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• Singleton Properties

  - by coffeeaddict

  Ok, if I create a singleton class and expose the singleton object through a public static property...I understand that. But my singleton class has other properties in it. Should those be static? Should those also be private? I just want to be able to access all properties of my singleton class by doing this: MySingletonClass.SingletonProperty.SomeProperty2 Where SingletonProperty returns me the single singleton instance. I guess my question is, how do you expose the other properties in the singleton class..make them private and then access them through your public singleton static property?

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• Function Object in Java .

  - by Tony

  I wanna implement a javascript like method in java , is this possible ? Say , I have a Person class : public class Person { private String name ; private int age ; // constructor ,accessors are omitted } And a list with Person objects: Person p1 = new Person("Jenny",20); Person p2 = new Person("Kate",22); List<Person> pList = Arrays.asList(new Person[] {p1,p2}); I wanna implement a method like this: modList(pList,new Operation (Person p) { incrementAge(Person p) { p.setAge(p.getAge() + 1)}; }); modList receives two params , one is a list , the other is the "Function object", it loops the list ,and apply this function to every element in the list. In functional programming language,this is easy , I don't know how java do this? Maybe could be done through dynamic proxy, does that have a performance trade off?

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• Multiple Submit Buttons problem in Struts2

  - by umesh awasthi

  Hi All, Trying to work with multiple submit buttons within a single form in struts2 application but not able to work. here is the jsp code i am using <tr> <td class="button"><input type="submit" value="Import" name="destinationImport" class="button"></td> <td class="button"><input type="submit" value="Export" name="destinationExport" class="button"></td> </tr> here is the java part private boolean destinationImport; private boolean destinationExport; and there respective setter and getter but i am sure is that Struts2 type convertor is having problem converting the String value to boolean do any one have idea how to achieve this Thanks in advance

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• NotifyIcon behaviour on Windows 7 with MouseClick, MouseDoubleClick events

  - by binball

  I have strange behaviour with my app after run it on Windows 7. It's connected with NotifyIcon while app is minimized. What should happens: 1) Click once on icon with mouse left button then Balloon with some text should appears 2) Double click on icon will show again app window On Windows 7 MouseDoubleClick is also fired but window is not showing. I don't know why. The same code works good on Windows XP. private void notifyIcon_MouseClick(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { this.NotifyIconShowBalloonWithData(); } } private void notifyIcon_MouseDoubleClick(object sender, MouseEventArgs e) { this.Show(); WindowState = FormWindowState.Normal; notifyIcon.Visible = false; } What did I wrong? :)

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• Problems with listening an event in child object in Actionscript

  - by Raigomaru

  I have two classes. The first one (the starting class): package { import flash.display.Sprite; import flash.events.KeyboardEvent; import tetris.*; public class TetrisGame extends Sprite { private var _gameWell:Well; public function TetrisGame() { _gameWell = new Well(); addChild(_gameWell); } } } The second: package tetris { import flash.display.Sprite; import flash.events.KeyboardEvent; public class Well extends Sprite { public function Well() { super(); addEventListener(KeyboardEvent.KEY_DOWN, onKeyboard); } private function onKeyboard(event:KeyboardEvent):void { //some code is here } } } But when I press any buttons on my keyboard, the child class Well doesn't have any reaction. What's the problem?

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• Bound DataGridView not updating data source

