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  • C++ game architecture

    - by rxc
    I'm trying to make a game, but I'm not sure of the best way to set up the main loop and classes. For really small games, I could put everything in the main() loop, including event handling, collision checking, etc. However, for large games, that's seems like a highly inefficient way to get things done. The architecture I want is kind like the way the Minecraft coders did it (I quote Minecraft code because I've seen the source code when downloading MCP). They have objects entity classes EntityCow and EntityChicken and they have methods like onDeath(), onLivingUpdate(); and item classes like ItemSword have methods like onItemUse(). I've never seen these methods get called directly, but apparently, they get stored in a class called DataWatcher, which, I think "watches" all the data (as the name implies) and calls the appropriate methods in the objects. Is that how most games do it? If so, how is the DataWatcher class implemented? Any help or alternate suggestions is really appreciated.

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  • Entity framework architecture

    - by user1741807
    I want to make a entity framework application in Winforms C#. I'm new to entity framework, and don't know how to make the architecture. I want to have the model in a class library, and a GUI layer, and maybe a controller layer. I'm used to that architecture, but don't know have to handle the objects in other layers than the model. Have do I manage objects in the gui layer, when I can't have a reference to the model? I'm used to have some kind of dto, but what's the best way?

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  • What is the correct pattern to use in this case?

    - by nulliusinverba
    I'm sure this scenario has arisen before, and I want to know what experience has taught to be the best solution. I have a number of classes that are all of a kind. Say all the objects are "Content". They may be "Article", or "Book" for example. The reason I want the "Content" abstraction is because I want to define a number of behaviours for all "Content" objects and not have to build a new DB Table and 10 classes of essentially the same code for each type of "Content". For example, to attach a "Tag" or a "Premise" to a content object would be much nicer if, say, I just had two columns one for ContentID and one for TagID. A solution I've played around with is to have a Content table with a unique ID, and then to have foreign key references on all the other tables (Book, Article, etc). This has actually proven quite solid, but I'm just not sure about it. Do you know how to call this described pattern?

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  • How do I convert a partially transparent image into polygons?

    - by user82779
    I'm using GLEE2D, a level editor allowing me to import images, scale them, rotate them, and position them onto layers and export the data into XML format. However, it does not tell me objects' boundaries. I can calculate them, but only given the original image's polygons. How do I get polygons of objects in a transparent image? An example object (I outlined it): How would I turn the object, knowing the scaled size of the image, into polygons? Is there an algorithm for this? I'll use OpenGL to draw them.

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  • Java game applet development

    - by RomZes
    I'm getting 4 sec delay when sending objects over UDP. Working on small game and trying to implement multiplayer. For now just trying to synchronize movements of 2 balls on the screen. StartingPoint.java is my server(first player), that receiving serialized objects (coordinates). SecondPlayer.java is client that sending serialized objects to server. When I'm moving my first object it appears 4 seconds later on different screen. StartingPoint.java @Override public void run() { byte[] receiveData = new byte[256]; byte[] sendData = new byte[256]; // DatagramSocket socketS; try { socket = new DatagramSocket(5000); System.out.println("Socket created on "+ port + " port"); } catch (SocketException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } while(true){ b1.update(this); b3.update(); System.out.println("Starting server..."); //// Receiving and deserializing object try { //socket.setSoTimeout(1000); DatagramPacket packet = new DatagramPacket(buf, buf.length); socket.receive(packet); byte[] data = packet.getData(); ByteArrayInputStream in = new ByteArrayInputStream(data); ObjectInputStream is = new ObjectInputStream(in); // socket.setSoTimeout(300); b1 = (Ball) is.readObject(); } catch (IOException | ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } SecondPlayer.java @Override public void run() { while(true){ b.update(); networkSend(); repaint(); try { Thread.sleep(17); } catch (InterruptedException e) { e.printStackTrace(); } } public void networkSend(){ // Serialize to a byte array try { ByteArrayOutputStream bStream = new ByteArrayOutputStream(); ObjectOutputStream oo; oo = new ObjectOutputStream(bStream); oo.writeObject(b); oo.flush(); oo.close(); byte[] bufCar = bStream.toByteArray(); //socket = new DatagramSocket(); //socket.setSoTimeout(1000); InetAddress address = InetAddress.getByName("localhost"); DatagramPacket packet = new DatagramPacket(bufCar, bufCar.length, address, port); socket.send(packet); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

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  • How can I find the closest vector to another in a specific direction?

    - by Sniper
    Perhaps I am not phrasing it incorrectly in my searches, but I can not find anything on this. I have a vector3 with a specific direction that it is facing, I want to get the closest object to that position in that specific direction. Basically I want to get the object that is being aimed at. I have thought about finding all objects within a box and then finding the closest object to my vector from them results, but I am sure that there is a more efficient way. The Z axis is optional, the objects are most likely within a few meters of the search vector. http://i.stack.imgur.com/FafAu.jpg

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  • WPF TabItem Custom ContentTemplate

    - by lloydsparkes
    I have been strugging with this for a while, it would have been simple to do in WindowForms. I am making a IRC Client, there will be a number of Tabs one for each channel connect to. Each Tab needs to show a number of things, UserList, MessageHistory, Topic. In WindowForms i would just have inherited from TabItem, added some Custom Properties, and Controls, and done. In WPF i am having some slight issues with working out how to do it. I have tried many ways of doing it, and below is my current method, but i cannot get the TextBox to bind to the Topic Property. <Style TargetType="{x:Type t:IRCTabItem}" BasedOn="{StaticResource {x:Type TabItem}}" > <Setter Property="ContentTemplate"> <Setter.Value> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="540" /> <ColumnDefinition /> </Grid.ColumnDefinitions> <StackPanel Grid.Column="0"> <TextBox Text="{Binding Topic, RelativeSource={RelativeSource AncestorType={x:Type t:IRCTabItem}}}" /> </StackPanel> </Grid> </DataTemplate> </Setter.Value> </Setter> </Style> And the Codebehind public class IRCTabItem : TabItem { static IRCTabItem() { //This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class. //This style is defined in themes\generic.xaml //DefaultStyleKeyProperty.OverrideMetadata(typeof(IRCTabItem), // new FrameworkPropertyMetadata(typeof(IRCTabItem))); } public static readonly RoutedEvent CloseTabEvent = EventManager.RegisterRoutedEvent("CloseTab", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(IRCTabItem)); public event RoutedEventHandler CloseTab { add { AddHandler(CloseTabEvent, value); } remove { RemoveHandler(CloseTabEvent, value); } } public override void OnApplyTemplate() { base.OnApplyTemplate(); Button closeButton = base.GetTemplateChild("PART_Close") as Button; if (closeButton != null) closeButton.Click += new System.Windows.RoutedEventHandler(closeButton_Click); } void closeButton_Click(object sender, System.Windows.RoutedEventArgs e) { this.RaiseEvent(new RoutedEventArgs(CloseTabEvent, this)); } public bool Closeable { get; set; } public static readonly DependencyProperty CloseableProperty = DependencyProperty.Register("Closeable", typeof(bool), typeof(IRCTabItem), new FrameworkPropertyMetadata(true, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault)); public List<String> UserList { get; set; } public static readonly DependencyProperty UserListProperty = DependencyProperty.Register("UserList", typeof(List<String>), typeof(IRCTabItem), new FrameworkPropertyMetadata(new List<String>(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault)); public String Topic { get; set; } public static readonly DependencyProperty TopicProperty = DependencyProperty.Register("Topic", typeof(String), typeof(IRCTabItem), new FrameworkPropertyMetadata("Not Connected", FrameworkPropertyMetadataOptions.BindsTwoWayByDefault)); public bool HasAlerts { get; set; } public static readonly DependencyProperty HasAlertsProperty = DependencyProperty.Register("HasAlerts", typeof(bool), typeof(IRCTabItem), new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault)); } So my questions are: Am i doing it the right way (best practices)? If so how can i bind DataTemplate to Properties? If not so, what is the correct way of achieve what i am trying to achieve?

