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  • C#: Passing data to forms UI using BeginInvoke

    - by Bi
    Hi I am a C# newbie and have a class that needs to pass row information to a grid in the windows form. What is the best way to do it? I have put in some example code for better understanding. Thanks. public class GUIController { private My_Main myWindow; public GUIController( My_Main window ) { myWindow = window; } public void UpdateProducts( List<myProduct> newList ) { object[] row = new object[3]; foreach (myProduct product in newList) { row[0] = product.Name; row[1] = product.Status; row[2] = product.Day; //HOW DO I USE BeginInvoke HERE? } } } And the form class below: public class My_Main : Form { //HOW DO I GO ABOUT USING THIS DELEGATE? public delegate void ProductDelegate( string[] row ); public static My_Main theWindow = null; static void Main( ) { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); theWindow = new My_Main(); Application.Run(theWindow); } private void My_Main_Load( object sender, EventArgs e ) { /// Create GUIController and pass the window object gui = new GUIController( this ); } public void PopulateGrid( string[] row ) { ProductsGrid.Rows.Add(row); ProductsGrid.Update(); } } Thanks!

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  • Instantiating a class within a class

    - by Ink-Jet
    Hello. I'm trying to instantiate a class within a class, so that the outer class contains the inner class. This is my code: #include <iostream> #include <string> class Inner { private: std::string message; public: Inner(std::string m); void print() const; }; Inner::Inner(std::string m) { message = m; } void Inner::print() const { std::cout << message << std::endl; std::cout << message << std::endl; } class Outer { private: std::string message; Inner in; public: Outer(std::string m); void print() const; }; Outer::Outer(std::string m) { message = m; } void Outer::print() const { std::cout << message << std::endl; } int main() { Outer out("Hello world."); out.print(); return 0; } "Inner in", is my attempt at containing the inner within the outer, however, when I compile, i get an error that there is no matching function for call to Inner::Inner(). What have I done wrong? Thanks.

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  • eliminating duplicate Enum code

    - by Don
    Hi, I have a large number of Enums that implement this interface: /** * Interface for an enumeration, each element of which can be uniquely identified by it's code */ public interface CodableEnum { /** * Get the element with a particular code * @param code * @return */ public CodableEnum getByCode(String code); /** * Get the code that identifies an element of the enum * @return */ public String getCode(); } A typical example is: public enum IMType implements CodableEnum { MSN_MESSENGER("msn_messenger"), GOOGLE_TALK("google_talk"), SKYPE("skype"), YAHOO_MESSENGER("yahoo_messenger"); private final String code; IMType (String code) { this.code = code; } public String getCode() { return code; } public IMType getByCode(String code) { for (IMType e : IMType.values()) { if (e.getCode().equalsIgnoreCase(code)) { return e; } } } } As you can imagine these methods are virtually identical in all implementations of CodableEnum. I would like to eliminate this duplication, but frankly don't know how. I tried using a class such as the following: public abstract class DefaultCodableEnum implements CodableEnum { private final String code; DefaultCodableEnum(String code) { this.code = code; } public String getCode() { return this.code; } public abstract CodableEnum getByCode(String code); } But this turns out to be fairly useless because: An enum cannot extend a class Elements of an enum (SKYPE, GOOGLE_TALK, etc.) cannot extend a class I cannot provide a default implementation of getByCode(), because DefaultCodableEnum is not itself an Enum. I tried changing DefaultCodableEnum to extend java.lang.Enum, but this doesn't appear to be allowed. Any suggestions that do not rely on reflection? Thanks, Don

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  • RichTextBox text is not shown C#

    - by user271077
    using richtextbox control programatically i'm appending text to the richtextbox . richTextBox1.AppendText("hello"); somehow the text appears in the richTextBox1.Text but is not shown in the form. any idea of what might be the problem? (I checked the forecolor seems ok). Thanks in advance Edit: found the root cause (had by mistake the initializeComponent() twice. ) private void InitializeComponent() { this.richTextBox1 = new System.Windows.Forms.RichTextBox(); this.SuspendLayout(); // // richTextBox1 // this.richTextBox1.Location = new System.Drawing.Point(114, 104); this.richTextBox1.Name = "richTextBox1"; this.richTextBox1.Size = new System.Drawing.Size(100, 96); this.richTextBox1.TabIndex = 0; this.richTextBox1.Text = ""; // // Form1 // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.ClientSize = new System.Drawing.Size(284, 262); this.Controls.Add(this.richTextBox1); this.Name = "Form1"; this.Text = "Form1"; this.Load += new System.EventHandler(this.Form1_Load); this.ResumeLayout(false); } public Form1() { InitializeComponent(); InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { richTextBox1.AppendText("hello world"); }` but still curious about why did this cause this weird behavior?

