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• How to deal with clients and iterations in Agile team?

  - by Ondrej Slinták

  This thread is a follow up to my previous one. It's in fact 2 questions, so I hope no one minds, as they are dependent on each other. We are starting a new project at work and we consider it as a great opportunity to try Agile techniques in action. We had a brainstorming about ideas we read in several books and articles, and came up with concept that would suit us the best: 2 weeks iteration, followed by call with clients who would choose what stuff they want to have in next iteration. I just have few more questions, which we couldn't figure out ourselves. What to do in the first iteration? What to, generally, do in the first few iterations if we start from the scratch? Just give it a month of development to code core of the application or start with simple wire-frames with limited pre-coded functionality? What usually clients want to see? Shiny stuff that doesn't work or ugly stuff that does work? How to communicate with clients? Our initial thought it to set the process to something like this: Is it a good idea to have a Focal Point on client side or is it better to communicate straight with all the clients to prevent miscommunication? Any thoughts are welcome! Thanks in advance.

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• Refresher on Java classes in separate files

  - by JohnFaig

  I need a refresher on moving classes from one file into two files. My sample code is in one file called "external_class_file_main". The program runs fine and the code is shown below: Public class external_class_file_main { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } I move the get_a_random_number class to a separate file called "external_class_file". When I do this, I get the following error: Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method get_a_random_number(int, int) is undefined for the type external_class_file_main at external_class_file_main.main(external_class_file_main.java:20) The "external_class_file_main" now contains: public class external_class_file_main { public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } The "external_class_file" now contains: public class external_class_file { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } }

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• I am looking for an actual functional web browser control for .NET, maybe a C++ library

  - by Joshua

  I am trying to emulate a web browser in order to execute JavaScript code and then parse the DOM. The System.Windows.Forms.WebBrowser object does not give me the functionality I need. It let's me set the headers, but you cannot set the proxy or clear cookies. Well you can, but it is not ideal and messes with IE's settings. I've been extending the WebBrowser control pinvoking native windows functions so far, but it is really one hack on top of another. I can mess with the proxy and also clear cookies and such, but this control has its issues as I mentioned. I found something called WebKit .NET (http://webkitdotnet.sourceforge.net/), but I don't see support for setting proxies or cookie manipulation. Can someone recommend a c++/.NET/whatever library to do this: Basically tell me what I need to do to get an interface to similar this in .NET: // this should probably pause the current thread for the max timeout, // throw an exception on failure or return null w/e, VAGUELY similar to this string WebBrowserEmu::FetchBrowserParsedHtml(Uri url, WebProxy p, int timeoutSeconds, byte[] headers, byte[] postdata); void WebBrowserEmu::ClearCookies(); I am not responsible for my actions.

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• How should developers cope with so many GUI configuration combinations?

  - by shawn-harrison

  These days, any decent Windows desktop application must perform well and look good under the following conditions: XP and Vista and Windows 7. 32 bit and 64 bit. With and without Themes. With and without Aero. At 96 and 120 and perhaps custom DPIs. One or more monitors (screens). Each OS has its own preferred font. Oh my! What is a lowly little Windows desktop application developer to do? :( I'm hoping to get a thread started with suggestions on how to deal with this GUI dilemma. First off, I'm on Delphi 7. a) Does Delphi 2010 bring anything new to the table to help with this situation? b) Should we pick an aftermarket component suite and rely on them to solve all these problems? c) Should we go with an aftermarket skinning engine? d) Perhaps a more HTML-type GUI is the way to go. Can we make a relatively complex GUI app with HTML that doesn't require using a browser? (prefer to keep it form based) e) Should we just knuckle down and code through each one of these scenarios and quit bitching about it? f) And finally, how in the world are we supposed to test all these conditions?