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  • FluentNHibernate Unit Of Work / Repository Design Pattern Questions

    - by Echiban
    Hi all, I think I am at a impasse here. I have an application I built from scratch using FluentNHibernate (ORM) / SQLite (file db). I have decided to implement the Unit of Work and Repository Design pattern. I am at a point where I need to think about the end game, which will start as a WPF windows app (using MVVM) and eventually implement web services / ASP.Net as UI. Now I already created domain objects (entities) for ORM. And now I don't know how should I use it outside of ORM. Questions about it include: Should I use ORM entity objects directly as models in MVVM? If yes, do I put business logic (such as certain values must be positive and be greater than another Property) in those entity objects? It is certainly the simpler approach, and one I am leaning right now. However, will there be gotchas that would trash this plan? If the answer above is no, do I then create a new set of classes to implement business logic and use those as Models in MVVM? How would I deal with the transition between model objects and entity objects? I guess a type converter implementation would work well here. Now I followed this well written article to implement the Unit Of Work pattern. However, due to the fact that I am using FluentNHibernate instead of NHibernate, I had to bastardize the implementation of UnitOfWorkFactory. Here's my implementation: using System; using FluentNHibernate.Cfg; using FluentNHibernate.Cfg.Db; using NHibernate; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; namespace ELau.BlindsManagement.Business { public class UnitOfWorkFactory : IUnitOfWorkFactory { private static readonly string DbFilename; private static Configuration _configuration; private static ISession _currentSession; private ISessionFactory _sessionFactory; static UnitOfWorkFactory() { // arbitrary default filename DbFilename = "defaultBlindsDb.db3"; } internal UnitOfWorkFactory() { } #region IUnitOfWorkFactory Members public ISession CurrentSession { get { if (_currentSession == null) { throw new InvalidOperationException(ExceptionStringTable.Generic_NotInUnitOfWork); } return _currentSession; } set { _currentSession = value; } } public ISessionFactory SessionFactory { get { if (_sessionFactory == null) { _sessionFactory = BuildSessionFactory(); } return _sessionFactory; } } public Configuration Configuration { get { if (_configuration == null) { Fluently.Configure().ExposeConfiguration(c => _configuration = c); } return _configuration; } } public IUnitOfWork Create() { ISession session = CreateSession(); session.FlushMode = FlushMode.Commit; _currentSession = session; return new UnitOfWorkImplementor(this, session); } public void DisposeUnitOfWork(UnitOfWorkImplementor adapter) { CurrentSession = null; UnitOfWork.DisposeUnitOfWork(adapter); } #endregion public ISession CreateSession() { return SessionFactory.OpenSession(); } public IStatelessSession CreateStatelessSession() { return SessionFactory.OpenStatelessSession(); } private static ISessionFactory BuildSessionFactory() { ISessionFactory result = Fluently.Configure() .Database( SQLiteConfiguration.Standard .UsingFile(DbFilename) ) .Mappings(m => m.FluentMappings.AddFromAssemblyOf<UnitOfWorkFactory>()) .ExposeConfiguration(BuildSchema) .BuildSessionFactory(); return result; } private static void BuildSchema(Configuration config) { // this NHibernate tool takes a configuration (with mapping info in) // and exports a database schema from it _configuration = config; new SchemaExport(_configuration).Create(false, true); } } } I know that this implementation is flawed because a few tests pass when run individually, but when all tests are run, it would fail for some unknown reason. Whoever wants to help me out with this one, given its complexity, please contact me by private message. I am willing to send some $$$ by Paypal to someone who can address the issue and provide solid explanation. I am new to ORM, so any assistance is appreciated.

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  • Assigning an event or command to a DataTemplate in ResourceDictionary

    - by Scott
    I have the following class: public class Day { public int Date { get; set; } public String DayName { get; set; } public Day() { } public Day(int date, string dayName) { Date = date; DayName = dayName; CommandManager.RegisterClassCommandBinding(typeof(Day), new CommandBinding(DayClick, new ExecutedRoutedEventHandler(OnExecutedDayClick), new CanExecuteRoutedEventHandler(OnCanExecuteDayClick))); } public static readonly RoutedCommand DayClick = new RoutedCommand("DayClick", typeof(Day)); private static void OnCanExecuteDayClick(object sender, CanExecuteRoutedEventArgs e) { ((Day)sender).OnCanExecuteDayClick(e); } private static void OnExecutedDayClick(object sender, ExecutedRoutedEventArgs e) { ((Day)sender).OnExecutedDayClick(e); } protected virtual void OnCanExecuteDayClick(CanExecuteRoutedEventArgs e) { e.CanExecute = true; e.Handled = false; } protected virtual void OnExecutedDayClick(ExecutedRoutedEventArgs e) { string content = String.Format("Day {0}, which is {1}, was clicked.", Date.ToString(), DayName); MessageBox.Show(content); e.Handled = true; } } I am using the following DataTemplate (that is in a ResourceDictionary) to render it: <DataTemplate DataType="{x:Type local:Day}"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Rectangle Grid.ColumnSpan="2" x:Name="rectHasEntry" Fill="WhiteSmoke"/> <TextBlock Grid.Column="0" x:Name="textBlockDayName" Text="{Binding DayName}" FontFamily="Junction" FontSize="11" Background="Transparent" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,2,0,0"/> <TextBlock Grid.Column="1" x:Name="textBlockDate" Text="{Binding Date}" FontFamily="Junction" FontSize="11" Background="Transparent" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0,2,0,0"/> <Rectangle Grid.ColumnSpan="2" x:Name="rectMouseOver" Fill="#A2C0DA" Opacity="0" Style="{StaticResource DayRectangleMouseOverStyle}"> </Rectangle> </Grid> </DataTemplate> No problems so far, I can get it on screen. What I want to be able to do is assign a Command, or use an event, so that when the user clicks on the Day it will notify the parent of the Day object that it has been clicked. I've tried the following: <Rectangle.CommandBindings> <CommandBinding Command="{x:Static local:Day.NextDay}" Executed="{x:Static local:Day.OnExecutedDayClick}" CanExecute="{x:Static local:Day.OnCanExecuteDayClick}"/> </Rectangle.CommandBindings> to try and bind the commands that are in the Day class but it didn't work. I got an error stating: 'ResourceDictionary' root element requires a x:Class attribute to support event handlers in the XAML file. Either remove the event handler for the Executed event, or add a x:Class attribute to the root element. Which I think means that there is no code-behind file for a ResourceDictionary, or something to that effect. In any event, I'm not sure if I should be using Commands here, or somehow tying events to the Rectangle in question, or if this is even possible. I've seen various places where it sure looks like it's possible, I'm just unable to translate what I'm seeing into something that actually works, hence this post. Thanks in advance.

