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• Is this reference or code in mistake or bug?

  - by mikezang

  I copied some text from NSDate Reference as below, please check Return Value, it is said the format will be in YYYY-MM-DD HH:MM:SS ±HHMM, but I got as below in my app, so the reference is mistake? or code in mistake? Saturday, January 1, 2011 12:00:00 AM Japan Standard Time or 2011?1?1????0?00?00? ????? descriptionWithLocale: Returns a string representation of the receiver using the given locale. - (NSString *)descriptionWithLocale:(id)locale Parameters locale An NSLocale object. If you pass nil, NSDate formats the date in the same way as the description method. On Mac OS X v10.4 and earlier, this parameter was an NSDictionary object. If you pass in an NSDictionary object on Mac OS X v10.5, NSDate uses the default user locale—the same as if you passed in [NSLocale currentLocale]. Return Value A string representation of the receiver, using the given locale, or if the locale argument is nil, in the international format YYYY-MM-DD HH:MM:SS ±HHMM, where ±HHMM represents the time zone offset in hours and minutes from GMT (for example, “2001-03-24 10:45:32 +0600”)

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• Can I use properties in an ivy.xml file to avoid repeating version numbers of dependencies?

  - by scompt.com

  Here's what part of my ivy.xml looks like right now: <dependency org="org.springframework" name="org.springframework.core" rev="3.0.2.RELEASE" /> <dependency org="org.springframework" name="org.springframework.context" rev="3.0.2.RELEASE" /> <dependency org="org.springframework" name="org.springframework.jdbc" rev="3.0.2.RELEASE" /> <dependency org="org.springframework" name="org.springframework.beans" rev="3.0.2.RELEASE" /> <dependency org="org.springframework" name="org.springframework.jms" rev="3.0.2.RELEASE" /> Here's what I'd like it to look like: <dependency org="org.springframework" name="org.springframework.core" rev="${spring.version}" /> <dependency org="org.springframework" name="org.springframework.context" rev="${spring.version}" /> <dependency org="org.springframework" name="org.springframework.jdbc" rev="${spring.version}" /> <dependency org="org.springframework" name="org.springframework.beans" rev="${spring.version}" /> <dependency org="org.springframework" name="org.springframework.jms" rev="${spring.version}" /> Is this possible? What's the syntax?

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• Java and Jasper

  - by bhargava

  Hey Guys, I have integrated Jasper Reports on my netbeans platform and i am able to generate reports using the following code. Map<String, Object> params = new HashMap<String, Object>(); Connection conn = DriverManager.getConnection("databaseUrl", "userid","password"); JasperReport jasperReport = JasperCompileManager.compileReport(reportSource); JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, params, conn); JasperExportManager.exportReportToHtmlFile(jasperPrint, reportDest); JasperViewer.viewReport(jasperPrint); This stuff works perfect. But not i am trying to integrate Jasper with GWT.I have my server as glass fish server. I am getting the Connection object using the followind code. public static Connection getConnection() { try { String JNDI = "JNDI name"; InitialContext initCtx = new InitialContext(); javax.sql.DataSource ds = (javax.sql.DataSource) initCtx.lookup(JNDI); Connection conn = (Connection) ds.getConnection(); return conn; } catch (Exception ex) { ex.printStackTrace(); } return null; } and then Map params = new HashMap(); JasperReport jasperReport = JasperCompileManager.compileReport(reportSource); JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, params, getConnection()); JasperExportManager.exportReportToHtmlFile(jasperPrint, reportDest); JasperViewer.viewReport(jasperPrint); but i always get Error.I am implementing this on Server.I am having RPC calls to get this method to work when a button is clicked. Can you please help me how to work on this.(That is to integrate Jasper reports with GWT). I would highly appreciate any explanation with some code as i am just a beginner. Thanks

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• Why I can't get all UDP packets?

