Static fields on different machines

Hi:
Let us say I have a class
public class Client(){private int static someField;
I know if you are running Client.java on a single machine, obviously you will only get ONE incarnation of someField because it is static.
Now, let us say I run the Client.java on different machines, then there will be one someField genearted per each JVM , is that right??
can someone confirm??
I did a serach on Static field on the Forum, but nobody really touched on running it on different machines, so I thought I ask...

Yes, that's right.

Similar Messages

Static field initialization

Ok, I know this was a good practices issue in C++, where order of initializing static fields from different source files was unknown, but I'm not sure if Java is smart enough to figure it out.
So, say you have in one file
public class A{
public static B b = new B();
}And in the other:
public class C{
private static D d = A.b.getD();
}Will this always work? Or does it depend on the order in wich classes A and C are loaded.

jschell wrote:
In multiple threads on some systems (potentially) the construction of B() is not guaranted before access to 'b' is allowed.Class initialization is synchronized, so the construction of B() should be fully visible to other threads without explicit synchronization or making the field final.
From JLS 12.4.3:
Code generators need to preserve the points of possible initialization of a class or interface, inserting an invocation of the initialization procedure just described. If this initialization procedure completes normally and the Class object is fully initialized and ready for use, then the invocation of the initialization procedure is no longer necessary and it may be eliminated from the code-for example, by patching it out or otherwise regenerating the code.So class initialization is attempted whenever the code generator feels it might be the first use of a class.
And from 12.4.2:
The procedure for initializing a class or interface is then as follows:
1. Synchronize (§14.19) on the Class object that represents the class or interface to be initialized. This involves waiting until the current thread can obtain the lock for that object (§17.1).
2. If initialization is in progress for the class or interface by some other thread, then wait on this Class object (which temporarily releases the lock). When the current thread awakens from the wait, repeat this step.So the class is synchronized on until initialization (which includes all static initializers) finishes. This makes possible the class holder idiom for singletons.

Static field for apps running on different machines

Hi:
Let us say I have a class
public class Client(){
private int static someField;I know if you are running Client.java on a single machine, obviously you will only get ONE incarnation of someField because it is static.
Now, let us say I run the Client.java on different machines, then there will be one someField genearted per each JVM , is that right??
can someone confirm??
I did a serach on Static field on the Forum, but nobody really touched on running it on different machines, so I thought I ask...

There will be one instance of the static variable per JVM regardless of whether the JVMs are running on the same machine or different machines.

Static field component in virtual machine spec

Hello.
I can’t understand some point in JavaCard Virtual Machine Specification v2.2.2.
Section: 6.10 Static Field Component. See table 6-14. segment 4 – it describe “primitive types initialized to non-default values”. It is describes by two parameters : non_default_value_count, non_default_values[].non_default_values – is image of all static primitive fields independence of it type – byte, short, int. This image consist from data in big-endian order.
How I can use it at architecture with little-endian order?
I can’t parse where short or int – I can’t convert it. How I can do it?

As you pointed out it is not known from the CAP file format where single short or int values begin. At access time you know where the value starts and of which type it is. Therefore it looks like you have no choice but to convert the value at every access from or to big endian.
This is from a design perspective definitely not nice regarding the VM design but I don't think the performance penalty is too costly.

How to schedule multiple reports with different local to change static field language ?

Hi all,
we have requirement that we will place multiple schedule request on same server ,This schedule request will be different local setting with parameter value like: en-GB,en-US,Chinese...etc .We used translation Manager for this and it takes this parameter and change report language for static fields.
problem is that ,on server it is not working properly,we tested for one report .if we pass prompt value to change local setting in report the we need to log off and login again in CMC to reflect new local or on BI Launchpad we need to refresh page then it shows new language.
How we can do this with multiple scheduled report which will have different local value like en-GB,en-US,Chinese,German....?These schedule request are getting placed in server by one user .
Please help us with sample code.
Thanks
Madan

