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• Java - understanding servlets

  - by Trup

  I am working on a homework project that should implement a board game between 2 clients over an HttpServlet. I have couple of questions: 1) I read that HttpServlets must be stateless, however, for the sake of the game, I have to keep a lot of state(whose turn it is, the state of the board, etc). Do I have to keep this in the clients? Does the HttpServlet indeed have to be stateless, i.e. have no fields that track state? 2) I know that the clients will talk to the servlet via the doGet/doPost methods, but how can the servlet talk to the clients(for example, if player 1 just made a move and sent it to the servlet, the servlet has to tell client 2 what the move was). Thank you Also, if you can point me to a useful, simple example of a similar code online, I would be very grateful

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• How can I implement the same behavior as Dictionary.TryGetValue

  - by pblasucci

  So, given then following code type MyClass () = let items = Dictionary<string,int>() do items.Add ("one",1) items.Add ("two",2) items.Add ("three",3) member this.TryGetValue (key,value) = items.TrygetValue (key,value) let c = MyClass () let d = Dictionary<string,int> () d.Add ("one",1) d.Add ("two",2) d.Add ("three",3) And the following test code let r1,v1 = d.TryGetValue "one" let r2,v2 = c.TryGetValue "one" The r1,v1 line works fine. The r2,v2 line bombs; complaining c.TryGetValue must be given a tuple. Interestingly, in each line the signature of TryGetValue is different. How can I get my custom implementation to exhibit the same behavior as the BCL version? Or, asked another way, since F# has (implicitly) the concept of tuple parameters, curried parameters, and BCL parameters, and I know how to distinguish between curried and tuple-style, how can I force the third style (a la BCL methods)? Let me know if this is unclear.

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• Is MVC now the only way to write PHP?

  - by JasonS

  Hey... its XMAS Eve and something is bugging me... yes, I have work on my mind even when I am on holiday. The vast amount of frameworks available for PHP now use MVC. Even ASP.net has its own MVC module. I can see the attraction of MVC, I really can and I use it frequently. The only downside that I can see is that you have to fire up the whole system to execute a page request. Depending on your task this can be a little wasteful. So the question. In a professional environment is this the only way to use PHP nowadays or are their other design methods which have alternative benefits?

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• What's the proper way to use sqlite at xCode?

  - by Elliot Chen

  Hi, Experts: Can you please give some suggestions on sqlite using at xcode? Within my application, I use a sqlite DB to store all local data. Two methods can be used to retrieve those data during running time. 1, Load all the data into memory at initialization stage. (More memory used, less DB open/close operation needed) 2, Read corresponding records when necessary, free the occupied memory after using. (Good habit for memory using, but much DB open/close operations needs). I prefer to use method 2, but not sure whether too many DB opening/closing operations could affect app's efficiency. Or do you think I can 'upgrade' method 2 by opening DB when app launches and closing DB when app quits? Thanks for your suggestions very much!

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• How to Initialise a static Map in Java

  - by fahdshariff

  How would you initialise a static Map in Java? Method one: Static initialiser Method two: instance initialiser (anonymous subclass) or some other method? What are the pros and cons of each? Here is an example illustrating two methods: import java.util.HashMap; import java.util.Map; public class Test { private static final Map<Integer, String> myMap = new HashMap<Integer, String>(); static { myMap.put(1, "one"); myMap.put(2, "two"); } private static final Map<Integer, String> myMap2 = new HashMap<Integer, String>(){ { put(1, "one"); put(2, "two"); } }; }

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• How are CD Keys generated?

  - by The Rook

  CD Keys are the defacto-standard as an anti-piracy measure. To be honest this strikes me as Security Though Obscurity, although I really have no idea how CD Keys are generated. What is a good (secure) example of CD Key generation? What cryptographic primitive (if any) are they using? Is it a message digest? If so what data would they be hashing? What methods do developers employ to make it difficult for crackers to build their own key generators?

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• CodeIgniter Validation in Library does not accept callback.

