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  • .NET Working with Locking and Threads

    - by aherrick
    Work on this small test application to learn threading/locking. I have the following code, I would think that the line should only write to console once. However it doesn't seem to be working as expected. Any thoughts on why? What I'm trying to do is add this Lot object to a List, then if any other threads try and hit that list, it would block. Am i completely misusing lock here? class Program { static void Main(string[] args) { int threadCount = 10; //spin up x number of test threads Thread[] threads = new Thread[threadCount]; Work w = new Work(); for (int i = 0; i < threadCount; i++) { threads[i] = new Thread(new ThreadStart(w.DoWork)); } for (int i = 0; i < threadCount; i++) { threads[i].Start(); } // don't let the console close Console.ReadLine(); } } public class Work { List<Lot> lots = new List<Lot>(); private static readonly object thisLock = new object(); public void DoWork() { Lot lot = new Lot() { LotID = 1, LotNumber = "100" }; LockLot(lot); } private void LockLot(Lot lot) { // i would think that "Lot has been added" should only print once? lock (thisLock) { if(!lots.Contains(lot)) { lots.Add(lot); Console.WriteLine("Lot has been added"); } } } }

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  • Conditional Drag and Drop Operations in Flex/AS3 Tree

    - by user163757
    Good day everyone. I am currently working with a hierarchical tree structure in AS3/Flex, and want to enable drag and drop capabilities under certain conditions: Only parent/top level nodes can be moved Parent/top level nodes must remain at this level; they can not be moved to child nodes of other parent nodes Using the dragEnter event of the tree, I am able to handle condition 1 easily. private function onDragEnter(event:DragEvent):void { // only parent nodes (map layers) are moveable event.preventDefault(); if(toc.selectedItem.hasOwnProperty("layer")) DragManager.acceptDragDrop(event.target as UIComponent); else DragManager.showFeedback(DragManager.NONE); } Handling the second condition is proving to be a bit more difficult. I am pretty sure the dragOver event is the place for logic. I have been experimenting with calculateDropIndex, but that always gives me the index of the parent node, which doesn't help check if the potential drop location is acceptable or not. Below is some pseudo code of what I am looking to accomplish. private function onDragOver(e:DragEvent):void { // if potential drop location has parents // dont allow drop // else // allow drop } Can anyone provide advice how to implement this?

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  • COMException in System.WIndows.Forms.dll with Interactive Brokers TWS API

    - by Lirik
    Hi, I've been trying to run the sample project provided with the tutorial at stockbotprogramming http://www.stockbotprogramming.com/sharpcibtutorial1.php , but I keep getting a COMException every time I run the application. I have the TWS Client running and the sample VB projects provided with the API are able to connect just fine, but when I try to use the C# sample provided by the tutorial then I get the following exception: An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in System.Windows.Forms.dll Th exception happens when I try to add the TWS ActiveX control: namespace CSharpTutorial1 { public partial class Form1 : Form { private AxTWSLib.AxTws tws; public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { tws = new AxTWSLib.AxTws(); tws.BeginInit(); tws.Enabled = true; tws.Location = new System.Drawing.Point(32, 664); tws.Name = "tws"; Controls.Add(tws); // <-- EXCEPTION HERE! tws.EndInit(); tws.connect("127.0.0.1", 7496, 0); String msg = "Connected to TWS server version " + tws.serverVersion + "at " + tws.TwsConnectionTime; MessageBox.Show(msg); } } } Does anybody know what could be causing this exception? Any ideas on how to fix it?

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  • SSL Certificate without host name in it

    - by Sinuhe
    I have implemented a web service with server and client authentication using keytool. The problem is that this authentication doesn't work if I don't include the name of the host in it. For example: keytool -genkey -alias myAlias -keyalg RSA -keypass myPassword -storepass myPassword -keystore my.keystore -dname "CN=myhost" But I don't need and I don't like validation by host or by IP. Is there any way of avoiding it? Thanks.

