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  • Which design pattern is most appropriate?

    - by Anon
    Hello, I want to create a class that can use one of four algorithms (and the algorithm to use is only known at run-time). I was thinking that the Strategy design pattern sounds appropriate, but my problem is that each algorithm requires slightly different parameters. Would it be a bad design to use strategy, but pass in the relevant parameters into the constructor?. Here is an example (for simplicity, let's say there are only two possible algorithms) ... class Foo { private: // At run-time the correct algorithm is used, e.g. a = new Algorithm1(1); AlgorithmInterface* a; }; class AlgorithmInterface { public: virtual void DoSomething = 0; }; class Algorithm1 : public AlgorithmInterface { public: Algorithm1( int i ) : value(i) {} virtual void DoSomething(){ // Does something with int value }; int value; }; class Algorithm2 : public AlgorithmInterface { public: Algorithm2( bool b ) : value(b) {} virtual void DoSomething(){ // Do something with bool value }; bool value; };

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  • Property on business objects - getting and setting

    - by Mike
    Hi, I am using LINQ to SQL for the DataAccess layer. I have similar business objects to what is in the data access layer. I have got the dataprovider getting the message #23. On instantiation of the message, in the message constructor, it gets the MessageType and makes a new instance of MessageType class and fills in the MessageType information from the database. Therefore; I want this to get the Name of the MessageType of the Message. user.Messages[23].MessageType.Name I also want an administrator to set the MessageType user.Messages[23].MessageType = MessageTypes.LoadType(3); but I don't want the user to publicly set the MessageType.Name. But when I make a new MessageType instance, the access modifier for the Name property is public because I want to set that from an external class (my data access layer). I could change this to property to internal, so that my class can access it like a public variable, and not allow my other application access to modify it. This still doesn't feel right as it seems like a public property. Are public access modifiers in this situation bad? Any tips or suggestions would be appreciated. Thanks.

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  • How to create a generic C free function .

    - by nomemory
    I have some C structures related to a 'list' data structure. They look like this. struct nmlist_element_s { void *data; struct nmlist_element_s *next; }; typedef struct nmlist_element_s nmlist_element; struct nmlist_s { void (*destructor)(void *data); int (*cmp)(const void *e1, const void *e2); unsigned int size; nmlist_element *head; nmlist_element *tail; }; typedef struct nmlist_s nmlist; This way I can have different data types being hold in "nmlist_element-data" . The "constructor" (in terms of OOP) has the following signature: nmlist *nmlist_alloc(void (*destructor)(void *data)); Where "destructor" is specific function that de-allocated "data" (being hold by the nmlist_element). If I want to have a list containing integers as data, my "destructor" would like this: void int_destructor(void *data) { free((int*)data); } Still i find it rather "unfriendly" for me to write a destructor functions for every simple primitive data type. So is there a trick to write something like this ? (for primitives): void "x"_destructor(void *data, "x") { free(("x" *)data); } PS: I am not a macro fan myself, and in my short experience regarding C, i don't use them, unless necessary.

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  • Fastest Java way to remove the first/top line of a file (like a stack)

    - by christangrant
    I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

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  • jQuery's draggable grid

    - by Art
    It looks like that the 'grid' option in the constructor of Draggable is relatively bound to the original coordinates of the element being dragged - so simply put, if you have three draggable divs with their top set respectively to 100, 200, 254 pixels relative to their parent: <div class="parent-div" style="position: relative;"> <div id="div1" class="draggable" style="top: 100px; position: absolute;"></div> <div id="div2" class="draggable" style="top: 200px; position: absolute;"></div> <div id="div3" class="draggable" style="top: 254px; position: absolute;"></div> </div> Adn all of them are getting enabled for dragging with 'grid' set to [1, 100]: draggables = $('.draggable'); $.each(draggables, function(index, elem) { $(elem).draggable({ containment: $('#parent-div'), opacity: 0.7, revert: 'invalid', revertDuration: 300, grid: [1, 100], refreshPositions: true }); }); Problem here is that as soon as you drag div3, say, down, it's top is increased by 100, moving it to 354px instead of being increased by just mere 46px (254 + 46 = 300), which would get it to the next stop in the grid - 300px, if we are looking at the parent-div as a point of reference and "grid holder". I had a look at the draggable sources and it seem to be an in-built flaw - they just do all the calculations relative to the original position of the draggable element. I would like to avoid monkey-patching the code of draggable library and what I am really looking for here is the way how to make the Draggable calculate the grid positions relative to containing parent. However if monkey-patching is unavoidable, I guess I'll have to live with it. Thanks!

