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  • XNA Vector2 Rotation Question

    - by Tom Allen
    I'm messing about with some stuff in XNA and am trying to move an object around asteroids-style in that you press left and right to rotate and up/down to go forwards and backwards in the direction you are pointing. I've got the rotation of the sprite done, but i can't get the object to move in the direction you've pointed it, it always moves up and down on the x = 0 axis. I'm guessing this is straight forward but I just can't figure it out. My "ship" class has the following properties which are note worthy here: Vector2 Position float Rotation The "ship" class has an update method is where the input is handled and so far I've got the following: public void Update(GameTime gameTime) { KeyboardState keyboard = Keyboard.GetState(); GamePadState gamePad = GamePad.GetState(PlayerIndex.One); float x = Position.X; float y = Position.Y; if (keyboard.IsKeyDown(Keys.Left)) Rotation -= 0.1f; if (keyboard.IsKeyDown(Keys.Right)) Rotation += 0.1f; if (keyboard.IsKeyDown(Keys.Up)) y -= ??; if (keyboard.IsKeyDown(Keys.Down)) y += ??; this.Position = new Vector2(x, y); } Any help would be most appreciated!

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  • Is there a generic way of dealing with varying connection strings in C#?

    - by James Wiseman
    I have an application that needs to connect to a SQL database, and execute a SQL Agent Job. The connection string I am trying to access is stored in the registry, which is easily enough pulled out. This appliction is to be run on multiple computers, and I cannot guarantee the format of this connection string being consistent across these computers. Two that I have pulled out for example are: Data Source=Server1;Initial Catalog=DB1;Integrated Security=SSPI; Data Source=Server2;Initial Catalog=DB1;Provider=SQLNCLI.1;Integrated Security=SSPI;Auto Translate=False; I can use an object of type System.Data.SqlClient.SqlConnection to connect to the database with the first connection string, howevever, I get the following error when I pass the second to it: keyword not supported: 'provider' Similarly, I can use the an object of type System.Data.OleDb.OleDbConnection to connect to the database with the second connection string, howevever, I get the following error when I pass the first to it: An OLEDB Provider was not specified in the ConnectionString' I can solve this by scanning the string for 'Provider' and doing the connect conditionally, however I can't help but feel that there is a better way of doing this, and handle the connection strings in a more generic fashion. Does anyone have any suggestions?

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  • Gdata JavaScript Authsub continues redirect

    - by Krustal
    I am using the JavaScript Google Data API and having issues getting the AuthSub script to work correctly. This is my script currently: google.load('gdata', '1'); function getCookie(c_name){ if(document.cookie.length>0){ c_start=document.cookie.indexOf(c_name + "="); if(c_start!=-1){ c_start=c_start + c_name.length+1; c_end=document.cookie.indexOf(";",c_start); if(c_end==-1) c_end=document.cookie.length; return unescape(document.cookie.substring(c_start, c_end)); } } return ""; } function main(){ var scope = 'http://www.google.com/calendar/feeds/'; if(!google.accounts.user.checkLogin(scope)){ google.accounts.user.login(); } else { /* * Retrieve all calendars */ // Create the calendar service object var calendarService = new google.gdata.calendar.CalendarService('GoogleInc-jsguide-1.0'); // The default "allcalendars" feed is used to retrieve a list of all // calendars (primary, secondary and subscribed) of the logged-in user var feedUri = 'http://www.google.com/calendar/feeds/default/allcalendars/full'; // The callback method that will be called when getAllCalendarsFeed() returns feed data var callback = function(result) { // Obtain the array of CalendarEntry var entries = result.feed.entry; //for (var i = 0; i < entries.length; i++) { var calendarEntry = entries[0]; var calendarTitle = calendarEntry.getTitle().getText(); alert('Calendar title = ' + calendarTitle); //} } // Error handler to be invoked when getAllCalendarsFeed() produces an error var handleError = function(error) { alert(error); } // Submit the request using the calendar service object calendarService.getAllCalendarsFeed(feedUri, callback, handleError); } } google.setOnLoadCallback(main); However when I run this the page redirects me to the authentication page. After I authenticate it send me back to my page and then quickly sends me back to the authenticate page again. I've included alerts to check if the token is being set and it doesn't seem to be working. Has anyone has this problem?