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• Structuring input of data for localStorage

  - by WmasterJ

  It is nice when there isn't a DB to maintain and users to authenticate. My professor has asked me to convert a recent research project of his that uses Bespin and calculates errors made by users in a code editor as part of his research. The goal is to convert from MySQL to using HTML5 localStorage completely. Doesn't seem so hard to do, even though digging in his code might take some time. Question: I need to store files and state (last placement of cursor and active file). I have already done so by implementing the recommendations in another stackoverflow thread. But would like your input considering how to structure the content to use. My current solution Hashmap like solution with javascript objects: files = {}; // later, saving files[fileName] = data; And then storing in localStorage using some recommendations localStorage.setObject(files): Currently I'm also considering using some type of numeric id. So that names can be changed without any hassle renaming the key in the hashmap. What is your opinion on the way it is solved and would you do it any differently?

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• How do I make my program run with different privileges at Windows 7 startup?

  - by iira

  Hi, I am trying to add my program run in Windows 7 startup, but it doesn't work. My program has an embedded UAC manifest. My current way is by adding a string value at HKCU..\Run. I found a manual solution for Vista from http://social.technet.microsoft.com/Forums/en/w7itprosecurity/thread/81c3c1f2-0169-493a-8f87-d300ea708ecf Click Start, right click on Computer and choose “Manage”. Click “Task Scheduler” on the left panel. Click “Create Task” on the right panel. Type a name for the task. Check “Run with highest privileges”. Click Actions tab. Click “New…”. Browse to the program in the “Program/script” box. Click OK. On desktop, right click, choose New and click “Shortcut”. In the box type: schtasks.exe /run /tn TaskName where TaskName is the name of task you put in on the basics tab and click next. Type a name for the shortcut and click Finish. Additionally, you need to run the saved scheduled task shortcut to run the program instead of running the application shortcut to ignore the IAC prompt. When startup the system will run the program via the original shortcut. Therefore you need to change the location to run the saved task. Please: Open Regedit. Find the entry of the startup item in Registry. It will be stored in one of the following branches. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run HKEY_USERS.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run Double-click on the correct key, change the path to the saved scheduled task you created. Is there any free code to add item with privileges option in scheduled task? I haven't found the free one in torry.net. Thanks a lot.

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• pthread_exit and/or pthread_join causing Abort and SegFaults.

  - by MJewkes

  The following code is a simple thread game, that switches between threads causing the timer to decrease. It works fine for 3 threads, causes and Abort(core dumped) for 4 threads, and causes a seg fault for 5 or more threads. Anyone have any idea why this might be happening? #include <stdio.h> #include <stdlib.h> #include <pthread.h> #include <errno.h> #include <assert.h> int volatile num_of_threads; int volatile time_per_round; int volatile time_left; int volatile turn_id; int volatile thread_running; int volatile can_check; void * player (void * id_in){ int id= (int)id_in; while(1){ if(can_check){ if (time_left<=0){ break; } can_check=0; if(thread_running){ if(turn_id==id-1){ turn_id=random()%num_of_threads; time_left--; } } can_check=1; } } pthread_exit(NULL); } int main(int argc, char *args[]){ int i; int buffer; pthread_t * threads =(pthread_t *)malloc(num_of_threads*sizeof(pthread_t)); thread_running=0; num_of_threads=atoi(args[1]); can_check=0; time_per_round = atoi(args[2]); time_left=time_per_round; srandom(time(NULL)); //Create Threads for (i=0;i<num_of_threads;i++){ do{ buffer=pthread_create(&threads[i],NULL,player,(void *)(i+1)); }while(buffer == EAGAIN); } can_check=1; time_left=time_per_round; turn_id=random()%num_of_threads; thread_running=1; for (i=0;i<num_of_threads;i++){ assert(!pthread_join(threads[i], NULL)); } return 0; }

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• How to Parse an XML (using XELement) having multiple Namespace ?