  - by Max Yaffe

  I'm trying to bind a table of structures to a DataGridView. Loading and viewing the table is working fine but I can't edit a value and get it stored back into the table. Here's what I'm doing. I have a "primitive" data type, Real defined by public struct MyReal:IMyPrimative { public Double m_Real; //... public MyReal(String val) { m_Real = default(Double); Init(val); } //... } It gets used in a structure: public struct MyReal_Record : IMyRecord { public MyReal Freq { get; set;} MyReal_Record(String[] vals) { Init(vals); } } And the structure is used to define a table using a generic Binding List public class MyTable<S> : BindingList<S> where S: struct, IMyRecord { public Type typeofS; public MyTable() { typeofS = typeof(S); // ... } This table is used as a binding source for a grid, dynamically. private void miLoadFile_Click(object sender, EventArgs e) { MyModel.Table<Real_Record> RTable = new MyModel.Table<Real_Record>(); //... Table initialized here //set up grid with virtual mode dataGridView1.DataSource = RTable; } All of this works fine and I can create RTable, initialize it and display it in a grid. The grid allows editing and has events set for CellParsing and CellFormatting which look like: private void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e) { if (e.DesiredType != typeof(String)) return; e.Value = e.Value.ToString(); } private void dataGridView1_CellParsing(object sender, DataGridViewCellParsingEventArgs e) { if (e.DesiredType != typeof(MyReal)) return; e.Value = new MyReal(e.Value.ToString()); e.ParsingApplied = true; this.dataGridView1.UpdateCellValue(e.ColumnIndex, e.RowIndex); } When I edit a value in a cell, I can change the text. On leaving the cell, CellParsing fires and the event handler is called. Everything seems to be correct going into the CellParsing handler. e.DesiredType is MyReal. e.Value is a string with the new value. After the new MyReal is created from the string, e.Value is set correctly. RowIndex and ColumnIndex are correct. ReadOnly is set false. However, when I leave the cell, the system restores the original value to the cell. I thought the UpdateCellValue would replace the value in the dataSource but I seem to be missing something. What did I miss? Thanks, Max

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• Android: Creating custom class of resources

  - by Sebastian

  Hi, R class on android has it's limitations. You can't use the resources dynamically for loading audio, pictures or whatever. If you wan't for example, load a set of audio files for a choosen object you can't do something like: R.raw."string-upon-choosen-object" I'm new to android and at least I didn't find how you could do that, depending on what objects are choosen or something more dynamic than that. So, I thought about making it dynamic with a little of memory overhead. But, I'm in doubt if it's worth it or just working different with external resources. The idea is this: Modify the ant build xml to execute my own task. This task, is a java program that parses the R.java file building a set of HashMaps with it's pair (key, value). I have done this manually and It's working good. So I need some experts voice about it. This is how I will manage the whole thing: Generate a base Application class, e.g. MainApplicationResources that builds up all the require methods and attributes. Then, you can access those methods invoking getApplication() and then the desired method. Something like this: package [packageName] import android.app.Application; import java.util.HashMap; public class MainActivityResources extends Application { private HashMap<String,Integer> [resNameObj1]; private HashMap<String,Integer> [resNameObj2]; ... private HashMap<String,Integer> [resNameObjN]; public MainActivityResources() { super(); [resNameObj1] = new HashMap<String,Integer>(); [resNameObj1].put("[resNameObj1_Key1]", new Integer([resNameObj1_Value1])); [resNameObj1].put("[resNameObj1_Key2]", new Integer([resNameObj1_Value2])); [resNameObj2] = new HashMap<String,Integer>(); [resNameObj2].put("[resNameObj2_Key1]", new Integer([resNameObj2_Value1])); [resNameObj2].put("[resNameObj2_Key2]", new Integer([resNameObj2_Value2])); ... [resNameObjN] = new HashMap<String,Integer>(); [resNameObjN].put("[resNameObjN_Key1]", new Integer([resNameObjN_Value1])); [resNameObjN].put("[resNameObjN_Key2]", new Integer([resNameObjN_Value2])); } public int get[ResNameObj1](String resourceName) { return [resNameObj1].get(resourceName).intValue(); } public int get[ResNameObj2](String resourceName) { return [resNameObj2].get(resourceName).intValue(); } ... public int get[ResNameObjN](String resourceName) { return [resNameObjN].get(resourceName).intValue(); } } The question is: Will I add too much memory use of the device? Is it worth it? Regards,

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• How to access static members in a Velocity template?