  - by Jack

  My program use UdpClient to try to receive 27 responses from 27 hosts. The size of the response is 10KB. My broadband incoming bandwidth is 150KB/s. The 27 responses are sent from the hosts almost at the same time and for every 10 secs. However, I can only receive 8 - 17 responses each time. The number of responses that I can receive is quite dynamic but within the range. Can anyone tell me why? why can't I receive all? I understand UDP is not reliable. but I tried receiving 5 - 10 responses at the same time, it worked. I guess the network links are not so bad. The code is very simple. ON the 27 hosts, I just use UdpClient to send 10KB to my machine. On my machine, I have one UdpClient receive datagrams. Each time I get a data, I create a thread to handle it (basically handling it means just print out "I received 10KB", but it runs in a thread). listener = new UDPListener(Port); listener.Start(); while (true) { try { UDPContext context = listener.Accept(); ThreadPool.QueueUserWorkItem(new WaitCallback(HandleMessage), context); } catch (Exception) { } } If I reduce the size of the response down to 3KB, the case gets much better that roughly 25 responses can be received. Any more idea? UDP buffer problems???

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• Should a C++ constructor do real work?

  - by Wade Williams

  I'm strugging with some advice I have in the back of my mind but for which I can't remember the reasoning. I seem to remember at some point reading some advice (can't remember the source) that C++ constructors should not do real work. Rather, they should initialize variables only. The advice when on to explain that real work should be done in some sort of init() method, to be called separately after the instance was created. The situation is I have a class that represents a hardware device. It makes logical sense to me for the constructor to call the routines that query the device in order to build up the instance variables that describe the device. In other words, once new instantiates the object, the developer receives an object which is ready to be used, no separate call to object-init() required. Is there a good reason why constructors shouldn't do real work? Obviously it could slow allocation time, but that wouldn't be any different if calling a separate method immediately after allocation. Just trying to figure out what gotchas I not currently considering that might have lead to such advice.

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• .NET HttpModule does not send form variables to PHP file on RewritePath()

  - by jammus

  Hello friends. We have an application running on IIS 6 which uses a custom HttpModule to rewrite urls. This works great (well done us) except in the case where the Context.RewritePath destination is a .php file. The php file is executed as expected, however the $_POST collection is empty meaning it cannot access any forms which are submitted to rewritten urls. The problem does not exist when rewriting to .aspx files as the Request.Form collection is fine. My question therefore has two parts: Why is the $_POST collection not being populated? Is there a way to ensure that the .php $_POST collection is correctly populated after a rewrite? I don't have much to show in the way of code. There's just a simple: context.RewritePath(newPath); once the HttpModule has figured out where to send the request. Edit: Interestingly, if I do var_dump(file_get_contents('php://input')); in the PHP file (method described here) the contents of the form is displayed. So the data is reaching the PHP script but not the $_POST array.

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• friend declaration in C++

  - by Happy Mittal

  In Thinking in C++ by Bruce eckel, there is an example given regarding friend functions as // Declaration (incomplete type specification): struct X; struct Y { void f(X*); }; struct X { // Definition private: int i; public: friend void Y::f(X*); // Struct member friend }; void Y::f(X* x) { x->i = 47; } Now he explained this: Notice that Y::f(X*) takes the address of an X object. This is critical because the compiler always knows how to pass an address, which is of a fixed size regardless of the object being passed, even if it doesn’t have full information about the size of the type. If you try to pass the whole object, however, the compiler must see the entire structure definition of X, to know the size and how to pass it, before it allows you to declare a function such as Y::g(X). But when I tried void f(X); as declaration in struct Y, it shows no error. Please explain why?

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• How to: StructureMap and configuration based on runtime parameters?