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  • WTSVirtualChannelRead Only reads the first letter of the string.

    - by Scott Chamberlain
    I am trying to write a hello world type program for using virtual channels in the windows terminal services client. public partial class Form1 : Form { public Form1() { InitializeComponent(); } IntPtr mHandle = IntPtr.Zero; private void Form1_Load(object sender, EventArgs e) { mHandle = NativeMethods.WTSVirtualChannelOpen(IntPtr.Zero, -1, "TSCRED"); if (mHandle == IntPtr.Zero) { throw new Win32Exception(Marshal.GetLastWin32Error()); } } private void button1_Click(object sender, EventArgs e) { uint bufferSize = 1024; StringBuilder buffer = new StringBuilder(); uint bytesRead; NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, out bytesRead); if (bytesRead == 0) { MessageBox.Show("Got no Data"); } else { MessageBox.Show("Got data: " + buffer.ToString()); } } protected override void Dispose(bool disposing) { if (mHandle != System.IntPtr.Zero) { NativeMethods.WTSVirtualChannelClose(mHandle); } base.Dispose(disposing); } } internal static class NativeMethods { [DllImport("Wtsapi32.dll")] public static extern IntPtr WTSVirtualChannelOpen(IntPtr server, int sessionId, [MarshalAs(UnmanagedType.LPStr)] string virtualName); //[DllImport("Wtsapi32.dll", SetLastError = true)] //public static extern bool WTSVirtualChannelRead(IntPtr channelHandle, long timeout, // byte[] buffer, int length, ref int bytesReaded); [DllImport("Wtsapi32.dll")] public static extern bool WTSVirtualChannelClose(IntPtr channelHandle); [DllImport("Wtsapi32.dll", EntryPoint = "WTSVirtualChannelRead")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool WTSVirtualChannelRead( [In()] System.IntPtr hChannelHandle , uint TimeOut , [Out()] [MarshalAs(UnmanagedType.LPStr)] System.Text.StringBuilder Buffer , uint BufferSize , [Out()] out uint pBytesRead); } I am sending the data from the MSTSC COM object and ActiveX controll. public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { rdp.Server = "schamberlainvm"; rdp.UserName = "TestAcct"; IMsTscNonScriptable secured = (IMsTscNonScriptable)rdp.GetOcx(); secured.ClearTextPassword = "asdf"; rdp.CreateVirtualChannels("TSCRED"); rdp.Connect(); } private void button1_Click(object sender, EventArgs e) { rdp.SendOnVirtualChannel("TSCRED", "Hello World!"); } } //Designer code // // rdp // this.rdp.Enabled = true; this.rdp.Location = new System.Drawing.Point(12, 12); this.rdp.Name = "rdp"; this.rdp.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("rdp.OcxState"))); this.rdp.Size = new System.Drawing.Size(1092, 580); this.rdp.TabIndex = 0; I am getting a execption every time NativeMethods.WTSVirtualChannelRead runs Any help on this would be greatly appreciated. EDIT -- mHandle has a non-zero value when the function runs. updated code to add that check. EDIT2 -- I used the P/Invoke Interop Assistant and generated a new sigiture [DllImport("Wtsapi32.dll", EntryPoint = "WTSVirtualChannelRead")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool WTSVirtualChannelRead( [In()] System.IntPtr hChannelHandle , uint TimeOut , [Out()] [MarshalAs(UnmanagedType.LPStr)] StringBuilder Buffer , uint BufferSize , [Out()] out uint pBytesRead); it now receives the text string (Yea!) but it only gets the first letter of my test string(Boo!). Any ideas on what is going wrong? EDIT 3 --- After the call that should of read the hello world; BytesRead = 24 Buffer.Length = 1; Buffer.Capacity = 16; Buffer.m_StringValue = "H";

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  • nhibernate says 'mapping exception was unhandled' no persister for: MyNH.Domain.User

    - by mrblah
    Hi, I am using nHibernate and fluent. I created a User.cs: public class User { public virtual int Id { get; set; } public virtual string Username { get; set; } public virtual string Password { get; set; } public virtual string Email { get; set; } public virtual DateTime DateCreated { get; set; } public virtual DateTime DateModified { get; set; } } Then in my mappinds folder: public class UserMapping : ClassMap<User> { public UserMapping() { WithTable("ay_users"); Not.LazyLoad(); Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Username).Not.Nullable().WithLengthOf(256); Map(x => x.Password).Not.Nullable().WithLengthOf(256); Map(x => x.Email).Not.Nullable().WithLengthOf(100); Map(x => x.DateCreated).Not.Nullable(); Map(x => x.DateModified).Not.Nullable(); } } Using the repository pattern for the nhibernate blog: public class UserRepository : Repository<User> { } public class Repository<T> : IRepository<T> { public ISession Session { get { return SessionProvider.GetSession(); } } public T GetById(int id) { return Session.Get<T>(id); } public ICollection<T> FindAll() { return Session.CreateCriteria(typeof(T)).List<T>(); } public void Add(T product) { Session.Save(product); } public void Remove(T product) { Session.Delete(product); } } public interface IRepository<T> { T GetById(int id); ICollection<T> FindAll(); void Add(T entity); void Remove(T entity); } public class SessionProvider { private static Configuration configuration; private static ISessionFactory sessionFactory; public static Configuration Configuration { get { if (configuration == null) { configuration = new Configuration(); configuration.Configure(); configuration.AddAssembly(typeof(User).Assembly); } return configuration; } } public static ISessionFactory SessionFactory { get { if (sessionFactory == null) sessionFactory = Configuration.BuildSessionFactory(); return sessionFactory; } } private SessionProvider() { } public static ISession GetSession() { return SessionFactory.OpenSession(); } } My config: <?xml version="1.0" encoding="utf-8" ?> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2"> <session-factory> <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property> <property name="dialect">NHibernate.Dialect.MsSql2005Dialect</property> <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property> <property name="connection.connection_string">Server=.\SqlExpress;Initial Catalog=TestNH;User Id=dev;Password=123</property> <property name="show_sql">true</property> </session-factory> </hibernate-configuration> I created a console application to test the output: static void Main(string[] args) { Console.WriteLine("starting..."); UserRepository users = new UserRepository(); User user = users.GetById(1); Console.WriteLine("user is null: " + (null == user)); if(null != user) Console.WriteLine("User: " + user.Username); Console.WriteLine("ending..."); Console.ReadLine(); } Error: nhibernate says 'mapping exception was unhandled' no persister for: MyNH.Domain.User What could be the issue, I did do the mapping?