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  • question about jQuery droppable/draggable.

    - by FALCONSEYE
    I modified a sample photo manager application. photo manager application Instead of photos, I have employee records coming from a query. My version will let managers mark employees as on vacation, or at work. One of the things I did is to include employee ids like <a href="123">. I get the ids from event.target. This works for the click function but not for the "droppable" function. This is what I have for the click function: $('ul.gallery > li').click(function(ev) { var $item = $(this); var $unid = ev.target; var $target = $(ev.target); if ($target.is('a.ui-icon-suitcase')) { deleteImage($item,$unid); } else if ($target.is('a.ui-icon-arrowreturnthick-1-w')) { recycleImage($item,$unid); } return false; }); ev.target correctly gives the employee id. when i try the same in one of the droppable functions: $gallery.droppable({ accept: '#suitcase li', activeClass: 'custom-state-active', drop: function(ev, ui) { var $unid = ev.target; alert($unid); recycleImage(ui.draggable,$unid); } }); the alert(ui) gives me [object]. What's in this object? How do i get the href out of this? thanks

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  • entity framework vNext wish list

    - by Fred Yang
    I have been intensively studying and use ef4 in my project. I do feel the improvement that it has over version 1. But I found that I have something I cannot get around easily. Here is a list I want it to be better in ef vNext. the model designer should allow multiple view of the same model, so that I don't need cram all my entity into a single view. respect user's manual edit of edmx. Currently, the some database view object simply can not be imported to the model because the designer "smartly" think that the view does not have a primary key, so that I have to manually edit the edmx to correct designer's behavior. But in the next "update from database" task, designer will revert my customization. For now, I simply fallback to manually edit the edmx file at all, or I have to use compare tool to keep the new update, and rollback and put the new update into my old edmx file manually. Designer should be improved to allow default behavior and user's manual control. I want control not to let the designer refresh the change of imported object. support user defined table function. linq is about Composability, stored proc dos not support composability. I wish I could use user defined table function which support this. What are you wishes for EF vNext?

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • A generic error occurred in GDI+, JPEG Image to MemoryStream

    - by madcapnmckay
    Hi, This seems to be a bit of an infamous error all over the web. So much so that I have been unable to find an answer to my problem as my scenario doesn't fit. An exception gets thrown when I save the image to the stream. Weirdly this works perfectly with a png but gives the above error with jpg and gif which is rather confusing. Most similar problem out there relate to saving images to files without permissions. Ironically the solution is to use a memory stream as I am doing.... public static byte[] ConvertImageToByteArray(Image imageToConvert) { using (var ms = new MemoryStream()) { ImageFormat format; switch (imageToConvert.MimeType()) { case "image/png": format = ImageFormat.Png; break; case "image/gif": format = ImageFormat.Gif; break; default: format = ImageFormat.Jpeg; break; } imageToConvert.Save(ms, format); return ms.ToArray(); } } More detail to the exception. The reason this causes so many issues is the lack of explanation :( System.Runtime.InteropServices.ExternalException was unhandled by user code Message="A generic error occurred in GDI+." Source="System.Drawing" ErrorCode=-2147467259 StackTrace: at System.Drawing.Image.Save(Stream stream, ImageCodecInfo encoder, EncoderParameters encoderParams) at System.Drawing.Image.Save(Stream stream, ImageFormat format) at Caldoo.Infrastructure.PhotoEditor.ConvertImageToByteArray(Image imageToConvert) in C:\Users\Ian\SVN\Caldoo\Caldoo.Coordinator\PhotoEditor.cs:line 139 at Caldoo.Web.Controllers.PictureController.Croppable() in C:\Users\Ian\SVN\Caldoo\Caldoo.Web\Controllers\PictureController.cs:line 132 at lambda_method(ExecutionScope , ControllerBase , Object[] ) at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClassa.<InvokeActionMethodWithFilters>b__7() at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) InnerException: OK things I have tried so far. Cloning the image and working on that. Retrieving the encoder for that MIME passing that with jpeg quality setting. Please can anyone help.