  - by matt b

  I'm not sure if there is a way to do this in Velocity or not: I have a User POJO which a property named Status, which looks like an enum (but it is not, since I am stuck on Java 1.4), the definition looks something like this: public class User { // default status to User private Status status = Status.USER; public void setStatus(Status status) { this.status = status; } public Status getStatus() { return status; } And Status is a static inner class: public static final class Status { private String statusString; private Status(String statusString) { this.statusString = statusString; } public final static Status USER = new Status("user"); public final static Status ADMIN = new Status("admin"); public final static Status STATUS_X = new Status("blah"); //.equals() and .hashCode() implemented as well } With this pattern, a user status can easily be tested in a conditional such as if(User.Status.ADMIN.equals(user.getStatus())) ... ... without having to reference any constants for the status ID, any magic numbers, etc. However, I can't figure out how to test these conditionals in my Velocity template with VTL. I'd like to just print a simple string based upon the user's status, such as: Welcome <b>${user.name}</b>! <br/> <br/> #if($user.status == com.company.blah.User.Status.USER) You are a regular user #elseif($user.status == com.company.blah.User.Status.ADMIN) You are an administrator #etc... #end But this throws an Exception that looks like org.apache.velocity.exception.ParseErrorException: Encountered "User" at webpages/include/dashboard.inc[line 10, column 21] Was expecting one of: "[" ... From the VTL User Guide, there is no mention of accessing a Java class/static member directly in VTL, it appears that the right hand side (RHS) of a conditional can only be a number literal, string literal, property reference, or method reference. So is there any way that I can access static Java properties/references in a Velocity template? I'm aware that as a workaround, I could embed the status ID or some other identifier as a reference in my controller (this is a web MVC application using Velocity as the View technology), but I strongly do not want to embed any magic numbers or constants in the view layer.

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• Auto-Implemented Properties c#

  - by user311130

  Hi all, could someone explain me what's the idea behind using Auto-Implemented Properties c#? public class Customer { public int ID { get; set; } public string Name { get; set; } } I get the motivation to use properties for private field, so we can determine how one can access a private field. But here - it's just like defining the field to be public from the first place. no? Is there a difference between defining a field to be "public const" or define it to have a get-only property ? Thanks Elad

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• JSON.Net: deserializing polymorphic types without specifying the assembly

  - by Frank Schwieterman

  I see that using JSON.Net, I can decode polymorphic objects if a $type attribute specifies the specific type of the JSON object. In all the examples I've seen, $type includes the namespace. Is it possible to make this work including just a simple typename without the assembly? I'd be happy to specify a default assembly to the JsonSerializer if thats possible I am able to deserialize the JSON using: public class SingleAssemblyJsonTypeBinder : SerializationBinder { private readonly Assembly _assembly; private Dictionary _typesBySimpleName = new Dictionary(StringComparer.OrdinalIgnoreCase); private Dictionary _simpleNameByType = new Dictionary(); public SingleAssemblyJsonTypeBinder(Assembly assembly) { _assembly = assembly; _typesBySimpleName = new Dictionary<string, Type>(); foreach (var type in _assembly.GetTypes().Where(t => t.IsPublic)) { if (_typesBySimpleName.ContainsKey(type.Name)) throw new InvalidOperationException("Cannot user PolymorphicBinder on a namespace where multiple public types have same name."); _typesBySimpleName[type.Name] = type; _simpleNameByType[type] = type.Name; } } public override Type BindToType(string assemblyName, string typeName) { Type result; if (_typesBySimpleName.TryGetValue(typeName.Trim(), out result)) return result; return null; } public override void BindToName(Type serializedType, out string assemblyName, out string typeName) { string name; if (_simpleNameByType.TryGetValue(serializedType, out name)) { typeName = name; assemblyName = null;// _assembly.FullName; } else { typeName = null; assemblyName = null; } } } ... public static JsonSerializerSettings GetJsonSerializationSettings() { var settings = new JsonSerializerSettings(); settings.Binder = new SingleAssemblyJsonTypeBinder(typeof(MvcApplication).Assembly); settings.TypeNameHandling = TypeNameHandling.Objects; return settings; } .... var serializer = JsonSerializer.Create(settings); I haven't been able to make this work with MVC though, I'm configuring json deserialization per the code below in Application_Start, and the object is deserialized, but using the base type one. GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.Binder = new SingleAssemblyJsonTypeBinder(this.GetType().Assembly); GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameHandling = TypeNameHandling.All; GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameAssemblyFormat = FormatterAssemblyStyle.Simple;

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• Linq to NHibernate using Queryable.Where predicate

  - by Groo

  I am querying an SQLite database using LINQ to NHibernate. Person is an entity containing an Id and a Name: public class Person { public Guid Id { get; private set; } public string Name { get; private set; } } Let's say my db table contains a single person whose name is "John". This test works as expected: var query = from item in session.Linq<Person>() where (item.Name == "Mike") select item; // no such entity should exist Assert.IsFalse(query.Any()); but this one fails: var query = from item in session.Linq<Person>() select item; query.Where(item => item.Name == "Mike"); // following line actually returns the // "John" entry Assert.IsFalse(query.Any()); What am I missing?