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  • What is the reason of "Transaction context in use by another session"

    - by Shrike
    Hi, I'm looking for a description of the root of this error: "Transaction context in use by another session". I get it sometimes in one of my unittests so I can't provider repro code. But I wonder what is "by design" reason for the error. I've found this post: http://blogs.msdn.com/asiatech/archive/2009/08/10/system-transaction-may-fail-in-multiple-thread-environment.aspx and also that: http://msdn.microsoft.com/en-us/library/ff649002.aspx But I can't understand what "Multiple threads sharing the same transaction in a transaction scope will cause the following exception: 'Transaction context in use by another session.' " means. All words are understandable but not the point. I actually can share a system transaction between threads. And there is even special mechanism for this - DependentTransaction class and Transaction.DependentClone method. I'm trying to reproduce a usecase from the first post: 1. Main thread creates DTC transaction, receives DependentTransaction (created using Transaction.Current.DependentClone on the main thread 2. Child thread 1 enlists in this DTC transaction by creating a transaction scope based on the dependent transaction (passed via constructor) 3. Child thread 1 opens a connection 4. Child thread 2 enlists in DTC transaction by creating a transaction scope based on the dependent transaction (passed via constructor) 5. Child thread 2 opens a connection with such code: using System; using System.Threading; using System.Transactions; using System.Data; using System.Data.SqlClient; public class Program { private static string ConnectionString = "Initial Catalog=DB;Data Source=.;User ID=user;PWD=pwd;"; public static void Main() { int MAX = 100; for(int i =0; i< MAX;i++) { using(var ctx = new TransactionScope()) { var tx = Transaction.Current; // make the transaction distributed using (SqlConnection con1 = new SqlConnection(ConnectionString)) using (SqlConnection con2 = new SqlConnection(ConnectionString)) { con1.Open(); con2.Open(); } showSysTranStatus(); DependentTransaction dtx = Transaction.Current.DependentClone(DependentCloneOption.BlockCommitUntilComplete); Thread t1 = new Thread(o => workCallback(dtx)); Thread t2 = new Thread(o => workCallback(dtx)); t1.Start(); t2.Start(); t1.Join(); t2.Join(); ctx.Complete(); } trace("root transaction completes"); } } private static void workCallback(DependentTransaction dtx) { using(var txScope1 = new TransactionScope(dtx)) { using (SqlConnection con2 = new SqlConnection(ConnectionString)) { con2.Open(); trace("connection opened"); showDbTranStatus(con2); } txScope1.Complete(); } trace("dependant tran completes"); } private static void trace(string msg) { Console.WriteLine(Thread.CurrentThread.ManagedThreadId + " : " + msg); } private static void showSysTranStatus() { string msg; if (Transaction.Current != null) msg = Transaction.Current.TransactionInformation.DistributedIdentifier.ToString(); else msg = "no sys tran"; trace( msg ); } private static void showDbTranStatus(SqlConnection con) { var cmd = con.CreateCommand(); cmd.CommandText = "SELECT 1"; var c = cmd.ExecuteScalar(); trace("@@TRANCOUNT = " + c); } } It fails on Complete's call of root TransactionScope. But error is different: Unhandled Exception: System.Transactions.TransactionInDoubtException: The transaction is in doubt. --- pired. The timeout period elapsed prior to completion of the operation or the server is not responding. To sum up: I want to understand what "Transaction context in use by another session" means and how to reproduce it.

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  • Django manager for _set in model

    - by Daniel Johansson
    Hello, I'm in the progress of learning Django at the moment but I can't figure out how to solve this problem on my own. I'm reading the book Developers Library - Python Web Development With Django and in one chapter you build a simple CMS system with two models (Story and Category), some generic and custom views together with templates for the views. The book only contains code for listing stories, story details and search. I wanted to expand on that and build a page with nested lists for categories and stories. - Category1 -- Story1 -- Story2 - Category2 - Story3 etc. I managed to figure out how to add my own generic object_list view for the category listing. My problem is that the Story model have STATUS_CHOICES if the Story is public or not and a custom manager that'll only fetch the public Stories per default. I can't figure out how to tell my generic Category list view to also use a custom manager and only fetch the public Stories. Everything works except that small problem. I'm able to create a list for all categories with a sub list for all stories in that category on a single page, the only problem is that the list contains non public Stories. I don't know if I'm on the right track here. My urls.py contains a generic view that fetches all Category objects and in my template I'm using the *category.story_set.all* to get all Story objects for that category, wich I then loop over. I think it would be possible to add a if statement in the template and use the VIEWABLE_STATUS from my model file to check if it should be listed or not. The problem with that solution is that it's not very DRY compatible. Is it possible to add some kind of manager for the Category model too that only will fetch in public Story objects when using the story_set on a category? Or is this the wrong way to attack my problem? Related code urls.py (only category list view): urlpatterns += patterns('django.views.generic.list_detail', url(r'^categories/$', 'object_list', {'queryset': Category.objects.all(), 'template_object_name': 'category' }, name='cms-categories'), models.py: from markdown import markdown import datetime from django.db import models from django.db.models import permalink from django.contrib.auth.models import User VIEWABLE_STATUS = [3, 4] class ViewableManager(models.Manager): def get_query_set(self): default_queryset = super(ViewableManager, self).get_query_set() return default_queryset.filter(status__in=VIEWABLE_STATUS) class Category(models.Model): """A content category""" label = models.CharField(blank=True, max_length=50) slug = models.SlugField() class Meta: verbose_name_plural = "categories" def __unicode__(self): return self.label @permalink def get_absolute_url(self): return ('cms-category', (), {'slug': self.slug}) class Story(models.Model): """A hunk of content for our site, generally corresponding to a page""" STATUS_CHOICES = ( (1, "Needs Edit"), (2, "Needs Approval"), (3, "Published"), (4, "Archived"), ) title = models.CharField(max_length=100) slug = models.SlugField() category = models.ForeignKey(Category) markdown_content = models.TextField() html_content = models.TextField(editable=False) owner = models.ForeignKey(User) status = models.IntegerField(choices=STATUS_CHOICES, default=1) created = models.DateTimeField(default=datetime.datetime.now) modified = models.DateTimeField(default=datetime.datetime.now) class Meta: ordering = ['modified'] verbose_name_plural = "stories" def __unicode__(self): return self.title @permalink def get_absolute_url(self): return ("cms-story", (), {'slug': self.slug}) def save(self): self.html_content = markdown(self.markdown_content) self.modified = datetime.datetime.now() super(Story, self).save() admin_objects = models.Manager() objects = ViewableManager() category_list.html (related template): {% extends "cms/base.html" %} {% block content %} <h1>Categories</h1> {% if category_list %} <ul id="category-list"> {% for category in category_list %} <li><a href="{{ category.get_absolute_url }}">{{ category.label }}</a></li> {% if category.story_set %} <ul> {% for story in category.story_set.all %} <li><a href="{{ story.get_absolute_url }}">{{ story.title }}</a></li> {% endfor %} </ul> {% endif %} {% endfor %} </ul> {% else %} <p> Sorry, no categories at the moment. </p> {% endif %} {% endblock %}