  - by user981375

  In a nutshell - I want to be able to instantiate object based on runtime parameters. In this particular case there are only two parameters but the problem is that I'm facing different permutations of these parameters and it gets messy. Here is the situation: I want to get an instance of an object specific to, say, given country and then, say, specific state/province. So, considering the US, there are 50 possible combinations. In reality it's less than that but that's the max. Think of it this way, I want to find out what's the penalty for smoking pot in a given country/state, I pass this information in and I get instantiated object telling me what it is. To the code (for reference only): interface IState { string Penalty { get; } } interface ICountry { IState State { get; set; } string Name { get; } } class BasePenalty : IState { virtual public string Penalty { get { return "Slap on a wrist"; } } } class USA : ICountry { public USA(IState state) { State = state; } public IState State { get; set; } public string Name { get { return "USA"; } } } class Florida: BasePenalty { public override string Penalty { get { return "Public beheading"; } } } // and so on ... I defined other states // which have penalties other than the "Slap on a wrist" How do I configure my container that when given country and state combination it will return the penalty? I tried combinations of profile and contextual binding but that configuration was directly proportional to the number of classes I've created. I have already gone thru trouble of defining different combinations. I'd like to avoid having to do the same during container configuration. I want to inject State into the Country. Also, I'd like to return UsaBasePenalty value in case state is not specified. Is that possible? Perhaps these is something wrong with the design.

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• do the Python libraries have a natural dependence on the global namespace?

  - by msw

  I first ran into this when trying to determine the relative performance of two generators: t = timeit.repeat('g.get()', setup='g = my_generator()') So I dug into the timeit module and found that the setup and statement are evaluated with their own private, initially empty namespaces so naturally the binding of g never becomes accessible to the g.get() statement. The obvious solution is to wrap them into a class, thus adding to the global namespace. I bumped into this again when attempting, in another project, to use the multiprocessing module to divide a task among workers. I even bundled everything nicely into a class but unfortunately the call pool.apply_async(runmc, arg) fails with a PicklingError because buried inside the work object that runmc instantiates is (effectively) an assignment: self.predicate = lambda x, y: x > y so the whole object can't be (understandably) pickled and whereas: def foo(x, y): return x > y pickle.dumps(foo) is fine, the sequence bar = lambda x, y: x > y yields True from callable(bar) and from type(bar), but it Can't pickle <function <lambda> at 0xb759b764>: it's not found as __main__.<lambda>. I've given only code fragments because I can easily fix these cases by merely pulling them out into module or object level defs. The bug here appears to be in my understanding of the semantics of namespace use in general. If the nature of the language requires that I create more def statements I'll happily do so; I fear that I'm missing an essential concept though. Why is there such a strong reliance on the global namespace? Or, what am I failing to understand? Namespaces are one honking great idea -- let's do more of those!

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• Issue with class design to model user preferences for different classes

  - by Mulone

  Hi all, I'm not sure how to design a couple of classes in my app. Basically that's a situation: each user can have many preferences each preference can be referred to an object of different classes (e.g. album, film, book etc) the preference is expressed as a set of values (e.g. score, etc). The problem is that many users can have preferences on the same objects, e.g.: John: score=5 for filmid=apocalypsenow Paul: score=3 for filmid=apocalypsenow And naturally I don't want to duplicate the object film in each user. So I could create a class called "preference" holding a score and then a target object, something like: User{ hasMany preferences } Preference{ belongsTo User double score Film target Album target //etc } and then define just one target. Then I would create an interface for the target Classes (album, film etc): Interface canBePreferred{ hasMany preferences } And implement all of those classes. This could work, but it looks pretty ugly and it would requires a lot of joins to work. Do you have some patterns I could use to model this nicely? Cheers, Mulone

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• Mysterious HttpSession and session-config dependency

  - by OneMoreVladimir

  Good day. I'm developing a Java web app with Servlets\JSP using Tomcat 7.0. During request from client I put and object into the session and use forward. After the forward processing the same request the object can be retreived if the secure parameter is false otherwise it is not stored in session. <session-config> <session-timeout>15</session-timeout> <cookie-config> <http-only>true</http-only> <secure>true</secure> </cookie-config> <tracking-mode>COOKIE</tracking-mode> </session-config> I've figured out that "...cookies can be created with the 'secure' flag, which ensures that the browser will never transmit the specified cookie over non-SSL...". I've configured Tomcat to use SSL, but that haven't helped. Changing the tracking mode to SSL haven't helped as well. How do session-config and HttpSession object correlate in this case? What could be the problem?