  - by Subhen

  Hi I , I get the followinng Xresponse after parsing the XML document: <DIDL-Lite xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"> <item id="1182" parentID="40" restricted="1"> <title>Hot Issue</title> </item> As per the earlier thread, When there is a default namespace in the document, you must parse it as if it were a named namespace. For example. XNamespace ns = "urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"; var xDIDL = xResponse.Element(ns + "DIDL-Lite"); But in my case I have four different name space. I am not getting any results after using the following query , I am getting the response , Not Yeilding any results: XNamespace dc = "http://purl.org/dc/elements/1.1/"; var vAudioData = from xAudioinfo in xResponse.Descendants(ns + "DIDL-lite").Elements("item") select new RMSMedia { strAudioTitle = ((string)xAudioinfo.Element(dc + "title")).Trim(), }; I have no clue whats going on as am new to it. Please help

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• How do I rewrite a for loop with a shared dependency using actors

  - by Thomas Rynne

  We have some code which needs to run faster. Its already profiled so we would like to make use of multiple threads. Usually I would setup an in memory queue, and have a number of threads taking jobs of the queue and calculating the results. For the shared data I would use a ConcurrentHashMap or similar. I don't really want to go down that route again. From what I have read using actors will result in cleaner code and if I use akka migrating to more than 1 jvm should be easier. Is that true? However, I don't know how to think in actors so I am not sure where to start. To give a better idea of the problem here is some sample code: case class Trade(price:Double, volume:Int, stock:String) { def value(priceCalculator:PriceCalculator) = (priceCalculator.priceFor(stock)-> price)*volume } class PriceCalculator { def priceFor(stock:String) = { Thread.sleep(20)//a slow operation which can be cached 50.0 } } object ValueTrades { def valueAll(trades:List[Trade], priceCalculator:PriceCalculator):List[(Trade,Double)] = { trades.map { trade => (trade,trade.value(priceCalculator)) } } def main(args:Array[String]) { val trades = List( Trade(30.5, 10, "Foo"), Trade(30.5, 20, "Foo") //usually much longer ) val priceCalculator = new PriceCalculator val values = valueAll(trades, priceCalculator) } } I'd appreciate it if someone with experience using actors could suggest how this would map on to actors.

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• What are Code Smells? What is the best way to correct them?

  - by Rob Cooper

  OK, so I know what a code smell is, and the Wikipedia Article is pretty clear in its definition: In computer programming, code smell is any symptom in the source code of a computer program that indicates something may be wrong. It generally indicates that the code should be refactored or the overall design should be reexamined. The term appears to have been coined by Kent Beck on WardsWiki. Usage of the term increased after it was featured in Refactoring. Improving the Design of Existing Code. I know it also provides a list of common code smells. But I thought it would be great if we could get clear list of not only what code smells there are, but also how to correct them. Some Rules Now, this is going to be a little subjective in that there are differences to languages, programming style etc. So lets lay down some ground rules: ** ONE SMELL PER ANSWER PLEASE! & ADVISE ON HOW TO CORRECT! ** See this answer for a good display of what this thread should be! DO NOT downmod if a smell doesn't apply to your language or development methodology We are all different. DO NOT just quickly smash in as many as you can think of Think about the smells you want to list and get a good idea down on how to work around. DO downmod answers that just look rushed For example "dupe code - remove dupe code". Let's makes it useful (e.g. Duplicate Code - Refactor into separate methods or even classes, use these links for help on these common.. etc. etc.). DO upmod answers that you would add yourself If you wish to expand, then answer with your thoughts linking to the original answer (if it's detailed) or comment if its a minor point. DO format your answers! Help others to be able to read it, use code snippets, headings and markup to make key points stand out!

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• Java Servlet: getInitParameter not work in Service()

  - by Gabriele

  I've added some parameters in my web.xml config file, as follow: <context-param> <param-name>service1</param-name> <param-value>http://www.example.com/example2.html</param-value> </context-param> <context-param> <param-name>service2</param-name> <param-value>http://www.example.com/example2.html</param-value> </context-param> ... I try to get the parameter in my servlet, in particular in my service method: protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println(this.getServletContext().getInitParameter("service1")); ... but at runtime I have a NullPointerException... How can I get the parameter value included in web.xml? This is the stacktrace: GRAVE: Servlet.service() for servlet DispatcherServlet threw exception java.lang.NullPointerException at javax.servlet.GenericServlet.getServletContext(GenericServlet.java:160) at it.servlethope.DispatcherServlet.service(DispatcherServlet.java:66) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:381) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) DispatcherServlet.java:66 is the line where I try the getInitParameter()

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• Problem with futures in c++0x .

