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  • WPF binding problem

    - by Lolo
    I've got problem with binding in XAML/WPF. I created Action class witch extends FrameworkElement. Each Action has list of ActionItem. The problem is that the Data/DataContext properties of ActionItem are not set, so they are always null. XAML: <my:Action DataContext="{Binding}"> <my:Action.Items> <my:ActionItem DataContext="{Binding}" Data="{Binding}" /> </my:Action.Items> </my:Action> C#: public class Action : FrameworkElement { public static readonly DependencyProperty ItemsProperty = DependencyProperty.Register("Items", typeof(IList), typeof(Action), new PropertyMetadata(null, null), null); public Action() { this.Items = new ArrayList(); this.DataContextChanged += (s, e) => MessageBox.Show("Action.DataContext"); } public IList Items { get { return (IList)this.GetValue(ItemsProperty); } set { this.SetValue(ItemsProperty, value); } } } public class ActionItem : FrameworkElement { public static readonly DependencyProperty DataProperty = DependencyProperty.Register("Data", typeof(object), typeof(ActionItem), new PropertyMetadata( null, null, (d, v) => { if (v != null) MessageBox.Show("ActionItem.Data is not null"); return v; } ), null ); public object Data { get { return this.GetValue(DataProperty); } set { this.SetValue(DataProperty, value); } } public ActionItem() { this.DataContextChanged += (s, e) => MessageBox.Show("ActionItem.DataContext"); } } Any ideas?

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  • showDialog in Activity not displaying dialog

    - by Mohit Deshpande
    Here is my code: public class TasksList extends ListActivity { ... private static final int COLUMNS_DIALOG = 7; private static final int ORDER_DIALOG = 8; ... /** * @see android.app.Activity#onCreateDialog(int) */ @Override protected Dialog onCreateDialog(int id) { Dialog dialog; final String[] columns; Cursor c = managedQuery(Tasks.CONTENT_URI, null, null, null, null); columns = c.getColumnNames(); final String[] order = { "Ascending", "Descending" }; switch (id) { case COLUMNS_DIALOG: AlertDialog.Builder columnDialog = new AlertDialog.Builder(this); columnDialog.setSingleChoiceItems(columns, -1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { bundle.putString("column", columns[which]); } }); dialog = columnDialog.create(); case ORDER_DIALOG: AlertDialog.Builder orderDialog = new AlertDialog.Builder(this); orderDialog.setSingleChoiceItems(order, -1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { String orderS; if (order[which].equalsIgnoreCase("Ascending")) orderS = "ASC"; else orderS = "DESC"; bundle.putString("order", orderS); } }); dialog = orderDialog.create(); default: dialog = null; } return dialog; } /** * @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem) */ @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case SORT_MENU: showDialog(COLUMNS_DIALOG); showDialog(ORDER_DIALOG); String orderBy = bundle.getString("column") + bundle.getString("order"); Cursor tasks = managedQuery(Tasks.CONTENT_URI, projection, null, null, orderBy); adapter = new TasksAdapter(this, tasks); getListView().setAdapter(adapter); break; case FILTER_MENU: break; } return false; } The showDialog doesn't display the dialog. I used the Debugger and it does executes these statements, but the dialog doesn't show. }

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  • Question about singleton property

    - by Jack
    I'm reading the java tutorial for enums located here and have a question: http://java.sun.com/j2se/1.5.0/docs/guide/language/enums.html#Card The part i'm confused about is as follows: "The Card class, above, contains a static factory that returns a deck, but there is no way to get an individual card from its rank and suit. Merely exposing the constructor would destroy the singleton property (that only a single instance of each card is allowed to exist). Here is how to write a static factory that preserves the singleton property, using a nested EnumMap: " Now as I understand, changing the original private "Card" constructor to public would allow us to instantiate an unlimited number of copies of a "Card" object with a given suit+rank. The solution as proposed was to create an EnumMap which would store four Maps (one for each suit), which themselves contained 13 Card objects with the rank as their keys. And so now if you wanted to retrieve a specific Card object from the deck, you would just call the "valueOf" method. My question now is, what's the prevent you with calling the valueOf method as many times as you like? Wouldn't that lead to the same problem as making the original private constructor public? Thanks.

