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• GDI: Dynamical Multiple Graphics in a page?

  - by SirLenz0rlot

  Hi all, I'm quite new to drawing shapes, graphics, bitmaps etc. I googled for a few days,but still havent got a real clue what to do, so please help me: I want to draw a floorplan with certain objects(represented as circles) moving on it. When I click on a object, it needs to show something. So far, I ve been able to draw some circles on a graphic and been able to move the dots by clearing the graphic every time. Ofcourse, this isnt a real solution, since I cant keep track of the different objects on the floorplan (which i need for my clickevent and movings). I hope I explained my problem ok here. This is the (stripped version of the) sourcecode that gets called every second: (dev (of type Device) is the object i want to draw) Graphics gfx = FloorplanTabPage.CreateGraphics(); gfx.Clear(Color.White); foreach (Device dev in _deviceList) { Pen myPen = new Pen(Color.Black) { Width = 10 }; dev.InRoom != null) { myPen.Color = Color.DarkOrchid; int x = dev.InRoom.XPos + (dev.InRoom.Width / 2) - 5; int y = (dev.InRoom.YPos + (dev.InRoom.Height / 2) - 5; if (dev.ToRoom != null) { x = (x + (dev.ToRoom.XPos + (dev.ToRoom.Width / 2)) / 2; y = (y + (dev.ToRoom.YPos + (dev.ToRoom.Height / 2)) / 2; } gfx.DrawEllipse(myPen, x, y, 10, 10); gfx.DrawString(dev.Name, new Font("Arial", 10), Brushes.Purple, x, y - 15); } }

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• How can I use a compound condition in a join in Linq?

  - by Gary McGill

  Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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• XNA: What can cause SpriteBatch.End() to throw a NRE?

  - by Rosarch

  I don't understand what I'm doing wrong here: public void Draw(GameTime gameTime) // in ScreenManager { SpriteBatch.Begin(SpriteBlendMode.AlphaBlend); for (int i = 0; i < Screens.Count; i++) { if (Screens[i].State == Screen.ScreenState.HIDDEN) continue; Screens[i].Draw(gameTime); } SpriteBatch.End(); // null ref exception } SpriteBatch itself is not null. Some more context: public class MasterEngine : Microsoft.Xna.Framework.Game { public MasterEngine() { graphicsDeviceManager = new GraphicsDeviceManager(this); Components.Add(new GamerServicesComponent(this)); // ... spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); screenManager = new ScreenManager(assets, gameEngine, graphicsDeviceManager.GraphicsDevice, spriteBatch); } //... protected override void Draw(GameTime gameTime) { screenManager.Draw(gameTime); // calls the problematic method base.Draw(gameTime); } } Am I failing to initialize something properly? UPDATE: As an experiment, I tried this to the constructor of MasterEngine: spriteBatch = new SpriteBatch(graphicsDeviceManager.GraphicsDevice); spriteBatch.Begin(); spriteBatch.DrawString(assets.GetAsset<SpriteFont>("calibri"), "ftw", new Vector2(), Color.White); spriteBatch.End(); This does not cause a NRE. hmm.... UPDATE 2: This does cause an NRE: protected override void Draw(GameTime gameTime) { spriteBatch.Begin(); spriteBatch.End(); // boned here //screenManager.Draw(gameTime); base.Draw(gameTime); }

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• Short file names versus long file names in Windows

  - by normski

  I have some code which gets the short name from a file path, using GetShortNameW(), and then later retrieves the long name view GetLongNameA(). The original file is of the form "C:/ProgramData/My Folder/File.ext" However, following conversion to short, then back to long, the filename becomes "C:/Program Files/My Folder/Filename.ext". The short name is of the form "C:/PROGRA~2/MY_FOL~1/FIL~1.EXT" The short name is being incorrectly resolved. The code compiles using VS 2005 on Windows 7 (I cannot upgrade the project to VS2008) Does anybody have any idea why this might be happening? DWORD pathLengthNeeded = ::GetShortPathNameW(aRef->GetFilePath().c_str(), NULL, 0); if(pathLengthNeeded != 0) { WCHAR* shortPath = new WCHAR[pathLengthNeeded]; DWORD newPathNameLength = ::GetShortPathNameW(aRef->GetFilePath().c_str(), shortPath, pathLengthNeeded); if(newPathNameLength != 0) { UI_STRING unicodePath(shortPath); std::string asciiPath = StringFromUserString(unicodePath); pathLengthNeeded = ::GetLongPathNameA(asciiPath.c_str(),NULL, 0); if(pathLengthNeeded != 0) {// convert it back to a long path if possible. For goodness sake can't we use Unicode throughout?F char* longPath = new char[pathLengthNeeded]; DWORD newPathNameLength = ::GetLongPathNameA(asciiPath.c_str(), longPath, pathLengthNeeded); if(newPathNameLength != 0) { std::string longPathString(longPath, newPathNameLength); asciiPath = longPathString; } delete [] longPath; } SetFullPathName(asciiPath); } delete [] shortPath; }

