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  • Maintaining a pool of DAO Class instances vs doing new operator

    - by Fazal
    we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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  • Origin null is not allowed by Access-Control-Allow-Origin

    - by JIGGABITS
    I'm currently working with the SoundCloud API and would like to have a track embed when a button is clicked. I get two errors: XMLHttpRequest cannot load http://soundcloud.com/oembed.json?url=http%3A%2F%2Fapi.soundcloud.com%2Ftracks%2F48419073. Origin null is not allowed by Access-Control-Allow-Origin. AND Uncaught TypeError: Cannot read property 'html' of null Here is my code: <button onclick="getPopular()">+1</button> <div id="track"></div> <script src="http://connect.soundcloud.com/sdk.js" type="text/JavaScript"></script> <script type="text/JavaScript"> SC.initialize({ client_id: "**************", }); var getPopular = function() { SC.get("/tracks", {limit: 1}, function(tracks) { var track = tracks[0]; alert("Latest track: " + track.title); SC.oEmbed(track.uri, document.getElementById("track")); }); }; </script> I use an alert in my code to let me know that it is actually taking information from the SoundCloud API. I'm just not sure what else is preventing it from embedding. Thanks, ahead of time, or looking at my question. jiggabits

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  • Operator precedence and struct definition in C

    - by Yktula
    struct struct0 { int a; }; struct struct1 { struct struct0 structure0; int b; } rho; &rho->structure0; /* Reference 1 */ (struct struct0 *)rho; /* Reference 2 */ (struct struct0)rho; /* Reference 3 */ From reference 1, does the compiler take the address of rho, and then access structure0, or vice-versa? What does the line at reference 2 do? Since structure0 is the first member of struct1, would reference 3 be equivalent to reference 1?

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  • AS 3.0 reference problem

    - by vasion
    I am finding it hard to fugure out the reference system in AS 3.0. this is the code i have (i have trimmed it down in order to find the problem but to no avail) package rpflash.ui { import flash.display.Sprite; import flash.display.MovieClip; import flash.display.Stage; import nowplaying; import flash.text.TextField; public class RPUserInterface extends Sprite{ var np:nowplaying; public function RPUserInterface(){ } public function init(){ var np:nowplaying = new nowplaying(); this.addChild(np) } public function updateplayer(xml:XML){ var artist: String = xml.nowplaying.artist.toString(); var title: String = xml.nowplaying.title.toString(); trace("UI:update"); trace(this.np);// this gives me a null reference } } } and still i cannot access np!!! trace this.np gives me a null reference. i am not even trying to access it from a subling class. (btw i def want to know how to do that as well.)

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  • Does operator new allocate on THREAD heap?

    - by Jonas Byström
    My problem seems to be this: heap data allocated by one thread (that later dies) seems to die as well. As so: Thread X: starts Thread Y: starts Thread X: ptr = new some bytes Thread X: dies Thread Y: tries to use ptr - and crashes! So far, I've only seen this problem on Darwin (Mac OS 10.5 and 10.6), but haven't tried more other platforms than Windows and Linux (Ubuntu) where it works as expected. I've had this problem for some time, so any know-how or more information about this is highly appreciated!

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  • ms-access: DB engine cannot find input table or query

    - by every_answer_gets_a_point
    here's the query: SELECT * FROM (SELECT [Occurrence Number], [Occurrence Date], [1 0 Preanalytical (Before Testing)], [Cup Type], NULL as [2 0 Analytical (Testing Phase)], [2 0 Area], NULL as [3 0 Postanalytical ( After Testing)],NULL as [4 0 Other], [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([1 0 Preanalytical (Before Testing)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],[2 0 Analytical (Testing Phase)], [2 0 Area], NULL,NULL, [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([2 0 Analytical (Testing Phase)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],NULL, [2 0 Area], [3 0 Postanalytical ( After Testing)],NULL, [Practice Code], [Specimen ID #] FROM [Lab Occurrence Form] WHERE NOT ([3 0 Postanalytical ( After Testing)] IS NULL) UNION SELECT [Occurrence Number], [Occurrence Date],NULL, [Cup Type],NULL, [2 0 Area], NULL, [4 0 Other] FROM [Lab Occurrence Form], [Practice Code], [Specimen ID #] WHERE NOT ([4 0 Other] IS NULL) ) AS mySubQuery ORDER BY mySubQuery.[Occurrence Number]; for some reason it doesnt like [Practice Code]. it's definitely a column in the table so i dont understand the problem. the error is the microsoft office access database engine cannot find the input table or query 'Practice Code'........