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  • Solr WordDelimiterFilter + Lucene Highlighter

    - by Lucas
    I am trying to get the Highlighter class from Lucene to work properly with tokens coming from Solr's WordDelimiterFilter. It works 90% of the time, but if the matching text contains a ',' such as "1,500" the output is incorrect: Expected: 'test 1,500 this' Observed: 'test 11,500 this' I am not currently sure whether it is Highlighter messing up the recombination or WordDelimiterFilter messing up the tokenization but something is unhappy. Here are the relevant dependencies from my pom: org.apache.lucene lucene-core 2.9.3 jar compile org.apache.lucene lucene-highlighter 2.9.3 jar compile org.apache.solr solr-core 1.4.0 jar compile And here is a simple JUnit test class demonstrating the problem: package test.lucene; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertTrue; import java.io.IOException; import java.io.Reader; import java.util.HashMap; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.TokenStream; import org.apache.lucene.queryParser.ParseException; import org.apache.lucene.queryParser.QueryParser; import org.apache.lucene.search.Query; import org.apache.lucene.search.highlight.Highlighter; import org.apache.lucene.search.highlight.InvalidTokenOffsetsException; import org.apache.lucene.search.highlight.QueryScorer; import org.apache.lucene.search.highlight.SimpleFragmenter; import org.apache.lucene.search.highlight.SimpleHTMLFormatter; import org.apache.lucene.util.Version; import org.apache.solr.analysis.StandardTokenizerFactory; import org.apache.solr.analysis.WordDelimiterFilterFactory; import org.junit.Test; public class HighlighterTester { private static final String PRE_TAG = "<b>"; private static final String POST_TAG = "</b>"; private static String[] highlightField( Query query, String fieldName, String text ) throws IOException, InvalidTokenOffsetsException { SimpleHTMLFormatter formatter = new SimpleHTMLFormatter( PRE_TAG, POST_TAG ); Highlighter highlighter = new Highlighter( formatter, new QueryScorer( query, fieldName ) ); highlighter.setTextFragmenter( new SimpleFragmenter( Integer.MAX_VALUE ) ); return highlighter.getBestFragments( getAnalyzer(), fieldName, text, 10 ); } private static Analyzer getAnalyzer() { return new Analyzer() { @Override public TokenStream tokenStream( String fieldName, Reader reader ) { // Start with a StandardTokenizer TokenStream stream = new StandardTokenizerFactory().create( reader ); // Chain on a WordDelimiterFilter WordDelimiterFilterFactory wordDelimiterFilterFactory = new WordDelimiterFilterFactory(); HashMap<String, String> arguments = new HashMap<String, String>(); arguments.put( "generateWordParts", "1" ); arguments.put( "generateNumberParts", "1" ); arguments.put( "catenateWords", "1" ); arguments.put( "catenateNumbers", "1" ); arguments.put( "catenateAll", "0" ); wordDelimiterFilterFactory.init( arguments ); return wordDelimiterFilterFactory.create( stream ); } }; } @Test public void TestHighlighter() throws ParseException, IOException, InvalidTokenOffsetsException { String fieldName = "text"; String text = "test 1,500 this"; String queryString = "1500"; String expected = "test " + PRE_TAG + "1,500" + POST_TAG + " this"; QueryParser parser = new QueryParser( Version.LUCENE_29, fieldName, getAnalyzer() ); Query q = parser.parse( queryString ); String[] observed = highlightField( q, fieldName, text ); for ( int i = 0; i < observed.length; i++ ) { System.out.println( "\t" + i + ": '" + observed[i] + "'" ); } if ( observed.length > 0 ) { System.out.println( "Expected: '" + expected + "'\n" + "Observed: '" + observed[0] + "'" ); assertEquals( expected, observed[0] ); } else { assertTrue( "No matches found", false ); } } } Anyone have any ideas or suggestions?

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  • Ho to make Histogram Normalize and Equalize in java using JAI library?

    - by Jay
    I m making App in java using Swing component and JAI library. I make histogram of black and white or gray scale image.Is this method of making histogram correct? iif it is correct then how can i do normalization and Equalization of histogram in my App in java using JAI library?my code is below. in my code i make BufferedImage object and then make and plot histogram of that image . enter code here import java.awt.Color; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import javax.media.jai.JAI; import javax.media.jai.PlanarImage; import javax.swing.*; public class FinalHistogram extends JPanel { static int[] bins = new int[256]; static int[] newBins = new int[256]; static int x1 = 0, y1 = 0; static PlanarImage image = JAI.create("fileload", "alp_finger.tiff"); static BufferedImage bi = image.getAsBufferedImage(); FinalHistogram(int[] pbins) { for (int i = 0; i < 256; i++) { bins[i] = pbins[i]; newBins[i] = 0; } repaint(); } @Override protected void paintComponent(Graphics g) { for (int i = 0; i < 256; i++) { g.drawLine(150 + i, 300, 150 + i, 300 - (bins[i] / 300)); if (i == 0 || i == 255) { String sr = new Integer((i)).toString(); g.drawString(sr, 150 + i, 305); } System.out.println("bin[" + i + "]===" + bins[i]); } } public static void main(String[] args) throws IOException { int[] sbins = new int[256]; int pixel = 0; int k = 0; for (int x = 0; x < bi.getWidth(); x++) { for (int y = 0; y < bi.getHeight(); y++) { pixel = bi.getRaster().getSample(x, y, 0); k = (int) (pixel / 256); sbins[k]++; //pixel = bi.getRGB(x, y) & 0x000000ff; //k=pixel; //int[] pixels = m_image.getRGB(0, 0, m_image.getWidth(), m_image.getHeight(), null, 0, m_image.getWidth()); //short currentValue = 0; //int red,green,blue; //for(int i = 0; i<pixels.length; i++){ //red = (pixels[i] >> 16) & 0x000000FF; //green = (pixels[i] >>8 ) & 0x000000FF; //blue = pixels[i] & 0x000000FF; //currentValue = (short)((red + green + blue) / 3); //Current value gives the average //Disregard the alpha //assert(currentValue >= 0 && currentValue <= 255); //Something is awfully wrong if this goes off... //m_histogramArray[currentValue] += 1; //Increment the specific value of the array //} } } JTabbedPane jtp = new JTabbedPane(); jtp.addTab("Histogram", new JScrollPane(new FinalHistogram(sbins))); JFrame frame = new JFrame(); frame.setSize(500, 500); frame.add(new JScrollPane(jtp)); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • No EJB receiver available for handling [appName:,modulename:HelloWorldSessionBean,distinctname:]