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  • Synchronize write to two collections

    - by glaz666
    I need to put some value to maps if it is not there yet. The key-value (if set) should always be in two collections (that is put should happen in two maps atomically). I have tried to implement this as follows: private final ConcurrentMap<String, Object> map1 = new ConcurrentHashMap<String, Object>(); private final ConcurrentMap<String, Object> map2 = new ConcurrentHashMap<String, Object>(); public Object putIfAbsent(String key) { Object retval = map1.get(key); if (retval == null) { synchronized (map1) { retval = map1.get(key); if (retval == null) { Object value = new Object(); //or get it somewhere synchronized (map2) { map1.put(key, value); map2.put(key, new Object()); } retval = value; } } } return retval; } public void doSomething(String key) { Object obj1 = map1.get(key); Object obj2 = map2.get(key); //do smth } Will that work fine in all cases? Thanks

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  • csharp get value datatemplate element

    - by To-me
    Hello, Here is my code <ListBox x:Name="myList" IsSynchronizedWithCurrentItem="True" SelectionChanged="editElement"> <ListBox.ItemTemplate> <DataTemplate x:Name="ElementItemTemplate"> <StackPanel Name="stackPanelElementItem" Orientation="Horizontal"> <Label Name="SelectedItemlabel" Content="{Binding}" /> <Button Name="buttonDelElement" Click="btnDelElement">Delete</Button> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> private void btnDelElement(object sender, RoutedEventArgs e) { ListBoxItem lbi2 = (ListBoxItem)(lstCursus.ItemContainerGenerator.ContainerFromItem(myList.Items.CurrentItem)); String selectedItem = lbi2.Content.ToString(); MessageBox.Show("Selected Item " + selectedItem + " ."); private void editCursus(object sender, RoutedEventArgs e) { MessageBox.Show("Selected Item " + selectedItem + " ."); /* some code to edit selected item using linq */ } My issue, SelectionChange doesn't work anymore and when I click on buttonDelElement, Selected Item doesn't change immediately. Please, any ideas?

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  • Having troubles inheriting base class

    - by Nick
    When I inherit the base class, it's telling me there is no such class This is enhanced.h: class enhanced: public changeDispenser // <--------where error is occuring { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine enhanced(int); // Constructor // Sets the Dollar amount to what the User wants void changeLoad(int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int dollar; }; This is enhanced.cpp: #include "enhanced.h" #include <iostream> using namespace std; enhanced::enhanced(int dol) { dollar = dol; } void enhanced::changeStatus() { cout << dollar << " dollars, "; changeDispenser::changeStatus(); } void enhanced::changeLoad(int d) { dollar = dollar + d; //changeDispenser::changeLoad; } This is changeDispenser.h: class changeDispenser { public: void changeStatus(); // Function: Lets the user know how much of each coin is in the machine changeDispenser(int, int, int, int); // Constructor // Sets the Quarters, Dimes, Nickels, and Pennies to what the User wants void changeLoad(int, int, int, int); // Function: Loads what change the user requests into the Coin Machine int dispenseChange(int); // Function: Takes the users amount of cents requests and dispenses it to the user private: int quarter; int dime; int nickel; int penny; }; I didn't include the driver file or the changeDispenser imp file, but in the driver, these are included #include "changeDispenser.h" #include "enhanced.h"

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  • How to avoid concurrent execution of a time-consuming task without blocking?