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  • Shuffling words in a sentence in javascript (coding horror - How to improve?)

    - by Bill Zimmerman
    Hi, I'm trying to do something that is fairly simple, but my code looks terrible and I am certain there is a better way to do things in javascript. I am new to javascript, and am trying to improve my coding. This just feels very messy. All I want to do is to randomly change the order some words on a web page. In python, the code would look something like this: s = 'THis is a sentence' shuffledSentence = random.shuffle(s.split(' ')).join(' ') However, this is the monstrosity I've managed to produce in javascript //need custom sorting function because javascript doesn't have shuffle? function mySort(a,b) { return a.sortValue - b.sortValue; } function scrambleWords() { var content = $.trim($(this).contents().text()); splitContent = content.split(' '); //need to create a temporary array of objects to make sorting easier var tempArray = new Array(splitContent.length); for (var i = 0; i < splitContent.length; i++) { //create an object that can be assigned a random number for sorting var tmpObj = new Object(); tmpObj.sortValue = Math.random(); tmpObj.string = splitContent[i]; tempArray[i] = tmpObj; } tempArray.sort(mySort); //copy the strings back to the original array for (i = 0; i < splitContent.length; i++) { splitContent[i] = tempArray[i].string; } content = splitContent.join(' '); //the result $(this).text(content); } Can you help me to simplify things?

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  • Checking if an SSH tunnel is up and running

    - by Jarmund
    I have a perl script which, when destilled a bit, looks like this: my $randport = int(10000 + rand(1000)); # Random port as other scripts like this run at the same time my $localip = '192.168.100.' . ($port - 4000); # Don't ask... backwards compatibility system("ssh -NL $randport:$localip:23 root\@$ip -o ConnectTimeout=60 -i somekey &"); # create the tunnel in the background sleep 10; # Give the tunnel some time to come up # Create the telnet object my $telnet = new Net::Telnet( Timeout => 10, Host => 'localhost', Port => $randport, Telnetmode => 0, Errmode => \&fail, ); # SNIPPED... a bunch of parsing data from $telnet The thing is that the target $ip is on a link with very unpredictable bandwidth, so the tunnel might come up right away, it might take a while, it might not come up at all. So a sleep is necessary to give the tunnel some time to get up and running. So the question is: How can i test if the tunnel is up and running? 10 seconds is a really undesirable delay if the tunnel comes up straight away. Ideally, i would like to check if it's up and continue with creating the telnet object once it is, to a maximum of, say, 30 seconds.

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  • Dealing with multiple generics in a method call

    - by thaBadDawg
    I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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  • Warning: cast increases required alignment

    - by dash-tom-bang
    I'm recently working on this platform for which a legacy codebase issues a large number of "cast increases required alignment to N" warnings, where N is the size of the target of the cast. struct Message { int32_t id; int32_t type; int8_t data[16]; }; int32_t GetMessageInt(const Message& m) { return *reinterpret_cast<int32_t*>(&data[0]); } Hopefully it's obvious that a "real" implementation would be a bit more complex, but the basic point is that I've got data coming from somewhere, I know that it's aligned (because I need the id and type to be aligned), and yet I get the message that the cast is increasing the alignment, in the example case, to 4. Now I know that I can suppress the warning with an argument to the compiler, and I know that I can cast the bit inside the parentheses to void* first, but I don't really want to go through every bit of code that needs this sort of manipulation (there's a lot because we load a lot of data off of disk, and that data comes in as char buffers so that we can easily pointer-advance), but can anyone give me any other thoughts on this problem? I mean, to me it seems like such an important and common option that you wouldn't want to warn, and if there is actually the possibility of doing it wrong then suppressing the warning isn't going to help. Finally, can't the compiler know as I do how the object in question is actually aligned in the structure, so it should be able to not worry about the alignment on that particular object unless it got bumped a byte or two?

