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Articles indexed Thursday May 27 2010

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  • Java File Handling, what did I do wrong?

    - by Urda
    Wrote up a basic file handler for a Java Homework assignment, and when I got the assignment back I had some notes about failing to catch a few instances: Buffer from file could have been null. File was not found File stream wasn't closed Here is the block of code that is used for opening a file: /** * Create a Filestream, Buffer, and a String to store the Buffer. */ FileInputStream fin = null; BufferedReader buffRead = null; String loadedString = null; /** Try to open the file from user input */ try { fin = new FileInputStream(programPath + fileToParse); buffRead = new BufferedReader(new InputStreamReader(fin)); loadedString = buffRead.readLine(); fin.close(); } /** Catch the error if we can't open the file */ catch(IOException e) { System.err.println("CRITICAL: Unable to open text file!"); System.err.println("Exiting!"); System.exit(-1); } The one comment I had from him was that fin.close(); needed to be in a finally block, which I did not have at all. But I thought that the way I have created the try/catch it would have prevented an issue with the file not opening. Let me be clear on a few things: This is not for a current assignment (not trying to get someone to do my own work), I have already created my project and have been graded on it. I did not fully understand my Professor's reasoning myself. Finally, I do not have a lot of Java experience, so I was a little confused why my catch wasn't good enough.

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  • Need help programming with Mclauren series and Taylor series!

    - by user352258
    Ok so here's what i have so far: #include <stdio.h> #include <math.h> //#define PI 3.14159 int factorial(int n){ if(n <= 1) return(1); else return(n * factorial(n-1)); } void McLaurin(float pi){ int factorial(int); float x = 42*pi/180; int i, val=0, sign; for(i=1, sign=-1; i<11; i+=2){ sign *= -1; // alternate sign of cos(0) which is 1 val += (sign*(pow(x, i)) / factorial(i)); } printf("\nMcLaurin of 42 = %d\n", val); } void Taylor(float pi){ int factorial(int); float x; int i; float val=0.00, sign; float a = pi/3; printf("Enter x in degrees:\n"); scanf("%f", &x); x=x*pi/180.0; printf("%f",x); for(i=0, sign=-1.0; i<2; i++){ if(i%2==1) sign *= -1.0; // alternate sign of cos(0) which is 1 printf("%f",sign); if(i%2==1) val += (sign*sin(a)*(pow(x-a, i)) / factorial(i)); else val += (sign*cos(a)*(pow(x-a, i)) / factorial(i)); printf("%d",factorial(i)); } printf("\nTaylor of sin(%g degrees) = %d\n", (x*180.0)/pi, val); } main(){ float pi=3.14159; void McLaurin(float); void Taylor(float); McLaurin(pi); Taylor(pi); } and here's the output: McLaurin of 42 = 0 Enter x in degrees: 42 0.733038-1.00000011.0000001 Taylor of sin(42 degrees) = -1073741824 I suspect the reason for these outrageous numbers goes with the fact that I mixed up my floats and ints? But i just cant figure it out...!! Maybe its a math thing, but its never been a strength of mine let alone program with calculus. Also the Mclaurin fails, how does it equal zero? WTF! Please help correct my noobish code. I am still a beginner...

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  • How to create a list of data clickable? asp.net

    - by Roger Filipe
    Hello, I am learning asp.net but I'm finding some problems. My doubt is how to make a list of titles of news contained in a database. And in this list, each of the titles when clicked is redirected to a page where you will be able to view the news in full (Title, Body, Author ..). What I got: - A database containing a table with the news, every news is associated with an identification code (ex: "ID"). - A page where you will make the listing. (Ex: site / listofnews.aspx) - I have a page that uses the method "querystring" to know what is the primarykey the news. (Ex: site/shownews.aspx?ID=12345, where "12345" is the primarykey of the news. Once it knows what is the primarykey of the news in the database, it loads each of the fields of the page (news.aspx) with the news, this part is working ok. - The data is retrieve using the Linq, so I receive a List of "News", the class "News" as ID, Title, Body, Author.. My doubt is how to make the listing clickable. In php I used this method (make a list of html links, in each link the href field is changed so that the tag "id" coincides with the news): //database used is oracle, $stmt is the query, you don´t need to understand how it works. oci_define_by_name($stmt, "ID", $id); oci_define_by_name($stmt, "TITLE", $title); if (!oci_execute($stmt, OCI_DEFAULT)) { $err = oci_error($stmt); trigger_error('Query failed: ' . $err['message'], E_USER_ERROR); } echo '<br />'; while (oci_fetch($stmt)) {<------While there is data from the database , create links $link = '<a href="site/shownews.php?ID='.$id.'" >'.$title.'</a>';<----the shownews.php?ID= $id, creates the link according with the ID echo $link<---Prints the link echo '<br />'; } How do i make the same with asp.net?