    - by Diego V
    I want to efficiently avoid concurrent execution of a time-consuming task in a heavily multi-threaded environment without making threads wait for a lock when another thread is already running the task. Instead, in that scenario, I want them to gracefully fail (i.e. skip its attempt to execute the task) as fast as possible. To illustrate the idea considerer this unsafe (has race condition!) code: private static boolean running = false; public void launchExpensiveTask() { if (running) return; // Do nothing running = true; try { runExpensiveTask(); } finally { running = false; } } I though about using a variation of Double-Checked Locking (consider that running is a primitive 32-bit field, hence atomic, it could work fine even for Java below 5 without the need of volatile). It could look like this: private static boolean running = false; public void launchExpensiveTask() { if (running) return; // Do nothing synchronized (ThisClass.class) { if (running) return; running = true; try { runExpensiveTask(); } finally { running = false; } } } Maybe I should also use a local copy of the field as well (not sure now, please tell me). But then I realized that anyway I will end with an inner synchronization block, that still could hold a thread with the right timing at monitor entrance until the original executor leaves the critical section (I know the odds usually are minimal but in this case we are thinking in several threads competing for this long-running resource). So, could you think in a better approach?

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  • Java Detect Variable Change Using PropertyChangeSupport and PropertyChangeListener

    - by Sam
    I'm trying to print out debug statements when some third party code changes a variable. For example, consider the following: public final class MysteryClass { private int secretCounter; public synchronized int getCounter() { return secretCounter; } public synchronized void incrementCounter() { secretCounter++; } } public class MyClass { public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // add code here to detect calls to incrementCounter and print a debug message } I don't have the ability to change the 3rd party MysteryClass, so I thought that I could use PropertyChangeSupport and PropertyChangeListener to detect changes to the secretCounter: public class MyClass implements PropertyChangeListener { private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this); public MyClass() { propertySupport.addPropertyChangeListener(this); } public void propertyChange(PropertyChangeEvent evt) { System.out.println("property changing: " + evt.getPropertyName()); } public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // do logic which involves increment and getting the value of MysteryClass } } Unfortunately, this did not work and I have no debug messages printed out. Does anyone see what is wrong with my implementation of the PropertyChangeSupport and Listener interfaces? I want to print a debug statement whenever incrementCounter is called or the value of secretCounter changes.

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  • How do I handle freeing unmanaged structures on application close?

    - by LostKaleb
    I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } }

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  • Implementing a Version check between an Abstract class and it's implementation

    - by Michael Stum
    I have this abstract class and concrete implementation (they are in different assemblies): public abstract class MyAbstractClass { private static readonly int MyAbstractClassVersion = 1; public abstract int ImplementedVersion { get; } protected MyAbstractClass() { CheckVersion(); } private void CheckVersion() { var message = string.Format( "MyAbstractClass implements Version {0}, concrete is Version {1}", RepositoryVersion, ImplementedVersion); if (!MyAbstractClassVersion.Equals(ImplementedVersion)) throw new InvalidOperationException(message); } } public class ConcreteClass : MyAbstractClass { public ConcreteClass() : base() { // ConcreteClass is guaranteed to have // a constructor that calls the base constructor // I just simplified the example } public override int ImplementedVersion { get { return 2; } } } As you see, I call CheckVersion() from the abstract constructor, to get rid of the "virtual member call in base constructor" message, but I am not sure if that's really the way to do it. Sure, it works, but that doesn't mean it will always work, will it? Also, I wonder if I can get the name of the Concrete Type from the CheckVersion() function? I know that adding new abstract members will force an error anyway (System.TypeLoadException) and I'm not sure if I want this type of strict Versioning, but I'm just curious how it would be done properly given only the abstract class and an implementation (I know I could do it by using interfaces and/or a Factory pattern).

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  • How to determine if the camera button is half pressed

    - by Matthew
    I am creating a small test camera application, and I would like to be able to implement a feature that allows focus text bars to be present on the screen while the hardware camera button is pressed half way down. I created a camera_ButtonHalfPress event to perform the focus action, but I am unsure of how to toggle the text bars I would like to show on the screen accordingly. Essentially, my goal would be to show the text bars while the camera button is pressed half way down, and then remove them if the button is pressed all the way or the button is released before being pressed all the way down. The button being released is the part I am having trouble with. What I have is as follows: MainPage.xaml.cs private void camera_ButtonHalfPress(object sender, EventArgs e) { //camera.Focus(); // Show the focus brackets. focusBrackets.Visibility = Visibility.Visible; } } private void camera_ButtonFullPress(object sender, EventArgs e) { // Hide the focus brackets. focusBrackets.Visibility = Visibility.Collapsed; camera.CaptureImage(); } } Currently, if the the user decides to release the camera button before it is pressed all the way, the focus brackets persist on the screen. How might I fix this issue?