    - by zoit
    I'm trying to develop my first EJB with an Example I found, I have the next mistake: Exception in thread "main" java.lang.IllegalStateException: No EJB receiver available for handling [appName:,modulename:HelloWorldSessionBean,distinctname:] combination for invocation context org.jboss.ejb.client.EJBClientInvocationContext@41408b80 at org.jboss.ejb.client.EJBClientContext.requireEJBReceiver(EJBClientContext.java:584) at org.jboss.ejb.client.ReceiverInterceptor.handleInvocation(ReceiverInterceptor.java:119) at org.jboss.ejb.client.EJBClientInvocationContext.sendRequest(EJBClientInvocationContext.java:181) at org.jboss.ejb.client.EJBInvocationHandler.doInvoke(EJBInvocationHandler.java:136) at org.jboss.ejb.client.EJBInvocationHandler.doInvoke(EJBInvocationHandler.java:121) at org.jboss.ejb.client.EJBInvocationHandler.invoke(EJBInvocationHandler.java:104) at $Proxy0.sayHello(Unknown Source) at com.ibytecode.client.EJBApplicationClient.main(EJBApplicationClient.java:16) I use JBOSS 7.1, and the code is this: HelloWorld.java package com.ibytecode.business; import javax.ejb.Remote; @Remote public interface HelloWorld { public String sayHello(); } HelloWorldBean.java package com.ibytecode.businesslogic; import com.ibytecode.business.HelloWorld; import javax.ejb.Stateless; /** * Session Bean implementation class HelloWorldBean */ @Stateless public class HelloWorldBean implements HelloWorld { /** * Default constructor. */ public HelloWorldBean() { } public String sayHello() { return "Hello World !!!"; } } EJBApplicationClient.java: package com.ibytecode.client; import javax.naming.Context; import javax.naming.NamingException; import com.ibytecode.business.HelloWorld; import com.ibytecode.businesslogic.HelloWorldBean; import com.ibytecode.clientutility.ClientUtility; public class EJBApplicationClient { public static void main(String[] args) { // TODO Auto-generated method stub HelloWorld bean = doLookup(); System.out.println(bean.sayHello()); // 4. Call business logic } private static HelloWorld doLookup() { Context context = null; HelloWorld bean = null; try { // 1. Obtaining Context context = ClientUtility.getInitialContext(); // 2. Generate JNDI Lookup name String lookupName = getLookupName(); // 3. Lookup and cast bean = (HelloWorld) context.lookup(lookupName); } catch (NamingException e) { e.printStackTrace(); } return bean; } private static String getLookupName() { /* The app name is the EAR name of the deployed EJB without .ear suffix. Since we haven't deployed the application as a .ear, the app name for us will be an empty string */ String appName = ""; /* The module name is the JAR name of the deployed EJB without the .jar suffix. */ String moduleName = "HelloWorldSessionBean"; /*AS7 allows each deployment to have an (optional) distinct name. This can be an empty string if distinct name is not specified. */ String distinctName = ""; // The EJB bean implementation class name String beanName = HelloWorldBean.class.getSimpleName(); // Fully qualified remote interface name final String interfaceName = HelloWorld.class.getName(); // Create a look up string name String name = "ejb:" + appName + "/" + moduleName + "/" + distinctName + "/" + beanName + "!" + interfaceName; return name; } } ClientUtility.java package com.ibytecode.clientutility; import java.util.Properties; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; public class ClientUtility { private static Context initialContext; private static final String PKG_INTERFACES = "org.jboss.ejb.client.naming"; public static Context getInitialContext() throws NamingException { if (initialContext == null) { Properties properties = new Properties(); properties.put("jboss.naming.client.ejb.context", true); properties.put(Context.URL_PKG_PREFIXES, PKG_INTERFACES); initialContext = new InitialContext(properties); } return initialContext; } } properties.file: remote.connectionprovider.create.options.org.xnio.Options.SSL_ENABLED=false remote.connections=default remote.connection.default.host=localhost remote.connection.default.port = 4447 remote.connection.default.connect.options.org.xnio.Options.SASL_POLICY_NOANONYMOUS=false This is what I have. Why I have this?. Thanks so much. Regards

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  • I can't get SetSystemTime to work in Windows Vista using C# with Interop (P/Invoke).

    - by Andrew
    Hi, I'm having a hard time getting SetSystemTime working in my C# code. SetSystemtime is a kernel32.dll function. I'm using P/invoke (interop) to call it. SetSystemtime returns false and the error is "Invalid Parameter". I've posted the code below. I stress that GetSystemTime works just fine. I've tested this on Vista and Windows 7. Based on some newsgroup postings I've seen I have turned off UAC. No difference. I have done some searching for this problem. I found this link: http://groups.google.com.tw/group/microsoft.public.dotnet.framework.interop/browse_thread/thread/805fa8603b00c267 where the problem is reported but no resolution seems to be found. Notice that UAC is also mentioned but I'm not sure this is the problem. Also notice that this gentleman gets no actual Win32Error. Can someone try my code on XP? Can someone tell me what I'm doing wrong and how to fix it. If the answer is to somehow change permission settings programatically, I'd need an example. I would have thought turning off UAC should cover that though. I'm not required to use this particular way (SetSystemTime). I'm just trying to introduce some "clock drift" to stress test something. If there's another way to do it, please tell me. Frankly, I'm surprised I need to use Interop to change the system time. I would have thought there is a .NET method. Thank you very much for any help or ideas. Andrew Code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace SystemTimeInteropTest { class Program { #region ClockDriftSetup [StructLayout(LayoutKind.Sequential)] public struct SystemTime { [MarshalAs(UnmanagedType.U2)] public short Year; [MarshalAs(UnmanagedType.U2)] public short Month; [MarshalAs(UnmanagedType.U2)] public short DayOfWeek; [MarshalAs(UnmanagedType.U2)] public short Day; [MarshalAs(UnmanagedType.U2)] public short Hour; [MarshalAs(UnmanagedType.U2)] public short Minute; [MarshalAs(UnmanagedType.U2)] public short Second; [MarshalAs(UnmanagedType.U2)] public short Milliseconds; } [DllImport("kernel32.dll")] public static extern void GetLocalTime( out SystemTime systemTime); [DllImport("kernel32.dll")] public static extern void GetSystemTime( out SystemTime systemTime); [DllImport("kernel32.dll", SetLastError = true)] public static extern bool SetSystemTime( ref SystemTime systemTime); //[DllImport("kernel32.dll", SetLastError = true)] //public static extern bool SetLocalTime( //ref SystemTime systemTime); [System.Runtime.InteropServices.DllImportAttribute("kernel32.dll", EntryPoint = "SetLocalTime")] [return: System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)] public static extern bool SetLocalTime([InAttribute()] ref SystemTime lpSystemTime); #endregion ClockDriftSetup static void Main(string[] args) { try { SystemTime sysTime; GetSystemTime(out sysTime); sysTime.Milliseconds += (short)80; sysTime.Second += (short)3000; bool bResult = SetSystemTime(ref sysTime); if (bResult == false) throw new System.ComponentModel.Win32Exception(); } catch (Exception ex) { Console.WriteLine("Drift Error: " + ex.Message); } } } }

