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  • C++ design question on traversing binary trees

    - by user231536
    I have a binary tree T which I would like to copy to another tree. Suppose I have a visit method that gets evaluated at every node: struct visit { virtual void operator() (node* n)=0; }; and I have a visitor algorithm void visitor(node* t, visit& v) { //do a preorder traversal using stack or recursion if (!t) return; v(t); visitor(t->left, v); visitor(t->right, v); } I have 2 questions: I settled on using the functor based approach because I see that boost graph does this (vertex visitors). Also I tend to repeat the same code to traverse the tree and do different things at each node. Is this a good design to get rid of duplicated code? What other alternative designs are there? How do I use this to create a new binary tree from an existing one? I can keep a stack on the visit functor if I want, but it gets tied to the algorithm in visitor. How would I incorporate postorder traversals here ? Another functor class?

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  • Question about 'git branching'

    - by michael
    Hi, I read this about git branch: http://book.git-scm.com/3_basic_branching_and_merging.html so I follow it and create 1 branch : experimental And I 1. switch to experimental branch (git checkout experimental) 2. make a bunch of changes 3. commit it (git commit -a) 4. switch to master branch (git checkout master) 5. make some changes and commit there 6. switch back to experimental (git checkout experimental) 7. merge master change to experimental (git merge master) 8. there are some conflicts but after I resolve them, I did 'git add myfile' And now i am stuck, I can't move back to master when I do $ git checkout master error: Entry 'res/layout/my_item.xml' would be overwritten by merge. Cannot merge. and I did: $ git rebase --abort No rebase in progress? and I did : $ git add res/layout/socialhub_list_item.xml $ git checkout master error: Entry 'res/layout/my_item.xml' would be overwritten by merge. Cannot merge. What can I do so that I can go back to my master branch? Thank you.

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  • WPF Combobox binding Question

    - by ebattulga
    I have a 2 Table. Product ProductName CategoryID Category ID CategoryName I'm filling combobox to table named 'category'. Code Product currentProduct=datacontext.products.FirstOrDefault(); this.datacontext=currentProduct; combobox1.Itemssource=datacontext.categories; XAML <Textbox Text="{Binding Path=ProductName}"></Textbox> <Combobox x:Name="combobox1" SelectedItem="Binding Path=CategoryID"></Combobox> When click save button, I'm doing datacontext.SubmitChanges() ProductName changed. But CategoryID not changed. My target is when i select from combobox, selected category ID set to CategoryID of currentProduct. (like currentProduct.CategoryID=(Category as combobox1.SelectedItem).ID) How to do is from xaml?

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  • Resilient backpropagation neural network - question about gradient

    - by Raf
    Hello Guys, First I want to say that I'm really new to neural networks and I don't understand it very good ;) I've made my first C# implementation of the backpropagation neural network. I've tested it using XOR and it looks it work. Now I would like change my implementation to use resilient backpropagation (Rprop - http://en.wikipedia.org/wiki/Rprop). The definition says: "Rprop takes into account only the sign of the partial derivative over all patterns (not the magnitude), and acts independently on each "weight". Could somebody tell me what partial derivative over all patterns is? And how should I compute this partial derivative for a neuron in hidden layer. Thanks a lot UPDATE: My implementation base on this Java code: www_.dia.fi.upm.es/~jamartin/downloads/bpnn.java My backPropagate method looks like this: public double backPropagate(double[] targets) { double error, change; // calculate error terms for output double[] output_deltas = new double[outputsNumber]; for (int k = 0; k < outputsNumber; k++) { error = targets[k] - activationsOutputs[k]; output_deltas[k] = Dsigmoid(activationsOutputs[k]) * error; } // calculate error terms for hidden double[] hidden_deltas = new double[hiddenNumber]; for (int j = 0; j < hiddenNumber; j++) { error = 0.0; for (int k = 0; k < outputsNumber; k++) { error = error + output_deltas[k] * weightsOutputs[j, k]; } hidden_deltas[j] = Dsigmoid(activationsHidden[j]) * error; } //update output weights for (int j = 0; j < hiddenNumber; j++) { for (int k = 0; k < outputsNumber; k++) { change = output_deltas[k] * activationsHidden[j]; weightsOutputs[j, k] = weightsOutputs[j, k] + learningRate * change + momentumFactor * lastChangeWeightsForMomentumOutpus[j, k]; lastChangeWeightsForMomentumOutpus[j, k] = change; } } // update input weights for (int i = 0; i < inputsNumber; i++) { for (int j = 0; j < hiddenNumber; j++) { change = hidden_deltas[j] * activationsInputs[i]; weightsInputs[i, j] = weightsInputs[i, j] + learningRate * change + momentumFactor * lastChangeWeightsForMomentumInputs[i, j]; lastChangeWeightsForMomentumInputs[i, j] = change; } } // calculate error error = 0.0; for (int k = 0; k < outputsNumber; k++) { error = error + 0.5 * (targets[k] - activationsOutputs[k]) * (targets[k] - activationsOutputs[k]); } return error; } So can I use change = hidden_deltas[j] * activationsInputs[i] variable as a gradient (partial derivative) for checking the sing?