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  • Global State and Singletons Dependency injection

    - by Manu
    this is a problem i face lot of times when i am designing a new app i'll use a sample problem to explain this think i am writing simple game.so i want to hold a list of players. i have few options.. 1.use a static field in some class private static ArrayList<Player> players = new ArrayList<Integer>(); public Player getPlayer(int i){ return players.get(i); } but this a global state 2.or i can use a singleton class PlayerList{ private PlayerList instance; private PlayerList(){...} public PlayerList getInstance() { if(instance==null){ ... } return instance; } } but this is bad because it's a singleton 3.Dependency injection class Game { private PlayerList playerList; public Game(PlayerList list) { this.list = list; } public PlayerList getPlayerList() { return playerList; } } this seems good but it's not, if any object outside Game need to look at PlayerList (which is the usual case) i have to use one of the above methods to make the Game class available globally. so I just add another layer to the problem. didn't actually solve anything. what is the optimum solution ? (currently i use Singleton approach)

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  • Query Entity Framework 4

    - by nick
    Hi, Is it possible to run a query on an EF4.0 data context and get all objects of a certain type? Say the context has books, genres & authors but I only have a generic parameter, t. Is it possible to get all of type just by using this t? I don't think it is :(

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  • Dispose, when is it called?

    - by Snake
    Consider the following code: namespace DisposeTest { using System; class Program { static void Main(string[] args) { Console.WriteLine("Calling Test"); Test(); Console.WriteLine("Call to Test done"); } static void Test() { DisposeImplementation di = new DisposeImplementation(); } } internal class DisposeImplementation : IDisposable { ~DisposeImplementation() { Console.WriteLine("~ in DisposeImplementation instance called"); } public void Dispose() { Console.WriteLine("Dispose in DisposeImplementation instance called"); } } } The Dispose just never get's called, even if I put a wait loop after the Test(); invocation. So that quite sucks. I want to write a class that is straightforward and very easy to use, to make sure that every possible resource is cleaned up. I don't want to put that responsibilty to the user of my class. Possible solution: use using, or call Dispose myself(basicly the same). Can I force the user to use a using? Or can I force the dispose to be called? Calling GC.Collect(); after Test(); doesn't work either. Putting di to null doesn't invoke Dispose either. The Deconstructor DOES work, so the object get's deconstructed when it exits Test()

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  • Should the argument be passed by reference in this .net example?

    - by Hamish Grubijan
    I have used Java, C++, .Net. (in that order). When asked about by-value vs. by-ref on interviews, I have always done well on that question ... perhaps because nobody went in-depth on it. Now I know that I do not see the whole picture. I was looking at this section of code written by someone else: XmlDocument doc = new XmlDocument(); AppendX(doc); // Real name of the function is different AppendY(doc); // ditto When I saw this code, I thought: wait a minute, should not I use a ref in front of doc variable (and modify AppendX/Y accordingly? it works as written, but made me question whether I actually understand the ref keyword in C#. As I thought about this more, I recalled early Java days (college intro language). A friend of mine looked at some code I have written and he had a mental block - he kept asking me which things are passed in by reference and when by value. My ignorant response was something like: Dude, there is only one kind of arg passing in Java and I forgot which one it is :). Chill, do not over-think and just code. Java still does not have a ref does it? Yet, Java hackers seem to be productive. Anyhow, coding in C++ exposed me to this whole by reference business, and now I am confused. Should ref be used in the example above? I am guessing that when ref is applied to value types: primitives, enums, structures (is there anything else in this list?) it makes a big difference. And ... when applied to objects it does not because it is all by reference. If things were so simple, then why would not the compiler restrict the usage of ref keyword to a subset of types. When it comes to objects, does ref serve as a comment sort of? Well, I do remember that there can be problems with null and ref is also useful for initializing multiple elements within a method (since you cannot return multiple things with the same easy as you would do in Python). Thanks.

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  • What is best practice in converting XML to Java object?

    - by newbie
    I need to convert XML data to Java objects. What would be best practice to convert this XML data to object? Idea is to fetch data via a web service (it doesn't use WSDL, just HTTP GET queries, so I cannot use any framework) and answers are in XML. What would be best practice to handle this situation?

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  • Ordered hash in JavaScript

    - by hekevintran
    JavaScript objects have no order stored for properties (according to the spec). Firefox seems preserve the order of definition of properties when using a for...in loop. Is this behaviour something that I can rely on? If not is there a piece of JavaScript code somewhere that implements an ordered hash type?

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  • c++, when do you need/have to pass data as (*&)

    - by ra170
    I came across people passing data objects as: declaration: DataObject * data = 0; calling it as: SomeMethod( data ); definition of Somethod: void SomeMethod(SomeObject * & object) My obvious question is, when and why do you have to do this (& *)? Is it passing the pointer as reference?

