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  • How to create digital signature that can not be used to reproduce the message twice

    - by freediver
    I am creating a client-server application and I'd like to send data from server to client securely. Using public/private key algorithms makes sense and in PHP we can use openssl_sign and openssl_verify functions to check that the data came by someone who has the private key. Now imagine that one of the actions sent by server to client is destructive in nature. If somebody uses an HTTP sniffer to catch this command (which will be signed properly) how can I further protect the communication to ensure that only commands coming from our server get processed by the client? I was thinking about using current UTC time as part of the encrypted data but client time might be off. Is there a simple solution to the problem?

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  • Task.wait not working as I imagined

    - by user2357446
    I am trying to download a file, wait for the file to finish downloading, and then read the file afterwards. I have the following methods to do this: private async Task startDownload(string link, string savePath) { WebClient client = new WebClient(); client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged); client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted); await client.DownloadFileTaskAsync(new Uri(link), savePath); } private void checkUpdateButton_Click(object sender, EventArgs e) { Task task = Task.Factory.StartNew(() => startDownload(versionLink, versionSaveTo)); task.Wait(); if (task.IsCompleted) { checkVersion(); } } The checkVersion() method reads the file that was downloaded. This is throwing an IOException saying that the file is in use by something else and cannot be read. I thought that having task.Wait would prevent the rest of the method from executing until the task was finished?

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  • Issues querying Access '07 database in C#

    - by Kye
    I'm doing a .NET unit as part of my studies. I've only just started, with a lecturer that as kinda failed to give me the most solid foundation with .NET, so excuse the noobishness. I'm making a pretty simple and generic database-driven application. I'm using C# and I'm accessing a Microsoft Access 2007 database. I've put the database-ish stuff in its own class with the methods just spitting out OleDbDataAdapters that I use for committing. I feed any methods which preform a query a DataSet object from the main program, which is where I'm keeping the data (multiple tables in the db). I've made a very generic private method that I use to perform SQL SELECT queries and have some public methods wrapping that method to get products, orders.etc (it's a generic retail database). The generic method uses a separate Connect method to actually make the connection, and it is as follows: private static OleDbConnection Connect() { OleDbConnection conn = new OleDbConnection( @"Provider=Microsoft.ACE.OLEDB.12.0; Data Source=C:\Temp\db.accdb"); return conn; } The generic method is as follows: private static OleDbDataAdapter GenericSelectQuery( DataSet ds, string namedTable, String selectString) { OleDbCommand oleCommand = new OleDbCommand(); OleDbConnection conn = Connect(); oleCommand.CommandText = selectString; oleCommand.Connection = conn; oleCommand.CommandType = CommandType.Text; OleDbDataAdapter adapter = new OleDbDataAdapter(); adapter.SelectCommand = oleCommand; adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey; adapter.Fill(ds, namedTable); return adapter; } The wrapper methods just pass along the DataSet that they received from the main program, the namedtable string is the name of the table in the dataset, and you pass in the query you wish to make. It doesn't matter which query I give it (even something simple like SELECT * FROM TableName) I still get thrown an OleDbException, stating that there was en error with the FROM clause of the query. I've just resorted to building the queries with Access, but there's still no use. Obviously there's something wrong with my code, which wouldn't actually surprise me. Here are some wrapper methods I'm using. public static OleDbDataAdapter GetOrderLines(DataSet ds) { OleDbDataAdapter adapter = GenericSelectQuery( ds, "orderlines", "SELECT OrderLine.* FROM OrderLine;"); return adapter; } They all look the same, it's just the SQL that changes.

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  • Two loops speeds drawing in a Jframe