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• pthread_join from a signal handler

  - by liv2hak

  I have a capture program which in addition do capturing data and writing it into a file also prints some statistics.The function that prints the statistics static void* report(void) { /*Print statistics*/ } is called roughly every second using an ALARM that expires every second.So The program is like void capture_program() { pthread_t report_thread while(!exit_now) { if(pthread_create(&report_thread,NULL,report,NULL)){ fprintf(stderr,"Error creating reporting thread! \n"); } /* Capturing code -------------- -------------- */ if(doreport) usleep(5); } } void *report(void *param) { while(true) { if(doreport) { doreport = 0 //access some register from hardware usleep(5) } } } The expiry of the timer sets the doreport flag.If this flag is set report() is called which clears the flag.I am using usleep to alternate between two threads in the program.This seems to work fine. I also have a signal handler to handle SIGINT (i.e CTRL+C) static void anysig(int sig) { if (sig != SIGINT) dagutil_set_signal_handler(SIG_DFL); /* Tell the main loop to exit */ exit_now = 1; return; } My question: 1) Is it safe to call pthread_join from inside the signal handler? 2) Should I use exit_now flag for the report thread as well?

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• iOS - is it possible to cache CGContextDrawImage?

  - by woot586

  I used the timing profile tool to identify that 95% of the time is spent calling the function CGContextDrawImage. In my app there are a lot of duplicate images repeatably being chopped from a sprite map and drawn to the screen. I was wondering if it was possible to cache the output of CGContextDrawImage in an NSMutableDictionay, then if the same sprite is requested again it can be just pull it from the cache rather than doing all the work of clipping and rendering it again. This is what i’ve got but I have not been to successful: Definitions if(cache == NULL) cache = [[NSMutableDictionary alloc]init]; //Identifier based on the name of the sprite and location within the sprite. NSString* identifier = [NSString stringWithFormat:@"%@-%d",filename,frame]; Adding to cache CGRect clippedRect = CGRectMake(0, 0, clipRect.size.width, clipRect.size.height); CGContextClipToRect( context, clippedRect); //create a rect equivalent to the full size of the image //offset the rect by the X and Y we want to start the crop //from in order to cut off anything before them CGRect drawRect = CGRectMake(clipRect.origin.x * -1, clipRect.origin.y * -1, atlas.size.width, atlas.size.height); //draw the image to our clipped context using our offset rect CGContextDrawImage(context, drawRect, atlas.CGImage); [cache setValue:UIGraphicsGetImageFromCurrentImageContext() forKey:identifier]; UIGraphicsEndImageContext(); Rendering a cached sprite There is probably a better way to render CGImage which is my ultimate caching goal but at the moment I’m just looking to successfully render the cached image out however this has not been successful. UIImage* cachedImage = [cache objectForKey:identifier]; if(cachedImage){ NSLog(@"Cached %@",identifier); CGRect imageRect = CGRectMake(0, 0, cachedImage.size.width, cachedImage.size.height); if (NULL != UIGraphicsBeginImageContextWithOptions) UIGraphicsBeginImageContextWithOptions(imageRect.size, NO, 0); else UIGraphicsBeginImageContext(imageRect.size); //Use draw for now just to see if the image renders out ok CGContextDrawImage(context, imageRect, cachedImage.CGImage); UIGraphicsEndImageContext(); }

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• How to pick a specific object from a Linq Query using Distinct?

