What is an 'instance variable'?
Can some please tell me what an 'instance variable' is? What is the difference between that and a normal variable?
An instance variable is any non-static variable in the class...this means that each time the class is intantiated, a new copy of this variable is created. Classes can also have "Static" variables in which only one copy of the variable exists among all instances of the class. If that variable is changed within any instance of the class, that change occurs for all current instances of the class.
Say you have this class:
public class Pizza
public static String shape = "Round";
public String topping;
public Pizza(String toppingIn)
topping = toppingIn;
public void changeShape(String newShape)
shape = newShape;
and you instantiate it twice
Pizza pepperoni = new Pizza("pepperoni");
Pizza sausage = new Pizza("sausague");
pepporoni.shape = "Round";
sausage.shape = "Round";
now change the value of that static variable:
pepporoni.changeShape("square");
now both sausage.shape and pepporoni.shape = "square"
Similar Messages
-
JDEVELOPER 10G, ADF BC: Passivate static instance variables in AM?
I understand the need to passivate/activate instance variables but what about static instance variables within an application module?
Thanks,
WesStatic variables - being class variables and not instance variables - persist without a need for passivation. Is there a particular reason or scenario why to use static variables? You have to consider that since all AM instances will share it, changing it in one AM instance - i.e. one user session - will affect all other AM instances - i.e. all other user sessions! You also have to consider the implications of multithreading when attempting to modify the static variable.
-
Scope of instance variables in servlets..
Hi all,
Sorry for asking a dumb question..
What is the scope of instance variables in a servlet? Is the scope is
limited to thread?
In other words, in the following example, i am setting "testStr", in one
request and when i tried to access the same instance variable from another
request, i am getting it as null. Does it mean instance variable is limited
to that particular thread/request?
thanks in advance..
-ramu
Oops ... I had misunderstood and had the problem backwards ;-)
> Is it known behavior? With registered servlet its working fine (a
> instance variable is shared by all requests)
I believe so; I typically deploy in a WAR so have not seen the problem that
you describe. Servlets can be reloaded, so what you saw could have been
caused bye a date/time mismatch between the .class file and the server's
current time. On the other hand, that could be how WebLogic works.
Peace,
Cameron Purdy
Tangosol, Inc.
http://www.tangosol.com
+1.617.623.5782
WebLogic Consulting Available
"Ramu" <[email protected]> wrote in message
news:[email protected]...
> Hi Purdy,
>
> I got it. I am testing the servlet as a unregistered servlet, which is
> creating instance for every new request!!!, which created this whole
> confusion. Is it known behavior? With registered servlet its working fine
(a
> instance variable is shared by all requests)
>
> > What theory? ;-) Instance variables are on the object, and the object
can
> > be used by multiple threads, thus allowing multiple threads to access
the
> > same instance variables.
> what i mean by theory here is, all instance variables in servlet should
be
> shared by all requests. Now i got it sir.
>
> Thank you..
> -ramu
>
>
> >
> > Peace,
> >
> > --
> > Cameron Purdy
> > Tangosol, Inc.
> > http://www.tangosol.com
> > +1.617.623.5782
> > WebLogic Consulting Available
> >
> >
> > "Ramu" <[email protected]> wrote in message
> > news:[email protected]...
> > > Hi,
> > >
> > > > No, an instance variable in a servlet class is not limited to a
> thread.
> > > There
> > > > is exactly one copy of the servlet created in memory and all
requests
> > pass
> > > > through the same instance, thus sharing any instance variables. A
> > couple
> > > of
> > > > things to remember:
> > > I totally agree with you, But i am wondering why my sample servlet(i
am
> > > attaching the file) is not sharing the instance variables across
> > > threads/reqs. (in 1st request set some string to "testStr" instance
> > > variable, in next request if you read the same instance variable, you
> will
> > > get null!!)
> > > Our current code is having instance variables. But right now we are
not
> > > getting any problems. But as per theory, instance variables should be
> > shared
> > > across threads/requests..
> > >
> > > Any how we are changing our code to remove all instance variables.
> > >
> > > thanks,
> > > -ramu
> > >
> > > >
> > > > 1.) Using instance or class variables in servlets that are not
> read-only
> > > is not
> > > > a good thing to do. This makes the servlet not thread-safe. To
> > maintain
> > > > variables across requests, sessions, etc., use the servlet-defined
> > objects
> > > to
> > > > store the state (e.g., request, session, etc.).
> > > >
> > > > 2.) If you modify the servlet class on disk, WebLogic will reload
the
> > > servlet
> > > > class thus discarding the old instance and creating a new one (of
> > course,
> > > this
> > > > depends on some configuration parameters for servlet reloading).
> > > >
> > > > Hope this helps,
> > > > Robert
> > > >
> > > > Ramu wrote:
> > > >
> > > > > Hi,
> > > > > thanks for quick reply.
> > > > > I am not at all using SingleThreadModel. See the following code.
> > > > > In first request i am passing "abc" value to testStr. But in
second
> > > request,
> > > > > I am getting null for testStr in second request. It looks like
(for
> > me)
> > > for
> > > > > non single threaded model also, scope of instance variables is
> > limited
> > > to
> > > > > Thread/Request.. But as per theory, because its not single
threaded
> > > model,
> > > > > only one instance should be there AND testStr(instace variables)
> > should
> > > be
> > > > > shared across the all threads. But i am not able see that
behaviour
> > > here.
> > > > > But if declare instance variable as static, o am able to share
it
> > > across
> > > > > all threads/requests.
