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• "Find all tiles connected to this one" project

  - by Omega

  Remember MS Paint? The bucket tool? If you used it and clicked on a pixel, all pixels connected to this pixel that are the same are affected. The theory is, I suppose, to check if there is any pixel adjacent to the selected one. If such pixel is the same type as the selected one, check for more adjacent pixels in this one, and so on. I want to implement something similar in VB.NET. Basically I have a 2D array map which represents the map. Let's assume there are only two types of tile: 0 and 1. Now, I got pretty much everything ready: I got my 2d map and I can tell which tile is clicked and tell what array indexes are the ones that represent such tile. Now for the "painting" process. Whenever I think about it, I can't figure a convenient way to execute such iteration. Can someone help me choosing a correct design/way/tip to achieve this?

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• Switching Between Cards in a CardLayout using getParent()

  - by plutoisaplanet

  Hey everyone, I am writing an application where I am using the CardLayout to swap between two panels that are placed right on top of one another. There's a JPanel called Top, and it's layout is the CardLayout. Inside this JPanel is a JPanel called CMatch. Whenever the user clicks the submit button in the CMatch panel, I want a new JPanel added to Top that is custom built based on what the user types in, and it will be shown instead of the original CMatch panel. All of this done using the CardLayout. These are all different classes in different files, however (the panel Top with CardLayout, the panel CMatch that is inside the Top panel, and the custom built panel). So i tried using the following to add the new panel to the Top panel and then have it shown: (this code takes place in the CMatch class): private void submitButtionActionPerformed(ActionEvent e) { CardLayout cl = (CardLayout)(this.getParent().getLayout()); cl.addLayoutComponent(new CChoice(), "college_choices"); cl.show(this.getParent(), "college_choices"); } However, this didn't work. So i was wondering, what am I doing wrong? Any advice is greatly appreciated, thanks!

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• C++: Static variable inside a constructor, are there any drawbacks or side effects?

  - by doc

  What I want to do: run some prerequisite code whenever instance of the class is going to be used inside a program. This code will check for requiremts etc. and should be run only once. I found that this can be achieved using another object as static variable inside a constructor. Here's an example for a better picture: class Prerequisites { public: Prerequisites() { std::cout << "checking requirements of C, "; std::cout << "registering C in dictionary, etc." << std::endl; } }; class C { public: C() { static Prerequisites prerequisites; std::cout << "normal initialization of C object" << std::endl; } }; What bothers me is that I haven't seen similar use of static variables so far. Are there any drawbacks or side-effects or am I missing something? Or maybe there is a better solution? Any suggestions are welcome.

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• Plugin architecture in C using libdl

  - by LukeN

  I've been toying around, writing a small IRC framework in C that I'm now going to expand with some core functionality - but beyond that, I'd like it to be extensible with plugins! Up until now, whenever I wrote something IRC related (and I wrote a lot, in about 6 different languages now... I'm on fire!) and actually went ahead to implement a plugin architecture, it was inside an interpreted language that had facilities for doing (read: abusing) so, like jamming a whole script file trough eval in Ruby (bad!). Now I want to abuse something in C! Basically there's three things I could do define a simple script language inside of my program use an existing one, embedding an interpreter use libdl to load *.so modules on runtime I'm fond of the third one and raather avoid the other two options if possible. Maybe I'm a masochist of some sort, but I think it could be both fun and useful for learning purposes. Logically thinking, the obvious "pain-chain" would be (lowest to highest) 2 - 1 - 3, for the simple reason that libdl is dealing with raw code that can (and will) explode in my face more often than not. So this question goes out to you, fellow users of stackoverflow, do you think libdl is up to this task, or even a realistic thought?

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• Can't declare an abstract method private....

  - by Zombies

  I want to do this, yet I can't. Here is my scenario and rational. I have an abstract class for test cases that has an abstract method called test(). The test() method is to be defined by the subclass; it is to be implemented with logic for a certain application, such as CRMAppTestCase extends CompanyTestCase. I don't want the test() method to be invoked directly, I want the super class to call the test() method while the sub class can call a method which calls this (and does other work too, such as setting a current date-time right before the test is executed for example). Example code: public abstract class CompanyTestCase { //I wish this would compile, but it cannot be declared private private abstract void test(); public TestCaseResult performTest() { //do some work which must be done and should be invoked whenever //this method is called (it would be improper to expect the caller // to perform initialization) TestCaseResult result = new TestCaseResult(); result.setBeginTime(new Date()); long time = System.currentTimeMillis(); test(); //invoke test logic result.setDuration(System.currentTimeMillis() - time); return result; } } Then to extend this.... public class CRMAppTestCase extends CompanyTestCase { public void test() { //test logic here } } Then to call it.... TestCaseResult result = new CRMAppTestCase().performTest();

