. But after observing the interfaces and EJB class, I got confused by the following facts:
1. the EJB class ConverterEJB does not 'implements' the remote interface Converter, although it does implement the two methods defined in that interface: dollarToYen() and yenToEuro()
Q: then who 'implements' Converter?
2. EJB Home ConvertEJB defines a single method create(),
Q: where is it implemented.
I can imagine sth between the EJB and its container must be doing sth, but it seems very foggy for me.
Can any expert clarify this a little bit?
thank you
Benjamin

Each session bean has a home interface, a remote interface and an implementation class.
In your case, that is probably ...
ConverterEJBHome is the home interface - it defines all the create() methods that can be used to establish the bean
ConvertEJBSession is the remote interface that defines all the methods on the bean that the client can call
ConverterEJBBean is the implementation class which contains all the create() methods and all the remote methods

Installing J2SE & J2EE

I'm running Apache Tomcat and J2SE to run JSP pages and from what I've read I need to also have J2EE installed to do certain "enterprise" things. Is this true and how do I install both to run on the same machine?

You need to have the j2ee.jar in your classpath. You can get it an Sun's download site.

Oracle 9iAS: J2SE, J2EE

Which version(s) of J2SE does 9iAS support: 1.1, 1.2, 1.3, 1.4?

See the FAQ on OTN (http://otn.oracle.com/products/ias/htdocs/9iasfaq902.html), Section 5.0 for details about J2EE 1.3 support.
Certification for J2EE 1.3 is currently underway and will be completed in a month or so. A preview release of OC4J stand alone is available at: http://otn.oracle.com/tech/java/oc4j/content_preview.html
Thanks,
Ashesh Parekh
Oracle9iAS Product Management

Linux, J2SE, J2EE

I have dowloaded both JDK Standard and Enterprise for Linux. I have installed them both successfully. Im having problems setting the paths. I do not have a /etc/profile file. What can I do to make everything work ok. Ive tried editing the .cshrc file, .bashrc file, all do not work. Im using Red Hat 7.1. If anyone has any suggestions, it would be very much appreciated.

You should have a /etc/profile.d directory. You may write the commands to a file in the directory, e.g.
<start of /etc/profile.d/javasetup.sh>
#!/bin/bash
export JAVA_HOME=/usr/java/whatever
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=.
<end of /etc/profile.d/javasetup.sh>
Then "source /etc/profile.d/javasetup.sh" and the environment should be set. When you next log in, you won't have to do the "source ..." command. That is only needed to apply the settings to the current environment.
Bhav

J2SE to J2EE

I'm considering a jump from J2SE to J2EE. My question is,
What are the main differences between the two?

"I have been using databases in some of my apps."
JDBC lies completely inside J2SE, J2EE does not add anything to it.
"I would like to add a servlet to my latest app."
If you are looking into using JSPs, Servlets, and the rest of J2EE to replace PHP server applications, then you are on the right track. If you just want to use a Servlet in a regular, desktop app, you are probably looking at it wrong (adding the necessary Servlet Container (web server) would be a huge footprint to the app, and prolly something that your users would not want on their computer...)
"...explain some of the advantages of using enterprise instead of the standard edition"
You don't use it instead of the standard edition, you use it on top of the standard edition. You use it to write web applications. That way, you have one centralized server that does the work. The user has versions of a client (a web browser or any client that can read the data you send... this could be a J2SE desktop app if you wanted...) that the user interacts with, and which in turn interacts with the server which does the work.
So J2EE is about layered control.
1) The client app displays info to the user and provides a means of interaction
2) The server stands as a listening device that sends messages to the correct part of the app and back to the user.
2) 1) The Servlets act as a control mechanism that runs the business logic (work)
2) 2) Other layers may handle data access and storage (databases, XML. EJBs?)
2) 3) Other layers may handle dispaly generation (JSPs) or return information (JMS)
The advantage is that your work is done in one place. Everyone who uses the app doesn't need to update everytime the application does. Every user doesn't need to have a DB on their computer. Users can communicate and share information more efficiently. At the same time no user gains access to someone else's data because the data storage and access is twice removed from the client...

Is my installaton of CF MX 7 using JVM or not?

I was recently directed to start using some "global logon"
software with my application on our company intranet. I don't know
if it is developed in-house or purchased.
When I talked to the person providing the software, he asked
if I was running "Windows and Coldfusion without JVM" or
"Coldfusion on Windows (using JVM)". I wrote it this way because
that is the way he asked it. Unfortunately, I didn't know the
answer to the question. That's not my expertise. We talked for a
while and he decided I needed his version for "without JVM".
I've been working with the software for a couple of weeks now
and it works, but only partially. It uses a cookie to provide
security information back to the application, then the application
is supposed to decrypt the cookie and get various pieces of info
about the user. I'm only getting a small part of the information.
I'm trying to get more information to determine if he sent me
the wrong version. How would I find out if I'm using JVM or not?
When I look in the CF Admin module at the "Java and JVM" tab, I see
the installation path for JVM is "E:/CFusionMX7/runtime/jre" and
some "JVM arguments" in a lower box. When I look in the "jre"
subdirectory, I find subdirectories for bin, lib, and javaws plus a
bunch of "License" files.
I'm out of ideas to "fix" the software so I'm wondering if
they sent the wrong one. Before you ask, I've already been on the
phone with the provider and the tech support people with no help
(obviously).
The server is running Windows server 2003, IIS, MySQL, and CF
MX 7.
TIA