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  • Does The Clear Method On A Collection Release The Event Subscriptions?

    - by DaveB
    I have a collection private ObservableCollection<Contact> _contacts; In the constructor of my class I create it _contacts = new ObservableCollection<Contact>(); I have methods to add and remove items from my collection. I want to track changes to the entities in my collection which implement the IPropertyChanged interface so I subscribe to their PropertyChanged event. public void AddContact(Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged += new PropertyChangedEventHandler(Contact_PropertyChanged); _contacts.Add(contact); } public void AddContact(int index, Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged += new PropertyChangedEventHandler(Contact_PropertyChanged); _contacts.Insert(index, contact); } When I remove an entity from the collection, I unsubscribe from the PropertyChanged event. I am told this is to allow the entity to be garbage collected and not create memory issues. public void RemoveContact(Contact contact) { ((INotifyPropertyChanged)contact).PropertyChanged -= Contact_PropertyChanged; _contacts.Remove(contact); } So, I hope this is all good. Now, I need to clear the collection in one of my methods. My first thought would be to call _contacts.Clear(). Then I got to wondering if this releases those event subscriptions? Would I need to create my own clear method? Something like this: public void ClearContacts() { foreach(Contact contact in _contacts) { this.RemoveContact(contact); } } I am hoping one of the .NET C# experts here could clear this up for me or tell me what I am doing wrong.

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  • boost::python string-convertible properties

    - by Checkers
    I have a C++ class, which has the following methods: class Bar { ... const Foo& getFoo() const; void setFoo(const Foo&); }; where class Foo is convertible to std::string (it has an implicit constructor from std::string and an std::string cast operator). I define a Boost.Python wrapper class, which, among other things, defines a property based on previous two functions: class_<Bar>("Bar") ... .add_property( "foo", make_function( &Bar::getFoo, return_value_policy<return_by_value>()), &Bar::setFoo) ... I also mark the class as convertible to/from std::string. implicitly_convertible<std::string, Foo>(); implicitly_convertible<Foo, std::string>(); But at runtime I still get a conversion error trying to access this property: TypeError: No to_python (by-value) converter found for C++ type: Foo How to achieve the conversion without too much boilerplate of wrapper functions? (I already have all the conversion functions in class Foo, so duplication is undesirable.

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  • Adding an ASP.NET Web User Control to a Control Dynamically

    - by RandomBen
    I have a simple ASP.NET Web User Control. It looks like this: <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="NewsArticle.ascx.cs" Inherits="Website.Controls.NewsArticle" %> <div> <asp:Literal ID="ltlBody" runat="server" /> </div> My code behind looks like this: namespace Website.Controls { public partial class NewsArticle : System.Web.UI.UserControl { public String bodyText { //get { return ltlBody.Text; } set { ltlBody.Text = value; } } } } On a .aspx page I have <asp:Panel ID="pNews" runat="server" /> In the code behind I have: foreach (vwNews news in newsQuery) { NewsArticle article = new NewsArticle(); aticle.bodyText = news.Body; pNews.Controls.Add(article); } Every time I run this code the newsQuery is populated correctly and I get to the line aticle.bodyText = news.Body; and then I received the error article.bodyText threw an exception of type 'System.NullReferenceException' I am not sure what is causing this error message or how to fix it. I would think that there should not be an issue. I tried creating a constructor for my Web User Control so that it would give default values to my properties but that didn't work. Any idea how to make this work? It doesn't seem like it should be that

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  • Generic cast type to primitive.

    - by Nix
    Is there a way to do the below? Imagine a generic result wrapper class. Where you have a type and an associated error list. When there is no result to return to the user we will use boolean to indicate success failure. I want to create a constructor that takes in an error list, and if the list is null or count 0, AND the type is a bool/Boolean i want to set it to true.... Seemingly simple, but amazingly not possible. public class Result<T>{ private T valueObject { get;set;} private List<Error> errors{ get;set;} public Result(T valueObj, List<Error> errorList){ this.valueObject = valueObj; this.errors = errorList; } public Result(List<Error> errors) { this.valueObject = default(ReturnType); if (valueObject is Boolean) { //Wont work compile //(valueObject as Boolean) = ((errors == null) || errors.Count == 0); //Compiles but detaches reference //bool temp = ((bool)(valueObject as object)) ; //temp = ((errors == null) || errors.Count == 0); } this.errors = errors; } } } Am I missing something simple? And in general I would prefer to do it without reflection.