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• How best to implement publicly accessible constants in C#

  - by DanM

  There seem to be three choices for implementing publicly accessible constants in C#. I'm curious if there are any good reason to choose one over the other or if it's just a matter of personal preference. Choice 1 - private field plus property getter private const string _someConstant = "string that will never change"; public string SomeConstant { get { return _someConstant; } } Choice 2 - property getter only public string SomeConstant { get { return "string that will never change"; } } Choice 3 - public field only public const string SomeConstant = "string that will never change"; Which do you recommend and why?

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• How come this image won't resize to fit the sprite?

  - by George Edison

  I have this snippet of ActionScript code that is supposed to resize an image to fit the sprite: package { import flash.display.Sprite; import flash.display.Bitmap; import flash.events.Event; public class Main extends Sprite { [Embed(source = 'img.png')] private var TheImage:Class; public static const TheImageWidth:Number = 1300; public static const TheImageHeight:Number = 1300; public function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); // entry point var image:Bitmap = new TheImage(); addChild(image); image.scaleX = width / TheImageWidth; image.scaleY = height / TheImageHeight; } } } Why isn't it working?

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• Timer in a Windows service - not really working?

  - by marc_s

  I have a Windows NT Service in C# which basically wakes up every x seconds, checks to see if any mail notifications need to be sent out, and then goes back to sleep. It looks something like this (the Timer class is from the System.Threading namespace): public partial class MyService : ServiceBase { private Timer _timer; private int _timeIntervalBetweenRuns = 10000; public MyService() { InitializeComponent(); } protected override void OnStart(string[] args) { // when NT Service starts - create timer to wake up every 10 seconds _timer = new Timer(OnTimer, null, _timeIntervalBetweenRuns, Timeout.Infinite); } protected override void OnStop() { // on stop - stop timer by freeing it _timer = null; } private void OnTimer(object state) { // when the timer fires, e.g. when 10 seconds are over // stop the timer from firing again by freeing it _timer = null; // check for mail and sent out notifications, if required - works just fine MailHandler handler = new MailHandler(); handler.CheckAndSendMail(); // once done, re-enable the timer by creating it from scratch _timer = new Timer(OnTimer, null, _timeIntervalBetweenRuns, _timeIntervalBetweenRuns); } } Sending the mail and all works just fine, and the service also wakes up every 10 seconds (in reality, this is a setting from a config file - simplified for this example). However, at times, the service seems to wake up too quickly.... 2010-04-09 22:50:16.390 2010-04-09 22:50:26.460 2010-04-09 22:50:36.483 2010-04-09 22:50:46.500 2010-04-09 22:50:46.537 ** why again after just 37 milliseconds...... ?? 2010-04-09 22:50:56.507 Works fine to 22:50:45.500 - why does it log another entry just 37 milliseconds later?? Here, it seems it's totally out of whack.... seems to wake up twice or even three times every time 10 seconds are over.... 2010-04-09 22:51:16.527 2010-04-09 22:51:26.537 2010-04-09 22:51:26.537 2010-04-09 22:51:36.543 2010-04-09 22:51:36.543 2010-04-09 22:51:46.553 2010-04-09 22:51:46.553 2010-04-09 22:51:56.577 2010-04-09 22:51:56.577 2010-04-09 22:52:06.590 2010-04-09 22:52:06.590 2010-04-09 22:52:06.600 2010-04-09 22:52:06.600 Any ideas why?? It's not a huge problem, but I'm concerned it might start to put too much load on the server, if the interval I configure (10 seconds, 30 seconds - whatever) seems to be ignored more and more, the longer the service runs. Have I missed something very fundamental in my service code?? Am I ending up with multiple timers, or something?? I can't seem to really figure it out..... have I picked the wrong timer (System.Threading.Timer) ? There's at least 3 Timer classes in .NET - why?? :-)