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  • implementing the generic interface

    - by user845405
    Could any one help me on implementing the generic interface for this class. I want to be able to use the below Cache class methods through an interface. Thank you for the help!. public class CacheStore { private Dictionary<string, object> _cache; private object _sync; public CacheStore() { _cache = new Dictionary<string, object>(); _sync = new object(); } public bool Exists<T>(string key) where T : class { Type type = typeof(T); lock (_sync) { return _cache.ContainsKey(type.Name + key); } } public bool Exists<T>() where T : class { Type type = typeof(T); lock (_sync) { return _cache.ContainsKey(type.Name); } } public T Get<T>(string key) where T : class { Type type = typeof(T); lock (_sync) { if (_cache.ContainsKey(key + type.Name) == false) throw new ApplicationException(String.Format("An object with key '{0}' does not exists", key)); lock (_sync) { return (T)_cache[key + type.Name]; } } } public void Add<T>(string key, T value) { Type type = typeof(T); if (value.GetType() != type) throw new ApplicationException(String.Format("The type of value passed to cache {0} does not match the cache type {1} for key {2}", value.GetType().FullName, type.FullName, key)); lock (_sync) { if (_cache.ContainsKey(key + type.Name)) throw new ApplicationException(String.Format("An object with key '{0}' already exists", key)); lock (_sync) { _cache.Add(key + type.Name, value); } } } } Could any one help me on implementing the generic interface for this class. I want to be able to use the below Cache class methods through an interface.

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  • Better way to catch trouble points

    - by mac
    User submits a CSV file which is consumed by a program. Values which are used throughout the program come from the CSV, natually if values are missed it is a problem. Below is my solution. Ip on top private List<String> currentFieldName = new ArrayList<String>(); As part of the method: try { setCurrentFieldName("Trim Space"); p.setTrimSpace(currentLineArray[dc.getTRIM_POSITION()].equals("yes") ? true : false); setCurrentFieldName("Ignore Case"); p.setIgnoreCase(currentLineArray[dc.getIGNORE_CASE_POSITION()].equals("yes") ? true : false); } catch (NullPointerException e) { throw new InputSpreadsheetValueUnassignedException("\"Type\" field not set: " + currentFieldName); } And the method which keeps track of a current field being looked at: private void setCurrentFieldName(String fieldName) { currentFieldName.clear(); currentFieldName.add(fieldName); } The idea there is that if user fails to submit value and i will end up getting null, before throwing an exception, i will know what value was not assigned. So, this being said, specific questions: Is what i have shown below an acceptable solution? Can you suggest something more elegant?

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  • Convert VBA to VBS

    - by dnLL
    I have a little VBA script with some functions that I would like to convert to a single VBS file. Here is an example of what I got: Private Declare Function GetPrivateProfileString Lib "kernel32" Alias "GetPrivateProfileStringA" (ByVal lpApplicationName As String, ByVal lpKeyName As Any, ByVal lpDefault As String, ByVal lpReturnedString As String, ByVal nSize As Long, ByVal lpFileName As String) As Long Private Function ReadIniFileString(ByVal Sect As String, ByVal Keyname As String) As String Dim Worked As Long Dim RetStr As String * 128 Dim StrSize As Long Dim iNoOfCharInIni As Integer Dim sIniString, sProfileString As String iNoOfCharInIni = 0 sIniString = "" If Sect = "" Or Keyname = "" Then MsgBox "Erreur lors de la lecture des paramètres dans " & IniFileName, vbExclamation, "INI" Access.Application.Quit Else sProfileString = "" RetStr = Space(128) StrSize = Len(RetStr) Worked = GetPrivateProfileString(Sect, Keyname, "", RetStr, StrSize, IniFileName) If Worked Then iNoOfCharInIni = Worked sIniString = Left$(RetStr, Worked) End If End If ReadIniFileString = sIniString End Function And then, I need to use this function to put some values in strings. VBS doesn't seem to like any of my var declaration ((Dim) MyVar As MyType). If I'm able to adapt that code to VBS, I should be able to do the rest of my functions too. How can I adapt/convert this to VBS? Thank you.