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  • MSP430 CMP operator

    - by Ludicrous
    Let's say I have the MSP430 assembly segment below: r15: 439c Memory map: 4390: 6045 0200 9c43 6400 8844 5044 363a 0000 Code: 448a: cmp #0x363a, 0x0(r15) 4490: jnz $+0x1c 4492: Code continues . . . 44ac: Jump to location The goal is to have the Z flag high. To do this with a cmp, both src and dst must be equal. If I have 363a in the memory location of r15, why is it that the resulting cmp does not trigger the Z flag? Through experimentation, I found that putting 3a36 in the memory location of r15 did in fact trigger the Z flag, but I don't understand why. If anyone could bring this to light, I would greatly appreciate it. If more information is needed, I will gladly provide it.

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  • How default assignment operator works in struct?

    - by skydoor
    Suppose I have a structure in C++ containing a name and a number, e.g. struct person { char name[20]; int ssn; }; Suppose I declare two person variables: person a; person b; where a.name = "George", a.ssn = 1, and b.name = "Fred" and b.ssn = 2. Suppose later in the code a = b; printf("%s %d\n",a.name, a.ssn);

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  • Arithmetic operator confusion

    - by Dusk
    Why I'm getting two different values while using the arithmetic operators for the same value of variables. I've just altered little bit my second program, which is resulted in giving me the different output. Could anyone please tell me why? int number=113; int rot=0; rot=number%10; rot*=100+number/10; System.out.println(rot);//333 int number=113; int rot=0; rot=number%10; rot=rot*100+number/10; System.out.println(rot);//311

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  • 'AND' vs '&&' as operator

    - by ts
    Actually, i am facing a codebase where developpers decided to use 'AND' and 'OR' instead of '&&' and '||'. I know that there is difference in operators precedence (&& goes before 'and'), but with given framework (prestashop to be precise) is clearly not a reason. So, my question: which version are you using? Is 'and' more readable than '&&'? || there is ~ difference?

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  • What does the '&' operator do in C++?

    - by rascher
    n00b question. I am a C guy and I'm trying to understand some C++ code. I have the following function declaration: int foo(const string &myname) { cout << "called foo for: " << myname << endl; return 0; } How does the function signature differ from the equivalent C: int foo(const char *myname) Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers? Similarly: const string &GetMethodName() { ... } What is the & doing here? Is there some website that explains how & is used differently in C vs C++?

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  • Java Operator Precedence Comparison

    - by Andrew
    Does java have a built-in method to compare precedence of two operators? For example, if I have a char '/' and a char '+' is there a method I can call that compares the two and returns true/false if the first is greater than the second (e.g. true)?

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  • Problem compiling c++ in CodeGear

    - by Carlos
    I have written a C++ program for a University assignment. I used Netbeans 6.8 running on my Mac and the code runs smoothly, no warnings, errors or problems/bugs. However when compiling and running on a Windows computer using CodeGear RAD Studio 2009 (C++ Builder) am getting several errors. [BCC32 Error] main.cpp(51): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(62): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(67): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(112): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(121): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(130): E2093 'operator==' not implemented in type 'string' for arguments of the same type [BCC32 Error] main.cpp(133): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(139): E2094 'operator<<' not implemented in type 'ostream' for arguments of type 'string' [BCC32 Error] main.cpp(153): E2094 'operator<<' not implemented in type 'fstream' for arguments of type 'string' [BCC32 Error] main.cpp(199): E2094 'operator>>' not implemented in type 'fstream' for arguments of type 'string' [BCC32 Error] main.cpp(219): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(231): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(240): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(262): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' [BCC32 Error] main.cpp(264): E2094 'operator>>' not implemented in type 'istream' for arguments of type 'string' These are the header files am using #include <iostream> #include <fstream> #include <cmath> #include <stdio> #include <windows> //I added this one just to check and still does not work (I didnt have it on Netbeans/Mac) using namespace std; Any ideas what is producing the errors and how can I fix it?

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  • Write Null/Nothing value with Databinding

    - by clawson
    I have extended a MaskedTextBox component to add some functionality. The text property of the extended MaskedTextBox is bound to a DateTime? property and the format of binding is set to a time format of "HH:mm:ss" (i.e. 24hr time). So that this masked text box will capture the display a time. The extra functionality I have added is to make the component readonly unless the component is double clicked or the enter button is pressed (the back color of the control helps to inform the users if the component is locked/readonly or not). When the enter button is pressed I also suspend the bindings so that bound data is updated the users input won't be lost. The information is then written back to the value and databindings resumed when the user presses the enter key again. This all works fine up to here, with values written and displayed as would be expected. However, I also want to write the null or nothing value to the DateTime? property if the user hasn't entered any text (or invalid text but let's just stick with no text) when enter key is pressed to submit the new value. Unlike with other valid entries in the MaskedTextBox, with no text entered when i execute: Me.DataBindings("Text").WriteValue() (when 'locking' the MaskedTextBox) it then branches to the bound properties Get method as I step into each line of code in the debugger (as opposed to the Set method with other valid entries) How can I write this null/nothing/"" value to the DateTime? property when no text "" is entered into the MaskedTextBox? Thanks for the help!