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• How do I refactor these two C# functions to abstract their logic from the specific class properties

  - by ObligatoryMoniker

  I have two functions whose underlying logic is the same but in one case it sets one property value on a class and in another case it sets a different one. How can I rewrite the following two functions to abstract away as much of the algorithm as possible so that I can make changes in logic in a single place? SetBillingAddress private void SetBillingAddress(OrderAddress newBillingAddress) { BasketHelper basketHelper = new BasketHelper(SiteConstants.BasketName); OrderAddress oldBillingAddress = basketHelper.Basket.Addresses[basketHelper.BillingAddressID]; bool NewBillingAddressIsNotOldBillingAddress = ((oldBillingAddress == null) || (newBillingAddress.OrderAddressId != oldBillingAddress.OrderAddressId)); bool BillingAddressHasBeenPreviouslySet = (oldBillingAddress != null); bool BillingAddressIsNotSameAsShippingAddress = (basketHelper.ShippingAddressID != basketHelper.BillingAddressID); bool NewBillingAddressIsNotShippingAddress = (newBillingAddress.OrderAddressId != basketHelper.ShippingAddressID); if (NewBillingAddressIsNotOldBillingAddress && BillingAddressHasBeenPreviouslySet && BillingAddressIsNotSameAsShippingAddress) { basketHelper.Basket.Addresses.Remove(oldBillingAddress); } if (NewBillingAddressIsNotOldBillingAddress && NewBillingAddressIsNotShippingAddress) { basketHelper.Basket.Addresses.Add(newBillingAddress); } basketHelper.BillingAddressID = newBillingAddress.OrderAddressId; basketHelper.Basket.Save(); } And here is the second one: SetShippingAddress private void SetBillingAddress(OrderAddress newShippingAddress) { BasketHelper basketHelper = new BasketHelper(SiteConstants.BasketName); OrderAddress oldShippingAddress = basketHelper.Basket.Addresses[basketHelper.ShippingAddressID]; bool NewShippingAddressIsNotOldShippingAddress = ((oldShippingAddress == null) || (newShippingAddress.OrderAddressId != oldShippingAddress.OrderAddressId)); bool ShippingAddressHasBeenPreviouslySet = (oldShippingAddress != null); bool ShippingAddressIsNotSameAsBillingAddress = (basketHelper.ShippingAddressID != basketHelper.BillingAddressID); bool NewShippingAddressIsNotBillingAddress = (newShippingAddress.OrderAddressId != basketHelper.BillingAddressID); if (NewShippingAddressIsNotOldShippingAddress && ShippingAddressHasBeenPreviouslySet && ShippingAddressIsNotSameAsBillingAddress) { basketHelper.Basket.Addresses.Remove(oldShippingAddress); } if (NewShippingAddressIsNotOldShippingAddress && NewShippingAddressIsNotBillingAddress) { basketHelper.Basket.Addresses.Add(newShippingAddress); } basketHelper.ShippingAddressID = newShippingAddress.OrderAddressId; basketHelper.Basket.Save(); } My initial thought was that if I could pass a class's property by refernce then I could rewrite the previous functions into something like private void SetPurchaseOrderAddress(OrderAddress newAddress, ref String CurrentChangingAddressIDProperty) and then call this function and pass in either basketHelper.BillingAddressID or basketHelper.ShippingAddressID as CurrentChangingAddressIDProperty but since I can't pass C# properties by reference I am not sure what to do with this code to be able to reuse the logic in both places. Thanks for any insight you can give me.

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• Should an event-sourced aggregate root have access to the event sourcing repository?