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  • GXT Performance Issues

    - by pearl
    Hi All, We are working on a rather complex system using GXT. While everything works great on FF, IE (especially IE6) is a different story (looking at more than 10 seconds until the browser renders the page). I understand that one of the main reasons is DOM manipulation which is a disaster under IE6 (See http://www.quirksmode.org/dom/innerhtml.html). This can be thought to be a generic problem of a front-end Javascript framework (i.e. GWT) but a simple code (see below) that executes the same functionality proofs otherwise. In fact, under IE6 - getSomeGWT() takes 400ms while getSomeGXT() takes 4 seconds. That's a x10 factor which makes a huge different for the user experience !!! private HorizontalPanel getSomeGWT() { HorizontalPanel pointsLogoPanel = new HorizontalPanel(); for (int i=0; i<350; i++) { HorizontalPanel innerContainer = new HorizontalPanel(); innerContainer.add(new Label("some GWT text")); pointsLogoPanel.add(innerContainer); } return pointsLogoPanel; } private LayoutContainer getSomeGXT() { LayoutContainer pointsLogoPanel = new LayoutContainer(); pointsLogoPanel.setLayoutOnChange(true); for (int i=0; i<350; i++) { LayoutContainer innerContainer = new LayoutContainer(); innerContainer.add(new Text("just some text")); pointsLogoPanel.add(innerContainer); } return pointsLogoPanel; } So to solve/mitigate the issue one would need to - a. Reduce the number of DOM manipulations; or b. Replace them with innerHTML. AFAIK, (a) is simply a side effect of using GXT and (b) is only possible with UiBinder which isn't supported yet by GXT. Any ideas? Thanks in advance!

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  • WinForms Load Event / Static Initialization Strangeness

    - by Eric J.
    Background I'm troubleshooting an WinForms 2.0 program that's already been burned to CD for distribution to an internet-challenged target audience. Some users are experiencing a fatal error that I can reproduce locally. Reproducing the Error I get the fatal error when I log into my Vista box using a standard user that I just created, even if I run the program as administrator. I do not get the fatal error when I log in as local administrator. I'm not sure that being administrator is necessarily the trigger (since runas did not help). I have reproduced this half a dozen times under each account with consistent results. The faulty code Base.cs (base class for several user controls, only one of which is shown on first screen) private void BaseWindow_Load(object sender, EventArgs e) { // This message shown once in both cases MessageBox.Show("BaseWindow_Load for " + this.GetType().FullName); SkinManager.ApplySkin(this); } SkinManager.cs private static Skin skin = null; public static void ApplySkin(UserControl applyTo) { if (skin == null) { skin = new Skin(SkinsDirectory, "Default"); } } Skin.cs internal Skin(string skinPath, string skinName) { config = SkinConfig.Load(path); } SkinConfig.cs public static SkinConfig Load(string path) { // This message shown only once running as Admin but twice running as standard user System.Windows.Forms.MessageBox.Show("@1"); // !!! LOCK path HERE !!! } A user control loads on the first form, which triggers a call to SkinManager.ApplySkin, which checks if skin is null and, if so assigns it (without thread synchronization or recursion protection), which ultimately causes a file to be opened. When logged in as local admin, that sequence completes just fine. When logged in as my test standard user, ApplySkin is always called a second time while skin is still null, causing a second attempt to load, causing the file to be locked on the second attempt. The error handling is draconian at this point and the program terminates. The Question While this code can be easily fixed, I would like to understand why the error is happening only in some cases.

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  • Java 1.4 singleton containing a mutable field

    - by Philippe
    Hi, I'm working on a legacy Java 1.4 project, and I have a factory that instantiates a csv file parser as a singleton. In my csv file parser, however, I have a HashSet that will store objects created from each line of my CSV file. All that will be used by a web application, and users will be uploading CSV files, possibly concurrently. Now my question is : what is the best way to prevent my list of objects to be modified by 2 users ? So far, I'm doing the following : final class MyParser { private File csvFile = null; private static Set myObjects = Collections.synchronizedSet(new HashSet); public synchronized void setFile(File file) { this.csvFile = file; } public void parse() FileReader fr = null; try { fr = new FileReader(csvFile); synchronized(myObjects) { myObjects.clear(); while(...) { // foreach line of my CSV, create a "MyObject" myObjects.add(new MyObject(...)); } } } catch (Exception e) { //... } } } Should I leave the lock only on the myObjects Set, or should I declare the whole parse() method as synchronized ? Also, how should I synchronize - both - the setting of the csvFile and the parsing ? I feel like my actual design is broken because threads could modify the csv file several times while a possibly long parse process is running. I hope I'm being clear enough, because myself am a bit confused on those multi-synchronization issues. Thanks ;-)

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  • How do I get the User Entered Value in AjaxControlToolkit ComboBox when the enter key is pressed?