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• Hibernate: fetching multiple bags efficiently

  - by Jens Jansson

  Hi! I'm developing a multilingual application. For this reason many objects have in their name and description fields collections of something I call LocalizedStrings instead of plain strings. Every LocalizedString is basically a pair of a locale and a string localized to that locale. Let's take an example an entity, let's say a book -object. public class Book{ @OneToMany private List<LocalizedString> names; @OneToMany private List<LocalizedString> description; //and so on... } When a user asks for a list of books, it does a query to get all the books, fetches the name and description of every book in the locale the user has selected to run the app in, and displays it back to the user. This works but it is a major performance issue. For the moment hibernate makes one query to fetch all the books, and after that it goes through every single object and asks hibernate for the localized strings for that specific object, resulting in a "n+1 select problem". Fetching a list of 50 entities produces about 6000 rows of sql commands in my server log. I tried making the collections eager but that lead me to the "cannot simultaneously fetch multiple bags"-issue. Then I tried setting the fetch strategy on the collections to subselect, hoping that it would do one query for all books, and after that do one query that fetches all LocalizedStrings for all the books. Subselects didn't work in this case how i would have hoped and it basically just did exactly the same as my first case. I'm starting to run out of ideas on how to optimize this. So in short, what fetching strategy alternatives are there when you are fetching a collection and every element in that collection has one or multiple collections in itself, which has to be fetch simultaneously.

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• Spring Dependency Injecting an annotated Aspect

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

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• JSP includes and MVC pattern

  - by xingyu

  I am new to JSP/Servlets/MVC and am writing a JSP page (using Servlets and MVC pattern) that displays information about recipies, and want the ability for users to "comment" on it too. So for the Servlet, on doGet(), it grabs all the required info into a Model POJO and forwards the request on to a JSP View for rendering. That is working just fine. I'd like the "comment" part to be a separate JSP, so on the RecipeView.jsp I can use to separate these views out. So I've made that, but am now a little stuck. The form in the CommentOnRecipe.jsp posts to a CommentAction servlet that handles the recording of the comment just fine. So when I reload the Recipe page, I can see the comment I just made. I'd like to: Reload the page automatically after commenting (no AJAX for now) Block the user from making more than one comment on each Recipe over a 1 day timeframe (via a Cookie). So I store a cookie indicating the product ID whenever the user makes a comment, so we can check this later? How would it work in a MVC context? Show a message to the user that they have already commented on the Recipe when they visit one which they have commented on I'm confused about using beans/including JSPs etc on how to achieve this. I know in ASP.NET land, it would be a UseControl that I would place on a page, or in ASP.NET MVC, it would be a PartialView of some sort. I'm just confused with the way this works in a JSP/Servlets/MVC context.

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• Run code before class instanciation in ActionScript 3

  - by soow.fr

  I need to run code in a class declaration before its instanciation. This would be especially useful to automatically register classes in a factory. See: // Main.as public class Main extends Sprite { public function Main() : void { var o : Object = Factory.make(42); } } // Factory.as public class Factory { private static var _factory : Array = new Array(); public static function registerClass(id : uint, c : Class) : void { _factory[id] = function () : Object { return new c(); }; } public static function make(id : uint) : Object { return _factory[id](); } } // Foo.as public class Foo { // Run this code before instanciating Foo! Factory.registerClass(42, Foo); } AFAIK, the JIT machine for the ActionScript language won't let me do that since no reference to Foo is made in the Main method. The Foo class being generated, I can't (and don't want to) register the classes in Main: I'd like to register all the exported classes in a specific package (or library). Ideally, this would be done through package introspection, which doesn't exist in ActionScript 3. Do you know any fix (or other solution) to my design issue?