    - by noahn567
    I have a program that requires two classes. The player-Names class, and the Player-Model class. I want the player-Names class to repaint every half second, and the Player-Model class to repaint 60 times per second because i want the movement to be smooth. The problem that i am having is that i want all of this to be done on one J-frame. How would i go about doing this? If you could lead me in the right direction or give me a little example that would be great! Thank you :). for some reason it wont let me post so i'm going to put in some random code import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import javax.swing.JComponent; import javax.swing.JFrame; public class PlayerNames extends JFrame { static int connectionTimer = 0; static int connectionTimer2 = 0; static int reconnect = 0; static int reconnectValue = 1; static int x = 0; static int reconnectWait = connectionTimer + reconnectValue; private static final long serialVersionUID = 1L; public graph gg = new graph(); public graph g = new graph(); private static GameClient socketClient; private GameServer socketServer; public static void main(int width, int height) { PlayerNames tt = new PlayerNames(); // PlayerGraphics t = new PlayerGraphics(); tt.setSize(width, height); if (Game.ServerOwner == 1) { tt.setTitle("Server: " + Game.username); } else { tt.setTitle("Username: " + Game.username); } tt.setVisible(true); tt.getContentPane().add(tt.gg); tt.getContentPane().add(tt.g); tt.setDefaultCloseOperation(EXIT_ON_CLOSE); tt.setResizable(false); }

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  • How to use Delegate in C# for Dictionary<int, List<string>>

    - by Emanuel
    The code: private delegate void ThreadStatusCallback(ReceiveMessageAction action, Dictionary<int, List<string>> message); ... Dictionary<int, List<string>> messagesForNotification = new Dictionary<int, List<string>>(); ... Invoke(new ThreadStatusCallback(ReceivesMessagesStatus), ReceiveMessageAction.Notification , messagesForNotification ); ... private void ReceivesMessagesStatus(ReceiveMessageAction action, object value) { ... } How can I send the two variable of type ReceiveMessageAction respectively Dictionary<int, List<string>> to the ReceivesMessagesStatus method. Thanks.

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  • Accessing a Clip Inside Another Clip in a Loaded SWF-File

    - by Anders
    I'm writing a card game in AS3. The artist I'm working with has produced (in Flash CS4) a single swf-file containing all the card graphics and animations. The structure of the fla working file looks something like this: - Scene - CardGraphics (Movie Clip) - CardFront - CardBack - CardValueImage (Movie Clip) ... In the program I create 52 instances of my Card class, each having a MovieClip instance created from the loaded swf. The idea is to set the frame of the CardValueImage MovieClip to correspond to the Card instance's suit and rank member variables. However, I can't figure out how I access CardValueImage and call gotoAndStop (or whatever method I will need to call). This is basically what I want to do: // Card Class [Embed(source = 'CardGraphics.swf')] private static var CardsClip:Class; private var clip:MovieClip = new CardsClip; // Card Constructor this.valueImageFrame = suit * 13 + rank; // Calculate which frame contains the // graphical representation of this card this.clip.CardValueImage.gotoAndStop(valueImageFrame);

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  • using a Singleton to pass credentials in a multi-tenant application a code smell?

    - by Hans Gruber
    Currently working on a multi-tenant application that employs Shared DB/Shared Schema approach. IOW, we enforce tenant data segregation by defining a TenantID column on all tables. By convention, all SQL reads/writes must include a Where TenantID = '?' clause. Not an ideal solution, but hindsight is 20/20. Anyway, since virtually every page/workflow in our app must display tenant specific data, I made the (poor) decision at the project's outset to employ a Singleton to encapsulate the current user credentials (i.e. TenantID and UserID). My thinking at the time was that I didn't want to add a TenantID parameter to each and every method signature in my Data layer. Here's what the basic pseudo-code looks like: public class UserIdentity { public UserIdentity(int tenantID, int userID) { TenantID = tenantID; UserID = userID; } public int TenantID { get; private set; } public int UserID { get; private set; } } public class AuthenticationModule : IHttpModule { public void Init(HttpApplication context) { context.AuthenticateRequest += new EventHandler(context_AuthenticateRequest); } private void context_AuthenticateRequest(object sender, EventArgs e) { var userIdentity = _authenticationService.AuthenticateUser(sender); if (userIdentity == null) { //authentication failed, so redirect to login page, etc } else { //put the userIdentity into the HttpContext object so that //its only valid for the lifetime of a single request HttpContext.Current.Items["UserIdentity"] = userIdentity; } } } public static class CurrentUser { public static UserIdentity Instance { get { return HttpContext.Current.Items["UserIdentity"]; } } } public class WidgetRepository: IWidgetRepository{ public IEnumerable<Widget> ListWidgets(){ var tenantId = CurrentUser.Instance.TenantID; //call sproc with tenantId parameter } } As you can see, there are several code smells here. This is a singleton, so it's already not unit test friendly. On top of that you have a very tight-coupling between CurrentUser and the HttpContext object. By extension, this also means that I have a reference to System.Web in my Data layer (shudder). I want to pay down some technical debt this sprint by getting rid of this singleton for the reasons mentioned above. I have a few thoughts on what an better implementation might be, but if anyone has any guidance or lessons learned they could share, I would be much obliged.