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  • C++ inheritance question

    - by user233973
    Hi guys, I have a C++ inheritance related question. I have a set of classes like this (I have not given the complete class structure coz I am lazy :) ). I want to access chiComponent class public methods using com pointer. How should I go about it? Note that I am having to change the object which "com" is pointing to in a lot of places. So I do not think I can have another chiComponent *ccom = <some_cast> com; ccom.chiComponentMethod() How should I go about it? class Component{ }; class chiComponent : public Component { public: void chiComponentMethod() { cout << "Hi! Chi component function called!!"; } } class parent { protected: Component *com; }; class child : public parent{ public: child() { com = new chiComponent(); } } Regards Arun

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  • C# - Exception messages in English?

    - by Carra
    We are logging any exceptions that happen in our system by writing the Exception.Message to a file. However, they are written in the culture of the client. And Turkish errors don't mean a lot to me. So how can we log any error messages in English without changing the users culture?

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  • Bang Notation and Dot Notation in VBA and MS-Access

    - by Nitrodist
    While perusing an application that I'm documenting, I've run across some examples of bang notation in accessing object properties/methods, etc. and in other places they use dot notation for what seems like the same purpose. Is there a difference or preference to using one or the other? Some simple googling only reveals limited information on the subject with some people actually using it in opposite cases. Perhaps there is a coding standards section from MS somewhere that indicates the method of madness?

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  • Incorrect error

    - by jspooner
    If you assign an invalid date (like December 39th) to a datetime column ActiveRecord returns a "can't be blank" error when is should probably return an error like "Not a valid date" My question. Is this expected rails behavior, a bug or, something that I could patch? class ExerciseLog < ActiveRecord::Base validates_presence_of :scheduled_datetime end Fire up the console. e = Log.new # lets set a date for Dec 39th which obviously doesn't exist e.scheduled_datetime = "2010-12-39" e.save => false # this is the confusing message since our form did post a valid date e.errors.on(:scheduled_datetime) => "can't be blank" e.scheduled_datetime = "2010-12-30" e.save => true I discovered this issue when I accidentally transposed the month and day values. btw This is in Rails 2.3.5

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  • Best use of Jquery sliders and PHP

    - by Coronier
    Hello there, I have two questions: What's the best way to send sliders' values to a PHP page ? I'm associating each slider (several per page) with an hidden form so far, but I wonder if there's a "cleaner" way to do this. Related to the 1st question; I've some trouble with the script: var score = $(this).slider( "option", "value" ); $(this).closest("input[type=='hidden']").val(score); It doesn't set the value of the hidden input. Can somebody tells me what's wrong ? Thanks

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  • Issue with IHttpHandler and relative URLs

    - by vtortola
    Hi, I've developed a IHttpHandler class and I've configured it as verb="*" path="*", so I'm handling all the request with it in an attempt of create my own REST implementation for a test web site that generates the html dynamically. So, when a request for a .css file arrives, I've to do something like context.Response.WriteFile(Server.MapPath(url)) ... same for pictures and so on, I have to response everything myself. My main issue, is when I put relative URLs in the anchors; for example, I have main page with a link like this <a href="page1">Go to Page 1</a> , and in Page 1 I have another link <a href="page2">Go to Page 2</a>. Page 1 and 2 are supposed to be at the same level (http://host/page1 and http://host/page2, but when I click in Go to Page 2, I got this url in the handler: ~/page1/~/page2 ... what is a pain, because I have to do an url = url.SubString(url.LastIndexOf('~')) for clean it, although I feel that there is nothing wrong and this behavior is totally normal. Right now, I can cope with it, but I think that in the future this is gonna bring me some headache. I've tried to set all the links with absolute URLs using the information of context.Request.Url, but it's also a pain :D, so I'd like to know if there is a nicer way to do these kind of things. Don't hesitate in giving me pretty obvious responses because I'm pretty new in web development and probably I'm skipping something basic about URLs, Http and so on. Thanks in advance and kind regards.