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  • What is happening in Crockford's object creation technique?

    - by Chris Noe
    There are only 3 lines of code, and yet I'm having trouble fully grasping this: Object.create = function (o) { function F() {} F.prototype = o; return new F(); }; newObject = Object.create(oldObject); (from Prototypal Inheritance) 1) Object.create() starts out by creating an empty function called F. I'm thinking that a function is a kind of object. Where is this F object being stored? Globally I guess. 2) Next our oldObject, passed in as o, becomes the prototype of function F. Function (i.e., object) F now "inherits" from our oldObject, in the sense that name resolution will route through it. Good, but I'm curious what the default prototype is for an object, Object? Is that also true for a function-object? 3) Finally, F is instantiated and returned, becoming our newObject. Is the "new" operation strictly necessary here? Doesn't F already provide what we need, or is there a critical difference between function-objects and non-function-objects? Clearly it won't be possible to have a constructor function using this technique. What happens the next time Object.create() is called? Is global function F overwritten? Surely it is not reused, because that would alter previously configured objects. And what happens if multiple threads call Object.create(), is there any sort of synchronization to prevent race conditions on F?

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  • Difficulty porting raw PCM output code from Java to Android AudioTrack API.

    - by IndigoParadox
    I'm attempting to port an application that plays chiptunes (NSF, SPC, etc) music files from Java SE to Android. The Android API seems to lack the javax multimedia classes that this application uses to output raw PCM audio. The closest analog I've found in the API is AudioTrack and so I've been wrestling with that. However, when I try to run one of my sample music files through my port-in-progress, all I get back is static. My suspicion is that it's the AudioTrack I've setup which is at fault. I've tried various different constructors but it all just outputs static in the end. The DataLine setup in the original code is something like: AudioFormat audioFormat = new AudioFormat( AudioFormat.Encoding.PCM_SIGNED, 44100, 16, 2, 4, 44100, true ); DataLine.Info lineInfo = new DataLine.Info( SourceDataLine.class, audioFormat ); DataLine line = (SourceDataLine)AudioSystem.getLine( lineInfo ); The constructor I'm using right now is: AudioTrack = new AudioTrack( AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT, AudioTrack.getMinBufferSize( 44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT ), AudioTrack.MODE_STREAM ); I've replaced constants and variables in those so they make sense as concisely as possible, but my basic question is if there are any obvious problems in the assumptions I made when going from one format to the other.

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  • Mutual class instances in C++

    - by SepiDev
    Hi guys. What is the issue with this code? Here we have two files: classA.h and classB.h classA.h: #ifndef _class_a_h_ #define _class_a_h_ #include "classB.h" class B; //???? class A { public: A() { ptr_b = new B(); //???? } virtual ~A() { if(ptr_b) delete ptr_b; //???? num_a = 0; } int num_a; B* ptr_b; //???? }; #endif //_class_a_h_ classB.h: #ifndef _class_b_h_ #define _class_b_h_ #include "classA.h" class A; //???? class B { public: B() { ptr_a = new A(); //???? num_b = 0; } virtual ~B() { if(ptr_a) delete ptr_a; //???? } int num_b; A* ptr_a; //???? }; #endif //_class_b_h_ when I try to compile it, the compiler (g++) says: classB.h: In constructor ‘B::B()’: classB.h:12: error: invalid use of incomplete type ‘struct A’ classB.h:6: error: forward declaration of ‘struct A’ classB.h: In destructor ‘virtual B::~B()’: classB.h:16: warning: possible problem detected in invocation of delete operator: classB.h:16: warning: invalid use of incomplete type ‘struct A’ classB.h:6: warning: forward declaration of ‘struct A’ classB.h:16: note: neither the destructor nor the class-specific operator delete will be called, even if they are declared when the class is defined.

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  • Threadsafe way of exposing keySet()

    - by Jake
    This must be a fairly common occurrence where I have a map and wish to thread-safely expose its key set: public MyClass { Map<String,String> map = // ... public final Set<String> keys() { // returns key set } } Now, if my "map" is not thread-safe, this is not safe: public final Set<String> keys() { return map.keySet(); } And neither is: public final Set<String> keys() { return Collections.unmodifiableSet(map.keySet()); } So I need to create a copy, such as: public final Set<String> keys() { return new HashSet(map.keySet()); } However, this doesn't seem safe either because that constructor traverses the elements of the parameter and add()s them. So while this copying is going on, a ConcurrentModificationException can happen. So then: public final Set<String> keys() { synchronized(map) { return new HashSet(map.keySet()); } } seems like the solution. Does this look right?