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• Have something loaded only when JList item is visibile

  - by elvencode

  Hello, i'm implementing a Jlist populated with a lot of elements. Each element corresponds to a image so i'd like to show a resized preview of them inside each row of the list. I've implemented a custom ImageCellRenderer extending the Jlabel and on getListCellRendererComponent i create the thumbnail if there'snt any for that element. Each row corresponds to a Page class where i store the path of the image and the icon applied to the JLabel. Each Page object is put inside a DefaultListModel to populate the JList. The render code is something like this: public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) { Page page = (Page) value; if (page.getImgIcon() == null) { System.out.println(String.format("Creating thumbnail of %s", page.getImgFilename())); ImageIcon icon = new ImageIcon(page.getImgFilename()); int thumb_width = icon.getIconWidth() > icon.getIconHeight() ? 128 : ((icon.getIconWidth() * 128) / icon.getIconHeight()); int thumb_height = icon.getIconHeight() > icon.getIconWidth() ? 128 : ((icon.getIconHeight() * 128) / icon.getIconWidth()); icon.setImage(getScaledImage(icon.getImage(), thumb_width, thumb_height)); page.setImgIcon(icon); } setIcon(page.getImgIcon()); } I was thinking that only a certain item is visibile in the List the cell renderer is called but i'm seeing that all the thumnails are created when i add the Page object to the list model. I've tried to load the items and after set the model in the JList or set the model first and after starting appending the items but the results are the same. Is there any way to load the data only when necessary or do i need to create a custom control like a JScrollPanel with stacked items inside where i check myself the visibility of each elements? Thanks

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• Unit Testing the Use of TransactionScope

  - by Randolpho

  The preamble: I have designed a strongly interfaced and fully mockable data layer class that expects the business layer to create a TransactionScope when multiple calls should be included in a single transaction. The problem: I would like to unit test that my business layer makes use of a TransactionScope object when I expect it to. Unfortunately, the standard pattern for using TransactionScope is a follows: using(var scope = new TransactionScope()) { // transactional methods datalayer.InsertFoo(); datalayer.InsertBar(); scope.Complete(); } While this is a really great pattern in terms of usability for the programmer, testing that it's done seems... unpossible to me. I cannot detect that a transient object has been instantiated, let alone mock it to determine that a method was called on it. Yet my goal for coverage implies that I must. The Question: How can I go about building unit tests that ensure TransactionScope is used appropriately according to the standard pattern? Final Thoughts: I've considered a solution that would certainly provide the coverage I need, but have rejected it as overly complex and not conforming to the standard TransactionScope pattern. It involves adding a CreateTransactionScope method on my data layer object that returns an instance of TransactionScope. But because TransactionScope contains constructor logic and non-virtual methods and is therefore difficult if not impossible to mock, CreateTransactionScope would return an instance of DataLayerTransactionScope which would be a mockable facade into TransactionScope. While this might do the job it's complex and I would prefer to use the standard pattern. Is there a better way?

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• The most expressive web app programming language/framework combination?

  - by Thor

  When concerned about creating web applications, I often ask myself how I can make the code easy to read and above all; how to make it easy to maintain. There has been alot of inventions in the last couple of years with probably millions of programmers sharing these thoughts. So, lets test if we can squeeze the distilled knowledge of millions of StackOverflow users for this ultimate answer: Which language/framework combination in the world right now is the most expressive to do common tasks? Please provide a simple example of simplicity, add a link to more information about the language, and no more than one entry per language/framework combination. Specifications: "Web application" in this context refers to applications that runs on a server and outputs HTML/Javascript/CSS for rendering on a client browser. Any server operating system is ok. "Language/Framework combination" can for example be like Java+Struts or Java+SpringWeb or Perl+CGI or Java+ZK "Most expressive" in this context is meant to be minimal code to do common tasks. "Common tasks" include simple output/input, i.e. form specifying, displaying and processing, as well as simply styling of output. I am more concerned about minimality than about complete functionality. A decent language design can have great potential even though it is not complete.