> > > > >
> > > > > note:
> > > > > From browser i am setting testStr to "abc" with URL like
> > > > > "localhost/test1?testStr=abc"
> > > > > And 2nd req from browser is like "localhost/test1" (on server
> output
> > i
> > > am
> > > > > getting null for testStr)
> > > > >
> > > > > Any ideas?
> > > > >
> > > > > thanks,
> > > > > -ravi
> > > > >
> > > > > import java.io.*;
> > > > > import javax.servlet.*;
> > > > > import javax.servlet.http.*;
> > > > >
> > > > > public class test1 extends HttpServlet
> > > > > {
> > > > > public String testStr;
> > > > >
> > > > > public void doGet (HttpServletRequest req, HttpServletResponse
res)
> > > > > throws ServletException, IOException
> > > > > {
> > > > > doPost(req, res);
> > > > > }
> > > > >
> > > > > public void doPost (HttpServletRequest req,
HttpServletResponse
> > res)
> > > > > throws ServletException, IOException
> > > > > {
> > > > > try {
> > > > > res.setContentType("text/html");
> > > > > PrintWriter out = res.getWriter();
> > > > > if(req.getParameter("testStr") != null)
> > > > > {
> > > > > testStr = req.getParameter("testStr");
> > > > > System.out.println("set testStr = " + testStr);
> > > > > }
> > > > > else{
> > > > > System.out.println("get testStr = " + testStr);
> > > > > }
> > > > >
> > > > > }
> > > > > catch(Exception e){
> > > > > e.printStackTrace();
> > > > > }
> > > > >
> > > > > }
> > > > > }
> > > > >
> > > > > "Cameron Purdy" <[email protected]> wrote in message
> > > > > news:[email protected]...
> > > > > > Yes or no, depending on if your servlet implements
> > SingleThreadModel.
> > > > > >
> > > > > > See the servlet 2.2 spec for documentation on how many instances
> of
> > a
> > > > > > servlet will be created. See the doc for the SingleThreadModel
> > > interface.
> > > > > >
> > > > > > Peace,
> > > > > >
> > > > > > --
> > > > > > Cameron Purdy
> > > > > > Tangosol, Inc.
> > > > > > http://www.tangosol.com
> > > > > > +1.617.623.5782
> > > > > > WebLogic Consulting Available
> > > > > >
> > > > > >
> > > > > > "Ramu" <[email protected]> wrote in message
> > > > > > news:[email protected]...
> > > > > > > Hi all,
> > > > > > >
> > > > > > > Sorry for asking a dumb question..
> > > > > > >
> > > > > > > What is the scope of instance variables in a servlet? Is the
> scope
> > > is
> > > > > > > limited to thread?
> > > > > > >
> > > > > > > In other words, in the following example, i am setting
> "testStr",
> > in
> > > one
> > > > > > > request and when i tried to access the same instance variable
> from
> > > > > another
> > > > > > > request, i am getting it as null. Does it mean instance
variable
> > is
> > > > > > limited
> > > > > > > to that particular thread/request?
> > > > > > >
> > > > > > > thanks in advance..
> > > > > > >
> > > > > > > -ramu
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > >
> > >
> > >
> > >
> >
> >
>
>
-
1.
Can we add instance variables to an existing standard agent
e.g. can we edit the metadata file for an UNIX host (default agent installation which OEM provides) and add owr own variable ?
2.
How do we edit and add the values under "Target Properties" for each agent. Couldn't find a Save button...The following properties look empty and just wondering how do we add them ?
Comment
Line of Business
Deployment Type
Location
Contact
Thank youI dont understant what you say 'instance variables'
Provide me what are your problem or what do you need
Regards
PD: The target properties of a host or database can edit with grid control console or if you edit the targets.xml file
the agent properties also can edit if you modify the emd.properties -
What's the difference between global variables and instance variables?
hi im just a biginner,
but what is the difference between these two?
both i declare them above the constructor right.
and both can access by any method in the class but my teacher said
global variables are not permitted in java....
but i don't know what that means....and i got started to confuse these two types,,
im confusing.......
and why my teacher said declaring global variables is not permitted,,,,,,
why.....instance variables are kindof like Global variables. I'm not surprised you are confused.
The difference is not in how they are declared, but rather in how they are used.
There are two different "styles" of programming
- procedural programming.
- object oriented programming.
Global variables are a term from Procedural programming.
In this style of programming, you have only one class, and one "main" procedure. You only create one instance of the class, and then "run" it.
There is one thread of control, which goes through various methods/procedures to accomplish your task.
In this style of programming instance variables ARE "global" variables. They are accessible to all methods. There is only one instance of the class, and thus only one instance of the variables.
Global variables are "bad" BECAUSE you can change them in any method you like. Even from places that shouldn't have to. Also if you use the same name as a global variable and a local variable, you can cause great trouble. This can lead to very subtle bugs, as the procedures interact in ways you don't expect.
The preferred method in procedural programming is to pass the values as parameters to the methods, and only refer to the parameters, and local variables. This means that you can track exactly what your method is doing, and what it affects. It makes it simpler to understand. If you use global variables in your methods, it becomes harder to understand.
So when are instance variables not global variables?
When you are actually using the class as an Object, rather than just a program to run. If you are creating multiple instances of an object, all with different values for their instance variables, then they are not global variables. For instance you declare a Person object with an attribute "firstname". Your "main" program then creates many instances of the Person object, each with their own "firstname"
I guess at the end of all this, it comes down to definitions.
Certainly you can write procedural code in java. You can treat your instance variables, for all intents and purposes like global variables.