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  • Source operator doesn't work in if construction in bash

    - by Igor
    Hello, I'd like to include a config file in my bash script with 2 conditions: 1) the config file name is constructed on-the-fly and stored in variable, and 2) in case if config file doesn't exist, the script should fail: config.cfg: CONFIGURED=yes test.sh: #!/bin/sh $CFG=config.cfg echo Source command doesn't work here: [ -f $CFG ] && ( source $CFG ) || (echo $CFG doesnt exist; exit 127) echo $CONFIGURED echo ... but works here: source $CFG echo $CONFIGURED What's wrong in [...] statement?

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  • == Operator and operands

    - by rahul
    I want to check whether a value is equal to 1. Is there any difference in the following lines of code Evaluated value == 1 1 == evaluated value in terms of the compiler execution

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  • getPackage() returning null when my JUnit test is run from Ant

    - by philharvey
    I'm having problems running a JUnit test. It runs fine in Eclipse, but now I'm trying to run it from the command-line using Ant. The problem is that the following code is returning null: getClass().getPackage(). I'm running my JUnit test like so: <junit fork="no" printsummary="yes" haltonfailure="no"> <classpath refid="junit.classpath" /> <batchtest fork="yes" todir="${reports.junit}"> <fileset dir="${junit.classdir}"> <include name="**/FileHttpServerTest.class" /> <exclude name="**/*$*" /> </fileset> </batchtest> <formatter type="xml" /> ... I Googled for this sort of error, and found a number of references to classloader misbehaviour. But I've found nothing gave me enough information to solve my problem. I really need getClass().getPackage() to not return null. Can anyone help me? Thanks, Phil

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  • Using sizeof operator on a typedef-ed struct

    - by sskanitk
    This might be something too obvious. However, I couldn't find the specific answer though many stackoverflow threads talk about different aspects of this. typedef struct _tmp { unsigned int a; unsigned int b; } tmp; int main() { int c=10; if (c <= sizeof tmp) { printf("less\n"); } else { printf("more\n"); } return 0; } I compile this prog as - g++ -lstdc++ a.cpp I get an error - expected primary-expression before ‘)’ token I think I am missing something very obvious and straightforward. But can't seem to pinpoint it :-/ Thanks!

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  • new operator in DllMain of MFC Extension Dll

    - by Picaro De Vosio
    Hi, Dll best practices document from Microsoft available Here recommends avoiding use of memory management function from the dynamic C Run-Time (CRT) within DllMain. But DllMain function of MFC Extension DLL is dynamically allocating the memory for CDynLinkLibrary in the code snippet available at MSDN "http://msdn.microsoft.com/en-us/library/1btd5ea3%28v=VS.80%29.aspx". Is it a violation of Dll Best Practices or ok to use in MFC extension DLL? thanks

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  • problem with QDataStream & QDataStream::operator>> ( char *& s )

    - by yan bellavance
    QFile msnLogFile(item->data(Qt::UserRole).toString()); QDataStream logDataStream; if(msnLogFile.exists()){ msnLogFile.open(QIODevice::ReadOnly); logDataStream.setDevice(&msnLogFile); QByteArray logBlock; logDataStream >> logBlock; } This code doesnt work. The QByte that results is empty. Same thing if I use a char* . Oddely enough the same code works in another program. Im tying to find the difference between both. This works if i use int,uint, quint8, etc

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  • and or operator in validates_presence_of of a Ruby on Rails model

    - by user284194
    I have an entry.rb model and I'm trying to make a semi-complicated validation. I want it to require one or more of the following fields: phone, phone2, mobile, fax, email or website. How would you write the intended code? Would something like this work? validates_presence_of :phone and or :phone2 and or :mobile and or :fax and or :email and or :website

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  • splat operator in groovy?

    - by IttayD
    def foo(map, name) { println(map) } foo("bar", hi: "bye") will print [hi:bye] Now I have a previous map that I wish to pass along to foo. In pseudo code, something like: def otherMap = [hi: "world"] foo("bar", hi: "bye", otherMap*) So that it prints [hi:world] This doesn't work of course. Also, trying to pass just the map mixes the order of arguments: def otherMap = [hi: "world"] foo("bar", otherMap) will print bar How can I fix this?

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