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  • converting NSTimer running not on main runloop to GCD

    - by Justin Galzic
    I have a task that runs periodically and it was originally designed to run on a separate run loop than the main runloop using NSThread and NSTimer. What's the best way to adapt this to take advantage of GCD? Current code: -(void)initiateSomeTask { [NSThread detachNewThreadSelector:@selector(startTimerTask) toTarget:self withObject:nil]; } -(void)startTimerTask { // We won't get back the main runloop since we're on a new thread NSRunLoop *myRunLoop = [NSRunLoop currentRunLoop]; NSPort *myPort = [NSMachPort port]; [myRunLoop addPort:myPort forMode:NSDefaultRunLoopMode]; NSTimer *myTimer = [NSTimer timerWithTimeInterval:10 /* seconds */ target:self selector:@selector(doMyTaskMethod) userInfo:nil repeats:YES]; [myRunLoop addTimer:myTimer forMode:NSRunLoopCommonModes]; [myRunLoop run]; } Is there anything I can do besides replace detachNewThreadSelector with dispatch_async?

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  • Facebook javascript in address bar, possible to replicate?

    - by DoMx
    This is my first experience with stackoverflow and I'm afraid my question asks of a lot for a first. I was looking at this thread: http://stackoverflow.com/questions/2634159/javascrypt-in-the-adress-bar-is-this-malicious and as you will see SLaks has very kindly deobfuscated the javascript and left us with what appears as the Javascript behind the automatic facebook invite code. As I'm fairly new to javascript, I was wondering, what other components were needed to get this code to work? You of course have the functions there and they are called by the obfuscated javascript but how exactly? Would it be possible to replicate this on a page of my own using the information available or is there more to this script I am missing? I am willing to financially assist somebody who could compile a solution for me. Thank you in advance.

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  • java.util.MissingResourceException

    - by ashwani66476
    Hello Crew I am getting below exception while running an application. This application read abc.properties file, Exception in thread "main" java.util.MissingResourceException: Can't find bundle for base name abc, locale en_US at java.util.ResourceBundle.throwMissingResourceException(ResourceBundle.java:853) at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:822) at java.util.ResourceBundle.getBundle(ResourceBundle.java:566) at com.ibm.dst.DailyExtract.getResourceBundle(DailyExtract.java:104) at com.ibm.dst.DailyExtract.main(DailyExtract.java:131) abc.properties file reside at the workspace. I am using RSA7 as IDE, is there any setting problem? any suggestions are welcome..... Thanks a lot in advance

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  • fubar'd a ruby installation on ubuntu, need helping purging it for reinstall

    - by tipu
    i originally followed these steps to get a RoR environmentgoing: https://help.ubuntu.com/community/RubyOnRails that worked. then i put 1.9.2 on here. then i decided i want the original setup, did a "whereis ruby" and deleted those directories manually. that fubar'd my ruby installation. i can't use the repository to what i originally had. how can i purge ruby from completely and start fresh? right now the specific error is this: /usr/lib/ruby/1.8/rubygems.rb:11:in `require': no such file to load -- thread (LoadError) from /usr/lib/ruby/1.8/rubygems.rb:11 from /usr/bin/gem1.8:8:in `require' from /usr/bin/gem1.8:8 tipu@tipu_ubuntu:~$

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  • Loading a datagrid with large amounts of data in silverlight?

    - by JD
    Hi I am breaking up my project in small sections and one of the sections involves loading a grid with possibily lots of records (could be up to 1000s of records in the database). Ideally I would like some sort of mechanism where as the users scrolls the grid, more data is retrieved. I have read that certain controls (datapager with RIA) do this but I would like to know how I could implement this myself or do something similiar? I was thinking about first loading 50 records at a time and when the user gets to scroll near the 50th record, then get another 50 as a start and so on. Not sure how I do this but this does not feel right or whether I should load ids of records in the grid and then get each row to load itself via an async thread but then I am hitting my database for each record? Thanks JD.