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  • Unable to step into interface implementation configured by unity application block

    - by Rahul
    I have configured a set of interface implementations with EntLib. unity block. The constructor of implementation classes work fine as soon as I run the application: 1. The interface to implement when I run the application the cctor runs fine, which shows that unity resolution was successful: But when I try to call a method of this class, the code just passes through without actually invoking the function of the implemented class: Edit: Added on June 11, 2012 Following is the Unity Configuration I have. (This is all the unity configuration I am doing) public class UnityControllerFactory : DefaultControllerFactory { private static readonly IUnityContainer container; private static UnityControllerFactory factory = null; static UnityControllerFactory() { container = new UnityContainer(); UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity"); section.Configure(container); factory = new UnityControllerFactory(); } public static UnityControllerFactory GetControllerFactory() { return factory; } protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType) { return container.Resolve(controllerType) as IController; } } I am unable to step into this code and the implementation simply skips out without executing anything. What is wrong here?

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  • Remotely connecting two non-local computers with sockets

    - by Velizar Hristov
    This question seems like something very obvious to ask, and yet I spent more than an hour trying to find an answer. First I host and wait for someone to connect. Then, from another instance of the application, I try to connect with a socket - for the constructor, I use InetAddress, port. The port is always right, and everything works if I use "localhost" for the address. However, if I type my IP, I get an IOException. I even sent the application to someone else, gave him my IP, and it didn't work. The aim of the application is to connect two computers. It's in Java. Here is the relevant code. Server: ServerSocket serverSocket = new ServerSocket(port); Socket clientSocket = serverSocket.accept(); Client: InetAddress a = InetAddress.getByName(ip); Socket s = new Socket(a, port); I don't get past that. Obviously, the values of int port and String ip are taken from text fields. Edit: the purpose of my application is to connect two non-local computers.

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  • C# getpixels() gets the correct value on xp and vista but is slightly off when used on windows 7

    - by user352288
    I have a C# program that works correctly on xp and vista but it needs to be used on windows 7, I have not been able to come up with a solution, it appears that getpixels just doesn't work right on windows 7. I am getting one of the RGB values because I am dealing with tiff grayscale images. System.Drawing.Bitmap image;// this is in a separate class image = new Bitmap(destination);// this is in the constructor Color t = image.GetPixel(j, i); // this is in a separate function int s = t.R when I print s, for example, image(0,0), it is supposed to be 220, it will be 221 I am doing edge detection on an image and I have to go through the image pixel by pixel, I have run the exact same program on XP,Vista,windows7 and windows 7 got different values. It wouldn't let me post images at all and only one link. The first image is the original image, the second is the correct image, also the one I get with XP and Vista, the final image is the image when running the same program in Windows 7. There is not much of a visible difference but it matters for what I am doing. Thanks for the help, it seems that I am having a hard time explaining my problem.

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  • Usage Rails 3.0 beta 3 without ActiveRecord ORM

    - by Anton
    Hi everybody! Just installed Rails 3.0 beta 3 in Windows 7. And started playing with some easy examples class SignupController < ApplicationController def index @user = User.new(params[:user]) if method.post? and @user.save redirect_to :root end end end class User def initialize(params = {}) @email = params[:email] @passw = params[:password] end def save end end <div align="center"> <% form_for :user do |form| %> <%= form.label :email %> <%= form.text_field :email %><br /> <%= form.label :password %> <%= form.text_field :password %><br /> <%= form.submit :Register! %> <% end %> </div> When I go to /signup I'm getting this error ArgumentError in SignupController#index wrong number of arguments(0 for 1) Is there a problem with constructor or what's wrong?Please, need your help!

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  • Class design when working with dataset

    - by MC
    If you have to retrieve data from a database and bring this dataset to the client, and then allow the user to manipulate the data in various ways before updating the database again, what is a good class design for this if the data tables will not have a 1:1 relationship with the class objects? Here are some I came up with: Just manipulate the DataSet itself on the client and then send it back to the database as is. This will work though obviously the code will be very dirty and not well-structured. Same as #1, but wrap the dataset code around classes. What I mean is that you may have a class that takes a dataset or a datatable in its constructor, and then provides public methods and properties to simplify the code. Inside these methods and properties it will be reading or manipulating the dataset. To update the database afterwards will be easy because you already have the updated dataset. Get rid of the dataset entirely on the client, convert to objects, then convert back to a dataset when needing to update the database. Is there any good resources where I can find information on this?