  - by Holli

  I have a list with two or more objects of class Agent. Name = "A" Priority = 0 ResultCount = 100 ; Name = "B" Priority = 1 ResultCount = 100 ; Both objects have the same ResultCount. In that case I only need one object and not two or more. I did this with a Linq Query with Distinct and an custom made Comparer. IEnumerable<Agent> distinctResultsAgents = (from agt in distinctUrlsAgents select agt).Distinct(comparerResultsCount); With this query I get only one object from the list but I never know which one. But I don't want just any object, I want object "B" because the Priority is higher then object "A". How can I do that? My custom Comparer is very simple and has a method like this: public bool Equals(Agent x, Agent y) { if (x == null || y == null) return false; if (x.ResultCount == y.ResultCount) return true; return false; }

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• In ArrayBlockingQueue, why copy final member field into local final variable?

  - by mjlee

  In ArrayBlockingQueue, any method that requires lock will get set 'final' local variable before calling 'lock()'. public boolean offer(E e) { if (e == null) throw new NullPointerException(); final ReentrantLock lock = this.lock; lock.lock(); try { if (count == items.length) return false; else { insert(e); return true; } } finally { lock.unlock(); } } Is there any reason to set a local variable 'lock' from 'this.lock' when field 'this.lock' is final also. Additionally, it also set local variable of E[] before acting on. private E extract() { final E[] items = this.items; E x = items[takeIndex]; items[takeIndex] = null; takeIndex = inc(takeIndex); --count; notFull.signal(); return x; } Is there any reason for copying to local final variable?

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• Python + Expat: Error on &#0; entities

  - by clacke

  I have written a small function, which uses ElementTree and xpath to extract the text contents of certain elements in an xml file: #!/usr/bin/env python2.5 import doctest from xml.etree import ElementTree from StringIO import StringIO def parse_xml_etree(sin, xpath): """ Takes as input a stream containing XML and an XPath expression. Applies the XPath expression to the XML and returns a generator yielding the text contents of each element returned. >>> parse_xml_etree( ... StringIO('<test><elem1>one</elem1><elem2>two</elem2></test>'), ... '//elem1').next() 'one' >>> parse_xml_etree( ... StringIO('<test><elem1>one</elem1><elem2>two</elem2></test>'), ... '//elem2').next() 'two' >>> parse_xml_etree( ... StringIO('<test><null>&#0;</null><elem3>three</elem3></test>'), ... '//elem2').next() 'three' """ tree = ElementTree.parse(sin) for element in tree.findall(xpath): yield element.text if __name__ == '__main__': doctest.testmod(verbose=True) The third test fails with the following exception: ExpatError: reference to invalid character number: line 1, column 13 Is the � entity illegal XML? Regardless whether it is or not, the files I want to parse contain it, and I need some way to parse them. Any suggestions for another parser than Expat, or settings for Expat, that would allow me to do that?

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• Pass view to viewmodel with datatemplate

  - by jpsstavares

  I have a ParameterView and ParameterViewModel, and I need the ParameterViewModel to have a reference to the Parameter view (more on that later). In the window I have a list of ParameterViewModels and in the ResourceDictionary I add the DataTemplate: <DataTemplate DataType="{x:Type my:ParameterViewModel}" > <my:ParameterView HorizontalAlignment="Left"/> </DataTemplate> I then bind an ItemsControl.ItemSource to the List of ParameterViewModels The problem is: How can I pass the ParameterView to the ParameterViewModel in this scenario? The reason I need the ParameterView in the ParameterViewModel is the following: I have a TextBox whose Text property is binded to the PropertyModelView.Name property. But I want to display a default string when the Name is empty or Null. I've tried to set the property value to the default string I want when that happens but the TextBox.Text is not set in this scenario. I do something like this: private string _name; public string Name { get { return _name; } set { if (value == null || value.Length == 0) Name = _defaultName; else _name = value; } } I've also tried to specifically set the TextBox.Text binding mode to TwoWay without success. I think this is a defense mechanism to prevent an infinite loop from happening but I don't know for sure. Any help on this front would also be highly appreciated. Thanks, José Tavares

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• Dynamic table memory usage

  - by Dan

  I use a dynamic table: <html> <body> <button id="button">Build table</button> <div id="container"> <script type="text/javascript"> window.onload=function(){ var table = null; var row = "<tr><td>111111111111111111111111111111111111111111111111111111</td>" + "<td>222222222222222222222222222222222222222222222222222222</td>" + "<td>333333333333333333333333333333333333333333333333333333</td></tr>"; var data = null; for (var i = 0; i < 2000; i++){ data += row; } var obj = document.getElementById("button"); obj.onclick=function buildTable(){ document.getElementById("container").innerHTML = "<div><table><tbody>" + data + "</tbody></table></div>"; }; }; </script> </body> </html> Using chromes task manager, each time new data is loaded the memory usage increases considerably and doesn't go down, so after some time the app consumes a lot of memory and requires the browser to be closed. Is there any change in the code I can use to solve this or is it a browser side problem?