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• .NET binary serialization conditionally without ISerializable

  - by SillyWhy

  I got 2 classes, for example: public class A { private B b; ... } public class B { ... } I need to serialize an object A using BinaryFormatter. When remoting it shall include the field b, but not when serialize to file. Here is what I added: [Serializable] public class A : MarshalByRefObject { private B b; [OnSerializing] private void OnSerializing(StreamingContext context) { if (context.State == StreamingContextStates.File) { this.b = null; } } ... } [Serializable] public class B : MarshalByRefObject { ... } I think this is a bad design because if another class C also contains B, in class C we must add the duplicate OnSerializing() logic as in A. Class B should decide what to do, not class A or C. I don't want to use ISerializable interface because there are too many variables in class B have to be added to SerializationInfo. I can create a SerializationSurrogate for class B, which perform nothing in GetObjectData() & SetObjectData(), then use it when serializing to file. However the same maintenance issue because whoever modify class B can't notice what going to happen during serialization & the existence of SerializationSurrogate. Is there a better alternative?

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• Pattern for version-specific implementations of a Java class

  - by Mike Monkiewicz

  So here's my conundrum. I am programming a tool that needs to work on old versions of our application. I have the code to the application, but can not alter any of the classes. To pull information out of our database, I have a DTO of sorts that is populated by Hibernate. It consumes a data object for version 1.0 of our app, cleverly named DataObject. Below is the DTO class. public class MyDTO { private MyWrapperClass wrapper; public MyDTO(DataObject data) { wrapper = new MyWrapperClass(data); } } The DTO is instantiated through a Hibernate query as follows: select new com.foo.bar.MyDTO(t1.data) from mytable t1 Now, a little logic is needed on top of the data object, so I made a wrapper class for it. Note the DTO stores an instance of the wrapper class, not the original data object. public class MyWrapperClass { private DataObject data; public MyWrapperClass(DataObject data) { this.data = data; } public String doSomethingImportant() { ... version-specific logic ... } } This works well until I need to work on version 2.0 of our application. Now DataObject in the two versions are very similar, but not the same. This resulted in different sub classes of MyWrapperClass, which implement their own version-specific doSomethingImportant(). Still doing okay. But how does myDTO instantiate the appropriate version-specific MyWrapperClass? Hibernate is in turn instantiating MyDTO, so it's not like I can @Autowire a dependency in Spring. I would love to reuse MyDTO (and my dozens of other DTOs) for both versions of the tool, without having to duplicate the class. Don't repeat yourself, and all that. I'm sure there's a very simple pattern I'm missing that would help this. Any suggestions?

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• How to set a EditText in a certain column of a TableLayout?

  - by Nick

  I have a TableLayout on one Android Activity UI. It has two columns. Now I need to add a new row, and put an EditText box in second column of that new row. And also, I want that EditText full fill the whole cell. I have some code like this: TableRow tr = new TableRow(context); EditText et = new EditText(context); et.SetMaxLines(4); etText.setLayoutParams(new TableRow.LayoutParams(1)); //set it to the second coloumn tr.addView(et); tl.addView(tr); //tl is the tableLayout It puts the EditText in the second column fine, but the EditText is too small. I tried to use etText.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); but that seems to disabled the TableRow.LayoutParams setting. I guess each control can only have one LayoutParamas setting. So, how to make the EditText as a 4 lines text editor and also make sure it is in the second column of that row? Thanks.

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• how to bind a list to a dropdown list in gridview

  - by user3721173

  I have a GridView that it contain a Drop-down list.I have a list that wanna to bind this list to drop-down in gridview. <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"OnSelectedIndexChanged="GridView1_SelectedIndexChanged" OnRowDataBound="GridView1_RowDataBound"> <Columns> <ItemTemplate> <asp:Label ID="Label2" runat="server"></asp:Label> <asp:DropDownList ID="DropDownList3" runat="server" AppendDataBoundItems="True" OnSelectedIndexChanged="DropDownList3_SelectedIndexChanged1" > </asp:DropDownList> </ItemTemplate> </asp:TemplateField> </Columns> and protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) { DropDownList dropdown = (DropDownList)e.Row.FindControl("DropDownList3"); ClassDal obj = new ClassDal(); List<phone> list = obj.GetAll(); dropdown.DataTextField = "phone"; dropdown.DataValueField = "id"; dropdown.DataSource = list.ToList(); dropdown.DataBind(); } and namespace sample_table { public class ClassDal { public List<phone> GetAll() { using (PracticeDBEntities1 context = new PracticeDBEntities1()) { return context.phone.ToList(); } } } } but i received this exception :Object reference not set to an instance of an object on the row: dropdown.DataTextField = "phone";

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• What are the original reasons for ToString() in Java and .NET?