  - by Lukas Oppermann

  Hey guys, my problem is the following: I am writing a login library. This library has a function _validation() and this uses the validation library to validate the data. With using normal validation methods it works just fine, but using a callback function just does not work. It is not called. I call it like this. $this->CI->form_validation->set_rules('user', 'Username', 'required|callback__check_user'); The functions name is _check_user and it uses the username _check_user($user). The function itself works fine and I can also call it in the class ($this-_check_user('username')) with a working result. I am guessing, there might be a problem because I am not workin in a controller so I have a CI instance $this-CI instead of just the original instance $this- Does anyone have a clue how to fix this? Thanks in advance.

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• Interacting With Class Objects in Ruby

  - by michaelmichael

  How can I interact with objects I've created based on their given attributes in Ruby? To give some context, I'm parsing a text file that might have several hundred entries like the following: ASIN: B00137RNIQ -------------------------Status Info------------------------- Upload created: 2010-04-09 09:33:45 Upload state: Imported Upload state id: 3 I can parse the above with regular expressions and use the data to create new objects in a "Product" class: class Product attr_reader :asin, :creation_date, :upload_state, :upload_state_id def initialize(asin, creation_date, upload_state, upload_state_id) @asin = asin @creation_date = creation_date @upload_state = upload_state @upload_state_id = upload_state_id end end After parsing, the raw text from above will be stored in an object that look like this: [#<Product:0x00000101006ef8 @asin="B00137RNIQ", @creation_date="2010-04-09 09:33:45 ", @upload_state="Imported ", @upload_state_id="3">] How can I then interact with the newly created class objects? For example, how might I pull all the creation dates for objects with an upload_state_id of 3? I get the feeling I'm going to have to write class methods, but I'm a bit stuck on where to start.

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• Best way to identify and dispose locked thread in java.

  - by Bala R

  I have to call a function 3rd party module on a new thread. From what I've seen, the call either completes quickly if everything went well or it just hangs for ever locking up the thread. What's a good way to start the thread and make the call and wait for a few secs and if the thread is still alive, then assuming it's locked up, kill (or stop or abandon) the thread without using any deprecated methods. I have something like this for now, but I'm not sure if this is the best way to do it and I want to avoid calling Thread.stop() as it's deprecated. Thanks. private void foo() throws Exception { Runnable runnable = new Runnable() { @Override public void run() { // stuff that could potentially lock up the thread. } }; Thread thread; thread = new Thread(runnable); thread.start(); thread.join(3500); if (thread.isAlive()) { thread.stop(); throw new Exception(); } }

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• Dynamically create PHPUnit tests from data-file

  - by DeletedAccount

  I have a data file with input and expected outputs. An example could be: input: output: 2 3 3 5 4 Exception 5 8 ... ... Currently I have a custom solution to read from the data file and perform a test for each {input,output} pair. I would like to convert this into a PHPUnit based solution and I would like to have one test per input using the test name forXassertY. So the first three tests would be called for2assert3(), for3assert5() and for4assertException(). I do not want to convert my existing data to tests if it's possible to create the test methods dynamically and keep the data file as the basis of these tests. I want to convert it to PHPUnit as I want to add some other tests later on and also process and view the output using Hudson. Suggestions?

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• When calling CRUD check if "parent" exists with read or join?

  - by Trick

  All my entities can not be deleted - only deactivated, so they don't appear in any read methods (SELECT ... WHERE active=TRUE). Now I have some 1:M tables on this entities on which all CRUD operations can be executed. What is more efficient or has better performance? My first solution: To add to all CRUD operations: UPDATE ... JOIN entity e ... WHERE e.active=TRUE My second solution: Before all CRUD operations check if entity is active: if (getEntity(someId) != null) { //do some CRUD } In getEntity there's just SELECT * FROM entity WHERE id=? AND active=TRUE. Or any other solution, recommendation,...?

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• Crystal Report print functionlity doesn't work after deployment?

  - by Ahmed

  I'm using crystal reports to build reports, everything is ok while development. But after deployment of website, print functionality doesn't work. I use _rptDocument.PrintToPrinter(1, false, 0, 0); to print report. I've tried two methods to deploy website Normal Publish option. Web Deployment Project. But I got the same output, print functionality doesn't work. Also, I tried to set default printer, this also doesn't work. Any ideas?

