SessionBean class can be defined static?

Can we define session bean class 'static'.In the EJB specification I cannot find any limitation on not defining a session bean class as static.
regards
ashish

Without more info of the other bits of your system
then it's hard to say what's best.
How are you accessing your database? Are you using
Entity Beans? CMP?
If so, you should use a session bean to help with
transactions.The current design is that for each list, I'm using a Stateful Session bean that contains a Vector of CMP EJB references. This list is what I would prefer to not have each session recreate as some of the lists contain hundreds of items (EJB's). It would be desirable in terms of memory and performance to create these Session beans intitially and have every session continue to reference them without having to recreating for each session.
But even so, if the application-level non EJB class representing the list contained EJB references, what happens when the session they were initially created under goes away? Will the container still hold a reference to these objects?
Like I said, I can make all these list objects and the objects they reference static application-level standard beans and create them only the first time they are referenced, but that circumvents using the container and EJB's for this part of the architecture.

Similar Messages

Why a non static member class can be defined in an interface

Non-static member classes are defined as instance members of other classes, just like fields and instance methods are defined in a class. An instance of a non-static member class always has an enclosing instance associated with it.
An interface can't be instantiated then how a non static member class will have an enclosing instance associated with it.
interface outer
        public class inner{
        public void p()
            System.out.println("inside interface's non static member class");
    public static class inner1{
            public void p(){System.out.println("inside interface's static member class");
public class Client {                                           // (11)
    public static void main(String[] args) {                    // (12)
    outer.inner nonStatic = new outer.inner();
        nonStatic.p();
    outer.inner1 stat = new outer.inner1();
      stat.p();
}inner is a non static member class even then " outer.inner nonStatic = new outer.inner();" working fine ?????????????

class outer
        public class inner{
        public void p()
            System.out.println("inside interface's non static member class");
public class Client {                                           // (11)
    public static void main(String[] args) {                    // (12)
    outer.inner nonStatic = new outer.inner();
    nonStatic.p();
}on compiling the above code the error message i got is
"not an enclosing class: outer"
the reason of this compilation error is "outer.inner nonStatic = new outer.inner();
it should be "outer.inner nonStatic = new outer(). new inner();"
now my question is
interface outer
        public class inner{
        public void p()
            System.out.println("inside interface's non static member class");
public class Client {                                           // (11)
    public static void main(String[] args) {                    // (12)
    outer.inner nonStatic = new outer.inner();
    nonStatic.p();
}on compiling the above code why compilation error is not coming??????????
i think now it is more clear what i am asking

Can we define 'Static Variables' in BPEL process ?

Is the idea of 'STATIC VARIABLES' supported in Oracle BPEL?
What I mean by that is, I need all my in-flight BPEL process INSTANCES to read a common variable and then decide the next course of action.
Is this possible?
Thanks in advance,
Mahendra

Hi Hans,
In Cocoa and Objective-C a static variable needs to be declared in the implementation file and not the header as you would normally do. Standard C variables can be set at the same time as the declaration but Cocoa objects need an extra step.
For example:
#import "TestObject.h"
// declare your static variable here
static NSArray *count;
@implementation TestObject
- (id) init {
self = [super init];
if (self != nil) {
// set the variable here
// the 'if' statement ensures it is only set once
if (!count) {
count = [[NSArray arrayWithObjects:@"One",@"Two",@"Three",Nil] retain];
return self;
@end
Hope this helps,
Martin.
PowerMac G5 1.6Ghz Mac OS X (10.4.9) 4 gig RAM & NVidia 6800 Ultra