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• Setting the type of a field in a superclass from a subclass (Java)

  - by Ibolit

  Hi. I am writing a project on Google App Engine, within it I have a number of abstract classes that I hope I will be able to use in my future projects, and a number of concrete classes inheriting from them. Among other abstract classes I have an abstract servlet that does user management, and I hava an abstract user. The AbstractUser has all the necessary fields and methods for storing it in the datastore and telling whether the user is registered with my service or not. It does not implement any project specific functionality. The abstract servlet that manages users, refers only to the methods declared in the AbstractUser class, which allows it to generate links for logging in, logging out and registering (for unregistered users). In order to implement the project-specific user functionality I need to subclass the Abstract user. The servlets I use in my project are all indirect descendants from that abstract user management servlet, and the user is a protected field in it, so the descendant servlets can use it as their own field. However, whenever i want to access any project specific method of the concrete user, i need to cast it to that type. i.e. (abstract user managing servlet) ... AbstractUser user = getUser(); ... abstract protected AbstractUser getUser(); (project-specific abstract servlet) @Override protected AbstractUser getUser() { return MyUserFactory.getUser(); } any other project specific servlet: int a = ((ConcreteUser) user).getA(); Well, what i'd like to do is to somehow make the type of “user” in the superclass depend on something in the project-specific abstract class. Is it at all possible? And i don't want to move all the user-management stuff into a project-specific layer, for i would like to have it for my future projects already written :) Thank you for your help.

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• Why should I prefer OSGi Services over exported packages?

  - by Jens

  Hi, I am trying to get my head around OSGi Services. The main question I keep asking myself is: What's the benefit of using services instead of working with bundles and their exported packages? As far as I know it seems the concept of Late Binding has something to do with it. Bundle dependencies are wired together at bundle start, so they are pretty fixed I guess. But with services it seems to be almost the same. A bundle starts and registers services or binds to services. Of course services can come and go whenever they want and you have to keep track of these chances. But the core idea doesn't seem that different to me. Another aspect to this seems to be that services are more flexible. There could be many implementations for one specific Interface. On the other hand there can be a lot of different implementations for a specific exported package too. In another text I read that the disadvantage of using exported packages is that they make the application more fragile than services. The author wrote that if you remove one bundle from the dependency graph other dependencies would no longer be met, thus possibly causing a domino effect on the whole graph. But couldn't the same happen if a service would go offline? To me it looks like service dependencies are no better than bundle dependencies. So far I could not find a blog post, book or presentation that could clearly describe why services are better than just exposing functionality by exporting and importing packages. To sum my questions up: What are the key benefits of using OSGi Services that make them superior to exporting and importing packages?

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• Best practice when removing entity regarding mappedBy collections?

  - by Daniel Bleisteiner

  I'm still kind of undecided which is the best practice to handle em.remove(entity) with this entity being in several collections mapped using mappedBy in JPA. Consider an entity like a Property that references three other entities: a Descriptor, a BusinessObject and a Level entity. The mapping is defined using @ManyToOne in the Property entity and using @OneToMany(mappedBy...) in the other three objects. That inverse mapping is defined because there are some situations where I need to access those collections. Whenever I remove a Property using em.remove(prop) this element is not automatically removed from managed entities of the other three types. If I don't care about that and the following page load (webapp) doesn't reload those entities the Property is still found and some decisions might be taken that are no longer true. The inverse mappings may become quite large and though I don't want to use something like descriptor.getProperties().remove(prop) because it will load all those properties that might have been lazy loaded until then. So my currently preferred way is to refresh the entity if it is managed: if (em.contains(descriptor)) em.refresh(descriptor) - which unloads a possibly loaded collection and triggers a reload upon the next access. Is there another feasible way to handle all those mappedBy collections of already loaded entites?