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  • HttpURLConnection timeout question

    - by Malachi
    I want to return false if the URL takes more then 5 seconds to connect - how is this possible using java? Here is the code I am using to check if the URL is valid HttpURLConnection.setFollowRedirects(false); HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection(); con.setRequestMethod("HEAD"); return (con.getResponseCode() == HttpURLConnection.HTTP_OK);

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  • XML::LibXML::XPathContext - Question

    - by sid_com
    This script works with and without XPathContext. Why should I use it with XPathContext? #!/usr/bin/env perl use warnings; use strict; use XML::LibXML; use 5.012; my $parser = XML::LibXML->new; my $doc = $parser->parse_string(<<EOT); <?xml version="1.0"?> <xml> Text im Dokument <element id="myID" name="myname" style="old" /> <object objid="001" objname="Object1" /> <element id="002" name="myname" /> </xml> EOT #/ # without XPathContext my $nodes = $doc->findnodes( '/xml/element[@id=002]' ); # with XPathContext #my $root = $doc->documentElement; #my $xc = XML::LibXML::XPathContext->new( $root ); #my $nodes = $xc->findnodes( '/xml/element[@id=002]' ); for my $node ( $nodes->get_nodelist ) { say "Node: ", $node->nodeName; print "Attribute: "; print $_->getName, '=', $_->getValue, ' ' for $node->attributes; say ""; }

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  • WPF MVVM Pattern, ViewModel DataContext question

    - by orangecl4now
    I used this side to create my demo application http://windowsclient.net/learn/video.aspx?v=314683 The site was very useful in getting my started and in their example, they created a file called EmployeeRepository.cs which appears to be the source for the data. In their example, the data was hard-wired in code. So I'm trying to learn how to get the data from a data source (like a DB). In my specific case, I want to get the data from a Microsoft Access DB. (READ ONLY, So I'll only use SELECT commands). using System.Collections.Generic; using Telephone_Directory_2010.Model; namespace Telephone_Directory_2010.DataAccess { public class EmployeeRepository { readonly List<Employee> _employees; public EmployeeRepository() { if (_employees == null) { _employees = new List<Employee>(); } _employees.Add(Employee.CreateEmployee("Student One", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); _employees.Add(Employee.CreateEmployee("Student Two", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); _employees.Add(Employee.CreateEmployee("Student Three", "IT201", "Information Technology", "IT4207", "Building1", "Room650")); } public List<Employee> GetEmployees() { return new List<Employee>(_employees); } } } I found another example where an Access DB is used but it doesn't comply with MVVM. So I was trying to figure out how to add the DB file to the project, how to wire it up and bind it to a listbox (i'm not that far yet). Below is my modified file using System.Collections.Generic; using Telephone_Directory_2010.Model; // integrating new code with working code using Telephone_Directory_2010.telephone2010DataSetTableAdapters; using System.Windows.Data; namespace Telephone_Directory_2010.DataAccess { public class EmployeeRepository { readonly List<Employee> _employees; // start // integrating new code with working code private telephone2010DataSet.telephone2010DataTable employeeTable; private CollectionView dataView; internal CollectionView DataView { get { if (dataView == null) { dataView = (CollectionView) CollectionViewSource.GetDefaultView(this.DataContext); } return dataView; } } public EmployeeRepository() { if (_employees == null) { _employees = new List<Employee>(); } telephone2010TableAdapter employeeTableAdapter = new telephone2010TableAdapter(); employeeTable = employeeTableAdapter.GetData(); this.DataContext = employeeTable; } public List<Employee> GetEmployees() { return new List<Employee>(_employees); } } } I get the following error messages when building Error 1 'Telephone_Directory_2010.DataAccess.EmployeeRepository' does not contain a definition for 'DataContext' and no extension method 'DataContext' accepting a first argument of type 'Telephone_Directory_2010.DataAccess.EmployeeRepository' could be found (are you missing a using directive or an assembly reference?) C:\Projects\VS2010\Telephone Directory 2010\Telephone Directory 2010\DataAccess\EmployeeRepository.cs 23 90 Telephone Directory 2010