I can only think to show a sort of example
public class Test1
User[] users;
public void printUsers(){
// loop through and print all the users
// uses a global variable
for(int i=0; i<users.length; i++){
users.printUser();
public void printUsers(User[] users){
// preferred method - pass it the info it needs to do the job
for(int i=0; i<users.length; i++){
users[i].printUser();
public Test1(){
User u1 = new User("Tom", 20);
User u2 = new User("Dick", 42);
User u3 = new User("Harry", 69);
users = new User[3];
users[0] = u1;
users[1] = u2;
users[2] = u3;
printUsers();
printUsers(users);
public static void main(String[] args)
new Test1();
class User{
String firstName;
int age;
public User(String name, int age){
this.firstName = name;
this.age = age;
public void printUser(){
// here they are used as instance variables and not global variables
System.out.println(firstName + " Age: " + age);
Shit thats a lot of typing, and I'm not even sure I've explained it any good.
Hope you can make some sense out of this drivel.
Cheers,
evnafets -
What is the difference between Instance variable and Global variable?
Hi folks,
Could you please explain me, "what is the difference between Instance variable and Global variable?"
Are they really same or not?
--SubbuHi flounder,
I too know that there is no such a term GLOBAL in java.
generally people use to say a variable which is accessible throught out the class or file has global access
and that will be called as a global variable...
my point is very much similar to what Looce said.
In simple that is not a technical term, but just a causual term.
In technically my question is, "What is the difference between a instance variable and public variable?".
Hi looce,
Thanks for the reply. even thats what my understanding too....in order to confirm that i raised this question..
Your reply has given a clear answer...... thanks again.
--Subbu -
How to use an BPM Instance Variable in JSP page
Hi All,
I am using the JSP Presentation, but i don't know how to use an Instance variable in JSP page, that instance already declared in the process. And Can u explain the syntax that to include the JS file into jsp page
Regards
Vasu.
Edited by bpmvasu at 04/03/2007 10:43 PMHi Mariano,
I'm using JSP presentation too. In "Interactive Component Call" active i'm using "Use JSP presentation", but i only can define one instance variable, i need to add more instance variables. In "Advanced" option of this task, i have the argument mapping .. but i don't understand how to use it.
I have a instance variable called "genders" of the type String[Int] (Associative Array) and i'm mapping this instance variable in "Arguments Show In" option of the advanced option of JSP presentation. In JSP presentation i have the code:
<select <f:fieldName att="person.gender"/>>
<c:forEach var="gender" begin="0" items="${genders}" varStatus="status">
<c:choose>
<c:when test="${person.gender == gender}">
<option value="<c:out value="${gender}"/>" selected="true"><c:out value="${gender}"/></option>
</c:when>
<c:otherwise>
<option value="<c:out value="${gender}"/>"><c:out value="${gender}"/></option>
</c:otherwise>
</c:choose>
</c:forEach>
</select>And in my screenflow i have the code:
genders[0] = "Male"
genders[1] = "Female"But when i run my application, i have the error: "The task could not be successfully executed. Reason: 'java.lang.ClassCastException: java.lang.Integer'."
What's the problem? -
Instance variable to hold the element of a tag in the xml file
Hi I have an xml file that is handled using this parser
<attr id="MY_NAME" >
this parser hanled the above tag but now I want to have it handle
<attr id="MY_NAME" desc="GOOD">
but I need to create an instance variable to handle the desc element in the attr tag .
Can some one help me out as this is not my file and I am having trouble to do please......
import java.util.*;
import java.io.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
The SupportMatrix class provides static variables and methods to simplify
the determination of whether or not a given attribute is supported for a
certain object type (queue manager, channel, etc.), depending on the version
and platform of the queue manager to which it belongs.
The SupportMatrix class may not be instantiated. Its constructor is private.
An instance of the class is created internally in the static initializer so
that the XML parsing methods are available.
A corresponding XML document, SupportMatrix.xml, is parsed to create the various
HashMaps which contain the version/platform dependency information. A number of
inner classes are used to represent the various elements of the XML matrix
definition.
Here's a sample document:
<!-- The supportmatrix tag opens the document -->
<supportmatrix>
<!-- Objects are keyed by classid. "1" is the classid of a queue manager object. -->
<object classid="1">
<!-- Versions group attributes according to the queue manager version where they
were introduced. The "base" cmdlevel encompasses all versions up to 5.1. -->
<version cmdlevel="base">
<!-- Attributes are defined by the attr tag. -->
<attr id="MQCA_Q_MGR_NAME">
<!-- Support elements define the platform-specific requirements for an attribute. -->
<support platforms="UNIX,WINDOWS,OS400,VMS,NSK" maxlen="48" type="MQCFST"/>
<support platforms="MVS" maxlen="4" type="MQCFST"/>
</attr>
<attr id="MQCA_Q_MGR_DESC">
<!-- Specific attribute characteristics, most notably maximum len for string parms,
are defined in the support element. As shown in the following example, it may
apply to all platforms. -->
<support platforms="all" maxlen="64" type="MQCFST"/>
</attr>
<!-- Support elements are optional. -->
<attr id="MQIA_PLATFORM"/>
<attr id="MQIA_COMMAND_LEVEL"/>
</version>
<!-- The version element may 'include' other versions. Note that object elements
may also refer to other objects via the 'include' parm of the object tag.
This is to allow common attributes (especially for queues and channels) to
be shared by multiple definitions in order to reduce some of the
redundancy. -->
<version cmdlevel="520" include="base">
</version>
</object>
</supportmatrix>
The inner classes, and their hierarchical relationships are as follows:
SupportObject - corresponds to the <object> element. Stored in a static HashMap, and
keyed by classid.