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• Moving checkmarks in checkbox lists after page reload - Firefox only

  - by DaveS

  I'm getting some strange behavior in Firefox whenever I put checkboxes inside a list (ol, ul, dl), and then dynamically insert buttons above the list. If I start with a something simple list like this: <dl class="c"> <dt><label for="a1"><input type="checkbox" id="a1" />one</label></dt> <dt><label for="a2"><input type="checkbox" id="a2" />two</label></dt> <dt><label for="a3"><input type="checkbox" id="a3" />three</label></dt> </dl> and add some jQuery like this: $(document).ready(function(){ var a = $('<button type="button">a</button>'); var b = $('<button type="button">b</button>'); $('<div/>').append(a).append(b).insertBefore($('.c')); }); ...then open it in Firefox, it looks fine at first. But check the first checkbox, reload the page, and the check-mark jumps to the second box. Reload again, and it jumps to the third. Reload yet again, and no checkboxes are left checked. If I leave out one of the buttons by dropping one of the append calls, it's fine. If I change the buttons to divs or something similar, it's fine. If I replace the dl tag with a div (and get rid of the dt tags), it's fine. But I need both buttons, and the checkboxes have to be in a list for what I'm trying to build. Does anybody know what's causing this?

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• Margin-Top push outer div down

  - by Daniel Hertz

  Hello, I have a header div as the first element in my wrapper div, but when I add a top margin to a h1 inside the header div it pushes the entire header div down. I realize this happens whenever I apply a top margin to the first visible element on a page. Here is a sample of the css. Thanks! div#header{ width: 100%; background-color: #000; position: relative; } div#header h1{ text-align: center; width: 375px; height: 50px; margin: 0 auto; font-size: 220%; text-indent: -5000px; background: url('../../images/name_logo.png') no-repeat; } html part <div id="header"> <h1><a href="/home.php">Title</a></h1> <ul id="navbar">

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• How do I handle freeing unmanaged structures in C# on application close?

  - by LostKaleb

  I have a C# project in which i use several unmanaged C++ functions. More so, I also have static IntPtr that I use as parameters for those functions. I know that whenever I use them, I should implement IDisposable in that class and use a destructor to invoke the Dispose method, where I free the used IntPtr, as is said in the MSDN page. public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private void Dispose(bool disposing) { // Check to see if Dispose has already been called. if (!this.disposed) { if (disposing) { component.Dispose(); } CloseHandle(m_InstanceHandle); m_InstanceHandle = IntPtr.Zero; disposed = true; } } [System.Runtime.InteropServices.DllImport("Kernel32")] private extern static Boolean CloseHandle(IntPtr handle); However, when I terminate the application, I'm still left with a hanging process in TaskManager. I believe that it must be related to the used of the MarshalAs instruction in my structures: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; } When I create such a structure should I also be careful to free the space it allocs using a destructor? [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct SipxAudioCodec { [MarshalAs(UnmanagedType.ByValTStr, SizeConst=32)] public string CodecName; public SipxAudioBandwidth Bandwidth; public int PayloadType; ~SipxAudioCodec() { Marshal.FreeGlobal(something...); } } Thanks in advance!

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• Website badge system

  - by linkyndy

  I am currently working on a widget-based website, built entirely on user socialization. Since a reputation system pays off for attracting users, I decided to implement one of these. Now, I would like to hear some solutions on how should this be implemented the right way (take, for example, Foursquare's badge system). Basically, I need to be able to do the following: have a badges table, where I can add, edit and delete badges; be able to enable and disable a badge; be able to introduce a new badge, but without writing new code - simply give some parameters to the add badge form regarding what should be followed in order for a user to receive a badge; be able to give badges in real time - meaning that whenever a user accomplishes whatever it needs to receive a badge, the system should know immediately to give the badge to that user; also, the system should not be overloaded with "badge listeners" - I believe interrogating each user request with every badge requirements is time consuming; These being said, I would like to hear your opinions on how to implement the right way a badge system (logic, database schema, methods etc.) Thank you very much!

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• Designers, Expression or SharePoint Designer, and real source control

  - by David Lively

  I'm trying desperately to move from VSS to a real source control system. Options include TFS and SVN. My designers need to keep their ability to modify source files and instantly preview their changes in a browser without having to commit their changes. Using FPSE with VSS, this works flawlessly, since saving a file causes the copy in the working folder on the dev server to be updated, so they can just save and refresh their browser which is pointed at the dev server. The site in question consists of 350k+ lines of classic ASP code and some new ASP.NET MVC. They only need to be able to modify views within the MVC code, not C#. Though Expression includes a version of Cassini for local debugging, Cassini does not support classic ASP. Surely someone has solved this problem before. It can't be necessary to install IIS on each designer's machine (this is absolutely untenable). I need a way to have a common working folder on a dev webserver updated whenever someone saves a file locally, just like using FPSE. I'd rather not write an FPSE proxy that knows how to talk to TFS/SVN. Any suggestions? (I know I've asked this question in the past, but I haven't yet found a solution.)