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  • Accessing Application Scoped Bean Causes NullPointerException

    - by user2946861
    What is an Application Scoped Bean? I understand it to be a bean which will exist for the life of the application, but that doesn't appear to be the correct interpretation. I have an application which creates an application scoped bean on startup (eager=true) and then a session bean that tries to access the application scoped bean's objects (which are also application scoped). But when I try to access the application scoped bean from the session scoped bean, I get a null pointer exception. Here's excerpts from my code: Application Scoped Bean: @ManagedBean(eager=true) @ApplicationScoped public class Bean1 implements Serializable{ private static final long serialVersionUID = 12345L; protected ArrayList<App> apps; // construct apps so they are available for the session scoped bean // do time consuming stuff... // getters + setters Session Scoped Bean: @ManagedBean @SessionScoped public class Bean2 implements Serializable{ private static final long serialVersionUID = 123L; @Inject private Bean1 bean1; private ArrayList<App> apps = bean1.getApps(); // null pointer exception What appears to be happening is, Bean1 is created, does it's stuff, then is destroyed before Bean2 can access it. I was hoping using application scoped would keep Bean1 around until the container was shutdown, or the application was killed, but this doesn't appear to be the case.

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  • JQuery/AJAX: Loading external DIVs using dynamic content

    - by ticallian
    I need to create a page that will load divs from an external page using Jquery and AJAX. I have come across a few good tutorials, but they are all based on static content, my links and content are generated by PHP. The main tutorial I am basing my code on is from: http://yensdesign.com/2008/12/how-to-load-content-via-ajax-in-jquery/ The exact function i need is as follows: Main page contains a permanent div listing some links containing a parameter. Upon click, link passes parameter to external page. External page filters recordset against parameter and populates div with results. The new div contains a new set of links with new parameters. The external div is loaded underneath the main pages first div. Process can then be repeated creating a chain of divs under each other. The last div in the chain will then direct to a new page collating all the previously used querystrings. I can handle all of the PHP work with populating the divs on the main and external pages. It's the JQuery and AJAX part i'm struggling with. $(document).ready(function(){ var sections = $('a[id^=link_]'); // Link that passes parameter to external page var content = $('div[id^=content_]'); // Where external div is loaded to sections.click(function(){ //load selected section switch(this.id){ case "div01": content.load("external.php?param=1 #section_div01"); break; case "div02": content.load("external.php?param=2 #section_div02"); break; } }); The problem I am having is getting JQuery to pass the dynamically generated parameters to the external page and then retrieve the new div. I can currently only do this with static links (As above).

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  • Retrieving Data in A NSTableView

    - by Heisennberg
    I have a three column Table View populated by two NSMutableDictionaries which share the same keys (ie key | value1 | value2 ) with dict1(key,value1) and dict2(key,value2). I want to manually enter data in the third column and create the key/value objects in dict2. But when I do that, my code picks the wrong key :S Here's the code for the delegate : - (void)tableView:(NSTableView *)aTableView setObjectValue:(id)anObject forTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex { if ([[aTableColumn identifier] isEqualToString:@"value2"]) { [dict2 setValue:anObject forKey:[[[aTableView tableColumnWithIdentifier:@"key"] dataCellForRow:rowIndex] stringValue ]]; } } Any idea ?

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  • Abstract over X

    - by Bruno Bieth
    Sorry for this english related question but I only came across that expression in the context of IT. What does abstracting over something mean ? For example abstracting over objects or abstracting over classes. Thanks

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  • GC generation 3 appearing in windbg

    - by Johnv2020
    I've a dump file of a process I'm running (trying to find a memory leak) One thing I've noticed is that when I dump the bigger objects via !do windbg tells me that they are GC generation 3 ?? All of these are byte arrays so when I look at all the byte arrays in the dump I can see GC generations 0, 1, 2 & 3. Could someone explain whats going on here as I thought there was only 3 generations of GC.

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  • Undo implementation - DOM manipulations

    - by sonofdelphi
    Is there a library that can be used for implementing undo/redo functionality for DOM element manipulations in JavaScript? I'm writing an app that moves around DOM elements, enables editing and deletion of those elements. There are event-handlers and other objects associated with each element operated upon. Not sure whether I need to roll my own implementation of the Command pattern for this. Surely, there must be something available? If not, suggestions and pointers would be a great help.

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  • Sort std::vector by an element inside?

    - by user146780
    I currently have a std::vector which holds std::vector of double. I'd want to sort it by the second element of the double vectore. ex: instead of sorting by MyVec[0] or myvec[1] I wat it to sort myVec[0] and myvec[1] based on myvec[0][1] myvec[1][1]. Basically sort by a contained value, not the objects in it. so if myvec[0][1] is less than myvec[1][1] then myvec[0] and myvec[1] will swap. Thanks

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  • Convert any object to pretty HTML in java

    - by ripper234
    How can I convert a given object (in a generic way with reflection) to pretty printable HTML? What ready made library do you recommend that does this? I need support for simple nested objects (as long as they don't create loops in the object graph). I tried to convert it to JSON, but DefaultPrettyPrinter is not HTML friendly.

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