  - by JD Courtoy

  I'm working on an event-sourced CQRS implementation, using DDD in the application / domain layer. I have an object model that looks like this: public class Person : AggregateRootBase { private Guid? _bookingId; public Person(Identification identification) { Apply(new PersonCreatedEvent(identification)); } public Booking CreateBooking() { // Enforce Person invariants var booking = new Booking(); Apply(new PersonBookedEvent(booking.Id)); return booking; } public void Release() { // Enforce Person invariants // Should we load the booking here from the aggregate repository? // We need to ensure that booking is released as well. var booking = BookingRepository.Load(_bookingId); booking.Release(); Apply(new PersonReleasedEvent(_bookingId)); } [EventHandler] public void Handle(PersonBookedEvent @event) { _bookingId = @event.BookingId; } [EventHandler] public void Handle(PersonReleasedEvent @event) { _bookingId = null; } } public class Booking : AggregateRootBase { private DateTime _bookingDate; private DateTime? _releaseDate; public Booking() { //Enforce invariants Apply(new BookingCreatedEvent()); } public void Release() { //Enforce invariants Apply(new BookingReleasedEvent()); } [EventHandler] public void Handle(BookingCreatedEvent @event) { _bookingDate = SystemTime.Now(); } [EventHandler] public void Handle(BookingReleasedEvent @event) { _releaseDate = SystemTime.Now(); } // Some other business activities unrelated to a person } With my understanding of DDD so far, both Person and Booking are seperate aggregate roots for two reasons: There are times when business components will pull Booking objects separately from the database. (ie, a person that has been released has a previous booking modified due to incorrect information). There should not be locking contention between Person and Booking whenever a Booking needs to be updated. One other business requirement is that a Booking can never occur for a Person more than once at a time. Due to this, I'm concerned about querying the query database on the read side as there could potentially be some inconsistency there (due to using CQRS and having an eventually consistent read database). Should the aggregate roots be allowed to query the event-sourced backing store by id for objects (lazy-loading them as needed)? Are there any other avenues of implementation that would make more sense?

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• Eclipse RCP and JFace: Problems with Images in Context menu and TreeViewer

  - by Juri

  I'm working on an Eclipse RCP application. Today I experienced some troubles when displaying images in the context menu. What I wanted to do is to add a column to my table containing images of stars for representing a user rating. On Windows, this causes some problems, since the star images are squeezed up on the left corner of the table cell instead of expanding on the whole cell, but I'll solve that somehow. In addition I have a context menu on the table, with an entry called "rate" where again the different stars from 1 to 5 (representing the rating level) are shown, such that the user can click on it for choosing different ratings. That works fine on Windows. Now I switched to Linux (Ubuntu) to see how it works out there, and strangely, the stars in the table cell are layed out perfectly, while the stars on the context menu don't even show up. On the context menu I'm using an action class where I'm setting the image descriptor for the star images: public class RateAction extends Action { private final int fRating; private IStructuredSelection fSelection; public RateAction(int rating, IStructuredSelection selection) { super("", AS_CHECK_BOX); fRating = rating; fSelection = selection; setImageDescriptor(createImageDescriptor()); } /** * Creates the correct ImageDescriptor depending on the given rating * @return */ private ImageDescriptor createImageDescriptor() { ImageDescriptor imgDescriptor = null; switch (fRating) { case 0: return OwlUI.NEWS_STARON_0; case 1: return OwlUI.NEWS_STARON_1; case 2: return OwlUI.NEWS_STARON_2; case 3: return OwlUI.NEWS_STARON_3; case 4: return OwlUI.NEWS_STARON_4; case 5: return OwlUI.NEWS_STARON_5; default: break; } return imgDescriptor; } /* * @see org.eclipse.jface.action.Action#getText() */ @Override public String getText() { //return no text, since the images of the stars will be displayed return ""; } ... } Does somebody know why this strange behaviour appears? Thanks a lot. (For some strange reason, the images don't appear. Here are the direct URLs: http://img187.imageshack.us/img187/4427/starsratingho4.png http://img514.imageshack.us/img514/8673/contextmenuproblemgt1.png) //Edit: I did some tries and it seems as if the images just don't appear when using a Checkbox style for the context menu (see constructor of the RateAction). When I switched to a PushButton style, the images appeared, although not correctly scaled, but at least they were shown.

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• Java synchronized method lock on object, or method?

  - by wuntee

  If I have 2 synchronized methods in the same class, but each accessing different variables, can 2 threads access those 2 methods at the same time? Does the lock occur on the object, or does it get as specific as the variables inside the synchronized method? Example: class x{ private int a; private int b; public synchronized void addA(){ a++; } public synchronized void addB(){ b++; } } Can 2 threads access the same instance of class x performing x.addA() and x.addB() at the same time?