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  • MonoTouch Load image in background

    - by user1058951
    I am having a problem trying to load an image and display it using System.Threading.Task My Code is as follows Task DownloadTask { get; set; } public string Instrument { get; set; } public PriceChartViewController(string Instrument) { this.Instrument = Instrument; DownloadTask = Task.Factory.StartNew(() => { }); } private void LoadChart(ChartType chartType) { NSData data = new NSData(); DownloadTask = DownloadTask.ContinueWith(prevTask => { try { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true; NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument)); data = NSData.FromUrl(nsUrl); } finally { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false; } }); DownloadTask = DownloadTask.ContinueWith(t => { UIImage image = new UIImage(data); chartImageView = new UIImageView(image); chartImageView.ContentScaleFactor = 2f; View.AddSubview(chartImageView); this.Title = chartType.Title; }, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.FromCurrentSynchronizationContext()); } The second Continue with does not seem to be being called? Initially my code looked like the following without the background processing and it worked perfectly. private void oldLoadChart(ChartType chartType) { UIApplication.SharedApplication.NetworkActivityIndicatorVisible = true; NSUrl nsUrl = new NSUrl(chartType.Uri(Instrument)); NSData data = NSData.FromUrl(nsUrl); UIImage image = new UIImage(data); chartImageView = new UIImageView(image); chartImageView.ContentScaleFactor = 2f; View.AddSubview(chartImageView); this.Title = chartType.Title; UIApplication.SharedApplication.NetworkActivityIndicatorVisible = false; } Does anyone know what I am doing wrong?

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  • Project Naming Convention Feedback Please

    - by Sam Striano
    I am creating a ASP.NET MVC 3 application using Entity Framework 4. I am using the Repository/Service Pattern and was looking for feedback. I currently have the following: MVC Application (GTG.dll) GTG GTG.Controllers GTG.ViewModels Business POCO's (GTG.Business.dll) This contains all business objects (Customer, Order, Invoice, etc...) EF Model/Repositories (GTG.Data.dll) GTG.Business (GTG.Context.tt) I used the Entity POCO Generator Templates. GTG.Data.Repositories Service Layer (GTG.Data.Services.dll) GTG.Data.Services - Contains all of the service objects, one per aggregate root. The following is a little sample code: Controller Namespace Controllers Public Class HomeController Inherits System.Web.Mvc.Controller Function Index() As ActionResult Return View(New Models.HomeViewModel) End Function End Class End Namespace Model Namespace Models Public Class HomeViewModel Private _Service As CustomerService Public Property Customers As List(Of Customer) Public Sub New() _Service = New CustomerService _Customers = _Service.GetCustomersByBusinessName("Striano") End Sub End Class End Namespace Service Public Class CustomerService Private _Repository As ICustomerRepository Public Sub New() _Repository = New CustomerRepository End Sub Function GetCustomerByID(ByVal ID As Integer) As Customer Return _Repository.GetByID(ID) End Function Function GetCustomersByBusinessName(ByVal Name As String) As List(Of Customer) Return _Repository.Query(Function(x) x.CompanyName.StartsWith(Name)).ToList End Function End Class Repository Namespace Data.Repositories Public Class CustomerRepository Implements ICustomerRepository Public Sub Add(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Add End Sub Public Sub Delete(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Delete End Sub Public Function GetByID(ByVal ID As Integer) As Business.Customer Implements IRepository(Of Business.Customer).GetByID Using db As New GTGContainer Return db.Customers.FirstOrDefault(Function(x) x.ID = ID) End Using End Function Public Function Query(ByVal Predicate As System.Linq.Expressions.Expression(Of System.Func(Of Business.Customer, Boolean))) As System.Linq.IQueryable(Of Business.Customer) Implements IRepository(Of Business.Customer).Query Using db As New GTGContainer Return db.Customers.Where(Predicate) End Using End Function Public Sub Save(ByVal Entity As Business.Customer) Implements IRepository(Of Business.Customer).Save End Sub End Class End Namespace

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  • How can i initialise a server on startup?

