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  • Why does Java ArrayList use per-element casting instead of per-array casting?

    - by user1111929
    What happens inside Java's ArrayList<T> (and probably many other classes) is that there is an internal Object[] array = new Object[n];, to which T Objects are written. Whenever an element is read from it, a cast return (T) array[i]; is done. So, a cast on every single read. I wonder why this is done. To me, it seems like they're just doing unnecessary casts. Wouldn't it be more logical and also slightly faster to just create a T[] array = (T[]) new Object[n]; and then just return array[i]; without cast? This is only one cast per array creation, which is usually far less than the number of reads. Why is their method to be preferred? I fail to see why my idea isn't strictly better?

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  • C#, Generic Lists and Inheritance

    - by Andy
    I have a class called Foo that defines a list of objects of type A: class Foo { List<A> Items = new List<A>(); } I have a class called Bar that can save and load lists of objects of type B: class Bar { void Save(List<B> ComplexItems); List<B> Load(); } B is a child of A. Foo, Bar, A and B are in a library and the user can create children of any of the classes. What I would like to do is something like the following: Foo MyFoo = new Foo(); Bar MyBar = new Bar(); MyFoo.Items = MyBar.Load(); MyBar.Save(MyFoo.Items); Obviously this won't work. Is there a clever way to do this that avoids creating intermediate lists? thanks, Andy

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  • ASP.NET MVC2 - usage of LINQ-generated class (validation problem)

    - by ile
    There are few things not clear to me about ASP.NET MV2. In database I have table Contacts with several fields, and there is an additional field XmlFields of which type is xml. In that field are stored additional description fields. There are 4 classes: Contact class which corresponds to Contact table and is defined by default when creating LINQ classes ContactListView class which inherits Contact class and has some additional properties ContactXmlView class that contains fields from XmlFields field ContactDetailsView class which merges ContactListView and ContactXmlView into one class and this one is used to display data in view pages ContactListView class has re-defined some properties from Contact class (so that I can add [Required] filter used for validation) - but I get warning message: 'ObjectTest.Models.Contacts.ContactListView.FirstName' hides inherited member 'SA.Model.Contact.FirstName'. Use the new keyword if hiding was intended. ContactDetailsView class is also used in a form when creating new contact and adding it to database. I am not sure if this is correct way, and the warning message confuses me a bit. Any advise about this? Thanks, Ile EDIT According to Jakob's instructions I tried it from scratch: [MetadataType(typeof(Person_Validation))] public partial class Person { } public class Person_Validation { [Required] string FirstName { get; set; } [Required] string LastName { get; set; } [Required] int Age { get; set; } } In Controller I have this: [HttpPost] public ActionResult Create(Person person, FormCollection collection) { if (ModelState.IsValid) { try { personRepository.Add(person); personRepository.Save(); } catch { return View(person); } } return RedirectToAction("Index"); } View: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Validate.Models.Person>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Create </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Create</h2> <% using (Html.BeginForm()) {%> <%= Html.ValidationSummary(true) %> <fieldset> <legend>Fields</legend> <div class="editor-label"> <%= Html.LabelFor(model => model.FirstName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.FirstName) %> <%= Html.ValidationMessageFor(model => model.FirstName) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.LastName) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.LastName) %> <%= Html.ValidationMessageFor(model => model.LastName) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Age) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Age) %> <%= Html.ValidationMessageFor(model => model.Age) %> </div> <p> <input type="submit" value="Create" /> </p> </fieldset> <% } %> <div> <%= Html.ActionLink("Back to List", "Index") %> </div> </asp:Content> When posting new person with no values, nothing happens (page is just reloaded). When posting with some values, person is added to db. I have no idea what am I doing wrong.

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  • PropertyGrid + interface

    - by nilphilus
    public interface ITest { void Somethink(); } public class Test1 : ITest { public void Somethink() { /* do stuff */ } public int Test1Property { get; set; } } public class Test2 : ITest { public void Somethink() { /* do stuff */ } public float Test2Property { get; set; } } //Main class public class MainClass { [TypeConverter(ExpandableObjectConverter)] public ITest test { get; set; } } Ok, i have sth like this. Instance of MainClass is selected by PropertyGrid. How to make a DropDownList of objects of classes which implement ITest (here Test1 and Test2)

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  • Writing .NET in dynamic language?