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  • Flash compiler error 1061: Call to a possibly undefined method run... but run exists!

    - by Zane Geiger
    So I've been working on making a game in Processing but I think Flash would be a better way to get more people playing it, so I've decided to learn Flash. The problem is that I keep getting really stupid errors on incredibly simple things. For instance, I want to make a 'Block' object to use in a platform game. So I make a new .as file, name it Block.as, and define the Block class within it like so: package { public class Block { public function Block() { // constructor code } public function run() { } } } I don't want to add the code yet, I just want to ensure that this works. So in my main timeline code, I try to create an instance of the Block object and execute its run method: var block1:Block = new Block(); block1.run(); Every time it gives me this inane error: Scene 1, Layer 'Layer 1', Frame 1, Line 2 1061: Call to a possibly undefined method run through a reference with static type Block. What undefined method!? It's defined RIGHT THERE in Block.as. The class file is even in the same folder and everything. I'm getting REALLY annoyed at how poorly Flash handles such a ridiculously simple project. Does anyone know why Flash hates me?

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  • How to use Comparator in Java to sort

    - by Dan
    I learned how to use the comparable but I'm having difficulty with the Comparator. I am having a error in my code: Exception in thread "main" java.lang.ClassCastException: New.People cannot be cast to java.lang.Comparable at java.util.Arrays.mergeSort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.Collections.sort(Unknown Source) at New.TestPeople.main(TestPeople.java:18) Here is my code: import java.util.Comparator; public class People implements Comparator{ private int id; private String info; private double price; public People(int newid, String newinfo, double newprice){ setid(newid); setinfo(newinfo); setprice(newprice); } public int getid() { return id; } public void setid(int id) { this.id = id; } public String getinfo() { return info; } public void setinfo(String info) { this.info = info; } public double getprice() { return price; } public void setprice(double price) { this.price = price; } public int compare(Object obj1, Object obj2) { Integer p1 = ((People)obj1).getid(); Integer p2 = ((People)obj2).getid(); if (p1 p2 ){ return 1; } else if (p1 < p2){ return -1; } else return 0; } } import java.util.ArrayList; import java.util.Collections; public class TestPeople { public static void main(String[] args) { ArrayList peps = new ArrayList(); peps.add(new People(123, "M", 14.25)); peps.add(new People(234, "M", 6.21)); peps.add(new People(362, "F", 9.23)); peps.add(new People(111, "M", 65.99)); peps.add(new People(535, "F", 9.23)); Collections.sort(peps); for(int i=0;i I believe it has to do something with the casting in the compare method but I was playing around with it and still could not find the solution

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  • Deal with undefined values in code or in the template?

    - by David
    I'm writing a web application (in Python, not that it matters). One of the features is that people can leave comments on things. I have a class for comments, basically like so: class Comment: user = ... # other stuff where user is an instance of another class, class User: name = ... # other stuff And of course in my template, I have <div>${comment.user.name}</div> Problem: Let's say I allow people to post comments anonymously. In that case comment.user is None (undefined), and of course accessing comment.user.name is going to raise an error. What's the best way to deal with that? I see three possibilities: Use a conditional in the template to test for that case and display something different. This is the most versatile solution, since I can change the way anonymous comments are displayed to, say, "Posted anonymously" (instead of "Posted by ..."), but I've often been told that templates should be mindless display machines and not include logic like that. Also, other people might wind up writing alternate templates for the same application, and I feel like I should be making things as easy as possible for the template writer. Implement an accessor method for the user property of a Comment that returns a dummy user object when the real user is undefined. This dummy object would have user.name = 'Anonymous' or something like that and so the template could access it and print its name with no error. Put an actual record in my database corresponding to a user with user.name = Anonymous (or something like that), and just assign that user to any comment posted when nobody's logged in. I know I've seen some real-world systems that operate this way. (phpBB?) Is there a prevailing wisdom among people who write these sorts of systems about which of these (or some other solution) is the best? Any pitfalls I should watch out for if I go one way vs. another? Whoever gives the best explanation gets the checkmark.