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  • Help with simple query - why isn't an index being used?

    - by Randy Minder
    I have the following query: SELECT MAX([LastModifiedTime]) FROM Workflow There are approximately 400M rows in the Workflow table. There is an index on the LastModifiedTime column as follows: CREATE NONCLUSTERED INDEX [IX_Workflow_LastModifiedTime] ON [dbo].[Workflow] ( [LastModifiedTime] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 100) The above query takes 1.5 minutes to execute. Why wouldn't SQL Server use the above index and simply retrieve the last row in the index to get the maximum value? Thanks.

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  • having trouble with jpa, looks to be reading from cache when told to ignore

    - by jeff
    i'm using jpa and eclipselink. it says version 2.0.2.v20100323-r6872 for eclipselink. it's an SE application, small. local persistence unit. i am using a postgres database. i have some code the wakes up once per second and does a jpa query on a table. it's polling to see whether some fields on a given record change. but when i update a field in sql, it keeps showing the same value each time i query it. and this is after waiting, creating a new entitymanager, and giving a query hint. when i query the table from sql or python, i can see the changed field. but from within my jpa query, once i've read the value, it never changes in later executions of the query -- even though the entity manager has been recreated. i've tried telling it to not look in the cache. but it seems to ignore that. very puzzling, can you help please? here is the method. i call this once every 3 seconds. the tgt.getTrlDlrs() println shows me i get the same value for this field on every call of the method ("value won't change"). even if i change the field in the database. when i query the record from outside java, i see the change right away. also, if i stop the java program and restart it, i see the new value printed out immediately: public void exitChk(EntityManagerFactory emf, Main_1 mn){ // this will be a list of the trade close targets that are active List<Pairs01Tradeclosetgt> mn_res = new ArrayList<Pairs01Tradeclosetgt>(); //this is a list of the place number in the array list above //of positions to close ArrayList<Integer> idxsToCl = new ArrayList<Integer>(); EntityManager em = emf.createEntityManager(); em.getTransaction().begin(); em.clear(); String qryTxt = "SELECT p FROM Pairs01Tradeclosetgt p WHERE p.isClosed = :isClosed AND p.isFilled = :isFilled"; Query qMn = em.createQuery(qryTxt); qMn.setHint(QueryHints.CACHE_USAGE, CacheUsage.DoNotCheckCache); qMn.setParameter("isClosed", false); qMn.setParameter("isFilled", true); mn_res = (List<Pairs01Tradeclosetgt>) qMn.getResultList(); // are there any trade close targets we need to check for closing? if (mn_res!=null){ //if yes, see whether they've hit their target for (int i=0;i<mn_res.size();i++){ Pairs01Tradeclosetgt tgt = new Pairs01Tradeclosetgt(); tgt = mn_res.get(i); System.out.println("value won't change:" + tgt.getTrlDlrs()); here is my entity class (partial): @Entity @Table(name = "pairs01_tradeclosetgt", catalog = "blah", schema = "public") @NamedQueries({ @NamedQuery(name = "Pairs01Tradeclosetgt.findAll", query = "SELECT p FROM Pairs01Tradeclosetgt p"), @NamedQuery(name = "Pairs01Tradeclosetgt.findByClseRatio", query = "SELECT p FROM Pairs01Tradeclosetgt p WHERE p.clseRatio = :clseRatio")}) public class Pairs01Tradeclosetgt implements Serializable { private static final long serialVersionUID = 1L; @Id @Basic(optional = false) @Column(name = "id") @SequenceGenerator(name="pairs01_tradeclosetgt_id_seq", allocationSize=1) @GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "pairs01_tradeclosetgt_id_seq") private Integer id; and my persitence unit: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="testpu" transaction-type="RESOURCE_LOCAL"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <class>mourv02.Pairs01Quotes</class> <class>mourv02.Pairs01Pair</class> <class>mourv02.Pairs01Trderrs</class> <class>mourv02.Pairs01Tradereq</class> <class>mourv02.Pairs01Tradeclosetgt</class> <class>mourv02.Pairs01Orderstatus</class> <properties> <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://192.168.1.80:5432/blah"/> <property name="javax.persistence.jdbc.password" value="secret"/> <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/> <property name="javax.persistence.jdbc.user" value="noone"/> </properties> </persistence-unit> </persistence>