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• NSArray vs. SQLite for Complex Queries on iPhone

  - by GingerBreadMane

  Developing for iPhone, I have a collection of points that I need to make complex queries on. For example: "How many points have a y-coordinate of 10" and "Return all points with an X-coordinate between 3 and 5 and a y-coordinate of 7". Currently, I am just cycling through each element of an NSArray and checking to see if each element matches my query. It's a pain to write the queries though. SQLite would be much nicer. I'm not sure which would be more efficient though since a SQLite database resides on disk and not in memory (to my understanding). Would SQLite be as efficient or more efficient here? Or is there a better way to do it other than these methods that I haven't thought of? I would need to perform the multiple queries with multiple sets of points thousands of times, so the best performance is important.

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• How do I correctly use generics?

  - by ninjasense

  I basically am making webrequests and recieving a JSON response. Depending on the request, I am parsing JSON request into objects I have created. The parsing is pretty much the same no matter what the object Im parsing into looks like. So I have a bunch of methods doing the same work only with different objects, I was wondering how I could accomplish this with generics? Here is an example public static ArrayList<Contact> parseContacts(String responseData) { ArrayList<Contact> Contacts = new ArrayList<Contact>(); try { JSONArray jsonContacts = new JSONArray(responseData); if (!jsonContacts.isNull(0)) { for (int i = 0; i < jsonContacts.length(); i++) { Contacts.add(new Contact(jsonContacts.getJSONObject(i))); } } } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { } return Contacts; }

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• How to filter Delphi 2010 compiler output (hints)?

  - by Paul-Jan

  I'm trying to get rid of some hints(*) the Delphi compiler emits. Browsing through the ToolsAPI I see a IOTAToolsFilter that looks like it might help me accomplish this through it's Notifier, but I'm not sure how to invoke this (through what xxxServices I can access the filter). Can anyone tell me if I´m on the right track here? Thanks! (*) In particular, H2365 about overridden methods not matching the case of the parent. Not so nice when you have about 5 million lines of active code with a slightly different code convention than Embarcadero's. We've been working without hints for months now, and we kinda miss 'm. :-)

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• What should I do that GWT use <th> instead of <td>?

  - by Paulus

  To build a HTML table I use direct DOM instead of a predefined Widget to set thead and tbody. But when I insert a cell with the insertCell() method GWT inserts an td element but should insert an th element. So TableElement table = Document.get().createTableElement(); TableSectionElement thead = table.createTHead(); TableRowElement headRow = thead.insertRow(-1); headRow.insertCell(-1).setInnerText( "header1" ); gives table/thead/tr/td but should give table/thead/tr/th Any idea how to solve this problem? Use the "old-school" DOM.createXXX()-Methods?

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• Is there a concise way to create an InputSupplier for an InputStream in Google Guava?

  - by Fabian Steeg

  There are a few factory methods in Google Guava to create InputSuppliers, e.g. from a byte[]: ByteStreams.newInputStreamSupplier(bytes); Or from a File: Files.newInputStreamSupplier(file); Is there a similar way to to create an InputSupplier for a given InputStream? That is, a way that's more concise than an anonymous class: new InputSupplier<InputStream>() { public InputStream getInput() throws IOException { return inputStream; } }; Background: I'd like to use InputStreams with e.g. Files.copy(...) or ByteStreams.equal(...).

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• Error handling and polymorphism

  - by Neeraj

  I have an application with some bunch of code like this: errCode = callMainSystem(); switch (errCode){ case FailErr: error("Err corresponding to val1\n"); case IgnoreErr: error("Err corresponding to val2\n"); ... ... default: error("Unknown error\n"); } The values are enum constants. Will it make some sense to have something like: // Error* callMainSystem() ... Some code return FaileErr(); // or some other error // handling code Error* err = callMainSystem(); err->toString(); The Error class may be made singleton as it only has to print error messages. What are the pros and cons of above methods,size is an important criteria as the application needs to be supported on embedded devices as well. P.S: I don't want to use exception handling because of portability issues and associated overheads.

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• Interview question: difference between object and object-oriented languages.

