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  • What is the need of collection framework in java?

    - by JavaUser
    Hi, What is the need of Collection framework in Java since all the data operations(sorting/adding/deleting) are possible with Arrays and moreover array is suitable for memory consumption and performance is also better compared with Collections. Can anyone point me a real time data oriented example which shows the difference in both(array/Collections) of these implementations. Thx

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  • SQL Server 2005 red herring error "The user does not have permission to perform this action"

    - by Sylvia
    We're getting the error "The user does not have permission to perform this action" during times of heavy load (regularly, when a trim job occurs). The error clears up when the service accessing sql server is restarted, so it's obviously not a real permissions problems. What kind of situations could cause an error like this, when it's not really a permissions problem? Any ideas of good places to start looking? thanks for any insights...

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  • Which programming language to choose? (for a specific problem/domain, details inside)

    - by Bijan
    I am building a trading portfolio management system that is responsible for production, optimization, and simulation of non-high frequency trading portfolios (dealing with 1min or 3min bars of data, not tick data). I plan on employing Amazon web services to take on the entire load of the application. I have four choices that I am considering as language. a) Java b) C++ c) C# d) Python Here is the scope of the extremes of the project scope. This isn't how it will be, maybe ever, but it's within the scope of the requirements: Weekly simulation of 10,000,000 trading systems. (Each trading system is expected to have its own data mining methods, including feature selection algorithms which are extremely computationally-expensive. Imagine 500-5000 features using wrappers. These are not run often by any means, but it's still a consideration) Real-time production of portfolio w/ 100,000 trading strategies Taking in 1 min or 3 min data from every stock/futures market around the globe (approx 100,000) Portfolio optimization of portfolios with up to 100,000 strategies. (rather intensive algorithm) Speed is a concern, but I believe that Java can handle the load. I just want to make sure that Java CAN handle the above requirements comfortably. I don't want to do the project in C++, but I will if it's required. The reason C# is on there is because I thought it was a good alternative to Java, even though I don't like Windows at all and would prefer Java if all things are the same. Python - I've read somethings on PyPy and pyscho that claim python can be optimized with JIT compiling to run at near C-like speeds.... That's pretty much the only reason it is on this list, besides that fact that Python is a great language and would probably be the most enjoyable language to code in, which is not a factor at all for this project, but a perk. To sum up: - real time production - weekly simulations of a large number of systems - weekly/monthly optimizations of portfolios - large numbers of connections to collect data from There is no dealing with millisecond or even second based trades. The only consideration is if Java can possibly deal with this kind of load when spread out of a necessary amount of EC2 servers. Thank you guys so much for your wisdom.

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  • XNA - Mouse coordinates to word space transformation

    - by Gabriel Butcher
    I have a pretty annoying problem. I would like to create a drawing program, using winform + XNA combo. The most important part would be to transform the mouse position into the XNA drawn grid - I was able to make it for the translations, but it only work if I don't zoom in - when I do, the coordinates simply went horrible wrong. And I have no idea what I doing wrong. I tried to transform with scaling matrix, transform with inverse scaling matrix, multiplying with zoom, but none seems to work. In the beginning (with zoom value = 1) the grid starts from (0,0,0) going to (Width, Height, 0). I was able to get coordinates based on this grid as long as the zoom value didn't changed at all. I using a custom shader, with orthographic projection matrix, identity view matrix, and the transformed world matrix. Here is the two main method: internal void Update(RenderData data) { KeyboardState keyS = Keyboard.GetState(); MouseState mouS = Mouse.GetState(); if (ButtonState.Pressed == mouS.RightButton) { camTarget.X -= (float)(mouS.X - oldMstate.X) / 2; camTarget.Y += (float)(mouS.Y - oldMstate.Y) / 2; } if (ButtonState.Pressed == mouS.MiddleButton || keyS.IsKeyDown(Keys.Space)) { zVal += (float)(mouS.Y - oldMstate.Y) / 10; zoom = (float)Math.Pow(2, zVal); } oldKState = keyS; oldMstate = mouS; world = Matrix.CreateTranslation(new Vector3(-camTarget.X, -camTarget.Y, 0)) * Matrix.CreateScale(zoom / 2); } internal PointF MousePos { get { Vector2 mousePos = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); Matrix trans = Matrix.CreateTranslation(new Vector3(camTarget.X - (Width / 2), -camTarget.Y + (Height / 2), 0)); mousePos = Vector2.Transform(mousePos, trans); return new PointF(mousePos.X, mousePos.Y); } } The second method should return the coordinates of the mouse cursor based on the grid (where the (0,0) point of the grid is the top-left corner.). But is just don't work. I deleted the zoom transformation from the matrix trans, as I didnt was able to get any useful result (most of the time, the coordinates was horrible wrong, mostly many thousand when the grid's size is 500x500). Any idea, or suggestion? I trying to solve this simple problem for two days now :\