  - by Eternal Learner

  Hi, I have written a small program , to understand how futures work in c++0x. while running the code I get an error like " error: 'printEn' was not declared in this scope". I am unable to understand what the problem is..Kindly point out what I am doing wrong here and if possible write the correct code for the same.. #include <future> #include <iostream> using namespace std; int printFn() { for(int i = 0; i < 100; i++) { cout << "thread " << i << endl; } return 1; } int main() { future<int> the_answer2=async(printEn); future<int> the_answer1=async(printEn); return 0; }

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• Core Data: Deleting causes 'NSObjectInaccessibleException' from NSOperation with a reference to a deleted object

  - by Bryan Irace

  My application has NSOperation subclasses that fetch and operate on managed objects. My application also periodically purges rows from the database, which can result in the following race condition: An background operation fetches a bunch of objects (from a thread-specific context). It will iterate over these objects and do something with their properties. A bunch of rows are deleted in the main managed object context. The background operation accesses a property on an object that was deleted from the main context. This results in an 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault' Ideally, the objects that are fetched by the NSOperation can be operated on even if one is deleted in the main context. The best way I can think to achieve this is either to: Call [request setReturnsObjectsAsFaults:NO] to ensure that Core Data won't try to fulfill a fault for an object that no longer exists in the main context. The problem here is I may need to access the object's relationships, which (to my understanding) will still be faulted. Iterate through the managed objects up front and copy the properties I will need into separate non-managed objects. The problem here is that (I think) I will need to synchronize/lock this part, in case an object is deleted in the main context before I can finish copying. Am I missing something obvious? It doesn't seem like what I'm trying to accomplish is too out of the ordinary. Thanks for your help.

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• Scala newbie vproducer/consumer attempt running out of memory

  - by Nick

  I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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• problm with MANIFEST.MF in jar

  - by Atul

  hi I have created jar in the following folder: /usr/local/bin/niidle.jar. And my MANIFEST.MF file is as follows: Manifest-Version: 1.0 Main-Class: com.ensarm.niidle.web.scraper.NiidleScrapeManager Class-Path: hector-0.6.0-17.jar And I verified that,this 'hector-0.6.0-17.jar' file is also present in the folder: /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar I don't want to give full class-path name in MANIFEST.MF file,because I have to run this jar on other's machine,so I gave only jar file name 'Class-Path=hector-0.6.0-17.jar' in MANIFEST.MF file. Inspite of mentioning the Class-Path in MANIFEST.MF file, when I run this using command: java -jar /usr/local/bin/niidle.jar arguments... It is showing error massage: --Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21) Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer 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) ... 1 more Please give me solution for this error message..

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• C socket programming: client send() but server select() doesn't see it

  - by Fantastic Fourier

  Hey all, I have a server and a client running on two different machines where the client send()s but the server doesn't seem to receive the message. The server employs select() to monitor sockets for any incoming connections/messages. I can see that when the server accepts a new connection, it updates the fd_set array but always returns 0 despite the client send() messages. The connection is TCP and the machines are separated by like one router so dropping packets are highly unlikely. I have a feeling that it's not select() but perhaps send()/sendto() from client that may be the problem but I'm not sure how to go about localizing the problem area. while(1) { readset = info->read_set; ready = select(info->max_fd+1, &readset, NULL, NULL, &timeout); } above is the server side code where the server has a thread that runs select() indefinitely. rv = connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)); printf("rv = %i\n", rv); if (rv < 0) { printf("MAIN: ERROR connect() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("connected\n"); sleep(3); char * somemsg = "is this working yet?\0"; rv = send(sockfd, somemsg, sizeof(somemsg), NULL); if (rv < 0) printf("MAIN: ERROR send() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); rv = sendto(sockfd, somemsg, sizeof(somemsg), NULL, &server_address, sizeof(server_address)); if (rv < 0) printf("MAIN: ERROR sendto() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); and this is the client side where it connects and sends messages and returns connected MAIN: rv is 4 MAIN: rv is 4 any comments or insightful insights are appreciated.