quote:
Originally posted by:
Ian Skinner
Yes ColdFusion 5 and earlier where written in C and thus do
not use a
JVM at all and ColdFusion 6 and latter are written Java and
always use a
JVM. But that JVM can be subsumed inside of the ColdFusion
application
and thus only available for use by ColdFusion or it can be
installed
independently of ColdFusion and is thus available for use by
other
Java|JSP applications.
In other words the question is are you using either the
Standard or
Enterprise ColdFusion in Stand-Alone mode which embed the JVM
into the
ColdFusion installation. Or are you using Enterprise in
Multi-Home or
J2EE which install the JVM independently of ColdFusion and
can be used
by other applications.
CF, whether installed in Server configuration or Multiserver
configuration, uses a JVM included with CF. In either of these
configurations, JRun is also used as the J2EE application server
that the CF web app is deployed on. The only difference between
these 2 is this:
* In Server configuration, CF is installed with a
stripped-down JRun designed to run nothing but the CF web app. You
can't deploy other J2EE web apps, nor do you have access to the
full JRun install. In this configuration, the JVM used to run the
stripped-down JRun (and thus the CF web app) is installed at
{CF_Install_Root}/runtime/jre.
* In Multiserver configuration, JRun is installed, then CF
is deployed as a web app on the full JRun install. You can deploy
other J2EE web apps on this JRun install as well as change/access
whatever you'd like within JRun. The JVM included with the full
JRun install and used to run it, and thus the CF web app, is
installed at {JRun_Install_Root}/jre
CF, installed using J2EE configuration, is nothing more than
a web app (.war) that needs to be deployed on your
already-installed J2EE server.
The wording you use makes me think you confuse JVM with J2EE
app server. Especially this sentence:
"But that JVM can be subsumed inside of the ColdFusion
application
and thus only available for use by ColdFusion or it can be
installed
independently of ColdFusion and is thus available for use by
other
Java|JSP applications."
Replacing JVM with J2EE app server makes that sentence more
accurate.
The J2EE configuration doesn't install a JVM at all. It
simply packages up a .war/.ear file for you to deploy on your own
J2EE app server.

Types of JVM

Hi,
What is the differences among JVM of J2SE, JVM of J2EE and JVM of J2ME? if anyone knows plz help me..

What is the differences among JVM of J2SE, JVM of
of J2EE and JVM of J2ME? if anyone knows plz help me..There is no J2EE JVM. How about looking around at java.sun.com for looking up the differences?
Must be a homework, or else the other guy wouldn't have asked almost the same yesterday.

Any tool like Swing for J2EE?

Good afternoon, to see if I can clarify with your help.
I'll do a migration to Java application that we use in my business. I will not go much into detail, but basically it is an application that uses multiple users from several different profiles, so only one application that I have thought about doing is a "web platform" where it all together.
My knowledge of Java are regular, basic know-post-university J2SE, J2EE and little else. I started to do small things with JSP and good things seem to me comes in handy for my project, I have only one problem I have not found the solution (due to my ignorance). The problem is I do not know how to edit the forms-page visually. I do not know if there is anything Swing style, something like "design mode" where you can drag buttons, checkboxes, images ... but oriented to web. I've come to ask what I need is an editor such Dreamweaver, and then take the HTML to NetBeans ... the truth is that I'm lost.
For that, I need to know how to edit J2EE developers websites, whether directly in HTML or PHP, whether via a Java tool or by external programs as Dremweaver web editing, or otherwise not know.
Thank you very much.

Forget that visual editors exist. If you want to do dynamic web programming, learn to do it through code, not by clicking. This means you'll have to know how to read, write, change and debug HTML, CSS and Javascript; the very minimal set of skills required for any web developer. There is nothing stopping you from using a tool like Dreamweaver to create the basic HTML/CSS framework, but it stops there.
To make that process easier you may want to check out the Eclipse IDE as it has the ability to instantly make visual what you create without having to open your application in a browser, which can be a big help. That will add another thing to your TODO list though, learning how to properly use an IDE like Eclipse; you have to crawl before you can walk.