Unusual use of interface defining static factory class with getInstance

This question is prompted by a recent New to Java forum question ask about the differences between Interfaces and Abstract classes. Of course one of the standard things mentioned is that interfaces cannot actually implement a method.
One of my past clients, one of the 500 group, uses interfaces as class factories. The interface defines a pubic static class with a public static method, getInstance, that is called to generate instances of a class that implements the interface.
This architecture was very object-oriented, made good use of polymorphism and worked very well. But I haven't seen this architecture used anywhere else and it seemed a little convoluted.
Here is a 'pseudo' version of the basic interface template and use
-- interface that defines public static factory class and getInstance method
public interface abc {
    public static class FactoryClass
        public static abc getInstance ()
            return (abc) FactoryGenerator(new abcImpl(), abc.class);
-- call of interface factory to create an instance
abc myABC = abc.Factory.getInstance();1. Each main functional area ('abc' in the above) has its own interface factory
2. Each main functional area has its own implementation class for that interface
3. There is one generator (FactoryGenerator) that uses the interface class ('abc.class') to determine which implementation class to instantiate and return. The generator class can be configured at startup to control the actual class to return for any given interface.
I should mention that the people that designed this entire architecture were not novices. They wrote some very sophisticated multi-threaded code that rarely had problems, was high performance and was easy to extend to add new functionality (interfaces and implementing classes) - pretty much plug-n-play with few, if any, side-effects that affected existing modules.
Is this a best-practices method of designing factory classes and methods? Please provide any comments about the use of an architecture like this.

Thanks for the feedback.
>
I don't see how 'the generator class can be configured at startup to control the actual class to return for any given interface' can possibly be true given this pseudo-code.
>
I can see why that isn't clear just from what is posted.
The way it was explained to me at the time is that the interface uses standard naming conventions and acts like a template to make it easy to clone for new modules: just change 'abc' to 'def' in three places and write a new 'defImpl' class that extends the interface and the new interface and class can just 'plug in' to the framework.
The new 'defImpl' class established the baseline functionality that must be supported. This line
return (abc) FactoryGenerator(new abcImpl(), abc.class);uses the initial version of the new class that was defined, 'abcImpl()', when calling the FactoryGenerator and it acted as a 'minimum version supported'. The generator class could use configuration information, if provided, to provide a newer class version that would extend this default class. Their reasoning was that this allowed the framework to use multiple versions of the class as needed when bugs got fixed or new functionality was introduced.
So the initial objects would be an interface 'abc' and a class 'abcImpl'. Then the next version (bug fixes or enhancements) would be introduced by creating a new class, perhaps 'abcImpl_version2'. A configuration parameter could be passed giving 'abcImpl' as the base class to expect in the FactoryGenerator call and the generator would actually create an instance of 'abcImpl_version2' or any other class that extended 'abcImpl'.
It certainly go the job done. You could use multiple versions of the class for different environments as you worked new functionality from DEV, TEST, QA and PRODUCTION environments without changing the basic framework.
I've never seen any Java 'pattern' that looks like that or any pattern where an interface contained a class. It seemed really convoluted to me and seems like the 'versioning' aspect of it could have been accomplished in a more straightforward manner.
Thanks for the feedback. If you wouldn't mind expanding a bit on one comment you made then I will mark this ANSWERED and put it to rest.
>
I don't mind interfaces containing classes per se when necessary
>
I have never seen this except at this one site. Would you relate any info about where you have seen or used this or when it might be necessary?

Why a static class can implements a non-static interface?

public class Test {
     interface II {
          public void foo();
     static class Impl implements II {
          public void foo() {
               System.out.println("foo");
}Why a static class can implements a non-static interface?
In my mind, static members cann't "use" non-static members.

Why a static class can implements a
non-static interface?There's no such thing as a non-static member interface. They are always static even if you don't declare them as such.
An interface defines, well, a public interface to be implemented. It doesn't matter whether it is implemented by a static nested class or by an inner class (or by any class at all). It wouldn't make sense to enforce that it should be one or the other, since the difference between a static and non-static class is surely an irrelevant detail to the client code of the interface.
In my mind, static members cann't "use" non-static
members.
http://java.sun.com/docs/books/jls/third_edition/html/classes.html#246026
Member interfaces are always implicitly static. It is permitted but not required for the declaration of a member interface to explicitly list the static modifier.

Can one combine static and instance methods?