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  • RESTful principles question

    - by auser
    An intelligent coworker friend of mine brought up a question to me that I was uncertain how to answer and I'd like to pose it to the world. If a RESTful endpoint uses token-based authentication, aka a time-based token is required to access a resource and that token expires after a certain amount of time, would this violate the RESTful principle? In other words, if the same URL expires after a certain amount of time, so the resource returns a different response depending when it was requested, is that breaking REST?

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  • Rails 3 HTTP digest authentication

    - by Cimm
    Is HTTP digest authentication still supported in Rails 3? I tried the following code in Rails 2.3.5, it works. class Admin::BaseController < ApplicationController before_filter :authenticate USERS = { "lifo" => "world" } def authenticate authenticate_or_request_with_http_digest("Application") do |name| USERS[name] end end end Now, the same thing in Rails 3.0.0.beta) returns an error: can't convert nil into String Am I missing something or is this a bug in Rails 3? HTTP basic authentication works fine.

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  • What is the average color of a star?

    - by RCIX
    I am trying to procedurally generate point stars to create a starfield background for my game. I want to weight the color production based on an average star's real color. Can anyone point me in the direction of this sort of data?

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  • Python thinks I'm a different IP

    - by Yongho
    I'm trying to set a page that displays the visitor's IP. All the methods I have tried show an IP different from the IP my computer has. I've tried: Looking up http://www.whatismyip.com/automation/n09230945.asp Using socket.getaddrinfo(socket.gethostname(), None)[0][4][0] How can I find the real IP of the visitor?

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  • Sending HTML email from PHP

    - by KevinM
    I am trying to send a simple HTML e-mail from PHP. The code below simply results in a blank e-mail in GMail. It also has an empty attachment called 'noname', which is not at all what I want; though that might just be a symptom of it not working. The code I am using is: <?php //define the receiver of the email $to = '[email protected]'; //define the subject of the email $subject = 'Test HTML email'; //create a boundary string. It must be unique //so we use the MD5 algorithm to generate a random hash $random_hash = md5(date('r', time())); //define the headers we want passed. Note that they are separated with \r\n $headers = "From: [email protected]\r\nReply-To: [email protected]"; //add boundary string and mime type specification $headers .= "\r\nContent-Type: multipart/alternative; boundary=\"PHP-alt-".$random_hash."\""; //define the body of the message. ob_start(); //Turn on output buffering ?> --PHP-alt-<?php echo $random_hash; ?> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Hello World!!! This is simple text email message. --PHP-alt-<?php echo $random_hash; ?> MIME-Version: 1.0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: 7bit <h2>Hello World!</h2> <p>This is something with <b>HTML</b>formatting.</p> --PHP-alt-<?php echo $random_hash; ?>-- <? //copy current buffer contents into $message variable and delete current output buffer $message = ob_get_clean(); //send the email $mail_sent = @mail( $to, $subject, $message, $headers ); //if the message is sent successfully print "Mail sent". Otherwise print "Mail failed" echo $mail_sent ? "Mail sent" : "Mail failed";

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  • Using the standard Flash AS3 scrollbar class

    - by WebDevHobo
    Flash has a scrollbar class, documented here: http://help.adobe.com/en_US/AS3LCR/Flash_10.0/fl/controls/ScrollBar.html However, besides listing functions and variables, there's no real explanation of how to hook an instance of this class to a textfield. Everything I've tried either ends up in errors or the scrollbar not showing. The documentation lacks a clear way of how you should bind the textfield and the scrollbar toghether, and CS4 isn't providing any help either. Can someone explain, or link to an example of how scrollbars work with textfield?