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• Android: Gzip/Http supported by default?

  - by OneWorld

  I am using the code shown below to get Data from our server where Gzip is turned on. Does my Code already support Gzip (maybe this is already done by android and not by my java program) or do I have to add/change smth.? How can I check that it's using Gzip? For my opionion the download is kinda slow. private static InputStream OpenHttpConnection(String urlString) throws IOException { InputStream in = null; int response = -1; URL url = new URL(urlString); URLConnection conn = url.openConnection(); if (!(conn instanceof HttpURLConnection)) throw new IOException("Not an HTTP connection"); try { HttpURLConnection httpConn = (HttpURLConnection) conn; httpConn.setAllowUserInteraction(false); httpConn.setInstanceFollowRedirects(true); httpConn.setRequestMethod("GET"); httpConn.connect(); response = httpConn.getResponseCode(); if (response == HttpURLConnection.HTTP_OK) { in = httpConn.getInputStream(); if(in == null) throw new IOException("No data"); } } catch (Exception ex) { throw new IOException("Error connecting"); } return in; }

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• Appending Comment Number Anchors to Comments

  - by John

  Hello, I am using a PHP file called comments.php that has a query that enters values into a mySQL table called "comment." As the query does this, it auto-generates a field called "commentid", which is set to auto_increment in MySQL. The file also contains a loop what echoes out all comments for a given submission. It all works fine and dandy, but I want to simultaneously pull this "commentid" and turn it into a hashtag / anchor that when appended to the end of the URL makes that comment at the top of the user's browser. Someone said on another question that in order to do this one thing I should do is create an anchor on the row where the comment is being printed out. How can I do this? Thanks in advance, John The query that inserts comments into the MySQL table "comment": $query = sprintf("INSERT INTO comment VALUES (NULL, %d, %d, '%s', NULL)", $uid, $subid, $comment); mysql_query($query) or die(mysql_error()); The fields in the table "comment": commentid loginid submissionid comment datecommented The row in a loop where the comments are echoed out: echo '<td rowspan="3" class="commentname1">'.stripslashes($row["comment"]).'</td>';

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• Need a refresher course on property access...

  - by Code Sherpa

  Hi. I need help with accessing class properties within a given class. For example, take the below class: public partial class Account { private Profile _profile; private Email _email; private HostInfo _hostInfo; public Profile Profile { get { return _profile; } set { _profile = value; } } public Email Email { get { return _email; } set { _email = value; } } public HostInfo HostInfo { get { return _hostInfo; } set { _hostInfo = value; } } In the class "Account" exists a bunch of class properties such as Email or Profile. Now, when I want to access those properties at run-time, I do something like this (for Email): _accountRepository = ObjectFactory.GetInstance<IAccountRepository>(); string username = Cryptography.Decrypt(_webContext.UserNameToVerify, "verify"); Account account = _accountRepository.GetAccountByUserName(username); if(account != null) { account.Email.IsConfirmed = true; But, I get "Object reference not set..." for account.Email... Why is that? How do I access Account such that account.Email, account.Profile, and so on returns the correct data for a given AccountId or UserName. Here is a method that returns Account: public Account GetAccountByUserName(string userName) { Account account = null; using (MyDataContext dc = _conn.GetContext()) { try { account = (from a in dc.Accounts where a.UserName == userName select a).FirstOrDefault(); } catch { //oops } } return account; } The above works but when I try: account = (from a in dc.Accounts join em in dc.Emails on a.AccountId equals em.AccountId join p in dc.Profiles on em.AccountId equals p.AccountId where a.UserName == userName select a).FirstOrDefault(); I am still getting object reference exceptions for my Email and Profile properties. Is this simply a SQL problem or is there something else I need to be doing to be able to fully access all the properties within my Account class? Thanks!