Hi,
Can one define a method so that is can be used as both a static or an instance method?
Basically I'm trying to simplify my class to so that I can call a method either statically with parameters or instantiated using it's own attributes.
In other words, I'm trying to accomplish both of these with one method:
zcl_myclass=>do_something_static( im_key = '1234' ).
lv_myclass_instance->do_something( ).   " key in private attributes
Why would I want to do that?
I would like to avoid instantiation in some cases for performance reasons and would like to keep it simple by having only one method to do basically the same thing.
Any input or alternative suggestions welcome.
Cheers,
Mike

Ok, I may be reaching here a bit, I know, but maybe this may give you some ideas. After creating the object, pass it back to the method call.
report zrich_0001.
*       CLASS lcl_app DEFINITION
class lcl_app definition.
public section.
    data: a_attribute type string.
    class-methods: do_something importing im_str type string
                               im_ref type ref to lcl_app optional.
endclass.
*       CLASS lcl_app IMPLEMENTATION
class lcl_app implementation.
method do_something.
    if not im_ref is initial.
       im_ref->a_attribute = im_str.
      write:/ 'Do_Something - ', im_ref->a_attribute.
    else.
      write:/ 'Do_Something - ', im_str.
    endif.
endmethod.
endclass.
data: o_app type ref to lcl_app.
start-of-selection.
create object o_app.
call method o_app->do_something(
           exporting
               im_str = 'Instansiated'
               im_ref = o_app ).
call method lcl_app=>do_something(
           exporting
               im_str = 'Static' ).
Regards,
Rich Heilman

Why a nested class can instantiate an abstract class?

Hi people!
I'm studying for a SCJP 6, and i encountered this question that i can figure it out but i don't find any official information of my guess.
I have the following code:
public class W7TESTOQ2 {
    public static void main(String[] args) {
       // dodo dodo1 = new dodo();
        dodo dodo2 =new dodo(){public String get(){return "filan";}};
        dodo.brain b = dodo2.new brain(){public String get(){return "stored ";}};
        System.out.print(dodo2.get()+" ");
        System.out.println(b.get());
abstract class dodo
    public String get()
        return "poll";
    abstract class brain
        public abstract String get();
}I know that abstract classes cannot be instantiated but i see that in this example, with a nested anonymous class it does (dodo and brain classes). My guess is that declaring the nested class it makes a subclass of the abstract class and doing so it can be instantiated. But i can't find any documentation about this.
Does anybody know?
Really thanks in advance.
Regards,
Christian Vielma

cvielma wrote:
Another question about this. Why can't i declare a constructor in the nested class? (it gives me return type required)You cannot declare a constructor, because in one line you're declaring a new class (the anonymous inner class) as well as constructing an instance of it.
What you can do, however, is if the abstract class (or the superclass, in any case, it doesn't need to be abstract) defines several constructors, you can call them.
public abstract MyClass {
    public MyClass() {
        // Default do nothing constructor
    public MyClass(String s) {
        // Another constructor
// Elsewhere
MyClass myclass = new MyClass("Calling the string constructor") {
};But you can't define your own constructors in the anonymous inner class.
Also, since the class is anonymous, what would you name the constructor? :)
Edited by: Kayaman on 26.6.2010 22:37

Class constructor is actually "static" method, as Bruce Eckel says?

<Thinking in java> chapter 7 :
Even though constructors are not polymorphic (they?re actually static methods, but the static declaration is implicit), it?s important ...
Are constructors actually static methods? I do not think so. static method can only manipulate static members, but constructor can also deal with non-static members. In other words, constructor always associate with a object, while static method always associate with a class.
Why Mr. Eckel says that constructors are static?

From the JLS ?8.8.3
A constructor is always invoked with respect to an object, so it makes no sense for a constructor to be static, so no they are not.
Are constructors actually static methods?Constructor declarations are not members. Members are defined as the set fields, methods, nested classes and interfaces(JLS ?8). So they are not methods.