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  • Silencing GCC warnings when using an "Uncopyable" class

    - by Kazade
    I have several classes that I don't want to be copyable, some of these classes have pointer data members. To make these classes uncopyable I privately inherit the following class template: template <class T> class Uncopyable { protected: Uncopyable() {} virtual ~Uncopyable() {} private: Uncopyable(const Uncopyable &); T & operator=(const T&); }; Which I used like so: class Entity : private Uncopyable<Entity> { } This works fine, however when I compile with -Weffc++ I still get the following warning: class Entity has pointer data members but does not override Entity(const Entity&) or operator=(const Entity&) Why is it still giving me this warning?

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  • Read Call History from iPhone on iOS 5 and above

    - by Sandeep Dhama
    I am developing an application and need to read the users call history from iPhone.I have go though all the forums and google it and found that we can get the records from teh callHistory sqlite database by "private/var/root/Library/CallHistory/call_history.db". But this path is not working from iOS 5 and above. Seems like apple has changed all their database path and structure so that no one can accees it. I have also seen some of the application on iTunes who are capable of getting the users call history like:-https://itunes.apple.com/us/app/callog/id327883585?mt=8 I have also check a mac desktop utility called "WonderShare Dr.Fone" which will fetch all the data from your iPhone like call history messages, notes , etc.How this utility is fetching the call history records and other details? If their is any API or private APIs by which i can get the callHistory data path please let me know.

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  • Change array structure in PHP.

    - by Muhammad Sajid
    Refers to my previous question : Show values in TDropDownList in PRADO. ok fine the array i receive from query is an object array like : ContactRecord Object ( [id] => 1 [name] => leo [_recordState:protected] => 1 [_connection:protected] => [_invalidFinderResult:protected] => [_e:TComponent:private] => Array ( ) ) ContactRecord Object ( [id] => 2 [name] => ganda [_recordState:protected] => 1 [_connection:protected] => [_invalidFinderResult:protected] => [_e:TComponent:private] => Array ( ) ) If I convert it in to array like: Array ( [key 1] => leo [key 2] => ganda ) then I can populate values into TDropDownList. Now can anyone help me to convert array structure which I need ... ? Again thanks

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  • Is it a bad idea to use the new Dynamic Keyword as a replacement switch statement?

    - by WeNeedAnswers
    I like the new Dynamic keyword and read that it can be used as a replacement visitor pattern. It makes the code more declarative which I prefer. Is it a good idea though to replace all instances of switch on 'Type' with a class that implements dynamic dispatch. class VistorTest { public string DynamicVisit(object obj) { return Visit((dynamic)obj); } private string Visit(string str) { return "a string was called with value " + str; } private string Visit(int value) { return "an int was called with value " + value; } }

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  • Using Function return in global variable vb.net

    - by Cold Assassin
    Can't seem to figure out how to use a function return variable in global Dims example code: Public Class Main Dim Path As String = FixPath() Dim fixwrongtxt As String = Path & "tryme.txt" Private Sub Main_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load FixPath() On_load() End Sub Private Function FixPath() As String Path = "C:\test" MsgBox(Path) //First Message Box' Return Path End Function Sub On_load() MsgBox(fixwrongtxt) //Second Message Box End Sub End Class when I run it all I get the first message box that contains "C:\test" and I click ok and on the second messagebox I get "custom.dll" with out the "C:\test" or "Path Return" What am I doing wrong? I know I can't use // in vb.net. I have also tried adding "FixPath()" under Sub On_load() but got same result. Also the reason I have to have these global is because I have around 30 Subs that refer to "Path" Variable... Thanks

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  • .NET XmlSerializer fails with List<T>