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• Multicast File copy with Unicast responses

  - by kirbuchi

  I'm trying to do some multicast big file copies over to remote clients on the other side of a satellite link. The idea is to minimize the amount of traffic going up to the satellite. I tried using uftp without luck. The problem is that, even though we can reach clients via multicast from our central Hub, they aren't able to respond to a multicast address (it's not supported by the return link). As uftp needs to respond to a multicast address in order to report any missing packets I'm out of luck. So does anyone have any recommendations or alternatives I can use to do the trasfers? Any tip or pointer would be appreciated.

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• Spring Dependency Injecting an annotated Aspect

  Using Spring I've had some issues with doing a dependency injection on an annotated Aspect class. CacheService is injected upon the Spring context's startup, but when the weaving takes place, it says that the cacheService is null. So I am forced to relook up the spring context manually and get the bean from there. Is there another way of going about it? Here is an example of my Aspect: import org.apache.log4j.Logger; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import com.mzgubin.application.cache.CacheService; @Aspect public class CachingAdvice { private static Logger log = Logger.getLogger(CachingAdvice.class); private CacheService cacheService; @Around("execution(public *com.mzgubin.application.callMethod(..)) &&" + "args(params)") public Object addCachingToCreateXMLFromSite(ProceedingJoinPoint pjp, InterestingParams params) throws Throwable { log.debug("Weaving a method call to see if we should return something from the cache or create it from scratch by letting control flow move on"); Object result = null; if (getCacheService().objectExists(params))}{ result = getCacheService().getObject(params); } else { result = pjp.proceed(pjp.getArgs()); getCacheService().storeObject(params, result); } return result; } public CacheService getCacheService(){ return cacheService; } public void setCacheService(CacheService cacheService){ this.cacheService = cacheService; } }

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• Fibonacci in C works great with 1 - 18 but 19 does nothing at all...

  - by shevron

  Yeah right... we are forced to programm some good old C at our university... ;) So here's my problem: We got the assignment to program a little program that show a fibonacci sequence from 1 to n 1 to 18 works great. But from 19 the program does nothing at all and just exit as it's done. I can not find the error... so please give me a hint. :) #include #include #include #include int main(int argc, char **argv) { pid_t pid; int fib[argc]; int i, size; size = strtol(argv[1], NULL, 0L); fib[0] = 0; fib[1] = 1; pid = fork(); printf("size = %d \n", size); if(pid == 0){ for(i = 2; i 0){ // Parent, because pid 0 wait(NULL); printf("\n"); exit(1); } } Thanks already!

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• Unit Testing an Event Firing From a Thread

  - by Dougc

  I'm having a problem unit testing a class which fires events when a thread starts and finishes. A cut down version of the offending source is as follows: public class ThreadRunner { private bool keepRunning; public event EventHandler Started; public event EventHandler Finished; public void StartThreadTest() { this.keepRunning = true; var thread = new Thread(new ThreadStart(this.LongRunningMethod)); thread.Start(); } public void FinishThreadTest() { this.keepRunning = false; } protected void OnStarted() { if (this.Started != null) this.Started(this, new EventArgs()); } protected void OnFinished() { if (this.Finished != null) this.Finished(this, new EventArgs()); } private void LongRunningMethod() { this.OnStarted(); while (this.keepRunning) Thread.Sleep(100); this.OnFinished(); } } I then have a test to check that the Finished event fires after the LongRunningMethod has finished as follows: [TestClass] public class ThreadRunnerTests { [TestMethod] public void CheckFinishedEventFiresTest() { var threadTest = new ThreadRunner(); bool finished = false; object locker = new object(); threadTest.Finished += delegate(object sender, EventArgs e) { lock (locker) { finished = true; Monitor.Pulse(locker); } }; threadTest.StartThreadTest(); threadTest.FinishThreadTest(); lock (locker) { Monitor.Wait(locker, 1000); Assert.IsTrue(finished); } } } So the idea here being that the test will block for a maximum of one second - or until the Finish event is fired - before checking whether the finished flag is set. Clearly I've done something wrong as sometimes the test will pass, sometimes it won't. Debugging seems very difficult as well as the breakpoints I'd expect to be hit (the OnFinished method, for example) don't always seem to be. I'm assuming this is just my misunderstanding of the way threading works, so hopefully someone can enlighten me.