Hi,
The only approach I can think of is to create a template report which uses variables
For each column you would need to variable
v_columnAName and v_columnAValue
v_columnAName would have a if statement in it
=if([client]="clientA" or [client]="clientC";NameOf([firstName]);if([client]="clientB";NameOf([SSN]);NameOf([lastName]));
v_columnA would have a if statement in it
=if([client]="clientA" or [client]="clientC";[firstName];if([client]="clientB";[SSN],[lastName]));
This would only work when you had a small set of clients.
This might be more managable if it was done in the universe
Regards
Alan

Different behaviour reading static field Windows vs Linux

I have a class B that is a subclass of class A. Class A has a protected static field. In windows, reading this field from a static method of class B yields the desired results, meaning that the field has the value updated somewhere else. Running the same code in Linux, the field contains the value assigned to it at declaration time:
It goes like this:
package packageA;
public class A
protected static Collection items = new ArrayList();
public static void addItem(Object item)
items.add(item);
} // class A
package packageB;
public class B
extends A
public static void methodA()
System.out.println(A.modules.size());
System.out.println(B.modules.getSize());
System.out.println(modules.size());
} // class B
import packageA.A;
import packageB.B;
public static void void main(String[] args)
Object item;
item = new String("");
A.addItem(item);
B.method();
} // main(String[])
What is even more strange, is that if I run the above example in a new project, the results are as expected. But if I run this other project I am working on, the results are as if B.items is independent of A.items. Even if I implement a method A.getItems() and call it from B.method() to store the items in a variable local to B.method(), the result is an empty ArrayList.
My first attempt was to place the A and B classes in the same package, and since the results were as expected, I changed each class to its own package and the Main class to an independent package. The results do not change in this scenario.
Your help is appreciated.
The environment is:
Netbeans 5.5
JRE 1.6.0-b105
xubuntu (Linux 2.6.20-16-generic i686 GNU/Linux(
Juan Carlos

I have just noticed that the "odd" behaviour does not happen everywhere (but it does happen everytime).
I realized that there is another part of code that references the same static field and the value in that case is the correct one.
Also, while debugging under Netbeans (on the line of code that gives the unexpected value), the "tip" that is displayed when the cursor is placed over the name of the field, the value is correct.
So I decided to check the Call Stack and noticed some Hidden Source Calls. They are hidden because of a call to LoginContext.login() Furthermore, that call results in a call to AccessController.doPrivileged()
Could that be the problem? If so, how do I solve it. At this point I am lost here, I don't have an idea of where to go now.
Thanks.
JC

How can I share a static field between 2 class loaders?

Hi,
I've been googling for 2 days and it now seems I'm not understanding something because nobody seems to have my problem. Please, somebody tell me if I'm crazy.
The system's architecture:
I've got a web application running in a SunOne server. The app uses Struts for the MVC part and Spring to deal with business services and DAOs.
Beside the web app, beyond the application context, but in the same physical server, there are some processes, kind of batch processes that update tables and that kind of stuff, that run once a day. Theese processes are plain Java classes, with a main method, that are executed from ".sh" scripts with the "java" command.
What do I need to do?
"Simple". I need one of those Java processes to use one of the web app's service. This service has some DAOs injected by Spring. And the service itself is a bean defined in the Spring configuration file.
The solution is made-up of 2 parts:
1. I created a class, in the web app, with a static method that returns any bean defined in the Spring configuration file, or in other words, any bean in the application context. In my case, this method returns the service I need.
public class SpringApplicationContext implements ApplicationContextAware {
     private static ApplicationContext appContext;
     public void setApplicationContext(ApplicationContext context) throws BeansException {
          appContext = context;
     public static Object getBean(String nombreBean) {
          return appContext.getBean(nombreBean);
}The ApplicationContext is injected to the class by Spring through the setApplicationContext method. This is set in the Spring configuration file.
Well, this works fine if I call the getBean method from any class in the web app. But that's not what I need. I need to get a bean from outside the web app. From the "Java batch process".
2. Why doesn't it work from outside the web app? Because when I call getBean from the process outside the web app, a different class loader is executed to load the SpringApplicationContext class. Thus, the static field appContext is null. Am I right?
So, the question I need you to please answer me, the question I didn't find in Google:
How can I share the static field between the 2 class loaders?
If I can't, how can I load the SpringApplicationContext class, from the "Java batch process", with the same class loader my web app was started?
Or, do I need to load the SpringApplicationContext class again? Can't I use, from the process, the class already loaded by my web app?
I' sorry about my so extensive post...
Thank you very much!