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  • How do VoIP services connect to landlines?

    - by henry
    How do VoIP services, such as Skype and Yahoo, connect to landlines? We have a server connected to a landline using asterisk, so I'm thinking this server will bridge our VoIP conversation and connect it to a landline. But if this is the case, wouldn't Skype need a lot of servers placed around the whole world just to connect to landlines?

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  • What is a dictionary attack?

    - by Chris
    When we say dictionary attack, we don't really mean a real dictionary, do we? My guess is we mean a hacker's dictionary i.e. rainbow tables, right? My point is we're not talking about someone keying different passwords into the login box, we're talking about someone who has full access to your database (which has hashed passwords, not plain passwords) and this person is reversing the hashes, right?

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  • Need serious assembly help

    - by Jake
    I have been trying to learn assembly for a few years now. I get to do a "Hello, World" program but never further. I find it so hard. Is anyone able to point me to a place or maybe even themselves, teach me some? I have prior programming experice mainly in python. So i am not completely unfamiliar with programming.

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  • Nhibernate 3.0 and FluentNHibernate

    - by Keith Nicholas
    is anyone building the truck NHibernate and FluentNhibernate together? How's it working? are you using it for production systems? How is the Linq support? Is it nearly ready for release? Is there a nice and concise way to keep up to date with what is going on in the world of NHibernate? (ie, without having to read lots of blogs, and mailing lists )

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  • Why and why not Coldfusion (CFML) ?

    - by zarko.susnjar
    When you speak to your colleagues or you want to convince your client to use Coldfusion for some new project and not some other technology or language they heard of before, which arguments do you use? I'm asking because I'd like to make presentation to put in my company's portfolio and seems that I can't find any real life, non development kind of arguments. Yes, cfquery and cffunction access="remote" make our lives easier, but client doesn't care too much about us, right?

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  • Facebook Open Graph under a constrained application

    - by Hellnar
    Hello For an embedded system with internet (which works under a set-top box) I want to develop a primitive Facebook interface where users can type their user-names and password, showing their latest notificationsa, messages and other casual stuff via the recent Facebook Graph API. This middleware program uses Java ME to run programs (such as this simple facebook app) and it can connect to internet however it doesn't have a real web browser. Under this circumstance, is it possible to achieve such Facebook application? If you think so, what approach would you suggest ? Thanks

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  • advantage and disadvantage of smarty template

    - by Bharanikumar
    Hi , New to smarty , Why people's showing interest in framework , What are the advantages in that , also lot of people little bit avoiding template what is the reason , What is the real reason people choosing the smarty , How much really smarty best for web development , Regards Bharanikumar

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  • Zend Framework-Do images, mp3s, scripts, etc, just go in public folder?

    - by Joel
    I guess these are all questions that everyone must just know, because I'm not seeing this in the documentation :-D I understand that the public folder is the folder that the world has access to. I know it is the case with the css folder, but in migrating a traditional php website over, will my /images folder, /js folder /mp3s, etc Will those all just also be public folders that will be accessed via the layout or view.phtml pages? Thanks!

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  • Why does LINQ-to-Entites recognize my custom method?

    - by BlueRaja The Green Unicorn
    This works: (from o in Entities.WorkOrderSet select o) .Where(MyCustomMethod); This does not: (from o in Entities.WorkOrderSet select new { WorkOrder = o }) .Where(o => MyCustomMethod(o.WorkOrder); I understand why the second doesn't work - but why in the world does the first work!? Shouldn't I get a "custom method not recognized?" For reference, here is MyCustomMethod public bool MyCustomMethod(WorkOrder workOrder) { return !workOrder.WorkOrderNum.StartsWith("A", StringComparison.CurrentCultureIgnoreCase); }

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  • How can I demonstrate the benefits of abstractions to an old-time C programmer?

    - by Zaban Khuli
    Hi, there's this senior developer in my company that programs in C. I happen to be from functional background (ML, to be specific). This senior C programmer refuses to use abstractions because "abstraction is for lame programmers and _real_ programmers do not need it." I can not seem to convince him otherwise Is it a problem with only this programmer or do all C (and other lower level language) programmers have this opinion that abstraction is for lame programmers?

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