VersionObject - corresponds to the <version> element. Stored in a HashMap instance
variable of the SupportObject class, keyed by cmdlevel.
AttributeObject - corresponds to the <attr> element. Stored in a HashMap instance
variable of the VersionObject class, keyed by attribute name.
PlatformObject - corresponds to the <support> element. Stored in HashMaps belonging
to the AttributeObjects, keyed by platform. A single PlatformObject
instance is created when the support tag is encountered. The
"platforms" attribute of the support element is then processed. For
each platform in the comma-delimited list, an entry is added to the
collection of PlatformObjects. This is to greatly simplify later
lookups.
In order to support the 'include' feature of object and version elements, certain
functions are recursive. If the attribute to be validated is not found for the passed
cmdlevel, the 'parent' VersionObject is consulted by means of the 'include' value. If
the chain of VersionObjects has been exhausted and the attribute in question has still not
been located, the next SupportObject in the chain is consulted in a similar fashion.
public class SupportMatrix extends DefaultHandler {
/** The objects collection holds all the SupportObjects, keyed by classid. */
private static HashMap objects;
/** xmlFile will name the xml document to be parsed. Note that using the
default class loader expects the string to be the path to the file. It must
NOT begin with the '/' character. */
private static String xmlFile =
ResourceManager.getApplicationProperties().getProperty("SupportMatrixFile");
private Stack stack;
/** This static initializer allocates the static objects collection, creates an
instance of the SupportMatrix class for xml parsing purposes, and initiates
the parse operation to populate the collection. */
static {
objects = new HashMap();
// Create a parser and process the xml doc
SupportMatrix handler = new SupportMatrix();
InputSource is = null;
try {
is = new InputSource(ClassLoader.getSystemClassLoader().getResourceAsStream(xmlFile));
XMLReader xmlReader =
SAXParserFactory.newInstance().newSAXParser().getXMLReader();
xmlReader.setFeature("http://xml.org/sax/features/namespaces", true);
xmlReader.setContentHandler(handler);
if (is == null) {
System.err.println("No input stream, dammit");
xmlReader.parse(is);
} catch(Exception e) {
e.printStackTrace();
/** Private constuctor, used only for XML parsing. */
private SupportMatrix() {
stack = new Stack();
/** Add a SupportObject instance to the objects collection. */
private void addObject(SupportObject obj) {
String key = obj.getClassId();
objects.put(key, obj);
/* DefaultHandler methods */
/** Not used. */
public void characters(char[] ch, int start, int length) {}
/** Not used. */
public void endDocument() {}
/** For the version, object, and attr elements, pop the top element of the stack. */
public void endElement(String uri, String localName, String qName) {
if (localName.equals("version") || localName.equals("object") || localName.equals("attr")) {
stack.pop();
/** Not used. */
public void setDocumentLocator(Locator locator) {}
/** Not used. */
public void startDocument() {}
/** Most of the work is done here. Create the appropriate inner class instance for
element; for object, version, and attr, push the element onto the stack so that
child elements may be added to their collections as needed. */
public void startElement(String uri, String localName, String qName,
Attributes attributes) {
String include = attributes.getValue("include");
if (localName.equals("object")) {
SupportObject obj = new SupportObject(attributes.getValue("classid"), include);
addObject(obj);
stack.push(obj);
} else if ( localName.equals("version")) {
VersionObject ver = new VersionObject(attributes.getValue("cmdlevel"), include);
((SupportObject)stack.peek()).addVersion(ver);
stack.push(ver);
} else if ( localName.equals("attr")) {
AttributeObject a = new AttributeObject(attributes.getValue("id"));
//String desc = StringFactory.getString(attributes.getValue("desc"));
//if(desc != null)
// a.setAttribute();
String readonly = attributes.getValue("readonly");
String exclude = attributes.getValue("exclude");
if (include != null && exclude != null) {
Log.log(Log.ERROR, this, "include and exclude are mutually exclusive, exclude value ignored");
exclude = null;
if (include != null) {
a.setCondition(include, true);
if (exclude != null) {
a.setCondition(exclude, false);
if (readonly != null)
a.setReadonly(readonly.equals("y"));
((VersionObject)stack.peek()).addAttr(a);
stack.push(a);
} else if (localName.equals("support")) {
String platforms = attributes.getValue("platforms");
String readonly = attributes.getValue("readonly");
String maxlen = attributes.getValue("maxlen");
String type = attributes.getValue("type");
int attrType = 0;
if (type != null) {
if (type.equals("MQCFIN")) {
attrType = CMQCFC.MQCFT_INTEGER;
} else if (type.equals("MQCFIL")) {
attrType = CMQCFC.MQCFT_INTEGER_LIST;
} else if (type.equals("MQCFST")) {
attrType = CMQCFC.MQCFT_STRING;
} else if (type.equals("MQCFSL")) {
attrType = CMQCFC.MQCFT_STRING_LIST;
} else if (type.equals("EXBIN")) {
attrType = MqcConstants.EXCFT_BINARY;
} else if (type.equals("EXPCF")) {
attrType = MqcConstants.EXCFT_PCF;
PlatformObject p = null;
if (readonly == null) {
p = new PlatformObject(platforms);
} else {
p = new PlatformObject(platforms, readonly.equals("y"));
String exclude = attributes.getValue("exclude");
if (include != null && exclude != null) {
Log.log(Log.ERROR, this, "include and exclude are mutually exclusive, exclude value ignored");
exclude = null;
if (include != null)
p.setCondition(include, true);
if (exclude != null)
p.setCondition(exclude, false);
if (attrType != 0)
p.setType(attrType);
if (maxlen != null)
p.setLen(Integer.parseInt(maxlen));
((AttributeObject)stack.peek()).addPlatform(p);
public static boolean isExported(int attribute, TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isExported(name, node);
public static boolean isExported(String attribute, TopologyModelNode node) {
// Find the qmgr node to fetch platform and cmdlevel
TopologyModelNode qmgr = node.getModel().getQMgrNode(node.getAddress());
// If there's no qmgr for this node, it must be one of 'ours'.
if (qmgr == null)
return false; // None of 'our' objects can be exported to MQSC.