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  • PHP and Regular Expressions question?

    - by php
    I was wondering if the codes below are the correct way to check for a street address, email address, password, city and url using preg_match using regular expressions? And if not how should I fix the preg_match code? preg_match ('/^[A-Z0-9 \'.-]{1,255}$/i', $trimmed['address']) //street address preg_match ('/^[\w.-]+@[\w.-]+\.[A-Za-z]{2,6}$/', $trimmed['email'] //email address preg_match ('/^\w{4,20}$/', $trimmed['password']) //password preg_match ('/^[A-Z \'.-]{1,255}$/i', $trimmed['city']) //city preg_match("/^[a-zA-Z]+[:\/\/]+[A-Za-z0-9\-_]+\\.+[A-Za-z0-9\.\/%&=\?\-_]+$/i", $trimmed['url']) //url

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  • Basic Ruby on Rails Question about routing

    - by Acidburn2k
    I have a controller without any related model. This controller is to span some informations from various models. I have lots of actions there, which define certain views on the page. What would be the best way to organize routes for this controller. What I would like is to have /dashboard/something point to any action in the dashboard controller. Not actions like new/edit but arbitrary (showstats, etc). With trail and error I made something like this: map.dashboard 'dashboard/:action', :controller => 'dashboard', :action => :action Now it is possible to access those url using helper: dashboard_url('actionname') This approch seems to be working ok, but is this the way to go? I am not quite sure understand, how are the helper method names generated. How to generate same helper names as in basic controllers "action_controller_url" ? That would be more generic and made the code more consistent. Thanks in advance.

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  • another porter stemming algorithm implementation question ?

    - by mike
    Hi, I am trying to implement porter stemming algorithm, but i am having difficualties understanding this point Step 1c (*v*) Y -> I happy -> happi sky -> sky Isn't that the the opposite of what we want to do , why does the algorithim convert the Y into I. for the complete algorithm here http://tartarus.org/~martin/PorterStemmer/def.txt Thanks

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  • LINQ-to-XML selection based on node values, newbie question

    - by mmcglynn
    Given the following XML, I would like to return all eventtitles where the eventtype id = 23. My current query only looks at the first eventtype, so returns the wrong result. <event> <eventtitle>Garrison Keillor</eventtitle> <eventtypes> <eventtype id="24"/> <eventtype id="23"/> </eventtypes> </event> <event> <eventtitle>Joe Krown Trio featuring Walter Wolfman Washington</eventtitle> <eventtypes> <eventtype id="23"/> </eventtypes> </event> LINQ query: Dim query = _ From c In calXML...<event> _ Where c...<eventtypes>.<eventtype>.@id = "23" _ Select c.<eventtitle>.Value, c.<eventlocation>.Value For Each item In query Response.Write("<h3>" & item.eventtitle & "</h3>") Response.Write(item.eventlocation & "<br />") Next

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  • To (monkey)patch or not to (monkey)patch, that is the question