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• Multiple Exception Handling in one if statement [closed]

  - by JA3N

  I am having trouble with throwing and catching exceptions. Here is the code for assignSeat(), assignSeat is called in a try block in another class. void assignSeat(String passengerName, int x, int y) throws SeatOccupiedException, InvalidPassengerNameException { Seat tSeat = airplane.getSeat(x,y); if (tSeat!=null) { if (passengerName.isEmpty() || !passengerName.matches("[a-zA-Z]+")) { throw new InvalidPassengerNameException(); } //excluded else if else if (foundPassenger(passengerName)) { airplane.seatList.get(airplane.seatNumber(passengerName)).unOccupy(); tSeat.occupy(); for (int i = 0; i<passengers.size();i++) if (passengers.get(i).getName().equals(passengerName)) passengers.get(i).changeSeat(tSeat.getSeatName()); } else if (!tSeat.occupied) { tSeat.occupy(); addPassenger(passengerName, tSeat.getSeatName()); } else if (tSeat.occupied) { throw new SeatOccupiedException(); } } and here is the code that calls assignSeat() and is in another class (I won't copy the whole class to make it look clearer) if (afComp.currentAF != null) { try { afComp.currentAF.assignSeat(nameField.getText(), x, y); //<-Problem here, "Unhandled exception type SeatOccupiedException" } catch (SeatOccupiedException exception) //<-Problem here, "Unreachable catch block, This exception is never thrown from the try statement body" { } catch(InvalidPassengerNameException exception) //<-No problems. { } } Whats wrong with the try block? why won't it throw the SeatOccupiedException? Exception classes: SeatOccupied: package a2; public class SeatOccupiedException extends Exception { public SeatOccupiedException(){} } InvalidPassengerName: package a2; public class InvalidPassengerNameException extends Exception { public InvalidPassengerNameException() {} } Every class I have is in package a2 imports for class that calls assignSeat package a2; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.awt.event.MouseEvent; import java.awt.BorderLayout; import javax.swing.*; import javax.swing.event.*; imports for class that has assignSeat package a2; import java.util.ArrayList;

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• Memory Leakage using datatables

  - by Vix

  Hi, I have situation in which i'm compelled to retrieve 30,000 records each to 2 datatables.I need to do some manipulations and insert into records into the SQL server in Manipulate(dt1,dt2) function.I have to do this in 15 times as you can see in the for loop.Now I want to know what would be the effective way in terms of memory usage.I've used the first approach.Please suggest me the best approach. (1) for (int i = 0; i < 15; i++) { DataTable dt1 = GetInfo(i); DataTable dt2 = GetData(i); Manipulate(dt1,dt2); } (OR) (2) DataTable dt1 = new DataTable(); DataTable dt2 = new DataTable(); for (int i = 0; i < 15; i++) { dt1=null; dt2=null; dt1 = GetInfo(); dt2 = GetData(); Manipulate(dt1, dt2); } Thanks, Vix.

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• How to override part of an overload function in JavaScript

  - by Guan Yuxin

  I create a class with a function like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return -1; } basically it is just an overload function composed of index() and index(child). Then I create a sub class,SubObj or whatever, inherits from Obj SubObj.prototype.prototype=Obj; Now, it's time to override the index(child) function,however, index() is also in the function an I don't want to overwrite it too. One solution is to write like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return this._index(this); } Obj.prototype._index=function(this){ return -1; } SubObj.prototype._index=function(this){/* overwriteing */} But this will easily mislead other coders as _index(child) should be both private(should not be used except index() function) and public(is an overload function of index(),which is public) you guys have better idea?

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• Reusable non generic method for generic methods

  - by Jehof

  I have the following base interface public interface IHandler{ void Handle(IMessage message); } and an generic interface inheriting the base interface public interface IHandler<TMessage> : IHandler where TMessage : IMessage{ void Handle(TMessage message); } My classes can implement the interface IHandler<TMessage> mutiple times. IMessage is an base interface for messages and isn´t relevant here. Currently i´m implementing the interfaces as follows. public class ExampleHandler : IHandler<ExampleMessage>, IHandler<OtherExampleMessag>{ void IHandler.Handle(IMessage message){ ExampleMessage example = message as ExampleMessage; if (example != null) { Handle(example); } else { OtherExampleMessage otherExample = message as OtherExampleMessage; if (otherExample != null) { Handle(otherExample); } } public void Handle(ExampleMessage) { //handle message; } public void Handle(OtherExampleMessage) { //handle message; } } What bothers me is the way i have to implement the Handle(IMessage) method, cause in my opinion its many redundant code, and i have to extend the method each time when i implement a new IHandler<TMessage> interface on my class. What i´m looking for is a more generic way to implement the Handle(IMessage) method (maybe in a base class for Handlers), but i´m currently stuck how to do that.