Define static IP for both LAN and W-LAN devices with an Airport Extreme Base Station

Hey guys,
I have a lot of different devices connected to my Airport Extreme Base Station (5th Gen) either wirelessly or via ethernet cable. Since I control some of them via VNC and currently have to find the corresponding IP-addresses through trial-and-error, I'd like to define static IP-addresses for the computers in question. My network consists of a cable modem connected to a TP-Link WR1043ND router in the basement, from which an ethernet cable leads to the WAN-port of the aforementioned Airport Extreme Base Station on the 2nd floor. Two of the devices I want to remote-access are wired to a D-Link DES-1005D switch, which in turn is connected to the 1st ethernet port of the Airport Base Station. The remaining 3 remote clients are connected over 802.11n. All computers run Windows.
My problem now is that even though I was able to define static IP-addresses employing the "DHCP only" router mode, this didn't seem to work for the two computers connected via ethernet. Not only did I lose any internet connectivity with those, I even lost the ability to remote-connect to them using the VNC-viewer.
The question now is: how do I specify static IP-addresses for my ethernet devices correctly?
I hope you can help me.

My network consists of a cable modem connected to a TP-Link WR1043ND router in the basement, from which an ethernet cable leads to the WAN-port of the aforementioned Airport Extreme Base Station on the 2nd floor.
If you read the information in the other post, my answer would be the same here.
The Router Mode of DHCP Only is rarely used, and would only really be appropriate if your ISP was providing you with a fixed bank of multiple fixed or static IP addresses to use. This does not appear to be the case in your post.
If this were the case, the first IP address would be used as a Static IP address for your connection, and other devices on your network would receive the other fixed IP addresses.
99%+ of the time, you would use the Router Mode setting of DHCP and NAT on a network when you want the AirPort to perform as the main router for the network.
But......your post also indicates that you have another router upstream on your network from the AirPort Extreme. You would not want to run two routers in series on a network. That explains the problems that you are having.
The AirPort Extreme needs to be configured in Bridge Mode. It cannot be the "main" router on your network when you already have another router on the network. That is a fundamental networking rule.

Compiler says class can't be initialized

ok, i know abstract classes can't be initialized, but i am extending my base class, but my complier says that "class ClassificationParser can't be initialized" but i am not initializing it. IF anyone can point out a problem, which i just can't see please do. Thank you..
first is listed the base abstract class, second the extended class
package cattlemanager.utilities.parsers;
import java.util.Vector;
import java.io.File;
import java.io.IOException;
* Title: ClassificationParser
* Copyright: Copyright (c) 2001
* Company: None
* @author Harold Smith III
* @version 1.0
public abstract class ClassificationParser
 * This method returns the instance of a <code>Classification</code> objects
 * that the implementor can work with and use to there own extent. This allows
 * for the parser to read in all the file data, and insert it into the
 * <code>Classification</code> Objects that he or she wishes the user to
 * modify.
 * Important - The <code>Vector</code> that is returned will
 * contain a <code>Vector</code> of <code>Vector</code>'s that the implementor
 * must work with. The reason for a <code>Vector</code> of <code>Vector</code>'s
 * is the <code>Classification</code> data may contain several past <code>
 * Classification</code> records.
 * @return Vector the data vector.
public Vector getData()
{ return vInternalClassificationDataObject;
 * <code>parse</code> is the default parsing mechanism for the read in data
 * that the user can integrate into there records. Using the <code>parse</code>
 * method, the implemented class will read in the specified <code>File</code>
 * and the <code>Classification</code> Objects will be initialized with tthe
 * read in data.
 * @param File the file to be parsed, should follow the specified format
 * determined by the appropriate association.
 * @throws WrongFormatException if the file is not formatted to the standards
 * the association has laid out.
 * @throws IOException if there is a file problem.
public abstract void parse(File fName) throws WrongFormatException, IOException;
 * The internal <code>Vector</code> of objects that will be laid out as specified
 * in the <code>getData</code> method described within this class.
 * @see #getData
protected Vector vInternalClassificationDataObject;
package cattlemanager.utilities.parsers;
import java.io.File;
import java.io.FileInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.EOFException;
import java.util.StringTokenizer;
import java.util.Date;
import java.util.GregorianCalendar;
* Title: HolsteinAssociationClassificationParser
* Copyright: Copyright (c) 2001
* Company: None
* @author Harold Smith III
* @version 1.0
public class HolsteinAssociationClassificationParser extends ClassificationParser
private HolsteinAssociationClassificationParser()
{ try
 { parse(new File("demo.ext"));
 catch (Exception e)
 * Doesn't work?!
public static synchronized ClassificationParser createInstance()
{ return new HolsteinAssociationClassificationParser();
 * <code>parse</code> parses the <a href="www.holstein.com">Holstein
 * Association</a> classification data as laid out in there <code>File</code>
 * format. By using this parser, one can read in the records and access the
 * data that they need.
 * @param File the name of the file to be parsed.
 * @throws WrongFormatException if the file is not properly formated
private void parse(File fName) throws WrongFormatException, IOException
 try {
 // READ IN FILE
 * Creates an instance of a date for the format specified by the Holstein
 * Association
private Date createDate(String time)
{ GregorianCalendar c = (GregorianCalendar) GregorianCalendar.getInstance();
 c.set(Integer.parseInt(time.substring(0,4)), Integer.parseInt(time.substring(4,6))-1, Integer.parseInt(time.substring(6,8)));
 return c.getTime();
}