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  • Accessing Web.config directly in ASP.NET MVC 1

    - by Neil T.
    I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve?

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  • Android: CustomListAdapter

    - by primal
    Hi, I have implemented a custom list view which looks like the twitter timeline. adapter = new MyClickableListAdapter(this, R.layout.timeline, mObjectList); setListAdapter(adapter); The constructor for MyClickableListAdapter is as follows private class MyClickableListAdapter extends ClickableListAdapter{ public MyClickableListAdapter(Context context, int viewId, List objects) { super(context, viewId, objects); } ClickableListAdapter extends BaseAdapter and implements the necessary methods. The xml code for the list view is as follows <ListView android:id="@+id/android:list" android:layout_width="fill_parent" android:layout_height="wrap_content" /> This is what it looks like. I have 3 questions 1) I tried registering a context menu for the list view by adding the line after setting the list adapter registerforContextMenu(getListView()); But on long-click the menu doesnt get displayed. I cannot understand what I am doing wrong! 2) Is it possible to display a textview above the listview? I tried it by adding the code for textview above the listview. But then, only the textview gets displayed. 3) I have seen in many twitter clients that on clicking post a window pops up from the top covering only some portion of the screen and rest of the timeline is visible. How can this be done possibly without starting a new activity? Any help would be much appreciated..

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  • Java: Embedding Soundbank file in JAR

    - by Pyroclastic
    If I have a soundbank stored in a JAR, how would I load that soundbank into my application using resource loading...? I'm trying to consolidate as much of a MIDI program into the jar file as I can, and the last thing I have to add is the soundbank file I'm using, as users won't have the soundbanks installed. I'm trying to put it into my jar file, and then load it with getResource() in the Class class, but I'm getting an InvalidMidiDataException on a soundbank that I know is valid. Here's the code, it's in the constructor for my synthesizer object: try { synth = MidiSystem.getSynthesizer(); channels = synth.getChannels(); instrument = MidiSystem.getSoundbank(this.getClass().getResource("img/soundbank-mid.gm")).getInstruments(); currentInstrument = instrument[0]; synth.loadInstrument(currentInstrument); synth.open(); } catch (InvalidMidiDataException ex) { System.out.println("FAIL"); instrument = synth.getAvailableInstruments(); currentInstrument = instrument[0]; synth.loadInstrument(currentInstrument); try { synth.open(); } catch (MidiUnavailableException ex1) { Logger.getLogger(MIDISynth.class.getName()).log(Level.SEVERE, null, ex1); } } catch (IOException ex) { Logger.getLogger(MIDISynth.class.getName()).log(Level.SEVERE, null, ex); } catch (MidiUnavailableException ex) { Logger.getLogger(MIDISynth.class.getName()).log(Level.SEVERE, null, ex); }

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  • C++ class is not being included properly.

    - by ravloony
    Hello all, I have a problem which is either something I have completely failed to understand, or very strange. It's probably the first one, but I have spent the whole afternoon googling with no success, so here goes... I have a class called Schedule, which has as a member a vector of Room. However, when I compile using cmake, or even by hand, I get the following: In file included from schedule.cpp:1: schedule.h:13: error: ‘Room’ was not declared in this scope schedule.h:13: error: template argument 1 is invalid schedule.h:13: error: template argument 2 is invalid schedule.cpp: In constructor ‘Schedule::Schedule(int, int, int)’: schedule.cpp:12: error: ‘Room’ was not declared in this scope schedule.cpp:12: error: expected ‘;’ before ‘r’ schedule.cpp:13: error: request for member ‘push_back’ in ‘((Schedule*)this)->Schedule::_sched’, which is of non-class type ‘int’ schedule.cpp:13: error: ‘r’ was not declared in this scope Here are the relevant bits of code: #include <vector> #include "room.h" class Schedule { private: std::vector<Room> _sched; //line 13 int _ndays; int _nrooms; int _ntslots; public: Schedule(); ~Schedule(); Schedule(int nrooms, int ndays, int ntslots); }; Schedule::Schedule(int nrooms, int ndays, int ntslots):_ndays(ndays), _nrooms(nrooms),_ntslots(ntslots) { for (int i=0; i<nrooms;i++) { Room r(ndays,ntslots); _sched.push_back(r); } } In theory, g++ should compile a class before the one that includes it. There are no circular dependencies here, it's all straightforward stuff. I am completely stumped on this one, which is what leads me to believe that I must be missing something. :-D