    - by Redshirt
    I'm using a singleton class to save all my settings info. It's first utilized by calling Settings.ValidateSettings(@"C:\MyApp"). The problem I'm having is that 'List Contacts' is causing the xmlserializer to fail to write the settings file, or to load said settings. If I comment out the List<T> then I have no problems saving/loading the xml file. What am I doing wrong? // The actual settings to save public class MyAppSettings { public bool FirstLoad { get; set; } public string VehicleFolderName { get; set; } public string ContactFolderName { get; set; } public List<ContactInfo> Contacts { get { if (contacts == null) contacts = new List<ContactInfo>(); return contacts; } set { contacts = value; } } private List<ContactInfo> contacts; } // The class in which the settings are manipulated public static class Settings { public static string SettingPath; private static MyAppSettings instance; public static MyAppSettings Instance { get { if (instance == null) instance = new MyAppSettings(); return instance; } set { instance = value; } } public static void InitializeSettings(string path) { SettingPath = Path.GetFullPath(path + "\\MyApp.xml"); if (File.Exists(SettingPath)) { LoadSettings(); } else { Instance.FirstLoad = true; Instance.VehicleFolderName = "Cars"; Instance.ContactFolderName = "Contacts"; SaveSettingsFile(); } } // load the settings from the xml file private static void LoadSettings() { XmlSerializer ser = new XmlSerializer(typeof(MyAppSettings)); TextReader reader = new StreamReader(SettingPath); Instance = (MyAppSettings)ser.Deserialize(reader); reader.Close(); } // Save the settings to the xml file public static void SaveSettingsFile() { XmlSerializer ser = new XmlSerializer(typeof(MyAppSettings)); TextWriter writer = new StreamWriter(SettingPath); ser.Serialize(writer, Settings.Instance); writer.Close(); } public static bool ValidateSettings(string initialFolder) { try { Settings.InitializeSettings(initialFolder); } catch (Exception e) { return false; } // Do some validation logic here return true; } } // A utility class to contain each contact detail public class ContactInfo { public string ContactID; public string Name; public string PhoneNumber; public string Details; public bool Active; public int SortOrder; }

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  • xml to xsd to c# class - C# 3.0, .net 3.5

    - by uno
    Following this articlelink text one of the comments from 'zanoni' said he did it this way Using .NET 3.5: [XmlRoot] public class EmailConfiguration { [XmlElement] public string DataBoxID { get; set; } [XmlElement] public DefaultSendToAddressCollectionClass DefaultSendToAddressCollection { get; set; } } public class DefaultSendToAddressCollectionClass { [XmlElement] public string[] EmailAddress { get; set; } } How would I get my class to be as what he described? I ran the xsd tool and it is in the fashion as what shane posted in the above link [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class EmailConfiguration : object, System.ComponentModel.INotifyPropertyChanged { private string dataBoxIDField; private EmailConfigurationDefaultSendToAddressCollection[] defaultSendToAddressCollectionField; /// <remarks/> [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] public string DataBoxID { get { return this.dataBoxIDField; } set { this.dataBoxIDField = value; this.RaisePropertyChanged("DataBoxID"); } }

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  • External SWF Loading problem

    - by Glycerine
    I have an SWF loading in an SWF containing a papervision scene. I've done it before yet problem is, I get an error - I'm not sure what the issue really is. private function downloadSWF(url:String):void { trace(url); var urlRequest:URLRequest = new URLRequest(url); var loader:Loader = new Loader(); loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, loaderProgressEventHandler); loader.load(urlRequest); } private function loaderProgressEventHandler(ev:ProgressEvent):void { loader.preloaderCircle.percent = ev.bytesLoaded / ev.bytesTotal; } When the application runs the code - I get the error: TypeError: Error #1009: Cannot access a property or method of a null object reference. at com.dehash.pv3d.examples.physics::WowDemo() Why am I getting this if the loading hasn't even complete yet? Thanks in advance guys.

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  • Doubt in abstract classes

    - by mohit
    public abstract class Person { private String name; public Person(String name) { this.name = name; System.out.println("Person"); } public String getName() { return name; } abstract public String getDescription(); } public class Student extends Person { private String major; public Student(String name, String major) { super(name); this.major = major; } public String getMajor() { return major; } @Override public String getDescription() { return "student" + super.getName() + " having" + major; } } public class PersonTest { public static void main(String[] args) { Person person = new Student("XYZ", "ABC"); System.out.println(person.getDescription()); } } Ques: We cannot create objects of abstract classes, then why Person Constructor has been invoked, even its an abstract class?