zibilico wrote:
But maybe, if the web service stuff gets to complicated or it doesn't fulfill my needs, I'll set up a separate Spring context, that gets loaded everytime I run the "Java batch process". It'll have it's own Spring configuration files (these will be a fragment of the web app's config files), where I'll define only the beans I need to use, say the service and the 2 DAOs, and also the DB connection. Additionally, I'll set the classpath to use the beans classes of the web app. Thus, if the service and DAOs were modified in the app server, the process would load the modified classes in the following execution.You'll almost certainly have to do that even if you do use RMI, Web services etc. to connect.
What I suggest is that you split your web project into two source trees, the stuff that relates strictly to the web front end and the code which will be shared with the batch. The latter can then be treated as a library used by both the batch and web projects. That can include splitting Spring configuration files into common and specific, the common beans file can be retrieved from the classpath with an include. I regularly split web projects this way anyway, it helps impose decoupling between View/Controller and Model layers.
On the other hand, you might consider running these batch processes inside the web server on background threads.

How can i look up a EJB residing in different machine from client side?

hai ,
How can i look up a EJB residing in different machine from client side?
this is my code...........i don't know what should i use as Initial Context Factory...................i am using a sun appserver 8............
package com.parx.lms.lmsdelegate;
import com.parx.lms.exception.LMSException;
import javax.naming.Context;
import javax .ejb.CreateException;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;
import java.rmi.RemoteException;
import com.parx.lms.controller.*;
import com.parx.lms.vo.UserVo;
import com.parx.lms.exception.BusinessException;
import java.util.Hashtable;
import java.lang.*;
public class LmsDelegate{
private final static String JNDI_NAME="LmsBean";
private static String url="http://localhost:4848";
public static Lms lms = null;
public void getController() throws CreateException,
NamingException,RemoteException{
if(lms == null){
Hashtable h=new Hashtable();
h.put(Context.INITIAL_CONTEXT_FACTORY," ********what should i use here???????*************************");
h.put(Context.PROVIDER_URL,url);
System.out.println("Before Loading Context in Delegate");
Context ctx=new InitialContext(h);
System.out.println("Loaded Context in Delegate");
Object obj=ctx.lookup(JNDI_NAME);
System.out.println("Loaded Object in Delegate");
System.out.println("Before Loading Home in Delegate");
LmsHome home = (LmsHome )PortableRemoteObject.narrow(obj,com.parx.lms.controller.LmsHome.class);
System.out.println("Loaded Home in Delegate");
lms = home.create();
System.out.println("Loaded remote in Delegate");
public void addUserDelegate(UserVo vo) throws BusinessException{
try{
getController();
System.out.println("Before calling the addUser of Session");
lms.addUser(vo);
}catch(CreateException e){
System.out.println("Create Exception in Delegate due to--->"+e);
e.printStackTrace();
throw new BusinessException(e);
}catch(NamingException e){
System.out.println("Naming Exception in Delegate due to--->"+e);
e.printStackTrace();
throw new BusinessException(e);
catch(RemoteException e){
System.out.println("Remote Exception in Delegate due to--->"+e);
e.printStackTrace();
throw new BusinessException(e);
}catch(LMSException e){
System.out.println("duplicate user name--->"+e);
e.printStackTrace();
throw new BusinessException(e);
pls help me..........

h.put(Context.INITIAL_CONTEXT_FACTORY," ********what should i use here???????*************************")
Each app server provides their own jndi factory class. For ex for weblogic it is weblogic.jndi.WLInitialContextFactory. SInce you are using sun app server, check if there are any examples to find out or the docs.
private static String url="http://localhost:4848
Since the client is in a different machine the localhost is not going to work here. provide the url or the machine name of the system in which ur sunapp server is running. In addition u will need to have the stubs of the remote interfaces in ur client machine.