    - by gsakkis
    I was talking to a colleague about one rather unexpected/undesired behavior of some package we use. Although there is an easy fix (or at least workaround) on our end without any apparent side effect, he strongly suggested extending the relevant code by hard patching it and posting the patch upstream, hopefully to be accepted at some point in the future. In fact we maintain patches against specific versions of several packages that are applied automatically on each new build. The main argument is that this is the right thing to do, as opposed to an "ugly" workaround or a fragile monkey patch. On the other hand, I favor practicality over purity and my general rule of thumb is that "no patch" "monkey patch" "hard patch", at least for anything other than a (critical) bug fix. So I'm wondering if there is a consensus on when it's better to (hard) patch, monkey patch or just try to work around a third party package that doesn't do exactly what one would like. Does it have mainly to do with the reason for the patch (e.g. fixing a bug, modifying behavior, adding missing feature), the given package (size, complexity, maturity, developer responsiveness), something else or there are no general rules and one should decide on a case-by-case basis ?

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  • Validate a string in a table in SQL Server - CLR function or T-SQL (Question updated)

    - by Ashish Gupta
    I need to check If a column value (string) in SQL server table starts with a small letter and can only contain '_', '-', numbers and alphabets. I know I can use a SQL server CLR function for that. However, I am trying to implement that validation using a scalar UDF and could make very little here...I can use 'NOT LIKE', but I am not sure how to make sure I validate the string irrespective of the order of characters or in other words write a pattern in SQL for this. Am I better off using a SQL CLR function? Any help will be appreciated.. Thanks in advance Thank you everyone for their comments. This morning, I chose to go CLR function way. For the purpose of what I was trying to achieve, I created one CLR function which does the validation of an input string and have that called from a SQL UDF and It works well. Just to measure the performance of t-SQL UDF using SQL CLR function vs t- SQL UDF, I created a SQL CLR function which will just check if the input string contains only small letters, it should return true else false and have that called from a UDF (IsLowerCaseCLR). After that I also created a regular t-SQL UDF(IsLowerCaseTSQL) which does the same thing using the 'NOT LIKE'. Then I created a table (Person) with columns Name(varchar) and IsValid(bit) columns and populate that with names to test. Data :- 1000 records with 'Ashish' as value for Name column 1000 records with 'ashish' as value for Name column then I ran the following :- UPDATE Person Set IsValid=1 WHERE dbo.IsLowerCaseTSQL (Name) Above updated 1000 records (with Isvalid=1) and took less than a second. I deleted all the data in the table and repopulated the same with same data. Then updated the same table using Sql CLR UDF (with Isvalid=1) and this took 3 seconds! If update happens for 5000 records, regular UDF takes 0 seconds compared to CLR UDF which takes 16 seconds! I am very less knowledgeable on t-SQL regular expression or I could have tested my actual more complex validation criteria. But I just wanted to know, even I could have written that, would that have been faster than the SQL CLR function considering the example above. Are we using SQL CLR because we can implement we can implement lot richer logic which would have been difficult otherwise If we write in regular SQL. Sorry for this long post. I just want to know from the experts. Please feel free to ask if you could not understand anything here. Thank you again for your time.

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  • Java Regex Matcher Question

    - by Yang
    How do I match an URL string like this: img src = "http://stackoverflow.com/a/b/c/d/someimage.jpg" where only the domain name and the file extension (jpg) is fixed while others are variables? The following code does not seem working: Pattern p = Pattern.compile("<img src=\"http://stachoverflow.com/.*jpg"); // Create a matcher with an input string Matcher m = p.matcher(url); while (m.find()) { String s = m.toString(); }

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  • Yet another UITableView Question