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  • Is an ArrayList automaticaly declared static ,if it is an instance variable?(Java)

    - by Alex
    Hy ,what i`m trying to do is something like this: private class aClass { private ArrayList idProd; aClass(ArrayList prd) { this.idProd=new ArrayList(prd); } public ArrayList getIdProd() { return this.idProd; } } So if i have multiple instances of ArrayLIst (st1 ,st2 ,st3) and I want to make new objects of aClass : { aClass obj1,obj2,obj3; obj1=new aClass(st1); obj2=new aClass(st2); obj3=new aClass(st3); }why all of the aClass objects will return st3 if I access the method getIdProd() for each of them(obj1..obj3)? is an arraylist as a instance variable automatically declared static?

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  • Two components offering the same functionality, required by different dependencies

    - by kander
    I'm building an application in PHP, using Zend Framework 1 and Doctrine2 as the ORM layer. All is going well. Now, I happened to notice that both ZF1 and Doctrine2 come with, and rely on, their own caching implementation. I've evaluated both, and while each has its own pro's and cons, neither of them stand out as superior to the other for my simple needs. Both libraries also seem to be written against their respective interfaces, not their implementations. Reasons why I feel this is an issue is that during the bootstrapping of my application, I have to configure two caching drivers - each with its own syntax. A mismatch is easily created this way, and it feels inefficient to set up two connections to the caching backend because of this. I'm trying to determine what the best way forward is, and would welcome any insights you may be able to offer. What I've thought up so far are four options: Do nothing, accept that two classes offering caching functionality are present. Create a Facade class to stick Zend's interface onto Doctrine's caching implementation. Option 2, the other way around - create a Facade to map Doctrine's interface on a Zend Framework backend. Use multiple-interface-inheritance to create one interface to rule them all, and pray that there aren't any overlaps (ie: if both have a "save" method, they'll need to accept params in the same order due to PHP's lack of proper polymorphism). What option is best, or is there a "None of the above" variant that I'm not aware of?

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  • Flex DataGrid not Displaying Data

    - by asawilliams
    I have a custom dataGrid that acts more like a 2D list (if that makes sense at all). I am dynamically creating the columns and recreating the dataProvider to suit my needs. While debugging I can see that I am creating the columns and setting them to the dataGrid and creating and setting the dataProvider, but for some reason I am able to see the dataGrid and the columns but not the data. [Bindable] private var mockData:ArrayCollection = new ArrayCollection([ {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}, {value: "425341*"}]); ... <TwoDimensionalList width="100%" height="100%" numColumns="7" numRows="7" dataField="value" dataProvider="{mockData}"/> The snippet of code from the object only contains the important functions, everything else is not important (getters, setters, etc ...). While debugging I checked all the variables in the functions to make sure they were assigned and a value that I was expecting. [Snippet] public class TwoDimensionalList extends DataGrid { ... /** * Creates and sets properties of columns */ private function createColumns():void { var column:DataGridColumn; var cols:Array = this.columns; for(var i:uint=0; i < numColumns; i++) { column = new DataGridColumn("column"+i.toString()); column.dataField = "column"+i.toString(); cols[i]=column; } this.columns = cols; // go to the current gotoPage(this._currentPageNum); } /** * Sets the data for the dataprovider based on the * number of columns, rows, and page number. * * @param pageNum the page number of the data to be viewed in the DataGrids. */ private function gotoPage(pageNum:uint):void { _currentPageNum = pageNum; var startIndex:uint = (pageNum-1)*numColumns*numRows; var data:ArrayCollection = new ArrayCollection(); for(var i:uint=0; i < numRows; i++) { var obj:Object = new Object(); for(var j:uint=0; j < numColumns; j++) { if((i+(j*numRows)+startIndex) < _dataProvider.length) obj["column"+j.toString()] = String(_dataProvider.getItemAt(i+(j*numRows)+startIndex)["value"]); } data.addItem(obj); } this.dataProvider = data; } }

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  • VB.NET Window Screen Capture (ALT+PRINTSCREEN)

    - by Steve Thomas
    Hi, I found that code somewhere and I find it quite useful but I would like to find a way to make it work so it capture only the given window target. Maybe with a processID or Window Name. Even if that window is not active. I do not want to make that window active but want to get a screen capture like if I was doing Alt+PrintScreen on it. Here is the code that works for full Screen Capture Private bmpScreenShot As Bitmap Private gfxScreenshot As Graphics bmpScreenShot = New Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb) gfxScreenshot = Graphics.FromImage(bmpScreenShot) gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy) bmpScreenShot.Save(fileName, ImageFormat.Png) I use the Visual Basic 2008 Express Thank you in advance!