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  • Java Concurrency in practice sample question

    - by andy boot
    I am reading "Java Concurrency in practice" and looking at the example code on page 51. This states that if a thread has references to a shared object then other threads may be able to access that object before the constructor has finished executing. I have tried to put this into practice and so I wrote this code thinking that if I ran it enough times a RuntimeException("World is f*cked") would occur. But it isn't doing. Is this a case of the Java spec not guaranting something but my particular implementation of java guaranteeing it for me? (java version: 1.5.0 on Ubuntu) Or have I misread something in the book? Code: (I expect an exception but it is never thrown) public class Threads { private Widgit w; public static void main(String[] s) throws Exception { while(true){ Threads t = new Threads(); t.runThreads(); } } private void runThreads() throws Exception{ new Checker().start(); w = new Widgit((int)(Math.random() * 100) + 1); } private class Checker extends Thread{ private static final int LOOP_TIMES = 1000; public void run() { int count = 0; for(int i = 0; i < LOOP_TIMES; i++){ try { w.checkMe(); count++; } catch(NullPointerException npe){ //ignore } } System.out.println("checked: "+count+" times out of "+LOOP_TIMES); } } private static class Widgit{ private int n; private int n2; Widgit(int n) throws InterruptedException{ this.n = n; Thread.sleep(2); this.n2 = n; } void checkMe(){ if (n != n2) { throw new RuntimeException("World is f*cked"); } } } }

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  • Blackberry (Java) - Drawing graphics on top of rendered text/buttons etc

    - by paullb
    Based off the one of the demos I have the following code. Currently what displays in the simulator is just hte contents of the paint function, however the ObjectChoiceField is still selectable if one happens to click in the right location. I would like both the text contents and the paint function contents to appear. Is this possible? public CityInfoScreen() { //invoke the MainScreen constructor super(); //add a screen title LabelField title = new LabelField("City Information Kiosk", LabelField.ELLIPSIS | LabelField.USE_ALL_WIDTH); setTitle(title); //add a text label add(new RichTextField("Major U.S. Cities")); //add a drop-down list with three choices: //Los Angeles, Chicago, or New York //... String choices[] = {"Los Angeles","Chicago","New York"}; choiceField = new ObjectChoiceField("select a city", choices); add(choiceField); Manager man = this.getMainManager(); } ... public void paint(Graphics g){ super.paint(g); // g.drawRect(0,left,500,500+left); g.setGlobalAlpha(0); g.drawRect(100-left,100-top,200,200); String text = new Integer(left).toString(); String text2 = new Integer(top).toString(); g.drawText(text + " " + text2,120-left,120-top); }

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  • How to implement jsf validator?

    - by Krishna
    HI, I want to know how to implement Validator in JSF. What is the advantages of declaring the validator-id. When it will be called in the life cycle?. I have implemented the following code. Please find out what is wrong in the code. I am not seeing it called anywhere in the life cycle. <?xml version="1.0"?> <!DOCTYPE faces-config PUBLIC "-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.1//EN" "http://java.sun.com/dtd/web-facesconfig_1_1.dtd"> <faces-config> <lifecycle> <phase-listener>javabeat.net.jsf.JsfPhaseListener</phase-listener> </lifecycle> <validator> <validator-id>JsfValidator</validator-id> <validator-class>javabeat.net.jsf.JsfValidator</validator-class> </validator> <managed-bean> <managed-bean-name>jsfBean</managed-bean-name> <managed-bean-class>javabeat.net.beans.ManagedBean</managed-bean-class> <managed-bean-scope>request</managed-bean-scope> </managed-bean> <navigation-rule> <navigation-case> <from-outcome>success</from-outcome> <to-view-id>success.jsp</to-view-id> </navigation-case> </navigation-rule> </faces-config> public class JsfValidator implements Validator { public JsfValidator() { System.out.println("Inside JsfValidator Constructor"); } @Override public void validate(FacesContext facesContext, UIComponent uiComponent, Object object) throws ValidatorException { System.out.println("Inside Validator"); } }

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