  - by d.

  I've used ToString() modestly in the past and I've found it very useful in many circumstances. However, my usage of this method would hardly justify to put this method in none other than System.Object. My wild guess is that, at some point during the work carried out and meetings held to come up with the initial design of the .NET framework, it was decided that it was necessary - or at least extremely useful - to include a ToString() method that would be implemented by everything in the .NET framework. Does anyone know what the exact reasons were? Am I missing a ton of situations where ToString() proves useful enough as to be part of System.Object? What were the original reasons for ToString()? Thanks a lot! PS - Again: I'm not questioning the method or implying that it's not useful, I'm just curious to know what makes it SO useful as to be placed in System.Object. Side note - Imagine this: AnyDotNetNativeClass someInitialObject = new AnyDotNetNativeClass([some constructor parameters]); AnyDotNetNativeClass initialObjectFullCopy = AnyDotNetNativeClass.FromString(someInitialObject.ToString()); Wouldn't this be cool? EDIT(1): (A) - Based on some answers, it seems that .NET languages inherited this from Java. So, I'm adding "Java" to the subject and to the tags as well. If someone knows the reasons why this was implemented in Java then please shed some light! (B) - Static hypothetical FromString vs Serialization: sure, but that's quite a different story, right?

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• Random number generation in MVC applications

  - by SlimShaggy

  What is the correct way of generating random numbers in an ASP.NET MVC application if I need exactly one number per request? According to MSDN, in order to get randomness of sufficient quality, it is necessary to generate multiple numbers using a single System.Random object, created once. Since a new instance of a controller class is created for each request in MVC, I cannot use a private field initialized in the controller's constructor for the Random object. So in what part of the MVC app should I create and store the Random object? Currently I store it in a static field of the controller class and lazily initialize it in the action method that uses it: public class HomeController : Controller { ... private static Random random; ... public ActionResult Download() { ... if (random == null) random = new Random(); ... } } Since the "random" field can be accessed by multiple instances of the controller class, is it possible for its value to become corrupted if two instances attempt to initialize it simultaneously? And one more question: I know that the lifetime of statics is the lifetime of the application, but in case of an MVC app what is it? Is it from IIS startup till IIS shutdown?

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• Doctrine: How to traverse from an entity to another 'linked' entity?

  - by ropstah

  I'm loading 3 different tables using a cross-join in Doctrine_RawSql. This brings me back the following object: User -> User class (doctrine base class) Settings -> DoctrineCollection of Setting User_Settings -> DoctrineCollection of User_Setting The object above is the result of a many-to-many relationship between User and Setting where User_Setting acts as a reference table. User_Setting also contains another field named value. This obviously contains the value of the corresponding Setting. All good so far, however the Settings and User_Settings properties of the returned User object are in no way linked to each other (apart from the setting_id field ofcourse). Is there any direct way to traverse directly from the Settings property to the corresponding User_Settings property? This is the corresponding query: $sets = new Doctrine_RawSql(); $sets->select('{us.*}, {s.*}, {uset.*}') ->from('(User us CROSS JOIN Setting s) LEFT JOIN User_Setting uset ON us.user_id = uset.user_id AND s.setting_id = uset.setting_id') ->addComponent('us', 'User us') ->addComponent('uset', 'us.User_Setting uset') ->addComponent('s', 'us.Setting s') ->where('s.category_id = ? AND us.usr_auto_key = ?',array(1, 1)); $sets = $sets->execute();

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