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  • Android: FragmentAdapter and pageview do not update the view

    - by user1240937
    My trouble is: when i get new data, my viewpager that use my custom adapter do not update view. I discovered that many programmer got same bug, so i tried a lot of suggestion but no way works for me. So tired. One more time, read my source and help me understand why i fail with updating view pleaseee! Here is my FragmentAdapter: private class SwipeyTabsPagerAdapter extends FragmentPagerAdapter implements SwipeyTabsAdapter { private final Context mContext; private String[] datas; public SwipeyTabsPagerAdapter(Context context, FragmentManager fm, String[] ds) { super(fm); this.mContext = context; datas=ds; } @Override public int getItemPosition(Object object) { return POSITION_NONE; } @Override public Fragment getItem(int position) { Log.e("new item:", datas[position]); return SwipeyTabFragment.newInstance(datas[position]); } @Override public int getCount() { return datas.length; } public TextView getTab(final int position, SwipeyTabs root) { TextView view = (TextView) LayoutInflater.from(mContext).inflate( R.layout.swipey_tab_indicator, root, false); view.setText(datas[position]); view.setOnClickListener(new OnClickListener() { public void onClick(View v) { mViewPager.setCurrentItem(position); } }); return view; } } and here is where i set adapter: SwipeyTabsPagerAdapter adapter = new SwipeyTabsPagerAdapter(getApplicationContext(), getSupportFragmentManager(),dicts); mViewPager.setAdapter(adapter); mTabs.setAdapter(adapter); mViewPager.getAdapter().notifyDataSetChanged(); By logcat, can see clearly that: only first time, newItem be processed, so view can not be update.

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  • Problem with UITextView

    - by user367039
    I have a strange problem with trying to pass a string from one viewcontroller to another view controller if the string originates from a UITextview instead of UITextfield. Both UITextview.text and UITextfield.text are of type NSString. The following code takes either Textfield.text or Textview.text depending on the fieldType and puts it into a string called aString. NSString *aString = [[NSString alloc] init]; if (fieldType == 3) { aString = textView.text; } else { aString = textField.text; } When I examine aString on either cases, I can see that it has successfully assigned the text into aString. I then pass the string to the other view controller using this code. [delegate updateSite:aString :editedFieldKey :fieldType]; [self.navigationController popViewControllerAnimated:YES]; This works fine if aString originated from textfield.text but nothing happens except the view controller is popped if aString was from textview.text This is the code that takes aString and does stuff with it, however it doesn't even execute the first line of code "NSLog(@"Returned object: %@, field type:%@", aString,editedFieldKey);" if aString was from textview.text Any help will be appreciated. -(void)updateSite:(NSString *)aString :(NSString *)editedFieldKey :(int)fieldType { NSLog(@"Returned object: %@, field type:%@", aString,editedFieldKey); switch (fieldType) { case 0: //string [aDiveSite setValue:aString forKey:editedFieldKey] ; NSLog(@"String set %@",[aDiveSite valueForKey:editedFieldKey] ); break; case 1: //int [aDiveSite setValue:[NSNumber numberWithInt:aString.intValue] forKey:editedFieldKey]; NSLog(@"Integer set"); break; case 2: //float NSLog(@"Saving floating value"); [aDiveSite setValue:[NSNumber numberWithFloat:aString.floatValue] forKey:editedFieldKey]; NSLog(@"Float set"); break; case 3: //Text view [aDiveSite setValue:aString forKey:editedFieldKey]; NSLog(@"Textview text saved"); default: break; } [self.tableView reloadData]; }

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  • getSystemResourceAsStream() returns null