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• Why is it possible to enumerate a LinqToSql query after calling Dispose() on the DataContext?

  - by DanM

  I'm using the Repository Pattern with some LinqToSql objects. My repository objects all implement IDisposable, and the Dispose() method does only thing--calls Dispose() on the DataContext. Whenever I use a repository, I wrap it in a using person, like this: public IEnumerable<Person> SelectPersons() { using (var repository = _repositorySource.GetNew<Person>(dc => dc.Person)) { return repository.GetAll(); } } This method returns an IEnumerable<Person>, so if my understanding is correct, no querying of the database actually takes place until Enumerable<Person> is traversed (e.g., by converting it to a list or array or by using it in a foreach loop), as in this example: var persons = gateway.SelectPersons(); // Dispose() is fired here var personViewModels = ( from b in persons select new PersonViewModel { Id = b.Id, Name = b.Name, Age = b.Age, OrdersCount = b.Order.Count() }).ToList(); // executes queries In this example, Dispose() gets called immediately after setting persons, which is an IEnumerable<Person>, and that's the only time it gets called. So, a couple questions: How does this work? How can a disposed DataContext still query the database for results when I walk the IEnumerable<Person>? What does Dispose() actually do? I've heard that it is not necessary (e.g., see this question) to dispose of a DataContext, but my impression was that it's not a bad idea. Is there any reason not to dispose of it?

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• Automated generation of the "What's new in this version" reading

  - by lunohodov

  We all know it - this is the reading that lists the changes brought by each new version of our favorite software. Whenever it comes bundled as a file (Changes.txt, CHANGES, WhatsNew.txt, etc) or is presented within an installer this is usually the first thing we read before installing/updating. On a current project we have a Changelog.txt file that gets updated by hand every time a notable change occurs. However this often leads to "I forgot to update the changelog". So I am looking for a way to automate this. I am thinking of a script that extracts the changes from our commit messages (using a convention) and generates the file. For example a commit message like Updated json-glib to 0.7.6 [changes] - Fix crash on Windows - Fix issues with facebook contacts with very large UIDs. Would produce the following Changes.txt Version 1.9.18 (03/10/2010) Fix crash on Windows Fix issues with facebook contacts with very large UIDs. Does anyone know a better solution/tool for this or am I going to write my own? Thanks!

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• Maximized MFC window has dead region at the top

  - by John Calsbeek

  I'm trying to make a MFC window fullscreen whenever it is maximized. This window is being used to draw OpenGL content. So far it works fine—it fills the entire screen with the exception of the taskbar—but there's a dead black region at the top of the screen, 62 pixels in height. It's pretty darn close to the height of the Windows 7 taskbar, but it pretty much stays the same regardless of if the taskbar is on autohide or on a different side of the screen. When I get a CWind::OnSize callback, the height that is given is 988, which is 62 pixels short of the actual screen height (1050). I've tried to manually set the window height to 1050 with SetWindowPos, I've tried to give Windows the screen dimensions in CWnd::OnGetMinMaxInfo, and I've tried to give the screen dimensions to glViewport instead of the 988 pixels that I'm being given. None of these seem to work. I'm accomplishing the fullscreening with a call to… ModifyStyle(0, WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_SYSMENU | WS_CAPTION | WS_POPUP, 0); …in the SIZE_MAXIMIZED CWnd::OnSize callback, which works fine, except for this dead region. I don't know if it's an OpenGL thing or a Win32 thing or a MFC thing. The GetClientRect function for my window reports the false 988 height. The same OpenGL rendering code works fine in my Mac OS X build. Curiously enough, I have gotten the dead region to move around a bit when I play with the taskbar (autohiding it, moving it around the screen, etc.). I've gotten the dead area to shrink to about half—not sure if the other half went to the bottom of the window or not.