Static field changes for both instances

Whenever I construct a new object with a static field or use a set method on any of the instances of that object, the static field will change to the last modification made. In the case of my program, whenever the static String color field is changed to the last modification made. This only happens with the static fields, the other fields work just fine.
Why does this problem occur?

Sorry, I can't understand the question. If you have lots of different objects, all of the same class, they all share one copy of the static field, so if you invoke a method that changes the static field on one instance, all the other instances will see that change.
if you don't want this behaviour, don't make the field static; then each instance will have its own copy of the field.

Using Objects to Initialize Static Fields: Good or Bad

I have a Command interface and a bunch of Commands that implement it (i.e. CmdJoin,CmdQuit). These Commands' settings change at runtime (i.e. required access levels, String identifiers). I don't want to have to store an instance of each Command in a database to save their settings , so instead I'm using the obvious solution: making static fields in these commands for these settings. This way, I can use a Simple Factory to return a Command, change its settings, execute it, and forget it, and still have the settings for that Command apply to all Commands. Yet I want to be able to modify and access fields of different Commands polymorphically. How can I have these commands' settings-related fields be static while modifying and accessing these fields polymorphically?
Here's what I have though of. First of all, interfaces can't have static methods. Secondly, neither can abstract classes. I also can't extend a base class which implements these settings-related fields and their interface, because then the fields would belong to all child classes of this base class, whereas I just want it to belong to a certain child class of the base class (i.e. all instances of CmdJoin or CmdQuit).
I've thought of two solutions.
The first is implementing a concrete interface in an abstract base class (getting rid of the Command interface) and overriding it in child classes, so that I can use the interface of the base class and the fields of the child classes.
The second is having no base class, and just a bunch of Commands implementing the interface with their own static fields. I would initialize these fields by passing arguments to their constructors.
These solutions seem very sloppy though! Are there any better ways?

To clarify, I want all objects of type A to be able to respond to a static method declared in type A yet still remember their implementation of this static method. I provided two solutions that I have thought of, and I find them sloppy, so I'm asking if there's a better way.

Static fields

Can anyone tell me how compiler compiles static or 'final static' fields? Are they holding memory for whole period time of process, or when they're dereferenced, memory will be reclaimed during the process?
Thanks

I am fraid last response misunderstood my question
and comments. Say there are 5000 static integers in
application. It is 5000 bytes. Then there are 5000
static String fields and each has 40 characters (each
one is two bytes). Total static String may have
400000 bytes. Each time the class that contains these
fields is referenced at run time they take up memory.So are you saying that if these fields are not static? It wouldnot take memory? Or are you suggesting that there would always be only one instance of each of these classes so you wouldnot take more space if these fields are not static?
So when application runs forever, it will have a
great chance all these static will be loaded into
memory. So total is 405K bytes that is 'permanently'
stay in memory. You can claim this still a small
amount. But this is just an example and everythingFirst of all its totally insignificant as to how much memory is being taken. The reasons under consideration for declairng a variable static are totally different from what you are assuming but even if you think this way let me tell you this much making them member variables would take more memory since now these variables would be associated with their respective instances and not the class object. And donot tell me that each of these classes is going to have only on instance, so multiply the value with the no. of instances, if you could tell how many instances you would have.
is relative, depending on runtime system. So this is
my original questions: if I want to do something to
save a little bit memory that is permanently occupied
by these static stuffs. But I like to know how
compiler and runtime work: is that true if class is
dereferenced, static field memory will be also
reclaimed? If that is true, I don't need worry (that
means these static fields do not 'permanently' stay
in memory. If not true, I will review these fields toThis question has been answered in my previous post.
see which one could be defined as instance fields or
even defined on stack. The trade off always on
allocate memory on globe heap and keep reference to
it, or create object as needed.
From your comments, seems you think both static and
instance fields can be reclaimed memory if they are
dereferenced (only difference is static is one copy
and instance has multiple - that's obviously and not
question we need discuss)Again you are wrong over here. Read the replies posted again. Secondly I repeat members are not defined static or regular based on the constraints you have in mind and secondly, the way you are thinking that the memory model works is totally wrong. To cut the story short you would not save any memory but making these members regular (non static) On the other hand you might break things by stepping into unknown terrotory since you are not trying to comprehend why were they made static in the first place.