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  • Opening an SQL CE file at runtime with Entity Framework 4

    - by David Veeneman
    I am getting started with Entity Framework 4, and I an creating a demo app as a learning exercise. The app is a simple documentation builder, and it uses a SQL CE store. Each documentation project has its own SQL CE data file, and the user opens one of these files to work on a project. The EDM is very simple. A documentation project is comprised of a list of subjects, each of which has a title, a description, and zero or more notes. So, my entities are Subject, which contains Title and Text properties, and Note, which has Title and Text properties. There is a one-to-many association from Subject to Note. I am trying to figure out how to open an SQL CE data file. A data file must match the schema of the SQL CE database created by EF4's Create Database Wizard, and I will implement a New File use case elsewhere in the app to implement that requirement. Right now, I am just trying to get an existing data file open in the app. I have reproduced my existing 'Open File' code below. I have set it up as a static service class called File Services. The code isn't working quite yet, but there is enough to show what I am trying to do. I am trying to hold the ObjectContext open for entity object updates, disposing it when the file is closed. So, here is my question: Am I on the right track? What do I need to change to make this code work with EF4? Is there an example of how to do this properly? Thanks for your help. My existing code: public static class FileServices { #region Private Fields // Member variables private static EntityConnection m_EntityConnection; private static ObjectContext m_ObjectContext; #endregion #region Service Methods /// <summary> /// Opens an SQL CE database file. /// </summary> /// <param name="filePath">The path to the SQL CE file to open.</param> /// <param name="viewModel">The main window view model.</param> public static void OpenSqlCeFile(string filePath, MainWindowViewModel viewModel) { // Configure an SQL CE connection string var sqlCeConnectionString = string.Format("Data Source={0}", filePath); // Configure an EDM connection string var builder = new EntityConnectionStringBuilder(); builder.Metadata = "res://*/EF4Model.csdl|res://*/EF4Model.ssdl|res://*/EF4Model.msl"; builder.Provider = "System.Data.SqlServerCe"; builder.ProviderConnectionString = sqlCeConnectionString; var entityConnectionString = builder.ToString(); // Connect to the model m_EntityConnection = new EntityConnection(entityConnectionString); m_EntityConnection.Open(); // Create an object context m_ObjectContext = new Model1Container(); // Get all Subject data IQueryable<Subject> subjects = from s in Subjects orderby s.Title select s; // Set view model data property viewModel.Subjects = new ObservableCollection<Subject>(subjects); } /// <summary> /// Closes an SQL CE database file. /// </summary> public static void CloseSqlCeFile() { m_EntityConnection.Close(); m_ObjectContext.Dispose(); } #endregion }

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  • java - BigDecimal

    - by Mk12
    I was trying to make my own class for currencies using longs, but Apparently I should use BigDecimal (and then whenever I print it just add the $ sign before it). Could someone please get me started? What would be the best way to use BigDecimals for Dollar currencies, like making it at least but no more than 2 decimal places for the cents, etc. The api for BigDecimal is huge, and I don't know which methods to use. Also, BigDecimal has better precision, but isn't that all lost if it passes through a double? if I do new BigDecimal(24.99), how will it be different than using a double? Or should I use the constructor that uses a String instead? EDIT: I decided to use BigDecimals, and then use: private static final java.text.NumberFormat moneyt = java.text.NumberFormat.getCurrencyInstance(); { money.setRoundingMode(RoundingMode.HALF_EVEN); } and then whenever I display the BigDecimals, to use money.format(theBigDecimal). Is this alright? Should I have the BigDecimal rounding it too? Because then it doesn't get rounded before it does another operation.. if so, could you show me how? And how should I create the BigDecimals? new BigDecimal("24.99") ? Well, after many comments to Vineet Reynolds (thanks for keeping coming back and answering), this is what I have decided. I use BigDecimals and a NumberFormat. Here is where I create the NumberFormat instance. private static final NumberFormat money; static { money = NumberFormat.getCurrencyInstance(Locale.CANADA); money.setRoundingMode(RoundingMode.HALF_EVEN); } Here is my BigDecimal: private final BigDecimal price; Whenever I want to display the price, or another BigDecimal that I got through calculations of price, I use: money.format(price) to get the String. Whenever I want to store the price, or a calculation from price, in a database or in a field or anywhere, I use (for a field): myCalculatedResult = price.add(new BigDecimal("34.58")).setScale(2, RoundingMode.HALF_EVEN); .. but I'm thinking now maybe I should not have the NumberFormat round, but when I want to display do this: System.out.print(money.format(price.setScale(2, RoundingMode.HALF_EVEN); That way to ensure the model and things displayed in the view are the same. I don't do: price = price.setScale(2, RoundingMode.HALF_EVEN); Because then it would always round to 2 decimal places and wouldn't be as precise in calculations. So its all solved now, I guess. But is there any shortcut to typing calculatedResult.setScale(2, RoundingMode.HALF_EVEN) all the time? All I can think of is static importing HALF_EVEN... EDIT: I've changed my mind a bit, I think if I store a value, I won't round it unless I have no more operations to do with it, e.g. if it was the final total that will be charged to someone. I will only round things at the end, or whenever necessary, and I will still use NumberFormat for the currency formatting, but since I always want rounding for display, I made a static method for display: public static String moneyFormat(BigDecimal price) { return money.format(price.setScale(2, RoundingMode.HALF_EVEN)); } So values stored in variables won't be rounded, and I'll use that method to display prices.

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  • Overriding Object.Equals() instance method in C#; now Code Analysis / FxCop warning CA2218: "should