String classId = node.getClassId();
String cmdLevel = qmgr.getAttributeValue("MQIA_COMMAND_LEVEL");
String platform = qmgr.getAttributeValue("MQIA_PLATFORM");
return isExported(attribute, classId, cmdLevel, platform, node);
public static boolean isExported(int attribute, String classId, String cmdLevel, String platform,
TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isExported(name, classId, cmdLevel, platform, node);
/** Determine if an attribute is exportable. The attribute name, the classid of the object to
which it belongs, plus the command level and platform of the queue manager are all needed
to make this determination.
Start by finding the AttributeObject for the combination of attribute, classid, and
command level. If we can't find the AttributeObject, we assume that the attribute
is not exported. Otherwise, find out if it is exportable for the selected platform.
public static boolean isExported(String attribute, String classId, String cmdLevel, String platform,
TopologyModelNode node) {
AttributeObject attr = getAttributeObject(attribute, classId, cmdLevel);
if (attr == null) {
return false;
} else {
return attr.isExported(platform, node);
public static boolean isSupported(int attribute, TopologyModelNode node) {
String name = ResourceManager.getAttributeName(attribute);
return isSupported(name, node);
public static boolean isSupported(String attribute, TopologyModelNode node) {
// Find the qmgr node to fetch platform and cmdlevel
TopologyModelNode qmgr = node.getModel().getQMgrNode(node.getAddress());
// If there's no qmgr for this node, it must be one of 'ours'.
if (qmgr == null)
return true;
String classId = node.getClassId();
String cmdLevel = qmgr.getAttributeValue("MQIA_COMMAND_LEVEL");
String platform = qmgr.getAttributeValue("MQIA_PLATFORM");
return isSupported(attribute, classId, cmdLevel, platform);
public static boolean isSupported(int attribute, String classId, String cmdLevel, String platform) {
String name = ResourceManager.getAttributeName(attribute);
return isSupported(name, classId, cmdLevel, platform);
/** Determine if an attribute is supported. The attribute name, the classid of the object to
which it belongs, plus the command level and platform of the queue manager are all needed
to make this determination.
Start by finding the SupportObject for the classid. If it isn't there, we make the assumption
(for now) that the attribute is supported. The only classids for which this can occur are
broker, agent, and the various container objects.
Propagate the isSupported request to the chain of SupportObjects (based on 'include' values)
until we get a 'true' result or we run out of SupportObjects. */
public static boolean isSupported(String attribute, String classId, String cmdLevel, String platform) {
if (attribute == null)
return false;
SupportObject obj = (SupportObject)objects.get(classId);
// If the object type isn't even in the support matrix, we interpret that to
// mean that it's a Broker or Agent, in which case all attributes are supported
// at present.
if (obj == null)
return true;
boolean result = false;
while (result == false && obj != null) {
result = obj.isSupported(attribute, cmdLevel, platform);
if (result == false && obj.getInclude() != null) {
obj = (SupportObject)objects.get(obj.getInclude());
} else
obj = null;
return result;
/** Locate an AttributeObject for a given attribute name, object type, and command level.
This is a helper function for the getMaxLen and getType methods. */
private static AttributeObject getAttributeObject(String attr, String classID, String cmdLevel) {
AttributeObject result = null;
SupportObject obj = (SupportObject)objects.get(classID);
while (result == null && obj != null) {
result = obj.getAttr(attr, cmdLevel);
if (result == null && obj.getInclude() != null) {
obj = (SupportObject)objects.get(obj.getInclude());
} else
obj = null;
return result;
/** Determine the maximum length for a given combintation of attribute name, object type,
command level, and platform. If the AttributeObject can't be found, or if the length
hasn't been set, return -1. */
public static int getMaxLen(String attr, String classId, String cmdLevel, String platform) {
AttributeObject a = getAttributeObject(attr, classId, cmdLevel);
if (a == null)
return -1;
return a.getMaxLen(platform);
/** Determine the PCF parm type for a given combintation of attribute name, object type,
command level, and platform. If the AttributeObject can't be found, or if the length
hasn't been set, return -1. */
public static int getType(String attr, String classId, String cmdLevel, String platform) {
AttributeObject a = getAttributeObject(attr, classId, cmdLevel);
if (a == null)
return -1;
return a.getType(platform);
/** Inner class to contain platform-specific info for an attribute. */
class PlatformObject {
/** This instance variable will contain the comma-delimited string of all
platforms to which this object applies. */
private String platform;
private int maxlen;
private String condition = null;
private boolean include;
private boolean readonly;
private boolean lenSet;
private int attrType;
private boolean typeSet;
public PlatformObject(String p, boolean readonly) {
platform = p;
this.readonly = readonly;
lenSet = false;
typeSet = false;
public PlatformObject(String p) {
this(p, false);
public void setCondition(String condition, boolean include) {
this.condition = condition;
this.include = include;
public boolean isReadonly() {
return readonly;
public boolean isExported(TopologyModelNode node) {
if (condition != null) {
boolean test = false;
try {
test = Utilities.evaluateCondition(node, condition);
} catch (Exception e) {}
if (include ^ test)