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• Limiting object allocation over multiple threads

  - by John

  I have an application which retrieves and caches the results of a clients query. The client then requests different chunks of data and the application sends the relevant results and removes them from the cache. A new requirement for this application is that there needs to be a run-time configurable maximum number of results which may be cached. I've taken the naive approach and implemented this by using a counter under a lock which is incremented every time a result is cached and decremented whenever a result is removed from the cache. Unfortunately, this has drastically reduced the applications performance when processing a large number of concurrent requests. I have tried both a critical section lock and spin-lock; the performance improves a bit with a spin-lock, but is still unacceptably slow. Is there a better way to solve this problem which may improve performance? Right now I have a thread pool that services requests and each request is tied to a Request object which stores that cached results for that particular request. Here is a simplified pseudo code version of my current implementation: void ResultCallback( Result result, Request *request ) { lock totalResultsCached lock cachedLimit if( totalResultsCached + 1 > cachedLimit ) { unlock cachedLimit unlock totalResultsCached //cancel the request return; } ++totalResultsCached; unlock cachedLimit unlock totalResultsCached request.add(result) } void SendResults( int resultsToSend, Request *request ) { while ( resultsToSend > 0 ) { send(request.remove()) lock totalResultsCached --totalResultsCached unlock totalResultsCached --resultsToSend; } }

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• NHibernate with string primary key and relationships

  - by John_

  I've have just been stumped with this problem for an hour and I annoyingly found the problem eventually. THE CIRCUMSTANCES I have a table which users a string as a primary key, this table has various many to one and many to many relationships all off this primary key. When searching for multiple items from the table all relationships were brought back. However whenever I tried to get the object by the primary key (string) it was not bringing back any relationships, they were always set to 0. THE PARTIAL SOLUTION So I looked into my logs to see what the SQL was doing and that was returning the correct results. So I tried various things in all sorts of random ways and eventually worked out it was. The case of the string being passed into the get method was not EXACTLY the same case as it was in the database, so when it tried to match up the relationship items with the main entity it was finding nothing (Or at least NHIbernate wasn't because as I stated above the SQL was actually returning the correct results) THE REAL SOLUTION Has anyone else come across this? If so how do you tell NHibernate to ignore case when matching SQL results to the entity? It is silly because it worked perfectly well before now all of a sudden it has started to pay attention to the case of the string.

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• Perl: Value of response code in HTTP::Request

  - by lola

  Hi all, So, I am writing a code to get a document from the internet. The document size is around 200 KB. This is the code: !/usr/local/bin/perl -w use strict; use LWP::UserAgent; my $ua = LWP::UserAgent->new; my $url = "SOME URL"; my $req = HTTP::Request->new(GET => $url); my $res = $ua->request($req); if($res->is_success){ print $res->content ."\n"; } else{ print "Error: " . $res->status_line; } Now, the only problem is I can't mention what the URL is. However, the output is: "Error: 500 read timeout". When I checked the link externally, the data is being downloaded in under 5 seconds. I even changed the timeout to 1000s, but it still didn't work. How should I go about finding more information related to the response. The size of the file (around 200KB) is also not too great to warrant a read timeout. The server is also not a busy one, didn't give a problem whenever I checked the link on the browser. Thanks.

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• Reload a UITable on the fly when editing a UITextField inside one of the cells

  - by Saze

  I have a UITable containing some customs UITableCells. Those cells contain a few UILabels and a UITextField. The datasource of the table comes from a main controller's property. (This controller is also the delegate and the dataSource for the table). Here's a simplified screenshot of the UI: Now, I need to update "on the fly" the content of all the UILabels when the user edits one of the UITextFields. To do so, at the I am listening to the "Editing Changed" event at the UITextField level. This triggers the following action: - (IBAction) editChangeHandler: (id) sender { MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [[delegate.viewController.myDataSourceArray objectAtIndex:self.rowIndex] setANumber: [theTextField.text intValue]]; [delegate.viewController reloadRows]; } The reloadRows method in the viewController is as such: - (void) reloadRows { NSLog(@"called reloadRows"); //perform some calculations on the data source objects here... [theUITable reloadData]; } My problem here is that whenever the user changes the value in the field, the reloadRows method is successfully called, so is apparently the reloadData but it also causes the keyboard to be dismissed. So in the end, the user can only touch one key when editing the TextField before the keyboard is dismissed and the table reloaded. Does anybody knows a solution to this or have experienced the same issue?