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  • Visual Studio Key board Binding Poster

    - by Jeev
    If you prefer to use keyboard short cuts more than the mouse   ,please find below the links for the Visual studio Keyboard Binding PostersVisual Studio 2010 (inludes links for C++,VB,C# & F#)Visual Studio 2008 (C#) Visual Studio 2008(VB)

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  • Unable to connect to sharedfax error

    - by Owl
    I'm running SBS2k on a machine with a 56k modem for all outgoing faxes. We have a terminal server running server 2003 enterprise and in printers the sharedfax shows "unable to connect status". When you right-click, properties, it gives you an error saying the spool service is not running and you cannot view properties. The spooler service is indeed running on the 2k3 server because I can view the other printer's properties..and on 2k I show the Microsoft Shared Fax service AND Print Spooler as started. Here's the tricky part, I can add the shared fax printer on a domain computer locally (Windows XP) and it will show ready status and I can send faxes, they show up on the 2k server's fax console manager as in progress. I've sent a couple from a few different workstations today successfully, but still unable to send from 2k3 terminal services.

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  • How do I make a Windows virtual machine replicate to another datacenter/cloud?

    - by zippy
    We have a Windows 2008 VM running IIS and SQL Server Express (it's an all-in-one web application). We need to have another copy at our secondary datacenter site. What is the best way to do this? It doesn't have to be running all the time but it has to have almost the latest copy of the current VM. I took a look at VMWare Fault Tolerance and after the heart attack at the price I starting looking for another solution. If need be I wouldn't mind copying it over to a cloud VM provider, if I can find one that lets me copy my own VMs up and start them up without any conversion process.

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  • Android connait une croissance record, un graphique présente son évolution sur les 18 derniers mois

    Mise à jour du 27.05.2010 par Katleen Android connait une croissance record, un graphique présente son évolution sur les 18 derniers mois Un visuel infographique très complet, retraçant l'évolution d'Android au cours des 18 derniers mois. Il s'appuie sur les dernières statistiques dévoilées par Google il y a quelques jours lors de sa conférence I/O. Des chiffres rassurants suite à l'abandon des logiciels de Google au profit de ceux de Microsoft par plusieurs constructeurs. Les points clés transmis par ces i...

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  • What would be my best MySQL Synchronization method?

    - by Kerry
    We're moving a social media service to be on separate data centers with global load balancing, as our other hosting provider's entire data center went down. Twice. This means that both websites need to be synchronized in some sense -- I'm less worried about the code of the pages, that's easy enough to sync, but they need to have the same database data. From my research on SO, it seems MySQL Replication is a good option, but the MySQL manual, for scaling out, says that its best when there are far more reads then there are writes/updates: http://dev.mysql.com/doc/refman/5.0/en/replication-solutions-scaleout.html In our case, it's about equal. We're getting around 200-300 thousand requests a day right now, and we can grow rapidly. Every request is both a read and write request. What would be the best method or tool to handle this?

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  • Cancelling Two Way Data Binding In Silverlight

    - by DaveB
    I have an ObervableCollection of data items. This collection is bound to a ListBox. When the user selects a item from the listbox and clicks the Edit button a UserControl with the details of that item is displayed with the various properties bound to text boxes. Each binding mode is set for TwoWay. On this details UserControl, I would like to implement 2 buttons, OK and Cancel. This would be consistent with UIs in Windows. This application is using the Model-View_ViewModel pattern. Here is my question: 1) How can I implement the Cancel button when all the changes have already been committed?

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  • Cocoa JSON - Check whether array or dictionary

    - by Craig
    Hi, I am using the Cocoa JSON framework ( http://code.google.com/p/json-framework/ ) to communicate with an API. The problem is that the API returns a dictionary if there is an error but returns an array of the results if it works. Is there a good way to detect if the JSONValue is an array or a dictionary? Thanks.