return false;
return !readonly;
public void setLen(int len) {
maxlen = len;
lenSet = true;
public void setType(int type) {
attrType = type;
typeSet = true;
public String getPlatform() {
return platform;
public int getMaxLen() {
if (!lenSet)
return -1;
return maxlen;
public int getType() {
if (!typeSet)
return -1;
return attrType;
/** This class represents a specific MQSeries attribute. It can optionally contain
instances of the PlatformObject class as needed. When the 'platforms' collection
is empty, the attribute is supported on all platforms. It is also possible to
include a PlatformObject for the 'all' platform, if specific attribute characteristics
need representation. When the 'platforms' collection is non-empty, it will include one
entry for each platform where the attribute is supported. */
class AttributeObject {
private String attribute;
private String attrValue;
private HashMap platforms;
private String condition = null;
private boolean include;
private boolean readonly = false;
public AttributeObject(String a) {
this(a, false);
public AttributeObject(String a, boolean readonly) {
attribute = a;
platforms = new HashMap();
this.readonly = readonly;
public void setCondition(String condition, boolean include) {
this.condition = condition;
this.include = include;
public void setReadonly(boolean readonly) {
this.readonly = readonly;
public boolean isReadonly() {
return readonly;
public void addPlatform(PlatformObject p) {
for (StringTokenizer st = new StringTokenizer(p.getPlatform(), ","); st.hasMoreTokens() ;) {
platforms.put(st.nextToken(), p);
public PlatformObject getPlatform(String platform) {
PlatformObject p = (PlatformObject)platforms.get(platform);
if (p == null)
p = (PlatformObject)platforms.get("all");
return p;
public String getAttribute() {
return attribute;
public int getMaxLen(String platform) {
PlatformObject p = getPlatform(platform);
if (p == null)
return -1;
return p.getMaxLen();
public int getType(String platform) {
PlatformObject p = getPlatform(platform);
if (p == null)
return -1;
return p.getType();
public boolean isSupported(String platform) {
if (platforms.isEmpty()) {
return true;
if (platforms.containsKey(platform)) {
return true;
if (platforms.containsKey("all")) {
return true;
return false;
public boolean isExported(String platform, TopologyModelNode node) {
if (readonly) {
Log.log(Log.DEBUG, this, attribute + " is readonly, returning false");
return false;
if (condition != null) {
Log.log(Log.DEBUG, this, "Testing condition = " + condition);
boolean test = false;
try {
test = Utilities.evaluateCondition(node, condition);
Log.log(Log.DEBUG, this, "Condition result is " + test);
} catch (Exception e) {
Log.log(Log.ERROR, this, "Condition through an exception");
if (include ^ test)
return false;
if (platforms.isEmpty()) {
return true;
PlatformObject p = getPlatform(platform);
if (p == null) {
Log.log(Log.DEBUG, this, platform + " not found for " + attribute + ", returning false");
return false;
return p.isExported(node);
/** This class represents a specific value of a queue manager's command level. A
given instance of this class may 'include' a 'parent' instance through its
include instance variable. The traversal of the parent/child hierarchy is
delegated to the SupportObject class, since that is where the collection of
VersionObjects lives. */
class VersionObject {
private String cmdLevel;
private String include;
private HashMap attributes;
public VersionObject(String cmdLevel, String include) {
this.cmdLevel = cmdLevel;
this.include = include;
attributes = new HashMap();
public void addAttr(AttributeObject attr) {
attributes.put(attr.getAttribute(), attr);
public AttributeObject getAttr(String attr) {
return (AttributeObject)attributes.get(attr);
public String getCmdLevel() {
return cmdLevel;
public String getInclude() {
return include;
public boolean isSupported(String attr, String platform) {
AttributeObject obj = (AttributeObject)attributes.get(attr);
if (obj == null) {
return false;
} else
return obj.isSupported(platform);
/** This class represents an MQSeries object type, as identified by its classid, e.g.
queue manager or local queue. This class implements an include facility similar to
that described for the VersionObject. The traversal of that hierarchy is delegated
to the static isSupported method, because the collection of SupportObject instances
is a static variable of the SupportMatrix class. */
class SupportObject {
private String classId;
private String include;
private HashMap versions;
public SupportObject(String classId, String include) {
this.classId = classId;
this.include = include;
versions = new HashMap();
public void addVersion(VersionObject obj) {
String key = obj.getCmdLevel();
versions.put(key, obj);
public String getClassId() {
return classId;
public String getInclude() {
return include;
public boolean isSupported(String attr, String cmdLevel, String platform) {
boolean result = false;
VersionObject obj = (VersionObject)versions.get(cmdLevel);
if (obj == null)
obj = (VersionObject)versions.get("base");
// I don't actually know what it means if obj is null at this point.
// It probably can't happen.
if (obj == null)
return false;
while (result == false && obj != null) {
result = obj.isSupported(attr, platform);
if (result == false && obj.getInclude() != null) {
obj = (VersionObject)versions.get(obj.getInclude());
} else
obj = null;
return result;
public AttributeObject getAttr(String attr, String cmdLevel) {
AttributeObject result = null;
VersionObject obj = (VersionObject)versions.get(cmdLevel);
if (obj == null)
obj = (VersionObject)versions.get("base");
// I don't actually know what it means if obj is null at this point.