    - by Jason
    The Problem: The user entered value is missing in the .Text attribute of the AjaxControlToolkit ComboBox when the enter key pressed. Also the “on change” events events are not called but I am not using postbacks anyway so I do not care. Example: private void BuildFileListDetails(NHibernateDataProvider _providerM) { int resultsPage = Convert.ToInt32(ddlNavPageNumber.Text); const int RESULTS_PAGE_SIZE = 100; // The cbFileName.Text equals "" Not what user entered string searchFileName= cbFileName.Text; var xrfFiles = _providerM.GetXrfFiles(searchFileName, resultsPage, RESULTS_PAGE_SIZE); gvXrfFileList.DataSource = xrfFiles; gvXrfFileList.DataBind(); } My Solution: I needed to access the AjaxToolkit "ComboBox" imbedded TextBox control's .Text to access the value entered by user. private void BuildFileListDetails(NHibernateDataProvider _providerM) { int resultsPage = Convert.ToInt32(ddlNavPageNumber.Text); const int RESULTS_PAGE_SIZE = 100; string searchFileName; //The Solution: Access the AjaxToolkit "ComboBox" imbedded TextBox control's .Text to access the value entered by user. TextBox textBox = cbFileName.FindControl("TextBox") as TextBox; if (textBox != null) { searchFileName = textBox.Text; //textBox.Text = "User Entered Value" } else { searchFileName = cbFileName.Text; } var xrfFiles = _providerM.GetXrfFiles(searchFileName, resultsPage, RESULTS_PAGE_SIZE); gvXrfFileList.DataSource = xrfFiles; gvXrfFileList.DataBind(); }

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  • How to create Fibonacci Sequence in Java

    - by rfkrocktk
    I really suck at math. I mean, I REALLY suck at math. I'm trying to make a simple fibonacci sequence class for an algorithm I'll be using. I have seen the python example which looks something like this: a = 0 b = 1 while b < 10: print b a, b = b, b+a The problem is that I can't really make this work in any other language. I'd like to make it work in Java, since I can pretty much translate it into the other languages I use from there. This is the general thought: public class FibonacciAlgorithm { private Integer a = 0; private Integer b = 1; public FibonacciAlgorithm() { } public Integer increment() { a = b; b = a + b; return value; } public Integer getValue() { return b; } } All that I end up with is doubling, which I could do with multiplication :( Can anyone help me out? Math pwns me.

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  • C# .Net Serial DataReceived Event response too slow for high-rate data.

    - by Matthew
    Hi, I have set up a SerialDataReceivedEventHandler, with a forms based program in VS2008 express. My serial port is set up as follows: 115200, 8N1 Dtr and Rts enabled ReceivedBytesThreshold = 1 I have a device I am interfacing with over a BlueTooth, USB to Serial. Hyper terminal receives the data just fine at any data rate. The data is sent regularly in 22 byte long packets. This device has an adjustable rate at which data is sent. At low data rates, 10-20Hz, the code below works great, no problems. However, when I increase the data rate past 25Hz, there starts to recieve mulitple packets on one call. What I mean by this is that there should be a event trigger for every incoming packet. With higher output rates, I have tested the buffer size (BytesToRead command) immediatly when the event is called and there are multiple packets in the buffer then. I think that the event fires slowly and by the time it reaches the code, more packes have hit the buffer. One test I do is see how many time the event is trigger per second. At 10Hz, I get 10 event triggers, awesome. At 100Hz, I get something like 40 event triggers, not good. My goal for data rate is 100HZ is acceptable, 200Hz preferred, and 300Hz optimum. This should work because even at 300Hz, that is only 52800bps, less than half of the set 115200 baud rate. Anything I am over looking? public Form1() { InitializeComponent(); serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived); } private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e) { this.Invoke(new EventHandler(Display_Results)); } private void Display_Results(object s, EventArgs e) { serialPort1.Read(IMU, 0, serial_Port1.BytesToRead); }

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  • Synchronize DataGrid and DataForm in Silverlight 3