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• Easiest way to merge a changed list to the master list

  - by Kiran Chandrashekhar

  I have a two lists of class object : private List<IntVector> UserData = new List<IntVector>(); private List<IntVector> EditData = new List<IntVector>(); UserData is the Master List and EditData is another list which would be used to add, delete, or modify the list. One of the class memeber is CaseNo which would not change for an IntVector. I have made changes in the EditData and would like to merge the changes to the UserData. Any idea how to do it ?

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• C# NotifyIcon behaviour on Windows 7 with MouseClick, MouseDoubleClick events

  - by binball

  Hi, I have strange behaviour with my app after run it on Windows 7. It's connected with NotifyIcon while app is minimized. What should happens: 1) Click once on icon with mouse left button then Balloon with some text should appears 2) Double click on icon will show again app window On Windows 7 MouseDoubleClick is also fired but window is not showing. I don't know why. The same code works good on Windows XP. private void notifyIcon_MouseClick(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { this.NotifyIconShowBalloonWithData(); } } private void notifyIcon_MouseDoubleClick(object sender, MouseEventArgs e) { this.Show(); WindowState = FormWindowState.Normal; notifyIcon.Visible = false; } What did I wrong? :) Thanks in advance for your answer.

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• Unable to Calculate Position within Owner-Draw Text

  - by Jonathan Wood

  I'm trying to use Visual Studio 2012 to create a Windows Forms application that can place the caret at the current position within a owner-drawn string. However, I've been unable to find a way to accurately calculate that position. I've done this successfully before in C++. I've now tried numerous methods in C#. Originally, I tried using .NET classes to determine the correct position, but then I tried accessing the Windows API directly. In some cases, I came close, but after some time I still cannot place the caret accurately. I've created a small test program and posted key parts below. I've also posted the entire project here. The exact font used is not important to me; however, my application assumes a mono-spaced font. Any help is appreciated. Form1.cs This is my main form. public partial class Form1 : Form { private string TestString; private int AveCharWidth; private int Position; public Form1() { InitializeComponent(); TestString = "123456789012345678901234567890123456789012345678901234567890"; AveCharWidth = GetFontWidth(); Position = 0; } private void Form1_Load(object sender, EventArgs e) { Font = new Font(FontFamily.GenericMonospace, 12, FontStyle.Regular, GraphicsUnit.Pixel); } protected override void OnGotFocus(EventArgs e) { Windows.CreateCaret(Handle, (IntPtr)0, 2, (int)Font.Height); Windows.ShowCaret(Handle); UpdateCaretPosition(); base.OnGotFocus(e); } protected void UpdateCaretPosition() { Windows.SetCaretPos(Padding.Left + (Position * AveCharWidth), Padding.Top); } protected override void OnLostFocus(EventArgs e) { Windows.HideCaret(Handle); Windows.DestroyCaret(); base.OnLostFocus(e); } protected override void OnPaint(PaintEventArgs e) { e.Graphics.DrawString(TestString, Font, SystemBrushes.WindowText, new PointF(Padding.Left, Padding.Top)); } protected override bool IsInputKey(Keys keyData) { switch (keyData) { case Keys.Right: case Keys.Left: return true; } return base.IsInputKey(keyData); } protected override void OnKeyDown(KeyEventArgs e) { switch (e.KeyCode) { case Keys.Left: Position = Math.Max(Position - 1, 0); UpdateCaretPosition(); break; case Keys.Right: Position = Math.Min(Position + 1, TestString.Length); UpdateCaretPosition(); break; } base.OnKeyDown(e); } protected int GetFontWidth() { int AverageCharWidth = 0; using (var graphics = this.CreateGraphics()) { try { Windows.TEXTMETRIC tm; var hdc = graphics.GetHdc(); IntPtr hFont = this.Font.ToHfont(); IntPtr hOldFont = Windows.SelectObject(hdc, hFont); var a = Windows.GetTextMetrics(hdc, out tm); var b = Windows.SelectObject(hdc, hOldFont); var c = Windows.DeleteObject(hFont); AverageCharWidth = tm.tmAveCharWidth; } catch { } finally { graphics.ReleaseHdc(); } } return AverageCharWidth; } } Windows.cs Here are my Windows API declarations. public static class Windows { [Serializable, StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct TEXTMETRIC { public int tmHeight; public int tmAscent; public int tmDescent; public int tmInternalLeading; public int tmExternalLeading; public int tmAveCharWidth; public int tmMaxCharWidth; public int tmWeight; public int tmOverhang; public int tmDigitizedAspectX; public int tmDigitizedAspectY; public short tmFirstChar; public short tmLastChar; public short tmDefaultChar; public short tmBreakChar; public byte tmItalic; public byte tmUnderlined; public byte tmStruckOut; public byte tmPitchAndFamily; public byte tmCharSet; } [DllImport("user32.dll")] public static extern bool CreateCaret(IntPtr hWnd, IntPtr hBitmap, int nWidth, int nHeight); [DllImport("User32.dll")] public static extern bool SetCaretPos(int x, int y); [DllImport("User32.dll")] public static extern bool DestroyCaret(); [DllImport("User32.dll")] public static extern bool ShowCaret(IntPtr hWnd); [DllImport("User32.dll")] public static extern bool HideCaret(IntPtr hWnd); [DllImport("gdi32.dll", CharSet = CharSet.Auto)] public static extern bool GetTextMetrics(IntPtr hdc, out TEXTMETRIC lptm); [DllImport("gdi32.dll")] public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj); [DllImport("GDI32.dll")] public static extern bool DeleteObject(IntPtr hObject); }