    - by Hitesh Solanki
    Hiii... I want to get the content of properties file into InputStream class object using getSystemResourceAsStream(). I have built the sample code. It works well using main() method,but when i deploy the project and run on the server, properties file path cannot obtained ... so inputstream object store null value. Sample code is here.. public class ReadPropertyFromFile { public static Logger logger = Logger.getLogger(ReadPropertyFromFile.class); public static String readProperty(String fileName, String propertyName) { String value = null; try { //fileName = "api.properties"; //propertyName = "api_loginid"; System.out.println("11111111...In the read proprty file....."); // ClassLoader loader = ClassLoader.getSystemClassLoader(); InputStream inStream = ClassLoader.getSystemResourceAsStream(fileName); System.out.println("In the read proprty file....."); System.out.println("File Name :" + fileName); System.out.println("instream = "+inStream); Properties prop = new Properties(); try { prop.load(inStream); value = prop.getProperty(propertyName); } catch (Exception e) { logger.warn("Error occured while reading property " + propertyName + " = ", e); return null; } } catch (Exception e) { System.out.println("Exception = " + e); } return value; } public static void main(String args[]) { System.out.println("prop value = " + ReadPropertyFromFile.readProperty("api.properties", "api_loginid")); } }

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  • Invoking public method on a class in a different package via reflection

    - by KARASZI István
    I ran into the following problem. I have two different packages in package a I would like to call the implemented method of an interface in a package b but the implementing class has package visibility. So a simplifed code looks like this: package b; public final class Factory { public static B createB() { return new ImplB(); } public interface B { void method(); } static class ImplB implements B { public void method() { System.out.println("Called"); } } } and the Invoker: package a; import java.lang.reflect.Method; import b.Factory; import b.Factory.B; public final class Invoker { private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[] {}; private static final Object[] EMPTY_OBJECT_ARRAY = new Object[] {}; public static void main(String... args) throws Exception { final B b = Factory.createB(); b.method(); final Method method = b.getClass().getDeclaredMethod("method", EMPTY_CLASS_ARRAY); method.invoke(b, EMPTY_OBJECT_ARRAY); } } When I start the program it prints out Called as expected and throws an Exception because the package visibility prohibits the calling of the discovered method. So my question is any way to solve this problem? Am I missing something in Java documentation or this is simply not possible although simply calling an implemented method is possible without reflection.

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  • How do I serialise a graph in Java without getting StackOverflowException?

    - by Tim Cooper
    I have a graph structure in java, ("graph" as in "edges and nodes") and I'm attempting to serialise it. However, I get "StackOverflowException", despite significantly increasing the JVM stack size. I did some googling, and apparently this is a well known limitation of java serialisation: that it doesn't work for deeply nested object graphs such as long linked lists - it uses a stack record for each link in the chain, and it doesn't do anything clever such as a breadth-first traversal, and therefore you very quickly get a stack overflow. The recommended solution is to customise the serialisation code by overriding readObject() and writeObject(), however this seems a little complex to me. (It may or may not be relevant, but I'm storing a bunch of fields on each edge in the graph so I have a class JuNode which contains a member ArrayList<JuEdge> links;, i.e. there are 2 classes involved, rather than plain object references from one node to another. It shouldn't matter for the purposes of the question). My question is threefold: (a) why don't the implementors of Java rectify this limitation or are they already working on it? (I can't believe I'm the first person to ever want to serialise a graph in java) (b) is there a better way? Is there some drop-in alternative to the default serialisation classes that does it in a cleverer way? (c) if my best option is to get my hands dirty with low-level code, does someone have an example of graph serialisation java source-code that can use to learn how to do it?

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  • .NET MissingMethodException occuring on one of thousands of end-user machines -- any insight?