    - by tillda
    I'm confused by the possibility of writing .NET in dynamic languages, such as (Iron)Ruby. Particularly, I've seen code in IronRuby that used generics (...foo[String]), but I'm not aware of this feature in Ruby as it seems nonsense to me in dynamic languages. So, when I write .NET app in IronRuby, how is it with type safety and compilation? I thought that it is just as dynamic as Ruby everywhere else. I thought that if the Ruby syntax is OK all the type checking would be done at the runtime. Also, as far as I know, .NET itself is type-oriented - there are classes that heavily utilize the mentioned generics. How is this handled? And what about delegates? In dynamic languages I can have almost function-spaghetti and sometimes, its just fine (like hacking UI in javascript). Or do I have to care even about generic delegates?

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  • is right to implement a business logic in the type binding DI framwork?

    - by Martino
    public IRedirect FactoryStrategyRedirect() { if (_PasswordExpired) { return _UpdatePasswordRedirectorFactory.Create(); } else { return _DefaultRedirectorFactory.Create(); } } This strategy factory method can be replaced with type binding and when clause: Bind<IRedirect>.To<UpdatePasswordRedirector>.When(c=> c.kernel.get<SomeContext>().PasswordExpired()) Bind<IRedirect>.To<DefaultRedirector>.When(c=> not c.kernel.get<SomeContext>().PasswordExpired()) I wonder which of the two approaches is the more correct. What are the pros and cons. Especially in the case in which the logic is more complex with more variables to test and more concrete classes to return. is right to implement a business logic in the binding?

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  • Casting as Interface? Awesome.

    - by cam
    I was just experimenting around with one of my programs, trying to make it looks prettier and I found something interesting. I have an interface that 4 classes inherit from. I found that if I pass the Class as an object to a method like so: ClassTest classtest = new ClassTest(); DoOperation(classtest); private void DoOperation(object o) { ((InterfaceClass)o).DoThis(); } So I can pass any type of class that inherits from InterfaceClass, and it will preform the proper interface operation? This is the coolest thing I've ever found from OOP (something I've never really studied) I really thought interfaces were created for the sole purpose of organization for developers. Are there more uses for interfaces than this?

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  • frame variable cannot be found

    - by Umzz Mo
    I am making 3 board games, and I have started my coding off in one class. Now that i wanted to move around it is giving me problems. In my view class I just want to have the main frame where users can pick from the games. And in the other views, i.e the childrens of view class i want to have the interface for the actual games. Now that the Jframe frame = new frame was created in the parent class, it cannot find the variable frame in the children classes.

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  • TypoScript: {field:uid} replacement not working | Different CSS class per menu item

    - by Alex
    I have a header menu and try to define different CSS classes for each item. This is what I have: 20 = HMENU 20 { special = directory special.value = 107 1 = TMENU 1 { wrap = <ul class="foo" id="mymenu">|</ul> expAll = 1 NO = 1 NO.allWrap = <li class="first menu_{field:uid}">|</li> || <li class="menu_{field:uid}">|</li> || <li class="last menu_{field:uid}">|</li> } } But in the HTML output I simply get class="first menu_{field:uid}" and nothing is replaced.

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  • Design Documents for Python/Django?

    - by british_trader
    After working on a Django project for a while, I now have to do some design documents for it (UML type stuff). However the code doesn't have classes, but instead uses views.py with modules in it... What would be the best way to show the design of my application from the initial __init__.py, to the urls.py where the HTML requests are then filtered to the specific urls.py in each of the packages and then handled by the views.py? i.e. django-app urls.py views.py settings.py manager.py __init__.py django-package urls.py views.py

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  • maven: multi module HAR dependencies

    - by QuanNH
    I have a multiple module project The first module contains my hibernate xml files and data java beans and packages as har. The second module defines my DAO classes. This module has a dependancy on data java beans with in the har and is defined in pom.xml. <dependency> <groupId>myproject</groupId> <artifactId>myhar</artifactId> <version>1.0</version> <type>har</type> </dependency> The first module compiles, packages and installs fine into my local repository. The problem is when the second modules compiles it has a problem finding the packages and class defined in my har module. I get the following output from running mvn install package myproject.myhar does not exist and build fails.