    - by SpiralGray
    I've been banging my head against the wall for a couple of days on this and it's time to ask for help. I've got a DataGrid and DataForm on the same UserControl. I'm using an MVVM approach so there is a single ViewModel for the UserControl. That ViewModel has a couple of properties that are relevant to this discussion: public ObservableCollection<VehicleViewModel> Vehicles { get; private set; } public VehicleViewModel SelectedVehicle { get { return selectedVehicle; } private set { selectedVehicle = value; OnPropertyChanged( "SelectedVehicle" ); } } In the XAML I've got the DataGrid and DataForm defined as follows: <data:DataGrid SelectionMode="Single" ItemsSource="{Binding Vehicles}" SelectedItem="{Binding SelectedVehicle, Mode=TwoWay}" AutoGenerateColumns="False" IsReadOnly="True"> <dataFormToolkit:DataForm CurrentItem="{Binding SelectedVehicle}" /> So as the SelectedItem changes on the DataGrid it should push that change back to the ViewModel and when the ViewModel raises the OnPropertyChanged the DataForm should refresh itself with the information for the newly-selected VehicleViewModel. However, the setter for SelectedVehicle is never being called and in the Output window of VS I'm seeing the following error: System.Windows.Data Error: ConvertBack cannot convert value 'xxxx.ViewModel.VehicleViewModel' (type 'xxxx.ViewModel.VehicleViewModel'). BindingExpression: Path='SelectedVehicle' DataItem='xxxx.ViewModel.MainViewModel' (HashCode=31664161); target element is 'System.Windows.Controls.DataGrid' (Name=''); target property is 'SelectedItem' (type 'System.Object').. System.MethodAccessException: xxxx.ViewModel.MainViewModel.set_SelectedVehicle(xxxx.ViewModel.VehicleViewModel) It sounds like it's having a problem converting from a VehicleViewModel to an object (or back again), but I'm confused as to why that would be (or even if I'm on the right track with that assumption). Each row/item in the DataGrid should be a VehicleViewModel (because the ItemsSource is bound to an ObservableCollection of that type), so when the SelectedItem changes it should be dealing with an instance of VehicleViewModel. Any insight would be appreciated.

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  • Amazon EC2 and jbossws

    - by avjaz
    Hi - I've deployed a webservice to a Jboss instance running on Amazon EC2. The webservice works fine locally, but when I deploy on EC2, and go to the /jbossws/services page the Endpoint Address for the webservice is the private DNS of the ec2 instance (domU-X-X-X-X etc...), not the public dns (which I would like it to be). I've tried loading the wsdl by changing the private hostname to the public IP; that works, but when I try to call any of the operations I get a HostNotFoundException, I'm guessing due to the fact that the generated wsdl has the stanza: <service name='XXXService'> <port binding='tns:XXXBinding' name='XXXPort'> <soap:address location='http://domU-XX-XX-XX-XX-XX-XX.compute-1.internal:8080/xx/xx/xx'/> </port> </service> where http://domU-XX-XX-XX-XX-XX-XX.compute-1.internal is the internal dns of the ec2 instance. The wsdl is auto generated - Is there a JAXB annotation I can use so that I can force the generated wsdl to use the public dns of the EC2 instance? Many thanks -

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  • Webdev.Webserver has stopped working

    - by Alexander
    When I execute the code saveXML below it generates the error above, why?? using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Xml.Serialization; using System.IO; /// <summary> /// Summary description for Post /// </summary> public class Post { private int postIDCounter = 0; private String DateCreated; public Post() { Author = "unknown"; Title = "unkown"; Content = ""; DateCreated = DateTime.Now.ToString(); ID = postIDCounter++; } public int ID { get { return ID; } set { if (ID != value) ID = value; } } public string Author { get { return Author; } set { if (Author != value) Author = value; } } public string Title { get { return Title; } set { if (Title != value) Title = value; } } public string Content { get { return Content; } set { if (Content != value) Content = value; } } public void saveXML() { XmlSerializer serializer = new XmlSerializer(typeof(Post)); Stream writer = new FileStream("..'\'App_Data'\'posts'\'" + new Guid(ID.ToString()).ToString() + ".xml", FileMode.Create); serializer.Serialize(writer, this); writer.Close(); } }

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  • Deserialize generic collections - coming up empty