    - by djerry
    Hey all, I need to make some connections on startup of a server. I'm using the wcf technology for this client-server application. The problem is that the constructor of the server isn't called at any time, so for the moment, i initialize the connections when the first client makes a connection. But this generates problems in a further part. This is my server setup: private static ServiceHost _svc; static void Main(string[] args) { NetTcpBinding binding = new NetTcpBinding(SecurityMode.Message); Uri address = new Uri("net.tcp://localhost:8000"); _svc = new ServiceHost(typeof(MonitoringSystemService), address); publishMetaData(_svc, "http://localhost:8001"); _svc.AddServiceEndpoint(typeof(IMonitoringSystemService), binding, "Monitoring Server"); _svc.Open(); Console.WriteLine("Listener service gestart op net.tcp://localhost:8000/Monitoring"); Console.ReadLine(); } private static void publishMetaData(ServiceHost svc, string sEndpointAddress) { ServiceMetadataBehavior smb = svc.Description.Behaviors.Find<ServiceMetadataBehavior>(); if (smb != null) { smb.HttpGetEnabled = true; smb.HttpGetUrl = new Uri(sEndpointAddress); } else { smb = new ServiceMetadataBehavior(); smb.HttpGetEnabled = true; smb.HttpGetUrl = new Uri(sEndpointAddress); svc.Description.Behaviors.Add(smb); } } How can i start the server without waiting for a client to logon so i can initialize it. Thanks in advance.

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  • Question about singleton property

    - by Jack
    I'm reading the java tutorial for enums located here and have a question: http://java.sun.com/j2se/1.5.0/docs/guide/language/enums.html#Card The part i'm confused about is as follows: "The Card class, above, contains a static factory that returns a deck, but there is no way to get an individual card from its rank and suit. Merely exposing the constructor would destroy the singleton property (that only a single instance of each card is allowed to exist). Here is how to write a static factory that preserves the singleton property, using a nested EnumMap: " Now as I understand, changing the original private "Card" constructor to public would allow us to instantiate an unlimited number of copies of a "Card" object with a given suit+rank. The solution as proposed was to create an EnumMap which would store four Maps (one for each suit), which themselves contained 13 Card objects with the rank as their keys. And so now if you wanted to retrieve a specific Card object from the deck, you would just call the "valueOf" method. My question now is, what's the prevent you with calling the valueOf method as many times as you like? Wouldn't that lead to the same problem as making the original private constructor public? Thanks.

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • Basic C# problem

    - by Juan
    Determine if all the digits of the sum of n -numbers and swapped n are odd. For example: 36 + 63 = 99, y 409 + 904 = 1313. Visual Studio builds my code, there is still something wrong with it ( it doesnt return an answer) can you please help me here? using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { long num = Convert.ToInt64(Console.Read()); long vol = voltea(num); long sum = num + vol; bool simp = simpares(sum); if (simp == true) Console.Write("Si"); else Console.Write("No"); } static private bool simpares(long x) { bool s = false; long [] arreglo = new long [1000]; while ( x > 0) { arreglo [x % 10] ++; x /=10; } for (long i=0 ; i <= arreglo.Length ; i++) { if (arreglo [i]%2 != 0) s = true; } return s; } static private long voltea(long x) { long v = 0; while (v > 0) { v = 10 * v + x % 10; x /= 10; } return v; } } }

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  • Need help getting buttons to work...

    - by Mike Droid
    I am trying to get my first button to update a display number in my view when clicked. This view will have several buttons and "outputs" displayed. After reading examples and Q's here, I finally put something together that runs, but my first button is still not working; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.ship_layout); mSwitcher = (TextSwitcher) findViewById(R.id.eng_val); } private TextSwitcher mSwitcher; // Will be connected with the buttons via XML void onClick(View v){ switch (v.getId()) { case R.id.engplus: engcounter++; updateCounter(); break; case R.id.engneg: engcounter--; updateCounter(); break; } } private void updateCounter() { mSwitcher.setText(String.valueOf(engcounter)); } The .xml for this button is; <TextSwitcher android:id="@+id/eng_val" android:visibility="visible" android:paddingTop="9px" android:paddingLeft="50px" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/build" android:layout_toRightOf="@+id/engeq" android:textColor="#DD00ff00" android:textSize="24sp"/> This is within a Relative Layout that appears otherwise OK. When I had set the view to have a TextView with the number set as a string , the number displayed, but I could not figure out how to update the text with a numerical field. That may be my real problem. I have gone through many examples generally referenced from the dev. site (UI, Common Tasks, various samples), and I am still not seeing the connection here... Again, this is simply a try at getting variables to respond to buttons and update on the view. So, a few Q's for anyone that can help; 1) Is there any easier way of doing this (ie. send numerical value to View) ? 2) Why isn't my TextSwitcher displaying the number? 3) Should I be using a TextSwitcher here? 4) Any examples of this you can point me to?