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• Do something else if ReadWriteSlimlock is held

  - by user43838

  Hi everyone, I have implemented ReaderWriterLockSlim, Now i don't want it to wait at the lock. I want to do something else if the lock is held. I considered using is isWriterLockHeld but it does not makes much sense to me, Since if two threads come in at the same time and enter the if statement at the same time one will still be waiting at the lock here is my code. ReaderWriterLockSlim rw = GetLoadingLock(parameters); rw = GetLoadingLock(parameters); try { rw.EnterWriteLock(); item = this.retrieveCacheItem(parameters.ToString(), false); if (item != null) { parameters.DataCameFromCache = true; // if the data was found in the cache, return it immediately return item.data; } else { try { object loaditem = null; itemsLoading[parameters.ToString()] = true; loaditem = this.retrieveDataFromStore(parameters); return loaditem; } finally { itemsLoading.Remove(parameters.ToString()); } } } finally { rw.ExitWriteLock(); } Can anyone please guide me in the right direction with this. Thanks

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• Javascript cloned object looses its prototype functions

  - by Jake M

  I am attempting to clone an object in Javascript. I have made my own 'class' that has prototype functions. My Problem: When I clone an object, the clone cant access/call any prototype functions. I get an error when I go to access a prototype function of the clone: clone.render is not a function Can you tell me how I can clone an object and keep its prototype functions This simple JSFiddle demonstrates the error I get: http://jsfiddle.net/VHEFb/1/ function cloneObject(obj) { // Handle the 3 simple types, and null or undefined if (null == obj || "object" != typeof obj) return obj; // Handle Date if (obj instanceof Date) { var copy = new Date(); copy.setTime(obj.getTime()); return copy; } // Handle Array if (obj instanceof Array) { var copy = []; for (var i = 0, len = obj.length; i < len; ++i) { copy[i] = cloneObject(obj[i]); } return copy; } // Handle Object if (obj instanceof Object) { var copy = {}; for (var attr in obj) { if (obj.hasOwnProperty(attr)) copy[attr] = cloneObject(obj[attr]); } return copy; } throw new Error("Unable to copy obj! Its type isn't supported."); } function MyObject(name) { this.name = name; // I have arrays stored in this object also so a simple cloneNode(true) call wont copy those // thus the need for the function cloneObject(); } MyObject.prototype.render = function() { alert("Render executing: "+this.name); } var base = new MyObject("base"); var clone = cloneObject(base); clone.name = "clone"; base.render(); clone.render(); // Error here: "clone.render is not a function"

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• How can I keep the the logic to translate a ViewModel's values to a Where clause to apply to a linq query out of My Controller?

  - by Mr. Manager

  This same problem keeps cropping up. I have a viewModel that doesn't have any persistent backing. It is just a ViewModel to generate a search input form. I want to build a large where clause from the values the user entered. If the Action Accepts as a parameter SearchViewModel How do I do this without passing my viewModel to my service layer? Service shouldn't know about ViewModels right? Oh and if I serialize it, then it would be a big string and the key/values would be strongly typed. SearchViewModel this is just a snippet. [Display(Name="Address")] public string AddressKeywords { get; set; } /// <summary> /// Gets or sets the census. /// </summary> public string Census { get; set; } /// <summary> /// Gets or sets the lot block sub. /// </summary> public string LotBlockSub { get; set; } /// <summary> /// Gets or sets the owner keywords. /// </summary> [Display(Name="Owner")] public string OwnerKeywords { get; set; } In my controller action I was thinking of something like this. but I would think all this logic doesn't belong in my Controller. ActionResult GetSearchResults(SearchViewModel model){ var query = service.GetAllParcels(); if(model.Census != null){ query = query.Where(x=>x.Census == model.Census); } if (model.OwnerKeywords != null){ query = query.Where(x=>x.Owners == model.OwnerKeywords); } return View(query.ToList()); }

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