    - by AC
    I've got a settings object for my app that has two collections in it. The collections are simple List generics that contain a collection of property bags. When I serialize it, everything is saved with no problem: XmlSerializer x = new XmlSerializer(settings.GetType()); TextWriter tw = new StreamWriter(@"c:\temp\settings.cpt"); x.Serialize(tw, settings); However when I deserialize it, everything is restored except for the two collections (verified by setting a breakpoint on the setters: XmlSerializer x = new XmlSerializer(typeof(CourseSettings)); XmlReader tr = XmlReader.Create(@"c:\temp\settings.cpt"); this.DataContext = (CourseSettings)x.Deserialize(tr); What would cause this? Everything is pretty vanilla... here's a snippet from the settings object... omitting most of it. The PresentationSourceDirectory works just fine, but the PresentationModules' setter isn't hit: private string _presentationSourceDirectory = string.Empty; public string PresentationSourceDirectory { get { return _presentationSourceDirectory; } set { if (_presentationSourceDirectory != value) { OnPropertyChanged("PresentationSourceDirectory"); _presentationSourceDirectory = value; } } } private List<Module> _presentationModules = new List<Module>(); public List<Module> PresentationModules { get { var sortedModules = from m in _presentationModules orderby m.ModuleOrder select m; return sortedModules.ToList<Module>(); } set { if (_presentationModules != value) { _presentationModules = value; OnPropertyChanged("PresentationModules"); } } }

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  • What is "Either the application has not called WSAStartup, or WSAStartup failed"

    - by Am1rr3zA
    I develop a program which connect to a web-server through network every thing works fine until I try to use some dongle to protect my software. the dongle has network feature too and it's API work under network infrastructure. when I added the Dongle checking code to my program I got this error: "Either the application has not called WSAStartup, or WSAStartup failed" I don't have any idea what is going on? I put the block of code which encounter exception here. the scenario I got the exception is I log in to the program (everything works fine) the plug out the dongle then the program stop and ask for dongle and I plug in the dongle again and try to log in bu I got exception on line response = (HttpWebResponse)request.GetResponse(); DongleService unikey = new DongleService(); checkDongle = unikey.isConnectedNow(); if (checkDongle) { isPass = true; this.username = txtbxUser.Text; this.pass = txtbxPass.Text; this.IP = combobxServer.Text; string uri = @"https://" + combobxServer.Text + ":5002num_events=1"; request = (HttpWebRequest)WebRequest.Create(uri); request.Proxy = null; request.Credentials = new NetworkCredential(this.username, this.pass); ServicePointManager.ServerCertificateValidationCallback = ((sender, certificate, chain, sslPolicyErrors) => true); response = (HttpWebResponse)request.GetResponse(); Properties.Settings.Default.User = txtbxUser.Text; int index = _servers.FindIndex(p => p == combobxServer.Text); if (index == -1) { _servers.Add(combobxServer.Text); Config_Save.SaveServers(_servers); _servers = Config_Save.LoadServers(); } Properties.Settings.Default.Server = combobxServer.Text; // also save the password if (checkBox1.CheckState.ToString() == "Checked") Properties.Settings.Default.Pass = txtbxPass.Text; Properties.Settings.Default.settingLoginUsername = this.username; Properties.Settings.Default.settingLoginPassword = this.pass; Properties.Settings.Default.settingLoginPort = "5002"; Properties.Settings.Default.settingLoginIP = this.IP; Properties.Settings.Default.isLogin = "guest"; Properties.Settings.Default.Save(); response.Close(); request.Abort(); this.isPass = true; this.Close(); } else { MessageBox.Show("Please Insert Correct Dongle!", "Dongle Error", MessageBoxButtons.OK, MessageBoxIcon.Stop); }

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  • How to enable OutputCache with an IHttpHandler