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  • What can cause my code to run slower when the server JIT is activated?

    - by durandai
    I am doing some optimizations on an MPEG decoder. To ensure my optimizations aren't breaking anything I have a test suite that benchmarks the entire codebase (both optimized and original) as well as verifying that they both produce identical results (basically just feeding a couple of different streams through the decoder and crc32 the outputs). When using the "-server" option with the Sun 1.6.0_18, the test suite runs about 12% slower on the optimized version after warmup (in comparison to the default "-client" setting), while the original codebase gains a good boost running about twice as fast as in client mode. While at first this seemed to be simply a warmup issue to me, I added a loop to repeat the entire test suite multiple times. Then execution times become constant for each pass starting at the 3rd iteration of the test, still the optimized version stays 12% slower than in the client mode. I am also pretty sure its not a garbage collection issue, since the code involves absolutely no object allocations after startup. The code consists mainly of some bit manipulation operations (stream decoding) and lots of basic floating math (generating PCM audio). The only JDK classes involved are ByteArrayInputStream (feeds the stream to the test and excluding disk IO from the tests) and CRC32 (to verify the result). I also observed the same behaviour with Sun JDK 1.7.0_b98 (only that ist 15% instead of 12% there). Oh, and the tests were all done on the same machine (single core) with no other applications running (WinXP). While there is some inevitable variation on the measured execution times (using System.nanoTime btw), the variation between different test runs with the same settings never exceeded 2%, usually less than 1% (after warmup), so I conclude the effect is real and not purely induced by the measuring mechanism/machine. Are there any known coding patterns that perform worse on the server JIT? Failing that, what options are available to "peek" under the hood and observe what the JIT is doing there?

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  • MySQL More Tables or More Rows

    - by Pez Cuckow
    I am working on a game that I am going to open to the public to have on their game. The game stores lots of information (about 300 rows) per website and spends a lot of time updating values within this MySQL database. Is it better (faster/efficient) to add a new table for every website or to just have 1000's of rows in one table and add a column "website_id" or similar?

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  • DB Design to store custom fields for a table

    - by Fazal
    Hi All, this question came up based on the responses I got for the question http://stackoverflow.com/questions/2785033/getting-wierd-issue-with-to-number-function-in-oracle As everyone suggested that storing Numeric values in VARCHAR2 columns is not a good practice (which I totally agree with), I am wondering about a basic Design choice our team has made and whether there are better way to design. Problem Statement : We Have many tables where we want to give certain number of custom fields. The number of required custom fields is known, but what kind of attribute is mapped to the column is available to the user E.g. I am putting down a hypothetical scenario below Say you have a laptop which stores 50 attribute values for every laptop record. Each laptop attributes are created by the some admin who creates the laptop. A user created a laptop product lets say lap1 with attributes String, String, numeric, numeric, String Second user created laptop lap2 with attributes String,numeric,String,String,numeric Currently there data in our design gets persisted as following Laptop Table Id Name field1 field2 field3 field4 field5 1 lap1 lappy lappy 12 13 lappy 2 lap2 lappy2 13 lappy2 lapp2 12 This example kind of simulates our requirement and our design Now here if somebody is lookinup records for lap2 table doing a comparison on field2, We need to apply TO_NUMBER. select * from laptop where name='lap2' and TO_NUMBER(field2) < 15 TO_NUMBER fails in some cases when query plan decides to first apply to_number instead of the other filter. QUESTION Is this a valid design? What are the other alternative ways to solve this problem One of our team mates suggested creating tables on the fly for such cases. Is that a good idea How do popular ORM tools give custom fields or flex fields handling? I hope I was able to make sense in the question. Sorry for such a long text.. This causes us to use TO_NUMBER when queryio

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  • What does the "=>" mean in asp.net mvc?

    - by quakkels
    Hey SO, I've got a pretty noob question for ya. I keep seeing this syntax: <%= Html.LabelFor(model => model.Email) %> ...and I have no idea what the = means. I thought it was syntax for linq2sql or ado.net entity framework but I'm just using straight ado.net. I don't understand why the VWD used that syntax when generating the Create form. What does = mean?

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