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  • Type hinting and optional attributes in PHP

    - by Álvaro G. Vicario
    I have a class method that deals with dates: public function setAvailability(DateTime $start, DateTime $end){ } Since item availability can have lower limit, upper limit, both or none, I'd like to make setAvailability() accept NULL values as well. However, the NULL constant violates the type hinting: $foo->setAvailability(NULL, $end); triggers: Catchable fatal error: Argument 1 passed to Foo::setAvailability() must be an instance of DateTime, null given And, as far as I know, I cannot have a DateTime instance with no value. (Can I?) For a reason I cannot grasp, this seems to work: public function setAvailability(DateTime $start=NULL, DateTime $end=NULL){ } ... $foo->setAvailability(NULL, $end); But it looks like a hack that works by pure chance. How would you deal with unset dates in PHP classes?

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  • How can I know when SQL Full Text Index Population is finished?

    - by GarethOwen
    We are writing unit tests for our ASP.NET application that run against a test SQL Server database. That is, the ClassInitialize method creates a new database with test data, and the ClassCleanup deletes the database. We do this by running .bat scripts from code. The classes under test are given a connection string that connects to the unit test database rather than a production database. Our problem is, that the database contains a full text index, which needs to be fully populated with the test data in order for our tests to run as expected. As far as I can tell, the fulltext index is always populated in the background. I would like to be able to either: Create the full text index, fully populated, with a synchronous (transact-SQL?) statement, or Find out when the fulltext population is finished, is there a callback option, or can I ask repeatedly? My current solution is to force a delay at the end the class initialize method - 5 seconds seems to work - because I can't find anything in the documentation.

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  • NULL In a Class Destructor

    - by Hyper-DarkStar
    Simple question; Is it pointless to set a pointer( which allocates heap memory ) to NULL in the destructor? class SampleClass { public: SampleClass( int Init = 0 ) { Value = new int( Init ); } ~SampleClass( void ) { delete Value; Value = NULL; // Is this pointless? } int *Value; }; While on the subject of classes, when should I use the explicit keyword? Thanks.

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  • Mysql maven jpa skeleton

    - by coubeatczech
    Hi, is there a skeleton for a project using mysql, some eclipse/top link with RESOURCE_LOCAL as connection type? Preferably using maven. I'm searching for it for hours and can't get running even the sipmlest exaple. So if you had it ready and running, please, post :-). Even something as simple as these two classes only. @Entity public class Message implements Serializable{ public Message() {} public Message(String s){ this.s = s; } @Id String s; public String getS(){ return s; } } public class App { static private EntityManagerFactory emf; static private EntityManager em; public static void main( String[] args ) { emf = Persistence.createEntityManagerFactory("persistence"); em = emf.createEntityManager(); Message m = new Message("abc"); em.persist(m); } }

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  • How do I add jars needed to compile a maven project if they were never built with a pom?

    - by JasonH
    I'm just starting with maven, coming from years of working with Ant. I'm trying a basic task now, building a simple project that requires some libraries from a vendor. I have the jars in src\main\resources\VENDORNAME. When I run mvn compile it fails on compilation saying the libraries don't exist. I can't seem to add these as dependencies because I don't know their version number and as they are proprietary I can't find them in ibiblio or elsewhere. Without these Jars I can't compile my classes. Is there a way to use jars that didn't follow Maven's convention? I might not understand maven correctly, so any guidance is welcome. Much appreciated for any responses.