  - by Bar

  My friend was asked the following question: what's the difference between object language and object-oriented language? It's a little unintelligible question. What does term «object language» correspond to? Does that mean «pure» object-oriented language, like the Wikipedia article says: Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the way up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Smalltalk, Eiffel, Ruby, JADE, VB.NET.

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• Accessing entire netflix catalog via API v1.5

  - by Stone

  Netflix recently updated their API methods for obtaining the full Netflix catalog. I'm curious if anyone has had any success accessing these new xml documents and downloading them via API v1.5 (9/2012). Previously, you could download the entire Netflix catalog via one API call (which I had working perfectly). Now, there are supposedly two calls to make: one for dvd's and one for streaming movies. I cannot make these calls return anything except for an empty array. Please don't offer an answer unless you have personally downloaded the entire catalog via these new API's. Bonus points if you can tell me how to do it in Ruby. http://developer.netflix.com/blog/read/Update_Changes_for_the_Public_API

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• Is it possible to shrink rt.jar with ProGuard?

  - by PatlaDJ

  Is there a procedure by which you can optimize/shrink/select/obfuscate only 'used by your app' classes/methods/fields from rt.jar provided by Sun by using some optimization software like ProGuard (or maybe other?). Then you would actually be able to minimize the download size of your application considerably and make it much more secure ? Right? Related questions: Do you know if Sun's "jigsaw project" which is waited to come out, is intended to automatically handle this particular issue? Did somebody manage yet to form an opinion about Avian java alternative? Please share it here. Thank you.

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• Accessing wrapped method attribute in C#

  - by prostynick

  I have following code: public static void ProcessStep(Action action) { //do something here if (Attribute.IsDefined(action.Method, typeof(LogAttribute))) { //do something here [1] } action(); //do something here } For easy use I have some similar methods using method above. For example: public static void ProcessStep(Action<bool> action) { ProcessStep(() => action(true)); //this is only example, don't bother about hardcoded true } But when I use the second method (the one above), even if original action had attribute, code [1] will not be executed. How can I find if method is only wrapper and underlying method contains attribute and how to access this attribute?

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• C# Fake Enum TypeInitializationException

  - by userk

  I'm trying to create a class that works as a flexible enum. I came with this idea, with 2 additional static methods that allow me to add new members to that list and get only members from that list. public class LikeEnum { private static List<LikeEnum> list = new List<LikeEnum>() { new LikeEnum("One"), new LikeEnum("Two") }; private string value; private LikeEnum(string value) { this.value = value; } } Unfortunately the List list is only initialized as null so this doesn't work... Any ideas or suggestions?

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• How to control overlapping Alpha fades on iPhone...

  - by ReduxDJ

  I have two animation methods, basically the just repeat... How do I prevent them from overlapping and flickering, is there a convenient way to do this? Thanks, -(void) doPowerChangeAnimUp { powerIconChange .alpha = 0; [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDidStopSelector:@selector(animationDidStop:)]; [UIView setAnimationDelegate:self] ; [UIView setAnimationDuration:2]; [powerIconChange setAlpha:1]; [UIView commitAnimations]; } -(void)animationDidStop:(NSString *)animationID { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDelegate:self] ; [UIView setAnimationDidStopSelector:@selector(doPowerChangeAnimUp)]; [UIView setAnimationDuration:2]; [powerIconChange setAlpha:0]; [UIView commitAnimations]; }

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• Starting new transaction in Spring bean

  - by Marcus

  We have: @Transactional(propagation = Propagation.REQUIRED) public class MyClass implementes MyInterface { ... MyInterface has a single method: go(). When go() executes we start a new transaction which commits/rollbacks when the method is complete - this is fine. Now let's say in go() we call a private method in MyClass that has @Transactional(propagation = Propagation.REQUIRES_NEW. It seems that Spring "ignores" the REQUIRES_NEW annotation and does not start a new transaction. I believe this is because Spring AOP operates on the interface level (MyInterface) and does not intercept any calls to MyClass methods. Is this correct? Is there any way to start a new transaction within the go() transaction? Is the only way to call another Spring managed bean that has transactions configured as REQUIRES_NEW? Update: Adding that when clients execute go() they do so via a reference to the interface, not the class: @Autowired MyInterface impl; impl.go();

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