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• Sending an HTTP POST request through the android emulator doesn't work

  - by Sotirios Delimanolis

  I'm running a tomcat servlet on my local machine and an Android emulator with an app that makes a post request to the servlet. The code for the POST is below (without exceptions and the like): String strUrl = "http://10.0.2.2:8080/DeviceDiscoveryServer/server/devices/"; Device device = Device.getUniqueInstance(); urlParameters += URLEncoder.encode("user", "UTF-8") + "=" + URLEncoder.encode(device.getUser(), "UTF-8"); urlParameters += "&" + URLEncoder.encode("port", "UTF-8") + "=" + URLEncoder.encode(new Integer(Device.PORT).toString(), "UTF-8"); urlParameters += "&" + URLEncoder.encode("address", "UTF-8") + "=" + URLEncoder.encode(device.getAddress().getHostAddress(), "UTF-8"); URL url = new URL(strUrl); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setDoOutput(true); connection.setRequestMethod("POST"); OutputStreamWriter wr = new OutputStreamWriter(connection.getOutputStream()); wr.write(urlParameters); wr.flush(); wr.close(); Whenever this code is executed, the servlet isn't called. However if I change the type of the request to 'GET' and don't write anything to the outputstream, the servlet gets called and everything works fine. Am I just not making the POST correctly or is there some other error?

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• Google App Engine/GWT/Eclipse Plugin Newbie Question- how to autobuild client side resources?

  - by Dieter Hanover

  Hi there, I'm tinkering with the default GWT application generated by the Google Eclipse plugin when I click the Google "New Web Application Project" button in Eclipse 3.5. This will no doubt be familiar to many of you.. basically there is an h1 title stating "Web Application Starter Project," a text field, and a Send button. What I've found is that whenever I make changes to the client side resources, e.g. change the text on the Send button to "Submit" in the .java file, Eclipse does not appear to autobuild these resources. In fact I have to rebuild the entire project in order for these changes to be reflected in my browser. I do have "build automatically" selected in eclipse. I should state that this is my second GWT project, the first was almost entirely server side (restlet on GAE) and everything built automatically nicely. When I first tried this new project with updated client resources, on refreshing my browser, the browser stated "you may need to (re)compile your project." I'm not sure if this is relevant but I thought I'd mention it all the same. So what's going on? How do I get Eclipse/GWT to autobuild these client side resources? Cheers for any help you can offer! :-)

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• Cannot connect to mysql via servlet

  - by JBoy

  Hi all I have been since 2 days trying to figure out why my servlet does not connect to the database MySql. I have mysql installed and working properly and eclipse. Whenever i try to etabilish a connection i get the ClassNotFoundException for the com.mysql.jdbc.Driver, which is actually properly imported, the connector i'm using is the mysql-connector-java5.1.14 added properly as external jar so everything seems fine. here's my code protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String dbUrl="jdbc:mysql://localhost:3306/test"; String username="root"; String password=""; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); conn=DriverManager.getConnection(dbUrl); System.out.println("Connected!"); } catch (SQLException e) { e.printStackTrace(); System.out.println("not connected"); } catch(ClassNotFoundException x){ x.printStackTrace(); } catch(Exception e){ e.printStackTrace(); } } The stacktrace(part of): java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1645) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1491) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:375) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:164) i'm following the connection steps from a published java book and also in forums and tutorials i just see the same code, cannot figure out why that Exception comes. On a normal application which does not run on the server the Exception isn't thrown and the connection (in the exact same way) its successfull. Do you have any advice?

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• Practice of checking 'trueness' or 'equality' of conditional statements - does it really make sense?

  - by senthilkumar1033

  I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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• Grep without storing search to the "/ register in Vim

  - by Phro

  In my .vimrc I have a mapping that makes a line of text 'title capitalized': noremap <Leader>at :s/\v<(.)(\w{2,})/\u\1\L\2/g<CR> However, whenever I run this function, it highlights every word that is at least three characters long in my entire document. Of course I could get this behaviour to stop simply by appending :nohlsearch<CR> to the end of the mapping, but this is more of an awkward hack that still avoids a bigger problem: The last search has been replaced by \v<(.)(\w{2,}). Is there any way to use the search commands in Vim without storing the last search in the "/ register; a 'silent' search of sorts? That way, after running this title-making command, I can still use my previous search to navigate the document using n, N, etc. Edit Using @brettanomyces' answer, I found that simply setting the mapping: noremap <Leader>at :call setline(line('.'),substitute(getline('.'), '\v<(.)(\w{2,})', '\u\1\L\2', 'g'))<CR> will successfully perform the substitution without storing the searched text into the / register.

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