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  • Noob tab widget example not running

    - by michbeck
    hey all, i'm trying to reproduce the tabwidget example (http://developer.android.com/resources/tutorials/views/hello-tabwidget.html). i'm not really sure what's the problem, i've git no errors while compiling, but i cannot see the application on emulators screen :-/ would be excellent if maybe anyone could have a look at my classes and tell me what's my mistake? I've packed my project here: http://etanto.com/TabTest.zip thanx a lot in advance, folks! michbeck here's the console dump while the run: [2010-06-10 09:18:34 - TabTest] Launching a new emulator with Virtual Device 'Virtual1' [2010-06-10 09:18:35 - TabTest] New emulator found: emulator-5554 [2010-06-10 09:18:35 - TabTest] Waiting for HOME ('android.process.acore') to be launched... [2010-06-10 09:19:05 - TabTest] WARNING: Application does not specify an API level requirement! [2010-06-10 09:19:05 - TabTest] Device API version is 8 (Android 2.2) [2010-06-10 09:19:05 - TabTest] HOME is up on device 'emulator-5554' [2010-06-10 09:19:05 - TabTest] Uploading TabTest.apk onto device 'emulator-5554' [2010-06-10 09:19:05 - TabTest] Installing TabTest.apk... [2010-06-10 09:19:22 - TabTest] Success! [2010-06-10 09:19:22 - TabTest] \TabTest\bin\TabTest.apk installed on device [2010-06-10 09:19:22 - TabTest] Done!

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  • Separating data from the UI code with Linq to SQL entities

    - by Sir Psycho
    If it's important to keep data access 'away' from business and presentation layers, what alternatives or approaches can I take so that my LINQ to SQL entities can stay in the data access layer? So far I seem to be simply duplicating the classes produced by sqlmetal, and passing those object around instead simply to keep the two layers appart. For example, I have a table in my DB called Books. If a user is creating a new book via the UI, the Book class generated by sqlmetal seems like a perfect fit although I'm tightly coupling my design by doing so.

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  • Polymorphic behavior not being implemented

    - by Garrett A. Hughes
    The last two lines of this code illustrate the problem: the compiler works when I use the reference to the object, but not when I assign the reference to an array element. The rest of the code is in the same package in separate files. BioStudent and ChemStudent are separate classes, as well as Student. package pkgPoly; public class Poly { public static void main(String[] arg) { Student[] stud = new Student[3]; // create a biology student BioStudent s1 = new BioStudent("Tom"); // create a chemistry student ChemStudent s2 = new ChemStudent("Dick"); // fill the student body with studs stud[0] = s0; stud[1] = s1; // compiler complains that it can't find symbol getMajor on next line System.out.println("major: " + stud[0].getMajor() ); // doesn't compile; System.out.println("major: " + s0.getMajor() ); // works: compiles and runs correctly } }

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  • How can I Include Multiples Tables in my linq to entities eager loading using mvc4 C#

    - by EBENEZER CURVELLO
    I have 6 classes and I try to use linq to Entities to get the SiglaUF information of the last deeper table (in the view - MVC). The problem is I receive the following error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection." The view is like that: > @model IEnumerable<DiskPizzaDelivery.Models.EnderecoCliente> > @foreach (var item in Model) { > @Html.DisplayFor(modelItem => item.CEP.Cidade.UF.SiglaUF) > } The query that i use: var cliente = context.Clientes .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); The question is: How Can I improve this query to pre loading (eager loading) "Cidade" and "UF"? See below the classes: public partial class Cliente { [Key] [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] public int IdCliente { get; set; } public string Email { get; set; } public string Senha { get; set; } public virtual ICollection<EnderecoCliente> Enderecos { get; set; } } public partial class EnderecoCliente { public int IdEndereco { get; set; } public int IdCliente { get; set; } public string CEPEndereco { get; set; } public string Numero { get; set; } public string Complemento { get; set; } public string PontoReferencia { get; set; } public virtual Cliente Cliente { get; set; } public virtual CEP CEP { get; set; } } public partial class CEP { public string CodCep { get; set; } public string Tipo_Logradouro { get; set; } public string Logradouro { get; set; } public string Bairro { get; set; } public int CodigoUF { get; set; } public int CodigoCidade { get; set; } public virtual Cidade Cidade { get; set; } } public partial class Cidade { public int CodigoCidade { get; set; } public string NomeCidade { get; set; } public int CodigoUF { get; set; } public virtual ICollection<CEP> CEPs { get; set; } public virtual UF UF { get; set; } public virtual ICollection<UF> UFs { get; set; } } public partial class UF { public int CodigoUF { get; set; } public string SiglaUF { get; set; } public string NomeUF { get; set; } public int CodigoCidadeCapital { get; set; } public virtual ICollection<Cidade> Cidades { get; set; } public virtual Cidade Cidade { get; set; } } var cliente = context.Clientes .Where(c => c.Email == email) .Where(c => c.Senha == senha) .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); Thanks!