// It probably can't happen.
if (obj == null)
return null;
while (result == null && obj != null) {
result = obj.getAttr(attr);
if (result == null && obj.getInclude() != null)
obj = (VersionObject)versions.get(obj.getInclude());
else
obj = null;
return result;
}Are you the one who commented out the code you're looking for ?//String desc = StringFactory.getString(attributes.getValue("desc"));You just have to modify you AttributeObject class to hold a new field : String description. And then, it's up to you to create a new constructor or a new setter method.
Btw, this is not a Swing related question. -
What are the systems variables in oracle
Hai All
In oracle what is called system variable and types of system variables
Good answer hepls me
Thanks & Regards
Srikkanth.MSET System Variable Summary
Source:http://download.oracle.com/docs/cd/B19306_01/server.102/b14357/ch12040.htm
Oracle environment variables
The following environment variables are valid for Oracle::
ORACLE_HOME
ORACLE_BASE (optional)
ORA_NLS (optional)
NLS_LANG (optional)
TNS_ADMIN (optional)
Source:http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp?topic=/com.ibm.websphere.ii.foundation.conn.fw.orc.doc/configuring/iiylsorcenvvars.html
ORACLE_SID is the name of the database instance that you are using.
T2KDEV is set to the type of terminal you are using; sun if you are using openwindows; xsun if you are using X windows.
TERM is set to the type of terminal you are using. Note: If you are using openwindows, you may have to redefine the variable TERM to sun (instead of cmd-sun) and you should execute ORACLE from a shelltool.
TWO_TASK is set to the location where ORACLE server can be found and will normally be the name of the database instance. This variable helps simplify the command line for starting ORACLE tools.
Source:http://ugweb.cs.ualberta.ca/~c391/manual/chapt3.html
HTH
Girish Sharma
Edited by: Girish Sharma on Mar 3, 2010 9:16 AM
Link and Text added. -
Not able to access parent instance variable in outside of methods in child
Hi,
I am not getting why i am not able to access parent class instance variable outside the child class intance methods.
class Parent
int a;
class Child extends Parent
a = 1; // Here i am getting a compilation error that Syntax error on token "a", VariableDeclaratorId expected after this token
void someMethod()
a = 1; // Here i am not getting any compilation error while accessing parent class variable
}Can any one please let me know exact reason for this and what is the error talks about?
Thanks,
Uday
Edited by: Udaya Shankara Gandhi on Jun 13, 2012 3:30 AMYou can only put assignments or expressions inside methods, constructors or class initializors, or when declaring a variable.
It has nothing to the with Child extending Parent.
class Parent {
int a = 1;
{ a = 1; }
public Parent() {
a = 1;
public void method() {
a = 1;
} -
What is a container variable in BPM (Exchange Infrastructure)?
In BPM scenario with Exchange Infrastructure, I have come across container variable. What is this container variable? How it is used in BPM?
In another instance I read that to trigger a alert in BPM I have to create a container variable. So I have another question, What steps I have to follow to create a container variable and trigger alert?Hi,
To create alerts in XI , check this blog,
/people/michal.krawczyk2/blog/2005/09/09/xi-alerts--step-by-step
ALso, if you are on SP14 and above, check this note 913858.
The container variables that are accepted while createing Alerts in XI are available on this link,
http://help.sap.com/saphelp_nw04/helpdata/en/d0/d4b54020c6792ae10000000a155106/content.htm
Regards,
Bhavesh -
I have some questions about JSP presentation (Interactive Component Call in Screenflow):
- Only BPM Objects are possible to be mapped in JSP?
- Is possible to map two or more BPM Objects to the JSP?
- What is the difference of mapping using the variable "attributes" in argument mapping and the option "Select BPM object variable" in main task of Interactive Component Call activity?I seem to be having a similar problem.
If I include this fragment, for an instance variable called "contacts" which is a BPMObject of type "ITSSContactRequest".
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
%>
I get the following output:
xobject.ITSSContactManagement.ITSSContactRequest
and I can access the object via reflection:
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
Method getGeneralContacts = cl.getMethod("getGeneralContacts", null);
Object rv = getGeneralContacts.invoke(r);
%>
and access the rv variable accordingly.
However, if I try and cast the variable directly:
<%
Object r = request.getAttribute("contacts");
Class cl = r.getClass();
out.println(cl.getName());
xobject.ITSSContactManagement.ITSSContactRequest rq = (xobject.ITSSContactManagement.ITSSContactRequest)r;
%>
I get the following error message:
"The task could not be successfully executed. Reason: 'fuego.web.execution.exception.InternalForwardException: UnExpected error during internal forward process.'.
See log file for more information [Error code: workspace-1258985548580] "
The same error occurs if I try and import the object via
<%@ page import="xobject.ITSSContactManagement.ITSSContactRequest" %>
Thanks for any help. -
How to wash out an AM instance variable at the end of user session (logout)
We have a need to create AM instance variables to hold some session level data, which is too complex to be held in a transient VO.
What we observed is that the instance variable is not washed out at the end of the user session (i.e logout).
I think since the AM instance is not really destroyed but only release back to the pool the instance variable content persists and is carried over to the next session that access the AM instance.
What method in AM can be overridden to wash out this instance variable.
At the moment we are resetting it in prepareSession(), but this means that the information is still held till the next session access the AM.
It would be better to reset it when the AM is released back to the pool.
Any pointers would be helpful.At the moment we are resetting it in prepareSession(), but this means that the information is still held till the next session access the AM.
Note that prepareSession() is also invoked after AM activation so this can(and probaly will) reset your variable inside existing session.