Any way to have two identical versions of iTunes on different machines?

Hello, probably a fairly basic question, but I'm quite a new iPod/iTunes user and need some urgent help.
I have my iTunes and music library set up fine on my PC with Windows XP, and all of the according media is stored on my iPod. But I would like to transfer all of my existing library to my laptop, which runs Vista, so effectively having TWO identical libraries to the same user, but on two different machines. I'm wondering if anyone knows the easiest way to do this? I've tried a direct transfer and then import on my iTunes library (with the 'iTunes music' folder, which for some reason contains about a fifth of the music that is actually in the library itself), but this didn't work, as only about 700 of 5000 or so songs showed up in the new iTunes library (on the laptop)!
Any help? Hope this makes sense. Thanks.

Yes, it can be done, but it's not the standard thing to do. The first thing to note is that iTunes contains full path references to all your media. Windows XP & Windows Vista have different naming conventions for the default documents folders so under XP you'd expect to find the iTunes library at C:\Documents and Settings\<User>\My Documents\My Music\iTunes whereas under Vista it will be at C:\Users\<User>\Documents\Music\iTunes. If you are copying your library from XP to Vista you should put it at exactly the same path that it had on XP and then tweak the options in the Vista version to point to your desired location.
Connect your laptop & desktop together over a network & share the Music folders on both. Grab a free tool called SyncToy 2.0 and use it to create a pair of syncronised folders. This will allow you to make changes to one library, and then connect the two machines and re-sync. As a bonus you will be able to auto-sync your iPod with either library. It only becomes difficult if you make independant changes on each machine between syncing - the most recently updated files should overwrite the older ones, but the library can end up with out of date information. The following tools can help out here.
*Adding new items/removing orphans*
Try iTunes Folder Watch or iTunes Library Updater. Folder Watch is much faster on the adding files front, can be set to run in the background and includes a useful exclusion feature, however it’s really slow at removing orphans. iTLU is better for this although doing it manually after looking at a list of proposed removals generated by Folder Watch is probably faster still. iTLU can also be set to update iTunes when you've used 3rd party tools to change tag info.
Disable Windows Media Player's "Automatically update missing information" feature on both machines as this has a tendacncy to "touch" files without adding useful info. and wipes out the iTunes "No. of Tracks" field.
tt2

Generally when creating a Word file from either a Mac or Win7 pc and opening it on two different machines (either one first) it always prompts that the file is open and will be opened as read only. However opening a CSS file does not prompt that it is alr