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  • Selecting based on __key__ (a unique identifier) in google appengine [Java]

    - by Stavros
    I have public class QuantityType { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent private String type; } I am trying to setup a query to get the right QuantityType by it's key gql = "select * from QuantityType where __key__='aght52oobW1hIHTWVzc2FnZRiyAQw'"; But its not working because BadFilterError: BadFilterError: invalid filter: key filter value must be a Key; received aght52oobW1hIHTWVzc2FnZRiyAQw (a str). I have also tried to use gql = "select * from QuantityType where __key__=='" + KeyFactory.stringToKey(qTypeKey)+"'"; but it's now working.. How can I get a specific object from my datastore by it's key?

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  • Why does setting a form's enabled property crash the application?

    - by Ruirize
    private void launchbutton_Click(object sender, EventArgs e) { launchbutton.Enabled = false; Process proc = new Process(); proc.EnableRaisingEvents = true; proc.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden; //The arguments/filename is set here, just removed for privacy. proc.Exited += new EventHandler(procExit); proc.Start(); } private void procExit(object sender, EventArgs e) { MessageBox.Show("YAY","WOOT"); Thread.Sleep(2000); launchbutton.Enabled = true; } 2 Seconds after I quit the created process, my program crashes. Why?

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  • Sessions not persisting between requests

    - by klonq
    My session objects are only stored within the request scope on google app engine and I can't figure out how to persist objects between requests. The docs are next to useless on this matter and I can't find anyone who's experienced a similar problem. Please help. When I store session objects in the servlet and forward the request to a JSP using: getServletContext().getRequestDispatcher("/example.jsp").forward(request,response); Everything works like it should. But when I store objects to the session and redirect the request using: response.sendRedirect("/example/url"); The session objects are lost to the ether. In fact when I dump session key/value pairs on new requests there is absolutely nothing, session objects only appear within the request scope of servlets which create session objects. It appears to me that the objects are not being written to Memcache or Datastore. In terms of configuring sessions for my application I have set <sessions-enabled>true</sessions-enabled> In appengine-web.xml. Is there anything else I am missing? The single paragraph of documentation on sessions also notes that only objects which implement Serializable can be stored in the session between requests. I have included an example of the code which is not working below. The obvious solution is to not use redirects, and this might be ok for the example given below but some application data does need to be stored in the session between requests so I need to find a solution to this problem. EXAMPLE: The class FlashMessage gives feedback to the user from server-side operations. if (email.send()) { FlashMessage flash = new FlashMessage(FlashMessage.SUCCESS, "Your message has been sent."); session.setAttribute(FlashMessage.SESSION_KEY, flash); // The flash message will not be available in the session object in the next request response.sendRedirect(URL.HOME); } else { FlashMessage flash = new FlashMessage(FlashMessage.ERROR, FlashMessage.INVALID_FORM_DATA); session.setAttribute(FlashMessage.SESSION_KEY, flash); // The flash message is displayed without problem getServletContext().getRequestDispatcher(Templates.CONTACT_FORM).forward(request,response); } FlashMessage.java import java.io.Serializable; public class FlashMessage implements Serializable { private static final long serialVersionUID = 8109520737272565760L; // I have tried using different, default and no serialVersionUID public static final String SESSION_KEY = "flashMessage"; public static final String ERROR = "error"; public static final String SUCCESS = "success"; public static final String INVALID_FORM_DATA = "Your request failed to validate."; private String message; private String type; public FlashMessage (String type, String message) { this.type = type; this.message = message; } public String display(){ return "<div id='flash' class='" + type + "'>" + message + "</div>"; } }

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  • Cnoverting application to MVC architecture