    - by Joseph Kingry
    I have an IHttpHandler that I would like to hook into the OutputCache support so I can offload cached data to the IIS kernel. I know MVC must do this somehow, I found this in OutputCacheAttribute: public override void OnResultExecuting(ResultExecutingContext filterContext) { if (filterContext == null) { throw new ArgumentNullException("filterContext"); } // we need to call ProcessRequest() since there's no other way to set the Page.Response intrinsic OutputCachedPage page = new OutputCachedPage(_cacheSettings); page.ProcessRequest(HttpContext.Current); } private sealed class OutputCachedPage : Page { private OutputCacheParameters _cacheSettings; public OutputCachedPage(OutputCacheParameters cacheSettings) { // Tracing requires Page IDs to be unique. ID = Guid.NewGuid().ToString(); _cacheSettings = cacheSettings; } protected override void FrameworkInitialize() { // when you put the <%@ OutputCache %> directive on a page, the generated code calls InitOutputCache() from here base.FrameworkInitialize(); InitOutputCache(_cacheSettings); } } But not sure how to apply this to an IHttpHandler. Tried something like this, but of course this doesn't work: public class CacheTest : IHttpHandler { public void ProcessRequest(HttpContext context) { OutputCacheParameters p = new OutputCacheParameters { Duration = 3600, Enabled = true, VaryByParam = "none", Location = OutputCacheLocation.Server }; OutputCachedPage page = new OutputCachedPage(p); page.ProcessRequest(context); context.Response.ContentType = "text/plain"; context.Response.Write(DateTime.Now.ToString()); context.Response.End(); } public bool IsReusable { get { return true; } } }

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  • add elements to WPF Grid

    - by Konrad
    I wanted to make a function that populates a Grid in WPF with pictures. So I did that: private void setCellImage(Grid g, Image img, int column, int row) { Grid.SetColumn(img, column); Grid.SetRow(img, row); if (!g.Children.Contains(img)) g.Children.Add(img); g.UpdateLayout(); } And was using it by calling in that way: for (int i = 0; i < 15; i++) for(int j=0; j<15; j++) setCellImage(gameMap,background, i, j); But it wasn't working. it populated a grid only in cell 14,14 leaving all other cells blank. I thought that it may be my mistake that I should use another instances of Image but it wasn't that: private void setCellImage(Grid g, Image img, int column, int row) { Image _img = new Image(); _img = img; Grid.SetColumn(_img, column); Grid.SetRow(_img, row); if (!g.Children.Contains(_img)) g.Children.Add(_img); g.UpdateLayout(); } This thing is still not working.

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  • InsertOnSubmit - NullReferenceException

    - by Jackie Chou
    I have 2 Model AccountEntity [Table(Name = "Account")] public class AccountEntity { [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] public int id { get; set; } [Column(CanBeNull = false, Name = "email")] public string email { get; set; } [Column(CanBeNull = false, Name = "pwd")] public string pwd { get; set; } [Column(CanBeNull = false, Name = "row_guid")] public Guid guid { get; set; } private EntitySet<DetailsEntity> details_id { get; set; } [Association(Storage = "details_id", OtherKey = "id", ThisKey = "id")] public ICollection<DetailsEntity> detailsCollection { get; set; } } DetailsEntity [Table(Name = "Details")] public class DetailsEntity { public DetailsEntity(AccountEntity a) { this.Account = a; } [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "int")] public int id { get; set; } private EntityRef<AccountEntity> _account = new EntityRef<AccountEntity>(); [Association(IsForeignKey = true, Storage = "_account", ThisKey = "id")] public AccountEntity Account { get; set; } } Main using (Database db = new Database()) { AccountEntity a = new AccountEntity(); a.email = "hahaha"; a.pwd = "13212312"; a.guid = Guid.NewGuid(); db.Account.InsertOnSubmit(a); db.SubmitChanges(); } that has relationhip AccountEntity <- DetailsEntity (1-n) when i'm trying to insert a record exception throws NullReferenceException cause: by EntitySet null please help me make it insert