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  • Ridiculously Simple Erlang Question

    - by Aiden Bell
    Read (skimmed enough to get coding) through Erlang Programming and Programming Erlang. One question, which is as simple as it sounds: If you have a process Pid1 on machine m1 and a billion million messages are sent to Pid1, are messages handled in parallel by that process (I get the impression no) and is there any guarantee of order when processing messages? ie. Received in order sent? Coming from the whole C/Thread pools/Shared State background ... I want to get this concrete. I understand distributing an application, but want to ensure the 'raw bones' are what I expect before building processes and distributing workload. Also, am I right in thinking the whole world is currently flicking through Erlang texts ;)

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  • Parallel Task In C#.net

    - by Test123
    I have C#.net application. I wanted to run my application In Thread. But because of third party dll it dont allow to use application in multiThread. There is one object in thrid party dll ,which only allow to create instance at one time only. When i manually run application exe instnace multiple time & process my data it process successfully..(might because of each exe run with its application domain) Same thing i require to implement from C# code. for that i have created dll which can accessible by Type.GetTypeFromProgID()..but multiple dll instnace creating same problem. Is there any way i could achive manual parallelism through code to process same exe code in multiple application domain?

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  • Will PHP Die In Web Page Development World?

    - by Morgan Cheng
    I know that PHP is still the most popular web programming language in the world. This question just want to bring some of my concerns about PHP. PHP is naturally bound to C10K problem. Since PHP (generally run in Apache) cannot be event-driven or asynchronous, each HTTP request will occupy at least one thread or process. This makes it resistant to be more scalable. Currently, a lot of web sites (like Facebook) with high performance and scalability still depends on PHP in their front end servers. I suppose it is due to legacy reason. Is it possible that PHP will be replaced by language more suitable for C10K?

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  • What's the requests/second standard for scraping websites?

    - by feydr
    This was the closest question to my question and it wasn't really answered very well imo: http://stackoverflow.com/questions/2022030/web-scraping-etiquette I'm looking for the answer to #1: How many requests/second should you be doing to scrape? Right now I pull from a queue of links. Every site that gets scraped has it's own thread and sleeps for 1 second in between requests. I ask for gzip compression to save bandwidth. Are there standards for this? Surely all the big search engines have some set of guidelines they follow in regards to this.

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  • Forum board example schema in YAML format - modify for Nested set?

    - by takeshin
    I have created a forum board app, based on YAML schema found in 'real world examples' of Doctrine Manual, which looks similar to this: --- Forum_Category: columns: root_category_id: integer(10) parent_category_id: integer(10) name: string(50) description: string(99999) relations: Subcategory: class: Forum_Category local: parent_category_id foreign: id Rootcategory: class: Forum_Category local: root_category_id foreign: id Forum_Board: columns: category_id: integer(10) name: string(100) description: string(5000) relations: Category: class: Forum_Category local: category_id foreign: id Threads: class: Forum_Thread local: id foreign: board_id Forum_Entry: columns: author: string(50) topic: string(100) message: string(99999) parent_entry_id: integer(10) thread_id: integer(10) date: integer(10) relations: Parent: class: Forum_Entry local: parent_entry_id foreign: id Thread: class: Forum_Thread local: thread_id foreign: id Forum_Thread: columns: board_id: integer(10) updated: integer(10) closed: integer(1) relations: Board: class: Forum_Board local: board_id foreign: id Entries: class: Forum_Entry local: id foreign: thread_id How to modify this schema, to use NestedSet (Tree structure of threads and entries)?

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  • My C# program running as Windows Service is blocking Windows XP from hibernation

    - by sherpa
    I have Windows Service written in C#. It starts two threads, one is pooling a Web Service, second is waiting on a Monitor object for a new job to arrive. Besides that, the main thread acts as a WCF service host using NetNamedPipeBinding. It lets the client application to register a callback and then sends notifications back. The problem I have is that when this Windows Service is running, I cannot hibernate or Standby my computer which is running on Windows XP, SP3. When I set Windows to hibernate or standby, nothing happens. Then, at the moment when I go to Service Manager and stop the service, the system hibernation starts immediately. The service class extending the ServiceBase has properties like CanHandlePowerEvent, CanPauseAndContinue, etc. set to true... That didn't make any difference. The question is: what can be blocking the Hibernation/Standby from proceeding? What should I take care about to avoid it?