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  • Importing a Mercurial repository automatically (e.g. SVN Externals)

    - by dawmail333
    I have a project that I am developing built off CodeIgniter. The main part of the project is a private system I am creating, but I want to add it to source control, to gain all the associated goodies. Now I'm using Mercurial, so I did the whole hg init bit, so I've got the repository set up. Now, one of the things I've done is to make a library for CodeIgniter, which I use in this project. Now I want to make this library open, so I need a separate repo for that. For anyone unfamiliar with CodeIgniter library development, here's a reference: application /config <- configuration files /libraries <- library logic in here Now I will probably develop a few more libraries in the course of this project, so I can't just dump a repo in the application folder without clumping them all together. What I did was this: dev/ci/library <- library here dev/project <- project here Now in both of those folders, I have made a repository. What I want to do is make the project repository automatically reference the library repository, so I can have a private and a public repository, as I explained earlier. The main way to do this, I have read, is to use subrepositories, but I can only find examples on nested ones (which are unclear anyway, I find). How do I make it reference another repository like svn:externals?

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  • How can I create an instance of a class that I can use is more than one place in c#

    - by user1743574
    So I've been working on a class that details students of a university. I have one button that sets the details to a new instance of a class, and another to check if the student passed, through a method in my Class. The problem is that I create an instance of a class in the first button to add the values from what the user input, but I cannot use the second button to access the instance of the class created in the first button. private void button3_Click(object sender, EventArgs e) { Student student1 = new Student(); label1.Text = student1.text(); if (student1.hasPassed() == true) { passfailtextbox.Text = "Pass"; } else { passfailtextbox.Text = "Fail"; } } private void button1_Click(object sender, EventArgs e) { Student student1 = new Student(); student1.FirstName = firstnamebox.Text; student1.SecondName = secondnamebox.Text; student1.DateofBirth = DateTime.Parse(dobtextbox.Text).Date; student1.Course = coursetextbox.Text; student1.MatriculationNumber = int.Parse(matriculationtextbox.Text); student1.YearMark = double.Parse(yearmarktextbox.Text); } public Boolean hasPassed() { if (YearMark < 40) { return false; } else { return true; } } public string text() { return "Student" + " " + firstname + " " + secondname + " " + course + " " + dob.ToString() + " " + matriculationnumber.ToString() + " " + yearmark.ToString() ; }

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  • Why doesn't Win Forms application update label immediately?

    - by rosscj2533
    I am doing some experimenting with threads, and made a 'control' method to compare against where all the processing happens in the UI thread. It should run a method, which will update a label at the end. This method runs four times, but the labels are not updated until all 4 have completed. I expected one label to get updated about every 2 seconds. Here's the code: private void button1_Click(object sender, EventArgs e) { Stopwatch watch = new Stopwatch(); watch.Start(); UIThreadMethod(lblOne); UIThreadMethod(lblTwo); UIThreadMethod(lblThree); UIThreadMethod(lblFour); watch.Stop(); lblTotal.Text = "Total Time (ms): " + watch.ElapsedMilliseconds.ToString(); } private void UIThreadMethod(Label label) { Stopwatch watch = new Stopwatch(); watch.Start(); for (int i = 0; i < 10; i++) { Thread.Sleep(200); } watch.Stop(); // this doesn't set text right away label.Text = "Done, Time taken (ms): " + watch.ElapsedMilliseconds; } Maybe I'm just missing something basic, but I'm stuck. Any ideas? Thanks.

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