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  • How should I structure my iPhone OpenGL ES 1.1 game?

    - by Ryan
    I am building an iPhone OpenGL ES 1.1 game. I am using the OpenGL ES template provided by xcode. I am only using the ES1Renderer. I've coded some basic touch actions the user can take, and I've begun to think about the overall structure of the code. All I'm really doing is using C in the ES1Renderer.m for my entire game state. I have an array of bullet structs, an array on enemy structs, etc.. Besides using this structure, where my entire game state is in ES1Renderer.m as C arrays and structs, what other ways are there to structure the code? Should I be using C++ or Objective-C classes to represent the enemies so they are more modular? The main reason I ask this is because I don't normally code in C, C++ and Objective-C..so I am a little fuzzy on coming up with a good architecture here.

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  • Java: PriorityQueue returning incorrect ordering from custom comparator??

    - by Michael Simpson
    I've written a custom comparator to compare my node classes, but the java priority queue is not returning my items in the correct order. Here is my comparator: public int compare(Node n1, Node n2){ if (n1.getF() > n2.getF()){ return +1; } else if (n1.getF() < n2.getF()){ return -1; } else { // equal return 0; } } Where getF returns a double. However after inserting several Nodes into the priority queue, I print them out using: while(open.size() > 0) { Node t = (Node)(open.remove()); System.out.println(t.getF()); } Which results in: 6.830951894845301 6.830951894845301 6.0 6.0 5.242640687119285 7.4031242374328485 7.4031242374328485 8.071067811865476 Any ideas why this is so? Is my comparator wrong? Thanks. Mike

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  • PHP: How do I access child properties from a method in a base object?

    - by Nick
    I'd like for all of my objects to be able to return a JSON string of themselves. So I created a base class for all of my objects to extend, with an AsJSON() method: class BaseObject { public function AsJSON() { $JSON=array(); foreach ($this as $key = $value) { if(is_null($value)) continue; $JSON[$key] = $value; } return json_encode($JSON); } } And then extend my child classes from that: class Package extends BaseObject { ... } So in my code, I expect to do this: $Box = new Package; $Box-SetID('123'); $Box-SetName('12x8x6'); $Box-SetBoxX('12'); $Box-SetBoxY('8'); $Box-SetBoxZ('6'); echo $Box-AsJSON(); But the JSON string it returns only contains the BaseClass's properties, not the child properties. How do I modify my AsJSON() function so that $this refers to the child's properties, not the parent's?

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  • Avoid Circular Reference in Swing GUI

    - by drhorrible
    Maybe it's not worth worrying about in this scenario, but lets say you have two classes, a JFrame with all its components, and a server-like class that handles requests from remote clients. The user is able to start and stop server objects through the GUI, and is shown various events that happen to each server object. Whether or not I use an explicit pattern (like MVC), it seems like the JFrame needs a reference to the server class (to call start and stop) and the server needs a reference to the JFrame (to notify of it of certain events). Is this a problem, or am I looking at this situation in the wrong way?

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  • Unicode string handling using Windows API

    - by DeadMG
    I always assumed that Unicode string handling was some dark art. However, I've seen that the Windows API has functions for comparing Unicode strings, for example. Does that mean that it's actually feasible to write a Unicode string class that can perform simple actions like sorting, equality comparison, and extraction from a file? Or are there hidden gotchas in the use of these functions that makes it actually a really bad idea? I'm just looking at libraries like ICU and they seem incredibly over-complicated compared to what a Unicode string class backed by the Windows API could actually look like, which would resemble the Standard string classes quite closely.

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