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  • List replies in a winform

    - by andrew
    In my C# app I get an xml from a server that contains some replies like in a forum thread (with elements like author, time, body, title, whatever). When I get this xml, I create a new form in which i want to display these replies, and a little text box with an "add reply" button. I'd also like some edit buttons on perhaps my own replies in the reply list displayed in the form. The simplest way that came to my mind to display the replies is to put a web browser control in the form, generate a full html page in a string from the xml, and throw it in that web browser control. And under it i can put the text box with the add reply button. Everything is ok, except that i have no idea of how i could implement the edit function on my own replies (i mean i could add a link in there... but link to what) I would like to know if there is a way to get that edit event from the web browser control (my guess is i can't) or another (maybe simple/easy) idea of displaying the replies in a winform using other controls

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  • Force close error expecting irregulary

    - by user1506019
    I have problem. I created an application which loads random layour from resources and I have problem because program shows random layout and closes , sometimes after 2 times and sometimes after a dozen, and I dont know where is a problem, I tried to run it on my phone and I added in the manifest write_external_storage permission, and still the same error.Please help me, and try to resolve this problem. here is my code in : java : package ka.ka.ka; import java.util.Random; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class KAMASActivity extends Activity implements OnClickListener { Button button1; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this); } @Override public void onClick(View v) { int min = 1; int max = 6; int i1=0; Random r = new Random(); i1 = r.nextInt(max - min + 1) + min; if(i1==1){setContentView(R.layout.image1); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==2){setContentView(R.layout.image2); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==3){setContentView(R.layout.image3); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==4){setContentView(R.layout.image4); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==5){setContentView(R.layout.image5); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this);} if(i1==6){setContentView(R.layout.image6); button1 = (Button) findViewById(R.id.button1) ; button1.setOnClickListener(this); } } Android Manifest : <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="ka.ka.ka" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="7" /> <uses-permission android:name="android.permission.ACCESS_CHECKIN_PROPERTIES" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <application android:icon="@drawable/ikona" android:label="@string/app_name" > <activity android:name=".KAMASActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest> And he is logcat : 07-10 10:58:51.062: D/ddm-heap(218): Got feature list request 07-10 10:58:51.311: D/dalvikvm(218): GC freed 506 objects / 46032 bytes in 122ms 07-10 10:59:30.081: D/AndroidRuntime(218): Shutting down VM 07-10 10:59:30.081: W/dalvikvm(218): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 07-10 10:59:30.081: E/AndroidRuntime(218): Uncaught handler: thread main exiting due to uncaught exception 07-10 10:59:30.102: E/AndroidRuntime(218): java.lang.NullPointerException 07-10 10:59:30.102: E/AndroidRuntime(218): at ka.ka.ka.KAMASActivity.onClick(KAMASActivity.java:32) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.performClick(View.java:2364) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.onTouchEvent(View.java:4179) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.widget.TextView.onTouchEvent(TextView.java:6541) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.View.dispatchTouchEvent(View.java:3709) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 0 7-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow. java:1659) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.app.Activity.dispatchTouchEvent(Activity.java:2061) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.os.Handler.dispatchMessage(Handler.java:99) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.os.Looper.loop(Looper.java:123) 07-10 10:59:30.102: E/AndroidRuntime(218): at android.app.ActivityThread.main(ActivityThread.java:4363) 07-10 10:59:30.102: E/AndroidRuntime(218): at java.lang.reflect.Method.invokeNative(Native Method) 07-10 10:59:30.102: E/AndroidRuntime(218): at java.lang.reflect.Method.invoke(Method.java:521) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 07-10 10:59:30.102: E/AndroidRuntime(218): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 07-10 10:59:30.102: E/AndroidRuntime(218): at dalvik.system.NativeStart.main(Native Method) 07-10 10:59:30.121: I/dalvikvm(218): threadid=7: reacting to signal 3 07-10 10:59:30.121: E/dalvikvm(218): Unable to open stack trace file '/data/anr/traces.txt': Permission denied 07-10 10:59:32.562: I/Process(218): Sending signal. PID: 218 SIG: 9

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  • GroupLayout giving error with java swing

    - by Name
    I am getting some long list of error . Can anyone suggest me where i am wrong with group layout layout.setHorizontalGroup( layout.createSequentialGroup() .addComponent(new JLabel("Enter Book Name")) .addComponent(new JTextField("TextField", 20)) ); ERROR Exception in thread "main" java.lang.IllegalStateException: javax.swing.JTextField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=javax.swing.plaf.BorderUIResource$CompoundBorderUIResource@3d0bbf9e,flags=296,maximumSize=,minimumSize=,preferredSize=,caretColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],disabledTextColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=sun.swing.PrintColorUIResource[r=51,g=51,b=51],selectionColor=javax.swing.plaf.ColorUIResource[r=184,g=207,b=229],columns=20,columnWidth=0,command=,horizontalAlignment=LEADING] is not attached to a vertical group at javax.swing.GroupLayout.checkComponents(Unknown Source) at javax.swing.GroupLayout.prepare(Unknown Source)

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  • I cannot fetch appointments immediately via EWS on exchange server

    - by DappleHou
    I developed a transport agent for exchange server. In this agent, I code to invoke EWS to get appointments. I cannot get appointments immediately by the code. wait for a while, then go to get appointments again. This time, its OK. Why not immediately? Here is my code. To solve it, I have to get appointments repeatedly till find appointments. do{ webServiceData.FindItemsResults<webServiceData.Appointment> results = folder.FindAppointments(view); Thread.sleep(100); }while(results.Items.Count==0); Note that the code is inside transport agent. Is there any other solutions?