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• Scanner error that I can't figure out: NoSuchElementException

  - by iaacp

  It's crashing on the third line inside the do-while loop, and doesn't wait for my input: input = kb.nextInt(); Stack trace: Exception in thread "main" java.util.NoSuchElementException at java.util.Scanner.throwFor(Unknown Source) at java.util.Scanner.next(Unknown Source) at java.util.Scanner.nextInt(Unknown Source) at java.util.Scanner.nextInt(Unknown Source) at main.MainDriver.main(MainDriver.java:50) Relevant code: do { displayFullMenu(); System.out.print("Selection: "); input = kb.nextInt(); switch (input) { //Create new survey case 1: currentSurvey = new Survey(); break; //Display current survey case 2: currentSurvey.display(); break; //Save current survey case 3: saveSurvey(currentSurvey); break; //Load a survey case 4: currentSurvey = loadSurvey(); break; //Modify a survey case 5: currentSurvey.modify(); break; /*******************Test Functions*******************/ //Create new test case 6: currentSurvey = new Test(); break; //Display current test case 7: currentSurvey.display(); break; //Save current test case 8: saveSurvey(currentSurvey); break; //Load a test case 9: currentSurvey = loadTest(); break; //Modify a test case 10: currentSurvey.modify(); default: System.out.println("Invalid choice. Please make a valid choice: "); input = kb.nextInt(); System.out.println(); } } while (input != 99); kb.close(); It crashes after I choose option 9. It saves the file correctly, then goes back to the top of the loop, and crashes at the previously mentioned line. I want it to ask for more input. What gives?

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• What should be taught in a "Fundamentals of programming" course at university?

  - by Dervin Thunk

  I have started a new question (see here), because I think the topic is of importance in a more general form. The question is now: If you were a professor at a Computer Science Dept. in some university, what would make it into your course? This is a programming course, second term, first year computer science/computer engineering. Remember you have a limited amount of time, and students are of different levels of competence, and some may be scientists, but some will also go on to be programmers in companies of different kinds. You have to cater to all. Bonus: What language? (Although see this question for my current thoughts about this...) Maybe you want to attach a course outline from some university? See here for an even more general question about this. Answer: I can't really summarize this post... I guess it was too subjective. However, it looks like we have to cover the history of computing up to a certain extent, computer architecture (memory, registers, whatever), C, and finally some basic algos and data structures in a problem solving fashion. This will be the bare bones of the course. Thanks all. I will accept the most voted up answer to close the thread, as it should be done.

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• Diffrernce between BackgroundWorker.ReportProgress() and Control.Invoke()

  - by ohadsc

  What is the difference between options 1 and 2 in the following? private void BGW_DoWork(object sender, DoWorkEventArgs e) { for (int i=1; i<=100; i++) { string txt = i.ToString(); if (Test_Check.Checked) //OPTION 1 Test_BackgroundWorker.ReportProgress(i, txt); else //OPTION 2 this.Invoke((Action<int, string>)UpdateGUI, new object[] {i, txt}); } } private void BGW_ProgressChanged(object sender, ProgressChangedEventArgs e) { UpdateGUI(e.ProgressPercentage, (string)e.UserState); } private void UpdateGUI(int percent, string txt) { Test_ProgressBar.Value = percent; Test_RichTextBox.AppendText(txt + Environment.NewLine); } Looking at reflector, the Control.Invoke() appears to use: this.FindMarshalingControl().MarshaledInvoke(this, method, args, 1); whereas BackgroundWorker.Invoke() appears to use: this.asyncOperation.Post(this.progressReporter, args); (I'm just guessing these are the relevant function calls.) If I understand correctly, BGW Posts to the WinForms window its progress report request, whereas Control.Invoke uses a CLR mechanism to invoke on the right thread. Am I close? And if so, what are the repercussions of using either ? Thanks

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• iPhone: Does it ever make sense for an object to retain its delegate?