If you don't need to keep variable value between AM activations/passivations, you can use userData, for example:
this.getSession().getUserData().put("someKey", value);
UserData values are lost after AM passivation (by default).
If you need to keep UserData variable value for lifetime of user session, then you can override passivateState() and activateState() as in this sample:
Application State Management
Dario -
About "method", "instance variable" and "constructor"
Does a method need to be initialise?? if yes, how to write the code?
for example,is it:
public String mymethod( String args[]); ?
public double mymethod2 (); ?
what is the meaning of "instance variable" and "constructor"?
Please help.....THANKS!Previously posted to this OP:
Read the Java Tutorial: Learning the Java Language.
http://java.sun.com/docs/books/tutorial/java/index.html
� {� -
Binding a JavaFX variable to a Java class instance variable
Hi,
I am pretty new to JavaFX but have been developing in Java for many years. I am trying to develop a JavaFX webservice client. What I am doing is creating a basic scene that displays the data values that I am polling with a Java class that extends Thread. The Java class is reading temperature and voltage from a remote server and storing the response in an instance variable. I would like to bind a JavaFx variable to the Java class instance variable so that I can display the values whenever they change.
var conn: WebserviceConnection; // Java class that extends Thread
var response: WebserviceResponse;
try {
conn = new WebserviceConnection("some_url");
conn.start();
Thread.sleep(10000);
} catch (e:Exception) {
e.printStackTrace();
def bindTemp = bind conn.getResponse().getTemperature();
def bindVolt = bind conn.getResponse().getVoltage();
The WebserviceConnection class is opening a socket connection and reading some data in a separate thread. A regular socket connection is used because the server is not using HTTP.
When I run the application, the bindTemp and bindVolt are not updated whenever new data values are received.
Am I missing something with how bind works? Can I do what I want to do with 'bind'. I basically want to run a separate thread to retrieve data and want my UI to be updated when the data changes.
Is there a better way to do this than the way I am trying to do it?
Thanks for any help in advance.
-RichardHi,
If you don't want to constantly poll for value change, you can use the observer design pattern, but you need to modify the classes that serve the values to javafx.
Heres a simple example:
The Thread which updates a value in every second:
// TimeServer.java
public class TimeServer extends Thread {
private boolean interrupted = false;
public ValueObject valueObject = new ValueObject();
@Override
public void run() {
while (!interrupted) {
try {
valueObject.setValue(Long.toString(System.currentTimeMillis()));
sleep(1000);
} catch (InterruptedException ex) {
interrupted = true;
}The ValueObject class which contains the values we want to bind in javafx:
// ValueObject.java
import java.util.Observable;
public class ValueObject extends Observable {
private String value;
public String getValue() {
return this.value;
public void setValue(String value) {
this.value = value;
fireNotify();
private void fireNotify() {
setChanged();
notifyObservers();
}We also need an adapter class in JFX so we can use bind:
// ValueObjectAdapter.fx
import java.util.Observer;
import java.util.Observable;
public class ValueObjectAdapter extends Observer {
public-read var value : String;
public var valueObject : ValueObject
on replace { valueObject.addObserver(this)}
override function update(observable: Observable, arg: Object) {
// We need to run every code in the JFX EDT
// do not change if the update method can be called outside the Event Dispatch Thread!
FX.deferAction(
function(): Void {
value = valueObject.getValue();
}And finally the main JFX code which displays the canging value:
// Main.fx
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import threadbindfx.TimeServer;
var timeServer : TimeServer;
var valueObjectAdapter : ValueObjectAdapter = new ValueObjectAdapter();
timeServer = new TimeServer();
valueObjectAdapter.valueObject = timeServer.valueObject;
timeServer.start();
Stage {
title: "Time Application"
width: 250
height: 80
scene: Scene {
content: Text {
font : Font {
size : 24
x : 10, y : 30
content: bind valueObjectAdapter.value;
}This approach uses less cpu time than constant polling, and changes aren't dependent on the polling interval.
However this cannot be applied to code which you cannot change obviously.
I hope this helps.
Maybe you are looking for
-
Need help setting up a network with new Airport Extreme
Hey All I need some help. Networks, Wan, WPA it's all greek to me. Here's what I am trying to do, I have a newer imac, an ipod touch, a apple TV and the kids have a laptop running on Vista. I have a DSL internet connection through Verizon with a West
-
EA2 - Cannot connect LDAP-authenticated users in 10.1 and 10.2, OK in 9.2
First, the relevant versions and such: SQL Developer 1.5.0.52.03 (aka EA2) Oracle client 10.2.0.1 Oracle database 9.2.0.6, 9.2.0.7, 10.1.0.5, 10.2.0.2, 10.2.0.3. Hosts: Linux x86, Solaris Most of the users in my databases are set up as global users (
-
How to create a smooth transition from end of a movie clip to beginning of a movie clip?
I have a motion tween that is 180 frames in length. When the tween ends on the last frame and returns to the first frame to replay there is a slight jump in the tween. Is there anyway to stop the tween from jumping from last frame to the first?
-
Http request receives incomplete data
Hi, I have an application reading one free format file via http request. This is implemented as stored procedure in a 8.1.6 database on Windows NT. The method readContent (pasted later on)takes the BufferedReader of an InputStreamReader of the InputS
-
At the time of confirmation Costs are loaded to Production order
Dear All, At the time of confirmation of the Production orders the costs are not debited/loaded to the Production order. They are not credited to the cost centers although all the necessay master data (Work centers, Cost centers, cost rates ) is ther