ah stupid errors, i figured it out, i accidently created an instance in a class before i decided to change the class to abstract!

Can't make static reference to method while it is static

Hello, can somebody please help me with my problem. I created a jsp page wich includes a .java file I wrote. In this JSP I called a method in the class I created. It worked but when I made the method static and adjusted the calling of the method it started to complain while i didnt make an instance of the class. the error is:Can't make static reference to method
here is the code for the class and jsp:
public class PhoneCheckHelper {
public static String checkPhoneNumber(String phoneNumber) {
String newPhoneNumber ="";
for(int i=0; i<phoneNumber.length(); i++) {
char ch = phoneNumber.charAt(i);
if(Character.isDigit(ch)) {
newPhoneNumber += String.valueOf(ch);
return newPhoneNumber;
<html>
<head>
<title>phonecheck_handler jsp pagina</title>
<%@page import="java.util.*,com.twofoldmedia.text.*, java.lang.*" %>
</head>
<body>
<input type="text" value="<%= PhoneCheckHelper.checkPhoneNumber(request.getParameter("phonenumberfield")) %>">
</body>
</html>

Go over to the "New to Java" forum where that message is frequently explained. Do a search if you don't see it in the first page of posts.

Can't make static reference to method

hi all,
pls help me in the code i'm getting
" can't make static reference to method....."
kindly help me
the following code gives the error:
import java.rmi.*;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.io.*;
import java.io.IOException;
import java.io.LineNumberReader;
public class client
static String vcno;
static String vpin;
static String vamt;
static String vordid;
static String vptype;
//static String vreq;
static String vreq = "1";
static String vorgid;
static String vm1;
static String vs1;
static String vqty1;
static String vm2;
static String vs2;
static String vqty2;
static String vm3;
static String vs3;
static String vqty3;
static String vm4;
static String vs4;
static String vqty4;
public static void main(String args[])
try
ServerIntf serverintf=(ServerIntf)Naming.lookup("rmi://shafeeq/server");
int c;
StringBuffer sb;
FileReader f1=new FileReader("c:/testin.txt");
sb=new StringBuffer();
int line=0;
while ((c=f1.read())!=-1) {
sb.append((char)c);
LineNumberReader inLines = new LineNumberReader(f1);
String inputline;
String test;
while((inputline=inLines.readLine())!=null)
line=inLines.getLineNumber();
switch(line)
case 1: {
vcno = inLines.readLine();
System.out.println(vcno);
case 2: {
vpin = inLines.readLine();
System.out.println(vpin);
case 3: {
vptype = inLines.readLine();
System.out.println(vptype);
case 4: {
vamt = inLines.readLine();
System.out.println(vamt);
case 5: {
vordid = inLines.readLine();
System.out.println(vordid);
case 6: {
vorgid = inLines.readLine();
System.out.println(vorgid);
     case 7: {
vm1 = inLines.readLine();
System.out.println(vm1);
     case 8: {
vs1 = inLines.readLine();
System.out.println(vs1);
     case 9: {
vqty1 = inLines.readLine();
System.out.println(vqty1);
     case 10: {
vm2 = inLines.readLine();
System.out.println(vm2);
     case 11: {
vs2 = inLines.readLine();
System.out.println(vs2);
case 12: {
vqty2 = inLines.readLine();
System.out.println(vqty2);
case 13: {
vm3 = inLines.readLine();
System.out.println(vm3);
     case 14: {
vs3 = inLines.readLine();
System.out.println(vs3);
case 15: {
vqty3 = inLines.readLine();
System.out.println(vqty3);
case 16: {
vm4 = inLines.readLine();
System.out.println(vm4);
case 17: {
vs4 = inLines.readLine();
System.out.println(vs4);
case 18: {
vqty4 = inLines.readLine();
System.out.println(vqty4);
f1.close();
FileWriter f2=new FileWriter("c:/testout.txt");
String t;
t=ServerIntf.add(vcno,vpin,vamt,vordid,vptype,vreq,vorgid,vm1,vs1,vqty1,vm2,vs2, vqty2,vm3,vs3,vqty3,vm4,vs4,vqty4);
String str1 = " >>";
str1 = t + str1;
f2.write(str1);
System.out.println('\n'+"c:/testout.txt File updated");
f2.close();
catch(Exception e)
System.out.println("Error " +e);