  - by randombits

  According to the rules of memory management in a non garbage collected world, one is not supposed to retain a the calling object in a delegate. Scenario goes like this: I have a class that inherits from UITableViewController and contains a search bar. I run expensive search operations in a secondary thread. This is all done with an NSOperationQueue and subclasses NSOperation instances. I pass the controller as a delegate that adheres to a callback protocol into the NSOperation. There are edge cases when the application crashes because once an item is selected from the UITableViewController, I dismiss it and thus its retain count goes to 0 and dealloc gets invoked on it. The delegate didn't get to send its message in time as the results are being passed at about the same time the dealloc happens. Should I design this differently? Should I call retain on my controller from the delegate to ensure it exists until the NSOperation itself is dealloc'd? Will this cause a memory leak? Right now if I put a retain on the controller, the crashes goes away. I don't want to leak memory though and need to understand if there are cases where retaining the delegate makes sense. Just to recap. UITableViewController creates an NSOperationQueue and NSOperation that gets embedded into the queue. The UITableViewController passes itself as a delegate to NSOperation. NSOperation calls a method on UITableViewController when it's ready. If I retain the UITableViewController, I guarantee it's there, but I'm not sure if I'm leaking memory. If I only use an assign property, edge cases occur where the UITableViewController gets dealloc'd and objc_msgSend() gets called on an object that doesn't exist in memory and a crash is imminent.

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• How to change internal buffer size of DataInputStream

  - by Gaks

  I'm using this kind of code for my TCP/IP connection: sock = new Socket(host, port); sock.setKeepAlive(true); din = new DataInputStream(sock.getInputStream()); dout = new DataOutputStream(sock.getOutputStream()); Then, in separate thread I'm checking din.available() bytes to see if there are some incoming packets to read. The problem is, that if a packet bigger than 2048 bytes arrives, the din.available() returns 2048 anyway. Just like there was a 2048 internal buffer. I can't read those 2048 bytes when I know it's not the full packet my application is waiting for. If I don't read it however - it'll all stuck at 2048 bytes and never receive more. Can I enlarge the buffer size of DataInputStream somehow? Socket receive buffer is 16384 as returned by sock.getReceiveBufferSize() so it's not the socket limiting me to 2048 bytes. If there is no way to increase the DataInputStream buffer size - I guess the only way is to declare my own buffer and read everything from DataInputStream to that buffer? Regards

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• Why does GetWindowThreadProcessId return 0 when called from a service

  - by Marve

  When using the following class in a console application, and having at least one instance of Notepad running, GetWindowThreadProcessId correctly returns a non-zero thread id. However, if the same code is included in a Windows Service, GetWindowThreadProcessId always returns 0 and no exceptions are thrown. Changing the user the service launches under to be the same as the one running the console application didn't alter the result. What causes GetWindowThreadProcessId to return 0 even if it is provided with a valid hwnd? And why does it function differently in the console application and the service? Note: I am running Windows 7 32-bit and targeting .NET 3.5. public class TestClass { [DllImport("user32.dll")] static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr ProcessId); public void AttachToNotepad() { var processesToAttachTo = Process.GetProcessesByName("Notepad") foreach (var process in processesToAttachTo) { var threadID = GetWindowThreadProcessId(process.MainWindowHandle, IntPtr.Zero); .... } } } Console Code: class Program { static void Main(string[] args) { var testClass = new TestClass(); testClass.AttachToNotepad(); } } Service Code: public class TestService : ServiceBase { private TestClass testClass = new TestClass(); static void Main() { ServiceBase.Run(new TestService()); } protected override void OnStart(string[] args) { testClass.AttachToNotepad(); base.OnStart(args); } protected override void OnStop() { ... } }