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  • Java Session Like Object

    - by scriptmonster
    I have been developing a project and in this project i have designed my code to do the same job after a specified time interval continuously. The job that wanted to be done has a lot of distinct cycles. The interval is small to execute them normally thus i used threads. Until that point everything is clear for me. To decrease the process and information transaction i wanted to put an session like object that holds the given data and provide it to any thread at anytime. With this object i plan to not query the same configuration information from database at everytime but if it exists on the session take it else query and store on session. I'm not sure how to implement this structure. Regards,

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  • What's the best way to cancel an asynchronous WCF request?

    - by Pwninstein
    (Assuming a WCF method called "MyFunction") Currently, to support canceling a WCF request, I'm using the BeginMyFunction/EndMyFunction methods generated by svcutil (and handling an isCanceled flag when dispatching the results to the main thread). I'd like to use the MyFunctionAsync method (and hooking into MyFunctionAsyncCompleted event instead) for async calls instead of Begin/End. What is the best/supported way to handle canceling WCF requests if using MyFunctionAsyncCompleted, and still ensuring that the event doesn't get fired on a page that's no longer loaded (i.e. page navigation within a frame). Thanks!

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  • Using ASP.NET Session for Lifetime Management (Unity)

    - by Sigray
    I am considering using Unity to manage the lifetime of a custom user class instance. I am planning on extending the LifetimeManager with a custom ASP.NET session manager. What I want to be able to do is store and retrieve the currently logged in user object from my custom classes, and have Unity get the instance of User from the session object in ASP.NET, or (when in a Win32 project) retrieve it statically or from the current thread. So far my best solution is to create a static instance of my Unity container on startup, and use the Resolve method to get my User object from each of my classes. However, this seems to create a dependency on the unity container in my other classes. What is the more "Unity" way of accomplishing this goal? I would like to be able to read/replace the current User instance from any class.

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  • In Winform I need ASP.NET like membership and roles stuff. But Roles doesn't work

    - by user512602
    Hi, following http://www.theproblemsolver.nl/usingthemembershipproviderinwinforms.htm I set up the membership & roles providers in app.config and try use it in code. Authentication works well, bur roles always returns empty roles array for connected user. This part works: If Membership.ValidateUser(userName, password) Then ' Set the current application principal information to a known user Dim identity As GenericIdentity Dim principal As RolePrincipal Dim user As MembershipUser user = Membership.GetUser(userName) identity = New GenericIdentity(user.UserName) principal = New RolePrincipal(identity) Threading.Thread.CurrentPrincipal = principal This one doesn't: If principal.IsInRole("Club") Then LoggedInUserRole = "Club" Return True Exit Function End If No error is thrown though. Similarly, if I try to add a user to a known, existing role, an exception is thrown : If Not Roles.IsUserInRole(userName, "club") Then Roles.AddUserToRole(userName, "club") End If Exception msg is: Cannot find role '' (I mean the role name isn't given back in exception.) Any clue? Please do not tell me to use Windows Client Administration within project services, I need my own SQL DB connection + the client app services is a bloated dfeature, bug prone.

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  • Time order of messages

    - by Aiden Bell
    Read (skimmed enough to get coding) through Erlang Programming and Programming Erlang. One question, which is as simple as it sounds: If you have a process Pid1 on machine m1 and a billion million messages are sent to Pid1, are messages handled in parallel by that process (I get the impression no) and(answered below) is there any guarantee of order when processing messages? ie. Received in order sent? If so, how is clock skew handled in high traffic situations for ordering? Coming from the whole C/Thread pools/Shared State background ... I want to get this concrete. I understand distributing an application, but want to ensure the 'raw bones' are what I expect before building processes and distributing workload. Also, am I right in thinking the whole world is currently flicking through Erlang texts ;)

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  • Disabling multitasking on iPhone 3GS using UIApplicationExitsOnSuspend not working