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• How to handle JPA annotations for a pointer to a generic interface

  - by HDave

  I have a generic class that is also a mapped super class that has a private field that holds a pointer to another object of the same type: @MappedSuperclass public abstract class MyClass<T extends MyIfc<T>> implements MyIfc<T> { @OneToOne() @JoinColumn(name = "previous", nullable = true) private T previous; ... } My problem is that Eclipse is showing an error in the file at the OneToOne "Target Entity "T" for previous is not an Entity." All of the implementations of MyIfc are, in fact, Entities. I should also add that each concrete implementation that inherit from MyClass uses a different value for T (because T is itself) so I can't use the "targetEntity" attribute. I guess if there is no answer then I'll have to move this JPA annotation to all the concrete subclasses of MyClass. It just seems like JPA/Hibernate should be smart enough to know it'll all work out at run-time. Makes me wonder if I should just ignore this error somehow.

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• Catching constraint violations in JPA 2.0.

  - by Dennetik

  Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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• C# property definition

  - by Sunny

  For C# properties, I can do this: public class Employee{ public string Name { get; private set; } public Employee(string name){ Name = name; } } which means that the Name property can be set within the class Employee & can be read publicly. But, if I want to restrict the set to only within the constructors of the Employee class, I need to do: public class Employee{ public readonly string Name = String.Empty; public Employee(string name){ Name = name; } } But, for this case, I had to change the property to a field. Is there any reason this is not possible/allowed in C#: public class Employee{ public string Name { get; private readonly set; } public Employee(string name){ Name = name; } } IMO this will allow us to have properties which can be set only in the constructor & does not require us to change properties to fields... Thanks!

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• Extending mysqli and using multiple classes

  - by Mikk

  Hi, I'm new to PHP oop stuff. I'm trying to create class database and call other classes from it. Am I doing it the right way? class database: class database extends mysqli { private $classes = array(); public function __construct() { parent::__construct('localhost', 'root', 'password', 'database'); if (mysqli_connect_error()) { $this->error(mysqli_connect_errno(), mysqli_connect_error()); } } public function __call($class, $args) { if (!isset($this->classes[$class])) { $class = 'db_'.$class; $this->classes[$class] = new $class(); } return $this->classes[$class]; } private function error($eNo, $eMsg) { die ('MySQL error: ('.$eNo.': '.$eMsg); } } class db_users: class db_users extends database { public function test() { echo 'foo'; } } and how I'm using it $db = new database(); $db->users()->test(); Is it the right way or should it be done another way? Thank you.

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