    - by terence6
    I'm practicing writing MVC applications. I have a Mastermind game, that I would like to rewrite as MVC app. I have divided my code to parts, but instead of working game I'm getting empty Frame and an error in "public void paint( Graphics g )". Error comes from calling this method in my view with null argument. But how to overcome this ? MVC was quite simple with swing but awt and it's paint methods are much more complicated. Code of working app : http://paste.pocoo.org/show/224982/ App divided to MVC : Main : public class Main { public static void main(String[] args){ Model model = new Model(); View view = new View("Mastermind", 400, 590, model); Controller controller = new Controller(model, view); view.setVisible(true); } } Controller : import java.awt.*; import java.awt.event.*; public class Controller implements MouseListener, ActionListener { private Model model; private View view; public Controller(Model m, View v){ model = m; view = v; view.addWindowListener( new WindowAdapter(){ public void windowClosing(WindowEvent e){ System.exit(0); } }); view.addMouseListener(this); } public void actionPerformed( ActionEvent e ) { if(e.getSource() == view.checkAnswer){ if(model.isRowFull){ model.check(); } } } public void mousePressed(MouseEvent e) { Point mouse = new Point(); mouse = e.getPoint(); if (model.isPlaying){ if (mouse.x > 350) { int button = 1 + (int)((mouse.y - 32) / 50); if ((button >= 1) && (button <= 5)){ model.fillHole(button); } } } } public void mouseClicked(MouseEvent e) {} public void mouseReleased(MouseEvent e){} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} } View : import java.awt.*; import javax.swing.*; import java.awt.event.*; public class View extends Frame implements ActionListener { Model model; JButton checkAnswer; private JPanel button; static final int HIT_X[] = {270,290,310,290,310}, HIT_Y[] = {506,496,496,516,516}; public View(String name, int w, int h, Model m){ model = m; setTitle( name ); setSize( w,h ); setResizable( false ); this.setLayout(new BorderLayout()); button = new JPanel(); button.setSize( new Dimension(400, 100)); button.setVisible(true); checkAnswer = new JButton("Check"); checkAnswer.addActionListener(this); checkAnswer.setSize( new Dimension(200, 30)); button.add( checkAnswer ); this.add( button, BorderLayout.SOUTH); button.setVisible(true); for ( int i=0; i < model.SCORE; i++ ){ for ( int j = 0; j < model.LINE; j++ ){ model.pins[i][j] = new Pin(20,0); model.pins[i][j].setPosition(j*50+30,510-i*50); model.pins[i+model.SCORE][j] = new Pin(8,0); model.pins[i+model.SCORE][j].setPosition(HIT_X[j],HIT_Y[j]-i*50); } } for ( int i=0; i < model.LINE; i++ ){ model.pins[model.OPTIONS][i] = new Pin( 20, i+2 ); model.pins[model.OPTIONS][i].setPosition( 370,i * 50 + 56); } model.combination(); model.paint(null); } public void actionPerformed( ActionEvent e ) { } } Model: import java.awt.*; public class Model extends Frame{ static final int LINE = 5, SCORE = 10, OPTIONS = 20; Pin pins[][] = new Pin[21][LINE]; int combination[] = new int[LINE]; int curPin = 0; int turn = 1; int repaintPin; boolean isUpdate = true, isPlaying = true, isRowFull = false; public Model(){ } void fillHole(int color) { pins[turn-1][curPin].setColor(color+1); repaintPins( turn ); curPin = (curPin+1) % LINE; if (curPin == 0){ isRowFull = true; } } public void paint( Graphics g ) { g.setColor( new Color(238, 238, 238)); g.fillRect( 0,0,400,590); for ( int i=0; i < pins.length; i++ ) { pins[i][0].paint(g); pins[i][1].paint(g); pins[i][2].paint(g); pins[i][3].paint(g); pins[i][4].paint(g); } } public void update( Graphics g ) { if ( isUpdate ) { paint(g); } else { isUpdate = true; pins[repaintPin-1][0].paint(g); pins[repaintPin-1][1].paint(g); pins[repaintPin-1][2].paint(g); pins[repaintPin-1][3].paint(g); pins[repaintPin-1][4].paint(g); } } void repaintPins( int pin ) { repaintPin = pin; isUpdate = false; repaint(); } void check() { int junkPegs[] = new int[LINE], junkCode[] = new int[LINE]; int pegCount = 0, pico = 0; for ( int i = 0; i < LINE; i++ ) { junkPegs[i] = pins[turn-1][i].getColor(); junkCode[i] = combination[i]; } for ( int i = 0; i < LINE; i++ ){ if (junkPegs[i]==junkCode[i]) { pins[turn+SCORE][pegCount].setColor(1); pegCount++; pico++; junkPegs[i] = 98; junkCode[i] = 99; } } for ( int i = 0; i < LINE; i++ ){ for ( int j = 0; j < LINE; j++ ) if (junkPegs[i]==junkCode[j]) { pins[turn+SCORE][pegCount].setColor(2); pegCount++; junkPegs[i] = 98; junkCode[j] = 99; j = LINE; } } repaintPins( turn+SCORE ); if ( pico == LINE ){ isPlaying = false; } else if ( turn >= 10 ){ isPlaying = false; } else{ curPin = 0; isRowFull = false; turn++; } } void combination() { for ( int i = 0; i < LINE; i++ ){ combination[i] = 1 + (int)(Math.random()*5); System.out.print(i+","); } } } class Pin{ private int color, X, Y, radius; private static final Color COLORS[] = { Color.black, Color.white, Color.red, Color.yellow, Color.green, Color.blue, new Color(7, 254, 250)}; public Pin(){ X = 0; Y = 0; radius = 0; color = 0; } public Pin( int r,int c ){ X = 0; Y = 0; radius = r; color = c; } public void paint( Graphics g ){ int x = X-radius; int y = Y-radius; if (color > 0){ g.setColor( COLORS[color]); g.fillOval( x,y,2*radius,2*radius ); } else{ g.setColor( new Color(238, 238, 238) ); g.drawOval( x,y,2*radius-1,2*radius-1 ); } g.setColor( Color.black ); g.drawOval( x,y,2*radius,2*radius ); } public void setPosition( int x,int y ){ this.X = x ; this.Y = y ; } public void setColor( int c ){ color = c; } public int getColor() { return color; } } Any clues on how to overcome this would be great. Have I divided my code improperly ?