Yes, ServerIntf is the interface type. The instance serverIntf. You declared it somewhere at the top of the routine.
So what you must do is call t=serverIntf.add(...)This is probably just a mistype.

Applet in ie 5.0: class can not be Instantiated

Hi!
My problem is an Applet, which works fine with the appletviewer and with my iExplorer 5.0.
But when I tried to install my Application (the Applet is part of a J2EE-WebApp) on the tomcat of an other computer, I get the
"class can not be instantiated"-Error and iE 5.0 only displays a grey box in the size of the Applet. With the appletviewer it works.
I got the same tomcat, same mySQL and same browser on both computers.
I also invoked the application running in tomcat on my computer from 2 other computers - on one of them, the Applet was shown, on the other, I only got this grey box.
The version of the iExplorer was exactly the same.
What can be wrong?

Are you sure there is a static method in the Applet class named newAudioChip that takes a URL as an argument?

How can I define the possible entries for "invoicing process" at fkkinv_ma?

At the transaction code fkkinv_ma, I fill in the fields "Date ID" and "Identification" but I have a problem with the field of "Invoicing Process". When I psh theF4 button, there comes no search help. What should I do? Should I define the possible entries first? If I should, how can I define the possible entries for "invoicing process"? How is the customization done?
Thanks in advance for the answers.

You have to define them in the IMG
Financial Accounting (new)
Contract Account Recievable and Payable
Business Transactions
Invoicing
Invoice Types
You have to set up a number range, decide what type of Financial transactions should not be invoiced -- like Dunning Charges
then you have to have a developer create the form and form class of invoice.

How do I access classes and methods defined in a wsdl file

I have been provided a wsdl file I need to find out how do I access classes and methods defined in a wsdl file directly instead of doing a wsdl2java...

Several comments :
1- is there any reason to have blank chars inserted after the path ? Seems that you already have a problem there. If possible, try to solve the problem at the source
2- the end of line char is usually CR (Carriage Return, aka ASCII char 13 = $0D = Control-D). But LF (Line Feed = 10 = $0A = control-A) is also used (platform dependent). In LV, you can use the "Concatenate strings" function to add/insert control chars (found in the String Control Palette). However, this will not solve your problem of unwanted added blank chars at the end of your string.
3- you can use the Trim white space.vi (in the "Additionnal string functions" sub-palette) to remove ALL the spaces in your string
4- you can build your own "end space remover" function. :
reverse the string, wire to a "Match pattern" function, use " +" (space + "+") to search for any number of spaces, reverse again the "after substring".
5- there is no point 5 :-)
You may find interesting description of ASCII chars here
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

SessionBean class can be defined static?

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