    - by Yoooder
    This issue has me baffled, it's affecting a single user (to my knowledge) and hasn't been reproduced by us... The user is receiving a MissingMethodException, our trace file indicates it's occuring after we create a new instance of a component, when we're calling an Initialize/Setup method in preparation to have it do work (InitializeWorkerByArgument in the example) The Method specified by the error is an interface method, which a base class implements and classes derived from the base class can override as-needed The user has the latest release of our application All the provided code is shipped within a single assembly Here's a very distilled version of the component: class Widget : UserControl { public void DoSomething(string argument) { InitializeWorkerByArgument(argument); this.Worker.DoWork(); } private void InitializeWorkerByArgument(string argument) { switch (argument) { case "SomeArgument": this.Worker = new SomeWidgetWorker(); break; } // The issue I'm tracking down would have occured during "new SomeWidgetWorker()" // and would have resulted in a missing method exception stating that // method "DoWork" could not be found. this.Worker.DoWorkComplete += new EventHandler(Worker_DoWorkComplete); } private IWidgetWorker Worker { get; set; } void Worker_DoWorkComplete(object sender, EventArgs e) { MessageBox.Show("All done"); } } interface IWidgetWorker { void DoWork(); event EventHandler DoWorkComplete; } abstract class BaseWorker : IWidgetWorker { virtual public void DoWork() { System.Threading.Thread.Sleep(1000); RaiseDoWorkComplete(this, null); } internal void RaiseDoWorkComplete(object sender, EventArgs e) { if (DoWorkComplete != null) { DoWorkComplete(this, null); } } public event EventHandler DoWorkComplete; } class SomeWidgetWorker : BaseWorker { public override void DoWork() { System.Threading.Thread.Sleep(2000); RaiseDoWorkComplete(this, null); } }

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  • Java/Groovy File IO Replacing an Image File with it's own Contents - Why Does This Work?

    - by jboyd
    I have some JPG files that need to be replaced at runtime with a JFIF standardized version of themselves (we are using a vendor that gives us JPG that do not have proper headers so they don't work in certain applications)... I am able to create a new file from the existing image, then get a buffered image from that file and write the contents right back into the file without having to delete it and it works... imageSrcFolder.eachFileMatch ( ~/.*\.jpg/, { BufferedImage bi = ImageIO.read( it ) ImageIO.write( bi, "jpg", it ) }); The question I have is why? Why doesn't the file end up doubled in size? Why don't I have to delete it first? Why am I able to take a file object to an existing file and then treat it as if it were a brand new one? It seems that what I consider to be a "file" is not what the File object in java actually is, or else this wouldn't work at all. My code does exactly what I want it to do, but I'm not convinced it always will... it just seems way too easy

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  • Java - How to declare table[i][j] elements as instance variables?

    - by JDelage
    All, I am trying to code a Connect4 game. For this, I have created a P4Game class and a P4Board class which represents the i X j dimensions of the Connect4 board. In P4Game, I have the following: public class P4Game{ //INSTANCE VARIABLES private int nbLines; private int nbColumns; private P4Board [][] position; //CONSTRUCTOR public P4Game(int nbLines, int nbColumns){ this.nbColumns = nbColumns; this.nbLines = nbLines; P4Board [][] position = new P4Board [nbLines][nbColumns]; //Creates the table to receive the instances of the P4Board object.*/ for (int i=0; i<nbLines; i++){ for (int j=0; j<nbColumns; j++){ this.position[i][j] = new P4Board(i,j); //Meant to create each object at (line=i, column=j) } } } This causes a NullPointerException in the nested loops where I mention this.position[i][j]. I reference those objects in other methods of this class so I need them to be instance variables. I suppose the exception is due to the fact that I have not listed the table element position[i][j] as an instance variable at the beginning of the class. my question to people here is (1) is my assumption correct, and if so (2) what would be the syntax to declare instance variables of this form? Thank you all for your help with what I realize is a very basic question. Hopefully it will also benefit other newbies. Cheers, JDelage

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  • Creating a RESTful API - HELP!