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• how to return a list using SwingWorker

  - by Ender

  I have an assignment where i have to create an Image Gallery which uses a SwingWorker to load the images froma a file, once the image is load you can flip threw the image and have a slideshow play. I am having trouble getting the list of loaded images using SwingWorker. This is what happens in the background it just publishes the results to a TextArea // In a thread @Override public List<Image> doInBackground() { List<Image> images = new ArrayList<Image>(); for (File filename : filenames) { try { //File file = new File(filename); System.out.println("Attempting to add: " + filename.getAbsolutePath()); images.add(ImageIO.read(filename)); publish("Loaded " + filename); System.out.println("Added file" + filename.getAbsolutePath()); } catch (IOException ioe) { publish("Error loading " + filename); } } return images; } } when it is done I just insert the images in a List<Image> and that is all it does. // In the EDT @Override protected void done() { try { for (Image image : get()) { list.add(image); } } catch (Exception e) { } } Also I created an method that returns the list called getImages() what I need to get is the list from getImages() but doesn't seam to work when I call execute() for example MySwingWorkerClass swingworker = new MySwingWorkerClass(log,list,filenames); swingworker.execute(); imageList = swingworker.getImage() Once it reaches the imageList it doesn't return anything the only way I was able to get the list was when i used the run() instead of the execute() is there another way to get the list or is the run() method the only way?. or perhaps i am not understanding the Swing Worker Class.

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• NSTimer as a timeout mechanism

  - by alexantd

  I'm pretty sure this is really simple, and I'm just missing something obvious. I have an app that needs to download data from a web service for display in a UITableView, and I want to display a UIAlertView if the operation takes more than X seconds to complete. So this is what I've got (simplified for brevity): MyViewController.h @interface MyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSTimer *timer; } @property (nonatomic, retain) NSTimer *timer; MyViewController.m @implementation MyViewController @synthesize timer; - (void)viewDidLoad { timer = [NSTimer scheduledTimerWithTimeInterval:20 target:self selector:@selector(initializationTimedOut:) userInfo:nil repeats:NO]; [self doSomethingThatTakesALongTime]; [timer invalidate]; } - (void)doSomethingThatTakesALongTime { sleep(30); // for testing only // web service calls etc. go here } - (void)initializationTimedOut:(NSTimer *)theTimer { // show the alert view } My problem is that I'm expecting the [self doSomethingThatTakesALongTime] call to block while the timer keeps counting, and I'm thinking that if it finishes before the timer is done counting down, it will return control of the thread to viewDidLoad where [timer invalidate] will proceed to cancel the timer. Obviously my understanding of how timers/threads work is flawed here because the way the code is written, the timer never goes off. However, if I remove the [timer invalidate], it does.

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• Question about how to implement a c# host application with a plugin-like architecture

  - by devoured elysium

  I want to have an application that works as a Host to many other small applications. Each one of those applications should work as kind of plugin to this main application. I call them plugins not in the sense they add something to the main application, but because they can only work with this Host application as they depend on some of its services. My idea was to have each of those plugins run in a different app domain. The problem seems to be that my host application should have a set of services that my plugins will want to use and from what is my understanding making data flow in and out from different app domains is not that great of a thing. On one hand I'd like them to behave as stand-alone applications(although, as I said, they need to use lots of times the host application services), but on the other hand I'd like that if any of them crashes, my main application wouldn't suffer from it. What is the best (.NET) approach to this kind of situation? Make them all run on the same AppDomain but each one in a different Thread? Use different AppDomains? One for each "plugin"? How would I make them communicate with the Host Application? Any other way of doing this? Although speed is not an issue here, I wouldn't like for function calls to be that much slower than they are when we're working with just a regular .NET application. Thanks

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