Generally when creating a Word file from either a Mac or Win7 pc and opening it on two different machines (either one first) it always prompts that the file is open and will be opened as read only.
However opening a CSS file does not prompt that it is already open on or from any machine which is causing code edits to be lost.
What we found from out testing:
- The file can be saved from one user to the server and WILL NOT PROMPT on other machines until the saving machine has the Dreamweaver program closed completely
- The file can be closed and Dreamweaver minimised to the launch bar but it still will not register on other machines that it has been changed.
- Also, until the Dreamweaver program is closed on the machines, it will continue to open it's saved version of the file.
Example Scenario:
- User 1 opens test.css (which is 2000 lines) and adds some code to the end of the file to bring it up to 2500 lines
- Meanwhile User 2 opens test.css as well (opens as 2000 lines as User 1’s edits have not yet been saved) and adds in code to bring it to 2300 lines
- User 1 saves his file and closes it - but Dreamweaver is still open.
- User 2 also saves his file and leaves Dreamweaver open.
- The server will report the size and last edit of the file the same as User 2 as he was the last person to save it (and if you open from the Win7 Machine it will show as User 2’s 2300 line version)
- If User 1 then open's the file again (from either the 'recent' in Dreamweaver OR clicking on the file directly in Finder...which version opens.... The version that User 1 saved! Not the true version on the server, but the version that User 1 edited and saved with 2500 lines in it.
- Same for User 2, he will open 'his' version with 2300 lines in.
Other information:
- Files are opened directly from the server
- Sometimes the users will save incrementally and re-open
- Most of the time users will save incrementally and keep the files open
- The users will never not save incrementally and just save when closing the file once finished
- The users are usually working on the files all day
- It is always the bottom lines of code that are lost. It could be a case of the two versions being mixed up and cutting off the newly added lines based on the line count (possibly).
It is as if Dreamweaver is holding a cache of the version locally and then only properly looking back to the server when it has been completely closed. It is very difficult to see how the server is causing such an impact on these files, there are very few logs which are giving any indication to the root cause of the problems.
Anyone know if this is a known issue?
Is there a way that there can be a featured implemented on the server that doesn't allow another user to open a file if it is already open on another machine?
Thanks

Your server file handling has nothing, and really nothing to do with Adobe software. If files don't get locked for (over-)writing and/or lose connection to the program opening them, then your server is misconfigured. It's as plain and simple and that. Anything from "known file types"/ file associations not being set correctly, MIME types being botched, crooked user privileges and file permissions, missing Mac server extensions, delayed file writing on the server, generic network timeout issues and what have you. Either way, you have written a longwinded post with no real value since you haven't bothered to provide any proper technical info, most notably about the alleged server. Either way, the only way you can "fix" it is by straightening out your server and network configuration, not some magic switch in Adobe's software.
Mylenium

Problem with NIReport.llb\Print HTML Report using IE.vi on different machines

We have 5 machines here in our workgroup which have the same state regarding security patches and other system updates. We recently found out that there is a problem with the NIReport.llb\Print HTML Report using IE.vi on the different machines.
If I would open the VI on MachineA the control could be loaded. If I would open the VI on MachineB the control could be loaded. If I would copy the VI from MachineB to MachineA and open the VI the control could not be loaded. If I would copy the VI from MachineA to MachineB and open the VI on MachineB the control could be loaded. MachineB could load the version from MachineA and MachineB but on MachineA only the own version will load. I have seen that both versions have the same GUID for the Microsoft Webbrowser but are different in some other aereas.
Since printing HTML Reports is part of the application which will be distributed as application I want to know if someone else have seen such a behaviour or has got problems distributing an application.
Also I want to know which additional information is stored in an Active-X container about the control beside the GUID.
We have Win XP Prof SP2 with MS IE 6.0.2900.2180 on all machines in the workgroup.
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

Hi Tom,
this is the VI <vi.lib>\Utillitiy\NIReport.llb\Print HTML Report using IE.vi copied from a machine that can load and run the VI and it will print. On this machine the control in the VI is white.
This VI will give the "Control could not be loaded" message on my machine.
The file shdocvw.dll is 2006-10-23 16:18 size 1.460 KB and I verifyed that both machines have the same version of this file.
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions
Attachments:
Print HTML Report using IE.png ‏11 KB

Access application hosted on a different machine.

Hi,
I've written a simple web application to select an excel file through a jsp and write it's contents to text file. I select the execl file by browsing through the folders in my system. when i submit the form giving the location of the text file to which this excel file contents have to be written i'm getting the expected result. This application is hosted in Tomcat in my system. But when i tried accessing the application from another system my application is unable to find the excel file path selected in that machine. So i'm getting FileNotFoundException. Please suggest a solution.
Thanks,
Sudha

Hi,
I know that an application is hosted on a particular system. That application's job is to take the excel file selected by me and create a text file out of that. But as that application is hosted in a different machine it is unable to find the path i select. My doubt is like is it possible to have an application like this with actual source code and server on one system and user accessing from a different system and still able to find the path of the excel file the user is selecting?
Thanks,
Sudha

Static fields on different machines

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