Content of a presentation I will give - Please advise of faults

Hi,
As I mentioned in another thread I have to give a presentation on a chosen subject, I chose Java. This is quite important, at least for me it is anyway, I need to know what I am talking about and believe in what I am saying, I visit a seminar in July and this is about the most important part as well as a UNIX assignment. I have listed some of the things I will say below, please advise with what you might disagree with, if you can be bothered that is, I would be grateful :). If I get this wrong I dont get asked back to the academy full time to become SCJP certified and placed in the indusrty. I dont always want to stuck in retail :(
Title - The origins and benefits of Java
The early days
Java was part of a 1991 effort by Sun to produce a language and enviroment which would enable consumer electronics to be able to communicate with each other, they saw this as one of the next big things in I.T.
The sun team which James Gosling lead the coding side, set out to make an architecture neutral programming language which would be simply to use, secure and portable. Java was origianally called oak but didnt survive a patent check and was later renamed to Java.
Although, given there intial goals the project failed and they were turned down when showcasing a PDA called star 7 to potential customers within the industry they still had a created an extremley useful language in Java which was yet to realise its full potential.
Years ticked by before Javas big break came when Sun teamed up with Netscape to release the Hotjava browser which brought animation amongst other things to the Internet, its worth noting that Java was originally designed independant of the Internet but was later found to be a perfect match.
What is Java
Java itself is similar to both C and C++, it borrows its syntax from C and its object model from C++
Java is seen for a high level language anyways as easy to learn
Java code compiles slower than C/C++ one may ask why would we need Java?
Java's benefits
Java code compiles not into Native code like other languages, this is the main reason it runs slower but is the same reason Java is portable and secure.
This means a couple of important things in the world of networked computing, Security and portability.
Java code compiles into bytecode which is then interperted by a Java virtual machine (JVM). This means that only the JVM needs to implented for each different type of CPU or operating system. Where the internet or corperate networks are concerned this is a major plus as both are made up of many different machines.
Other benefits Java offers are Garbage collection, this is automatic memory managment, once the progam has finshed with an address in memory its automatically freed up, in other C/C++ this is left to programmer and can lead to errors and is also a waste of resource.
Also, in Java there are not Pointers like C/C++ instead, Java uses references, this is also a major plus in most cases, although pointers are moe powerful they cause many errors, java eleminates these errors by hiding the responsibility from the programmer, this means the programmer cant make common mistakes in C++ which are de-alocating memory twice or not at all, also this stops the programmer pointing to parts of memory which are out of bounds. This makes java more simple and user firendly.
Java has a massive class libary as standard, this library is on call for the programmer to call upon as needed, this library is packed with useful classes the progrmamer can use without having right the code himself.
Java is everywhere
Java is used in over 2.5billion devices these are listed below:
700 million computers
1 billion mobil phones
1.25 billion smart cards
plus set-top boxes, printers , webcams, games, lottery terminals, medical devices, parking payment stations etc.
and I will include a summary cover the main points of what I have listed above.
other things I might mention here and there.
Java is less expensive than .NET and other languages to use, with Java you pay a one off lisence fee rather than such as Microsoft who charge annual subscription.
Learning programming you may not see yourself as a programmer for consumer electronics but Java opens these doors to you.
Java is an excellent first language for people to learn who are starting out in programming, less confusing than C/C++ but still powerful.
=====================================================
Thats about it, so come and get me! I was rather make a fool out of myself in a forum rather than at a seminar so I dont mind if your harsh, the presentation is in powerpoint format and the above is what I plan to say with the aide of slides, I wont be using notes, as they expect confidence and a sound knowledge of your subject. I know it would be nice to mention more about J2SE/J2EE but I dont have the knowlege at this stage, that is why I chose only the origins and benefits. BTW the speech is only ment to run for about 10 minutes.
Thanks to anyone who took the time out to read the above and post any suggestions.
Mike

Java code compiles slower than C/C++ one may ask why
would we need Java?It runs slower. No one cares about compile time.
>
Java code compiles not into Native code like other
languages, this is the main reason it runs slower but
is the same reason Java is portable and secure.
That point needs more explaination. Security has many meanings and in some circumstances native code will be considered more secure.
>
Java is less expensive than .NET and other languages
to use, with Java you pay a one off lisence fee
rather than such as Microsoft who charge annual
subscription.
Not sure what you meant there.
MS charges for the IDE. Sun charges for their IDE as well. The compiler is free from both however.

Which CPU should I use

Hello,
our company want to buy new computers for the developers.
We have to use Windows XP as our OS because of third party products.
We develop J2SE + J2EE.
So my question:
Which CPU should we use?
I searched at google but didn't found any usefull sides about benchmarking an J2SE VM or J2EE VM.
Intel or AMD?
Are there some issues to be regarded?
Is the behavior of the VM different if you use an Intel or an AMD? (X86)
Our AppServer is JBoss 3.2.3.
Has Intel ore AMD some magic improvements for the SUN Java VM?
Any answer would be appreciated.
Thanks,
Oliver

Olli_ger,
Thanks for asking. To add more to the question, what about dual- and
multi-processors, such as Opteron 2xx and 8xx processors?
That is, can, and to what extent, does the Java compiler and the JVM
utilize multi-processors? And how is this done? Threads parceled out?
Using what algorithms? Are there "best practices" for writing code
that can exploit these chips?
Given the recent emergence of dual-core processors from both AMD and
Intel I would think Sun would have a white paper on this, but I've not
been able to find anything.
As I'm about to build a new system, and am looking at a dual processor
board that could take two dual-core chips, I'd really like to know.
Thanks again for opening the issue.
-BC

JVM, J2SE & J2EE - Confused!

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