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  • Complex error handling

    - by Caspin
    I've got a particularly ornery piece of network code. I'm using asio but that really doesn't matter for this question. I assume there is no way to unbind a socket other than closing it. The problem is that open(), bind(), and listen() can all throw a system_error. So I handled the code with a simple try/catch. The code as written in broken. using namespace boost::asio; class Thing { public: ip::tcp::endpoint m_address; ip::tcp::acceptor m_acceptor; /// connect should handle all of its exceptions internally. bool connect() { try { m_acceptor.open( m_address.protocol() ); m_acceptor.set_option( tcp::acceptor::reuse_address(true) ); m_acceptor.bind( m_address ); m_acceptor.listen(); m_acceptor.async_accept( /*stuff*/ ); } catch( const boost::system::system_error& error ) { assert(acceptor.is_open()); m_acceptor.close(); return false; } return true; } /// don't call disconnect unless connect previously succeeded. void disconnect() { // other stuff needed to disconnect is ommited m_acceptor.close(); } }; The error is if the socket fails to connect it will try to close it in the catch block and throw another system_error about closing an acceptor that has never been opened. One solution is to add an if( acceptor.is_open() ) in the catch block but that tastes wrong. Kinda like mixing C-style error checking with c++ exceptions. If I where to go that route, I may as well use the non-throwing version of open(). boost::system::error_code error; acceptor.open( address.protocol, error ); if( ! error ) { try { acceptor.set_option( tcp::acceptor::reuse_address(true) ); acceptor.bind( address ); acceptor.listen(); acceptor.async_accept( /*stuff*/ ); } catch( const boost::system::system_error& error ) { assert(acceptor.is_open()); acceptor.close(); return false; } } return !error; Is there an elegant way to handle these possible exceptions using RAII and try/catch blocks? Am I just wrong headed in trying to avoid if( error condition ) style error handling when using exceptions?

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  • issue in property file

    - by devuser
    I want to load the property file when tomcat is starting.so I'm using servletContextListener to do that and i can get values of property file to my web application. But i want to keep the same value after changing the property file once log into web application.But when i change the value of property file and log into system again it change the value to new one.I want to keep the same value that loaded when tomcat was starting.how can i implement this? My coding is as below import javax.servlet.*; import java.io.IOException; import java.util.Properties; import java.util.logging.Level; import java.util.logging.Logger; import java.io.*; import java.util.ResourceBundle; public final class sysProperties implements javax.servlet.ServletContextListener { private static Properties props = new Properties(); private static String file_name = "com/util/contact.properties"; public addSystemProperties() { } public void contextInitialized(ServletContextEvent servletContextEvent) { // Get the context ServletContext servletContext = servletContextEvent.getServletContext(); // Set a context attribute try { // props.load(servletContext.getResourceAsStream(file_name)); props.load(getClass().getClassLoader().getResourceAsStream(file_name)); System.out.println(" Application X is starting"); servletContext.setAttribute("h1",props.getProperty("home.h1")); servletContext.setAttribute("h2",props.getProperty("home.h2")); System.out.println("h1"+servletContext.getAttribute("h1")); System.out.println("h2"+ servletContext.getAttribute("h2")); ; } catch (Exception e) { System.out.println(" Error setting context attribute: " + e.getMessage()); } } public void contextDestroyed(ServletContextEvent servletContextEvent) { // Get the context ServletContext servletContext = servletContextEvent.getServletContext(); // Output the context variable we set earlier System.out.println(" Application X is shutting down"); System.out.println(" Value of h1 is: " + servletContext.getAttribute("h1")); System.out.println(" Value of h2 is: " + servletContext.getAttribute("h2")); // Clean up (not really necessary as the context is being destroyed, but let's be neat) servletContext.removeAttribute(props.getProperty("h1")); servletContext.removeAttribute(props.getProperty("h2")); } }

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  • IRequest / IResponse Pattern

    - by traderde
    I am trying to create an Interface-based Request/Response pattern for Web API requests to allow for asynchronous consumer/producer processing, but not sure how I would know what the underlying IResponse class is. public void Run() { List<IRequest> requests = new List<IRequest>(); List<IResponse> responses = new List<IResponse(); requests.Add(AmazonWebRequest); //should be object, trying to keep it simple requests.Add(EBayWebRequest); //should be object, trying to keep it simple foreach (IRequest req in requests) { responses.Add(req.GetResponse()); } foreach (IResponse resp in response) { typeof resp???? } } interface IRequest { IResponse GetResponse(); } interface IResponse { } public class AmazonWebServiceRequest : IRequest { public AmazonWebServiceRequest() { //get data; } public IResponse GetResponse() { AmazonWebServiceRequest request = new AmazonWebServiceRequest(); return (IResponse)request; } } public class AmazonWebServiceResponse : IResponse { XmlDocument _xml; public AmazonWebServiceResponse(XmlDocument xml) { _xml = xml; _parseXml(); } private void _parseXml() { //parse Xml into object; } } public class EBayWebRequest : IRequest { public EBayWebRequest () { //get data; } public IResponse GetResponse() { EBayWebRequest request = new EBayWebRequest(); return (IResponse)request; } } public class EBayWebResponse : IResponse { XmlDocument _xml; public EBayWebResponse(XmlDocument xml) { _xml = xml; _parseXml(); } private void _parseXml() { //parse Xml into object; } }

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  • Race condition during thread start?