    - by barbgal
    Hi, I have a strange issue in my iPhone application. I have created a UITableView with 4 Sections and 3 Rows so totally 12 Rows. But - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath The above method only gets called for 9 times instead of 12 times.why this happenning. My 4th section is not getting constructed but my 1st section gets duplicated as 4th section. Thanks for your time and help. Plese refer my code below @interface MainViewController : UITableViewController<UITextFieldDelegate,UITableViewDelegate,UITableViewDataSource> { } @end // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { CGRect frameRect = CGRectMake(0,0,320,460); UITableView *tableView = [[UITableView alloc] initWithFrame:frameRect style:UITableViewStyleGrouped]; tableView.delegate = self; tableView.dataSource = self; tableView.backgroundColor = [UIColor purpleColor]; tableView.scrollEnabled = YES; self.view = tableView; [tableView release]; [super viewDidLoad]; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { // Return the number of rows in the section. return 3; } - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return 4; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"CELL IS NIL %i", indexPath.section); static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; if (indexPath.section == 0) { if(indexPath.row == 0) { cell.text = @"Tmail"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else if ( indexPath.row == 1 ) { cell.text = @"English"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else { cell.text = @"Hindi"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } } else if (indexPath.section == 1) { if(indexPath.row == 0) { cell.text = @"Street"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else if ( indexPath.row == 1 ) { cell.text = @"City"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else { cell.text = @"State"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } } else if (indexPath.section == 2) { if(indexPath.row == 0) { cell.text = @"Salem"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else if ( indexPath.row == 1 ) { cell.text = @"Samalpatti"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else { cell.text = @"Chennai"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } } else if (indexPath.section == 3) { if(indexPath.row == 0) { cell.text = @"NOKIA"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else if ( indexPath.row == 1) { cell.text = @"SAMSUNG"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } else { cell.text = @"SONY"; UITextField *aField = [[UITextField alloc]initWithFrame:CGRectMake(100,10,200,40)]; aField.placeholder = @"Mandatory"; aField.delegate = self; aField.textColor = [UIColor blackColor]; [cell addSubview:aField]; [aField release]; } } } return cell; }

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  • Rails: simple bundler question with ruby-openid

    - by Joern Akkermann
    Hi! I just installed the ruby-openid gem and then bundled it by entering gem 'ruby-openid', :require => 'openid' in the gemfile. Then I started bundle install and bundle lock. Everything worked fine so far. But how can I now access the classes of ruby-openid. OpenID::method won't work for me. It raises a not found error. What have I forgot or done wrong? I'm absolutely new to bundler and the internet full of solutions for various versions, but I need one solution that's surely working. I'm thankful for any help!

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  • MVC Design Question

    - by 104286623826380127552
    On a MVC 2 website what I want to do is get a list of products / CategoryId. From that list, create a list of distinct CategoryId's. Then randomly pick a categoryId from the second list and use it to get all the products for that categoryId. I then want to store that CategoryId so that I don't display those products on the next run. I don't need any code examples to start. What I'm wondering is that I think I would put this code in a class in my model (Dll) and store the list of displayed CategoryId's in session. Is this a good solution or should I go another way? Thank you for you help

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  • Question about PE/COFF file formats - ECOFF, ANON, and BIGOBJ

    - by Zain
    Hi, I've peen looking at the PE/COFF format and it seems to be missing a few things about extensions to the format. Specifically, I'm trying to learn about ECOFF and ANON objects. from what I can tell, those're just two names for the same thing, which is also known as a BIGOBJ. The BIGOBJ allows you to create, surprise surprise, larger object files than the format otherwise allows. Can anyone confirm or correct this? Thanks

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  • Question about Java File Reader.

    - by Cris Carter
    Hello. I'm having some problems with the FileReader class. How do I specify an offset in the lines it goes through, and how do I tell it when to stop? Let's say I want it to go through each line in a .txt file, but only lines 100-200 and then stop? How would I do this? Right now I'm using ReadLine() but I don't think there's a way to specify offset with that. Any fast help is VERY appreciated. Thanks.

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  • Question about Jboss deployment

    - by Manoj
    Hi All, I am new to Jboss and deployment of web applications etc. I have two different war files deployed on the same Jboss server. Further they also share some classes which read different properties based on the application settings (Let's call a common class as CommonClass.class which is present in App1.war and App2.war; CommonClass has a member "FIELD1", so both these war files have CommonClass.class each of which reads different properties, into CommonClass.FIELD1). But during run-time when I access FIELD1 in one application (App2.war-CommonClass.FIELD1) it has the value from another application (App1.war-CommonClass.FIELD1). Is there any way I can explicitly specify so that JBoss treats these classes and fields to be different? so that both these classes can exist in memory yet hold their respective correct values? Thanks a ton, Manoj

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