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  • User Control as container

    - by Luca
    I'm designing a simple expander control. I've derived from UserControl, drawn inner controls, built, run; all ok. Since an inner Control is a Panel, I'd like to use it as container at design time. Indeed I've used the attributes: [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] Great I say. But it isn't... The result is that I can use it as container at design time but: The added controls go back the inner controls already embedded in the user control Even if I push to top a control added at design time, at runtime it is back again on controls embedded to the user control I cannot restrict the container area at design time into a Panel area What am I missing? Here is the code for completeness... why this snippet of code is not working? [Designer(typeof(ExpanderControlDesigner))] [Designer("System.Windows.Forms.Design.ParentControlDesigner, System.Design", typeof(IDesigner))] public partial class ExpanderControl : UserControl { public ExpanderControl() { InitializeComponent(); .... [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] internal class ExpanderControlDesigner : ControlDesigner { private ExpanderControl MyControl; public override void Initialize(IComponent component) { base.Initialize(component); MyControl = (ExpanderControl)component; // Hook up events ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); s.SelectionChanged += new EventHandler(OnSelectionChanged); c.ComponentRemoving += new ComponentEventHandler(OnComponentRemoving); } private void OnSelectionChanged(object sender, System.EventArgs e) { } private void OnComponentRemoving(object sender, ComponentEventArgs e) { } protected override void Dispose(bool disposing) { ISelectionService s = (ISelectionService)GetService(typeof(ISelectionService)); IComponentChangeService c = (IComponentChangeService)GetService(typeof(IComponentChangeService)); // Unhook events s.SelectionChanged -= new EventHandler(OnSelectionChanged); c.ComponentRemoving -= new ComponentEventHandler(OnComponentRemoving); base.Dispose(disposing); } public override System.ComponentModel.Design.DesignerVerbCollection Verbs { get { DesignerVerbCollection v = new DesignerVerbCollection(); v.Add(new DesignerVerb("&asd", new EventHandler(null))); return v; } } } I've found many resources (Interaction, designed, limited area), but nothing was usefull for being operative...

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