    - by NobleK
    Hello I am developing an iPhone app where I don’t want/need the multitasking capability and I want my app to initiate every time I open it. I have set the UIApplicationExitsOnSuspend property in the info.plist and it does work when I test it on my iPhone 4 and in the simulator (which is also an ”iPhone 4”). The app calls applicationDidEnterBackground followed by applicationWillTerminate. However, when testing it on my wifes iPhone 3GS the property seems to be completely ignored and the program gets suspended/resumed. Both phones are running iOS 4.2.1. Someone has also confirmed this issue in another thread, with no solutions unfortunately: iPhone: how to test if UIApplicationExitsOnSuspend is working? Is there something I am missing to make this work? Any other ways to accomplish this? Thanx in advance

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  • initializing a vector of custom class in c++

    - by Flamewires
    Hey basically Im trying to store a "solution" and create a vector of these. The problem I'm having is with initialization. Heres my class for reference class Solution { private: // boost::thread m_Thread; int itt_found; int dim; pfn_fitness f; double value; std::vector<double> x; public: Solution(size_t size, int funcNo) : itt_found(0), x(size, 0.0), value(0.0), dim(30), f(Eval_Functions[funcNo]) { for (int i = 1; i < (int) size; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[funcNo]; } } Solution() : itt_found(0), x(31, 0.0), value(0.0), dim(30), f(Eval_Functions[1]) { for (int i = 1; i < 31; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[1]; } } Solution operator= (Solution S) { x = S.GetX(); itt_found = S.GetIttFound(); dim = S.GetDim(); f = S.GetFunc(); value = S.GetValue(); return *this; } void start() { value = f (dim, x); } /* plus additional getter/setter methods*/ } Solution S(30, 1) or Solution(2, 5) work and initalizes everything, but I need X of these solution objects. std::vector<Solution> Parents(X) will create X solutions with the default constructor and i want to construct using the (int, int) constructor. Is there any easy(one liner?) way to do this? Or would i have to do something like: size_t numparents = 10; vector<Solution> Parents; Parents.reserve(numparents); for (int i = 0; i<(int)numparents; i++) { Solution S(31, 0); Parents.push_back(S); }

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  • Error in executing

    - by Saranya.R
    Hi........ I am interested in sending tweets using Java program.I wrote the following prgram.It doen't show any error in compiling.But while executing it shows "Exception in thread "main" java.lang.NoClassDefFoundError: hi Caused by: java.lang.ClassNotFoundException: hi at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) Could not find the main class: hi. Program will exit." This is my code.. package twitter; //import java.lang.object; import net.unto.twitter.*; import net.unto.twitter.TwitterProtos.Status; public class hi { public static void main(String args[]) { Api api = Api.builder().username("usename").password("password").build(); api.updateStatus("This is a test message.").build().post(); } } Can anybody help me ..Pls

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  • StringBuilder/StringBuffer vs. "+" Operator

    - by matt.seil
    I'm reading "Better, Faster, Lighter Java" (by Bruce Tate and Justin Gehtland) and am familiar with the readability requirements in agile type teams, such as what Robert Martin discusses in his clean coding books. On the team I'm on now, I've been told explicitly not to use the "+" operator because it creates extra (and unnecessary) string objects during runtime. But this article: http://www.ibm.com/developerworks/java/library/j-jtp01274.html Written back in '04 talks about how object allocation is about 10 machine instructions. (essentially free) It also talks about how the GC also helps to reduce costs in this environment. What is the actual performance tradeoffs between using "+," "StringBuilder," or "StringBuffer?" (In my case it is StringBuffer only as we are limited to Java 1.4.2.) StringBuffer to me results in ugly, less readable code, as a couple of examples in Tate's book demonstrates. And StringBuffer is thread-synchronized which seems to have its own costs that outweigh the "danger" in using the "+" operator. Thoughts/Opinions?

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  • Avoiding dog-piling or thundering herd in a memcached expiration scenario

    - by Quintin Par
    I have the result of a query that is very expensive. It is the join of several tables and a map reduce job. This is cached in memcached for 15 minutes. Once the cache expires the queries are obviously run and the cache warmed again. But at the point of expiration the thundering herd problem issue can happen. One way to fix this problem, that I do right now is to run a scheduled task that kicks in the 14th minute. But somehow this looks very sub optimal to me. Another approach I like is nginx’s proxy_cache_use_stale updating; mechanism. The webserver/machine continues to deliver stale cache while a thread kicks in the moment expiration happens and updates the cache. Has someone applied this to memcached scenario though I understand this is a client side strategy? If it benefits, I use Django.

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