    - by user296353
    Hi, I'm running the following code to start my threads, but they don't start as intended. For some reason, some of the threads start with the same objects (and some don't even start). If I try to debug, they start just fine (extra delay added by me clicking F10 to step through the code). These are the functions in my forms app: private void startWorkerThreads() { int numThreads = config.getAllItems().Count; int i = 0; foreach (ConfigurationItem tmpItem in config.getAllItems()) { i++; var t = new Thread(() => WorkerThread(tmpItem, i)); t.Start(); //return t; } } private void WorkerThread(ConfigurationItem cfgItem, int mul) { for (int i = 0; i < 100; i++) { Thread.Sleep(10*mul); } this.Invoke((ThreadStart)delegate() { this.textBox1.Text += "Thread " + cfgItem.name + " Complete!\r\n"; this.textBox1.SelectionStart = textBox1.Text.Length; this.textBox1.ScrollToCaret(); }); } Anyone able to help me out? Cheers!

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  • Project Euler: Programmatic Optimization for Problem 7?

    - by bmucklow
    So I would call myself a fairly novice programmer as I focused mostly on hardware in my schooling and not a lot of Computer Science courses. So I solved Problem 7 of Project Euler: By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the 10001st prime number? I managed to solve this without problem in Java, but when I ran my solution it took 8 and change seconds to run. I was wondering how this could be optimized from a programming standpoint, not a mathematical standpoint. Is the array looping and while statements the main things eating up processing time? And how could this be optimized? Again not looking for a fancy mathematical equation..there are plenty of those in the solution thread. SPOILER My solution is listed below. public class PrimeNumberList { private ArrayList<BigInteger> primesList = new ArrayList<BigInteger>(); public void fillList(int numberOfPrimes) { primesList.add(new BigInteger("2")); primesList.add(new BigInteger("3")); while (primesList.size() < numberOfPrimes){ getNextPrime(); } } private void getNextPrime() { BigInteger lastPrime = primesList.get(primesList.size()-1); BigInteger currentTestNumber = lastPrime; BigInteger modulusResult; boolean prime = false; while(!prime){ prime = true; currentTestNumber = currentTestNumber.add(new BigInteger("2")); for (BigInteger bi : primesList){ modulusResult = currentTestNumber.mod(bi); if (modulusResult.equals(BigInteger.ZERO)){ prime = false; break; } } if(prime){ primesList.add(currentTestNumber); } } } public BigInteger get(int primeTerm) { return primesList.get(primeTerm - 1); } }

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  • Databinding problem in dropdownlist box by generics in C#

    - by sakir-ali
    I want to implement stack in my program by Genericx. I have a textbox and button to add elements in stack, a dropdownlist box and a button to bind total stack in dropdownlist box. I have generic class and the code is below: [Serializable] public class myGenClass<T> { private T[] _elements; private int _pointer; public myGenClass(int size) { _elements = new T[size]; _pointer = 0; } public void Push(T item) { if (_pointer > _elements.Length - 1) { throw new Exception("Stack is full"); } _elements[_pointer] = item; _pointer++; } public T Pop() { _pointer--; if (_pointer < 0) { throw new Exception("Stack is empty"); } return _elements[_pointer]; } public T[] myBind() { T[] showall = new T[_pointer]; Array.Copy(_elements,showall, _pointer); T[] newarray = showall; Array.Reverse(showall); return showall; } } and my .cs page is below: public partial class _Default : System.Web.UI.Page { myGenClass<int> mystack = new myGenClass<int>(25); protected void Button1_Click(object sender, EventArgs e) { mystack.Push(Int32.Parse(TextBox1.Text)); //DropDownList1.Items.Add(mystack.Pop().ToString()); TextBox1.Text = string.Empty; TextBox1.Focus(); } protected void Button2_Click(object sender, EventArgs e) { //string[] db; //db = Array.ConvertAll<int, string>(mystack.myBind(), Convert.ToString); DropDownList1.DataSource = mystack.myBind(); DropDownList1.DataBind(); } } but when I bind the datasource property of dropdownlist box to generic type return array (i.e. myBind()), it shows empty... Please help..

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