    - by Martin Cox
    Hi Chaps Over the last few weeks I've been learning about iOS development, which has naturally led me into the world of APIs. Now, searching around on the Internet, I've come to the conclusion that using the REST architecture is very much recommended - due to it's supposed simplicity and ease of implementation. However, I'm really struggling with the implementation side of REST. I understand the concept; using HTTP methods as verbs to describe the action of a request and responding with suitable response codes, and so on. It's just, I don't understand how to code it. I don't get how I map a URI to an object. I understand that a GET request for domain.com/api/user/address?user_id=999 would return the address of user 999 - but I don't understand where or how that mapping from /user/address to some method that queries a database has taken place. Is this all coded in one php script? Would I just have a method that grabs the URI like so: $array = explode("/", ltrim(rtrim($_SERVER['REQUEST_URI'], "/"), "/")) And then cycle through that array, first I would have a request for a "user", so the PHP script would direct my request to the user object and then invoke the address method. Is that what actually happens? I've probably not explained my thought process very well there. The main thing I'm not getting is how that URI /user/address?id=999 somehow is broken down and executed - does it actually resolve to code? class user(id) { address() { //get user address } } I doubt I'm making sense now, so I'll call it a day trying to explain further. I hope someone out there can understand what I'm trying to say! Thanks Chaps, look forward to your responses. Martin p.s - I'm not a developer yet, I'm learning :)

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  • C#, Can I check on a lock without trying to acquire it?

    - by Biff MaGriff
    Hello, I have a lock in my c# web app that prevents users from running the update script once it has started. I was thinking I would put a notification in my master page to let the user know that the data isn't all there yet. Currently I do my locking like so. protected void butRefreshData_Click(object sender, EventArgs e) { Thread t = new Thread(new ParameterizedThreadStart(UpdateDatabase)); t.Start(this); //sleep for a bit to ensure that javascript has a chance to get rendered Thread.Sleep(100); } public static void UpdateDatabase(object con) { if (Monitor.TryEnter(myLock)) { Updater.RepopulateDatabase(); Monitor.Exit(myLock); } else { Common.RegisterStartupScript(con, AlreadyLockedJavaScript); } } And I do not want to do if(Monitor.TryEnter(myLock)) Monitor.Exit(myLock); else //show processing labal As I imagine there is a slight possibility that it might display the notification when it isn't actually running. Is there an alternative I can use? Edit: Hi Everyone, thanks a lot for your suggestions! Unfortunately I couldn't quite get them to work... However I combined the ideas on 2 answers and came up with my own solution.

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  • Identity.Name is disposed in a IIS7 Asp.NET MVC application Thread

    - by vIceBerg
    I have made the smallest demo project to illustrate my problem. You can download the sources Here Visual Studio 2008, .NET 3.5, IIS7, Windows 7 Ultimate 32 bits. The IIS Website is configured ONLY for Windows Authentication in an Integreated pipeline app pool (DefaultAppPool). Here's the problem. I have an Asp.NET MVC 2 application. In an action, I start a thread. The View returns. The thread is doing it's job... but it needs to access Thread.CurrentPrincipal.Identity.Name BANG The worker process of IIS7 stops. I have a window that says: "Visual Studio Just-In-Time Debugger An unhandled exception ('System.Object.DisposedException') occured in w3wp.exe [5524]" I checked with the debugger and the Thread.CurrentPrincipal.Identity is valid, but the Name property is disposed. If I put a long wait in the action before it returns the view, then the Thread can do it's job and the Identity.Name is not disposed. So I think the Name gets disposed when the view is returned. For the sake of the discussion, here's the code that the thread runs (but you can also download the demo project. The link is on top of this post): private void Run() { const int SECTOWAIT = 3; //wait SECTOWAIT seconds long end = DateTime.Now.Ticks + (TimeSpan.TicksPerSecond * SECTOWAIT); while (DateTime.Now.Ticks <= end) continue; //Check the currentprincipal. BANG!!!!!!!!!!!!! var userName = Thread.CurrentPrincipal.Identity.Name; } Here's the code that starts the thread public void Start() { Thread thread = new Thread(new ParameterizedThreadStart(ThreadProc)); thread.SetApartmentState(ApartmentState.MTA); thread.Name = "TestThread"; thread.Start(this); } static void ThreadProc(object o) { try { Builder builder = (Builder)o; builder.Run(); } catch (Exception ex) { throw; } } So... what am i doing wrong? Thanks

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