    - by Chris W. Rea
    I've got a complex class in my C# project on which I want to be able to do equality tests. It is not a trivial class; it contains a variety of scalar properties as well as references to other objects and collections (e.g. IDictionary). For what it's worth, my class is sealed. To enable a performance optimization elsewhere in my system (an optimization that avoids a costly network round-trip), I need to be able to compare instances of these objects to each other for equality – other than the built-in reference equality – and so I'm overriding the Object.Equals() instance method. However, now that I've done that, Visual Studio 2008's Code Analysis a.k.a. FxCop, which I keep enabled by default, is raising the following warning: warning : CA2218 : Microsoft.Usage : Since 'MySuperDuperClass' redefines Equals, it should also redefine GetHashCode. I think I understand the rationale for this warning: If I am going to be using such objects as the key in a collection, the hash code is important. i.e. see this question. However, I am not going to be using these objects as the key in a collection. Ever. Feeling justified to suppress the warning, I looked up code CA2218 in the MSDN documentation to get the full name of the warning so I could apply a SuppressMessage attribute to my class as follows: [SuppressMessage("Microsoft.Naming", "CA2218:OverrideGetHashCodeOnOverridingEquals", Justification="This class is not to be used as key in a hashtable.")] However, while reading further, I noticed the following: How to Fix Violations To fix a violation of this rule, provide an implementation of GetHashCode. For a pair of objects of the same type, you must ensure that the implementation returns the same value if your implementation of Equals returns true for the pair. When to Suppress Warnings ----- Do not suppress a warning from this rule. [arrow & emphasis mine] So, I'd like to know: Why shouldn't I suppress this warning as I was planning to? Doesn't my case warrant suppression? I don't want to code up an implementation of GetHashCode() for this object that will never get called, since my object will never be the key in a collection. If I wanted to be pedantic, instead of suppressing, would it be more reasonable for me to override GetHashCode() with an implementation that throws a NotImplementedException? Update: I just looked this subject up again in Bill Wagner's good book Effective C#, and he states in "Item 10: Understand the Pitfalls of GetHashCode()": If you're defining a type that won't ever be used as the key in a container, this won't matter. Types that represent window controls, web page controls, or database connections are unlikely to be used as keys in a collection. In those cases, do nothing. All reference types will have a hash code that is correct, even if it is very inefficient. [...] In most types that you create, the best approach is to avoid the existence of GetHashCode() entirely. ... that's where I originally got this idea that I need not be concerned about GetHashCode() always.

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  • AES Cipher not picking up IV

    - by timothyjc
    I am trying to use an IV with AES so that the encrypted text is unpredictable. However, the encrypted hex string is always the same. I have actually tried a few methods of attempting to add some randomness by passing some additional parameters to the cipher init call: 1) Manual IV generation byte[] iv = generateIv(); IvParameterSpec ivspec = new IvParameterSpec(iv); 2) Asking cipher to generate IV AlgorithmParameters params = cipher.getParameters(); params.getParameterSpec(IvParameterSpec.class); 3) Using a PBEParameterSpec byte[] encryptionSalt = generateSalt(); PBEParameterSpec pbeParamSpec = new PBEParameterSpec(encryptionSalt, 1000); All of these seem to have no influence on the encrypted text.... help!!! My code: package com.citc.testencryption; import java.security.NoSuchAlgorithmException; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.PBEKeySpec; import android.app.Activity; import android.os.Bundle; import android.util.Log; public class Main extends Activity { public static final int SALT_LENGTH = 20; public static final int PBE_ITERATION_COUNT = 1000; private static final String RANDOM_ALGORITHM = "SHA1PRNG"; private static final String PBE_ALGORITHM = "PBEWithSHA256And256BitAES-CBC-BC"; private static final String CIPHER_ALGORITHM = "PBEWithSHA256And256BitAES-CBC-BC"; private static final String TAG = Main.class.getSimpleName(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); try { String password = "password"; String plainText = "plaintext message to be encrypted"; // byte[] salt = generateSalt(); byte[] salt = "dfghjklpoiuytgftgyhj".getBytes(); Log.i(TAG, "Salt: " + salt.length + " " + HexEncoder.toHex(salt)); PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, PBE_ITERATION_COUNT); SecretKeyFactory keyFac = SecretKeyFactory.getInstance(PBE_ALGORITHM); SecretKey secretKey = keyFac.generateSecret(pbeKeySpec); byte[] key = secretKey.getEncoded(); Log.i(TAG, "Key: " + HexEncoder.toHex(key)); // PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, ITERATION_COUNT); Cipher encryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM); // byte[] encryptionSalt = generateSalt(); // Log.i(TAG, "Encrypted Salt: " + encryptionSalt.length + " " + HexEncoder.toHex(encryptionSalt)); // PBEParameterSpec pbeParamSpec = new PBEParameterSpec(encryptionSalt, 1000); // byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV(); // Log.i(TAG, encryptionCipher.getParameters() + " "); byte[] iv = generateIv(); IvParameterSpec ivspec = new IvParameterSpec(iv); encryptionCipher.init(Cipher.ENCRYPT_MODE, secretKey, ivspec); byte[] encryptedText = encryptionCipher.doFinal(plainText.getBytes()); Log.i(TAG, "Encrypted: " + HexEncoder.toHex(encryptedText)); // <== Why is this always the same :( Cipher decryptionCipher = Cipher.getInstance(CIPHER_ALGORITHM); decryptionCipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec); byte[] decryptedText = decryptionCipher.doFinal(encryptedText); Log.i(TAG, "Decrypted: " + new String(decryptedText)); } catch (Exception e) { e.printStackTrace(); } } private byte[] generateSalt() throws NoSuchAlgorithmException { SecureRandom random = SecureRandom.getInstance(RANDOM_ALGORITHM); byte[] salt = new byte[SALT_LENGTH]; random.nextBytes(salt); return salt; } private byte[] generateIv() throws NoSuchAlgorithmException { SecureRandom random = SecureRandom.getInstance(RANDOM_ALGORITHM); byte[] iv = new byte[16]; random.nextBytes(iv); return iv; } }

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  • Feedback on iterating over type-safe enums

    - by Sumant
    In response to the earlier SO question "Enumerate over an enum in C++", I came up with the following reusable solution that uses type-safe enum idiom. I'm just curious to see the community feedback on my solution. This solution makes use of a static array, which is populated using type-safe enum objects before first use. Iteration over enums is then simply reduced to iteration over the array. I'm aware of the fact that this solution won't work if the enumerators are not strictly increasing. template<typename def, typename inner = typename def::type> class safe_enum : public def { typedef typename def::type type; inner val; static safe_enum array[def::end - def::begin]; static bool init; static void initialize() { if(!init) // use double checked locking in case of multi-threading. { unsigned int size = def::end - def::begin; for(unsigned int i = 0, j = def::begin; i < size; ++i, ++j) array[i] = static_cast<typename def::type>(j); init = true; } } public: safe_enum(type v = def::begin) : val(v) {} inner underlying() const { return val; } static safe_enum * begin() { initialize(); return array; } static safe_enum * end() { initialize(); return array + (def::end - def::begin); } bool operator == (const safe_enum & s) const { return this->val == s.val; } bool operator != (const safe_enum & s) const { return this->val != s.val; } bool operator < (const safe_enum & s) const { return this->val < s.val; } bool operator <= (const safe_enum & s) const { return this->val <= s.val; } bool operator > (const safe_enum & s) const { return this->val > s.val; } bool operator >= (const safe_enum & s) const { return this->val >= s.val; } }; template <typename def, typename inner> safe_enum<def, inner> safe_enum<def, inner>::array[def::end - def::begin]; template <typename def, typename inner> bool safe_enum<def, inner>::init = false; struct color_def { enum type { begin, red = begin, green, blue, end }; }; typedef safe_enum<color_def> color; template <class Enum> void f(Enum e) { std::cout << static_cast<unsigned>(e.underlying()) << std::endl; } int main() { std::for_each(color::begin(), color::end(), &f<color>); color c = color::red; }

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