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• datatables.net plugin hides table behind left menu

  - by naveen

  I had a page that works perfectly in IE. Then I added the wonderful jQuery plugin datatables.net to it using this code in DOMReady with this code $('#articlestable-container table').dataTable({ "bPaginate": true, "bLengthChange": false, "bFilter": true, "bSort": false, "bInfo": false, "bAutoWidth": false }); Everything is fine in Webkit and Firefox browsers. See the image. But in IE, the table hides the menu that ideally should come over the table like this. As you can see, the sub-menu gets rendered behind the table. I don't think z-index is the culprit here. The sub-menu has z-index: 9999; anyway. What could be wrong? Any pointers to solve this will be very helpful.

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• Another C question

  - by maddy

  Hi all, I have a piece of code shown below #include <stdio.h> #include <stdlib.h> void Advance_String(char [2],int ); int Atoi_val; int Count22; int Is_Milestone(char [2],int P2); char String[2] = "00"; main() { while(1) { if(Is_Milestone(S,21==1) { if(atoi(S)==22) { Count_22 = Count_22 + 1; } } Atoi_val = atoi(S); Advance_String(S,Atoi_val); } } int Is_Milestone(char P1[2],int P2) { int BoolInit; char *Ptr = P1; int value = atoi(Ptr); BoolInit = (value > P2); return BoolInit; } void Advance_String(char P1[2],int Value) { if(Value!=7) { P1[1] = P1[1]+1; } else { P1[1] = '0'; P1[0] = P1[0]+1 ; } } Now my problem is Count22 never increments as the char increments never achieves the value 21 or above.Could anyone please tell me the reason for this unexpected behaviour?My question here is to find the value of Count22.Is there any problem with the code? Thanks and regards Maddy

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• How to check if a Statistics is auto-created in a SQL Server 2000 DB using T-SQL?

  - by The Shaper

  Hi all. A while back I had to come up with a way to clean up all indexes and user-created statistics from some tables in a SQL Server 2005 database. After a few attempts it worked, but now I gotta have it working in SQL Server 2000 databases as well. For SQL Server 2005, I used SELECT Name FROM sys.stats WHERE object_id = object_id(@tableName) AND auto_created = 0 to fetch Statistics that were user-created. However, SQL 2000 doesn't have a sys.stats table. I managed to fetch the indexes and statistics in a distinguishable way from the sysindexes table, but I just couldn't figure out what the sys.stats.auto_created match is for SQL 2000. Any pointers? BTW: T-SQL please.

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• PostMessage does not seem to be working.

  - by Vaccano

  I am trying to use PostMessage to send a tab key. Here is my code: // This class allows us to send a tab key when the the enter key // is pressed for the mooseworks mask control. public class MaskKeyControl : MaskedEdit { // [DllImport("coredll.dll", SetLastError = true, CharSet = CharSet.Auto)] // static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); [return: MarshalAs(UnmanagedType.Bool)] // I am calling this on a Windows Mobile device so the dll is coredll.dll [DllImport("coredll.dll", SetLastError = true)] static extern bool PostMessage(IntPtr hWnd, uint Msg, Int32 wParam, Int32 lParam); public const Int32 VK_TAB = 0x09; public const Int32 WM_KEYDOWN = 0x100; protected override void OnKeyDown(KeyEventArgs e) { if (e.KeyData == Keys.Enter) { PostMessage(this.Handle, WM_KEYDOWN, VK_TAB, 0); return; } base.OnKeyDown(e); } protected override void OnKeyPress(KeyPressEventArgs e) { if (e.KeyChar == '\r') e.Handled = true; base.OnKeyPress(e); } } When I press enter the code gets called, but nothing happens. Then I press TAB and it works fine. (So there is something wrong with my sending of the Tab Message.)

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• Which cast am I using?

  - by Knowing me knowing you

  I'm trying to cast away const from an object but it doesn't work. But if I use old C-way of casting code compiles. So which casting I'm suppose to use to achieve this same effect? I wouldn't like to cast the old way. //file IntSet.h #include "stdafx.h" #pragma once /*Class representing set of integers*/ template<class T> class IntSet { private: T** myData_; std::size_t mySize_; std::size_t myIndex_; public: #pragma region ctor/dtor explicit IntSet(); virtual ~IntSet(); #pragma endregion #pragma region publicInterface IntSet makeUnion(const IntSet&)const; IntSet makeIntersection(const IntSet&)const; IntSet makeSymmetricDifference(const IntSet&)const; void insert(const T&); #pragma endregion }; //file IntSet_impl.h #include "StdAfx.h" #include "IntSet.h" #pragma region ctor/dtor template<class T> IntSet<T>::IntSet():myData_(nullptr), mySize_(0), myIndex_(0) { } IntSet<T>::~IntSet() { } #pragma endregion #pragma region publicInterface template<class T> void IntSet<T>::insert(const T& obj) { /*Check if we are initialized*/ if (mySize_ == 0) { mySize_ = 1; myData_ = new T*[mySize_]; } /*Check if we have place to insert obj in.*/ if (myIndex_ < mySize_) {//IS IT SAFE TO INCREMENT myIndex while assigning? myData_[myIndex_++] = &T(obj);//IF I DO IT THE OLD WAY IT WORKS return; } /*We didn't have enough place...*/ T** tmp = new T*[mySize_];//for copying old to temporary basket std::copy(&myData_[0],&myData_[mySize_],&tmp[0]); } #pragma endregion Thanks.

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• Android - Persist file when app closes.

  - by Donal Rafferty

  I am creating a file in my Android application as follows: HEADINGSTRING = new String("Android Debugging " + "\n" "XML test Debugging"); } public void setUpLogging(Context context){ Log.d("LOGGING", "Setting up logging....."); try { // catches IOException below FileOutputStream fOut = context.openFileOutput(FILE_NAME,Context.MODE_APPEND); OutputStreamWriter osw = new OutputStreamWriter(fOut); // Write the string to the file osw.write(HEADINGSTRING); /* ensure that everything is * really written out and close */ osw.flush(); osw.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ Log.d("LOGGING", "Finished logging setup....."); } } And I write to the file during the running of the app as follows: public void addToLog(File file, String text) throws IOException { BufferedWriter bw = new BufferedWriter (new FileWriter(file, true)); bw.write ("\n" + text); bw.newLine(); bw.flush(); bw.close(); } This works fine but when my app closes the file gets deleted and when the app is run again all the information I wrote to it is gone. How can I make sure the file persists even after closure of the app? Update: I have changed MODE_PRIVATE to MODE_APPEND but the problem still remains.

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• Set Property Value on Master Page from Content Page

  - by Merk

  Hello, I tried following the advice posted here: http://stackoverflow.com/questions/1071920/set-property-value-on-master-page-from-content-page. Specifically the last post about creating a class. However, visual studio keeps giving me an error on my default.aspx.cs page when i try to set the value: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class _Default : BasePage { protected override int NavHighlight { get { return new{0} ; } } protected void Page_Load(object sender, EventArgs e) { } } It throws an error on new, the error being: cannot inplicity convert anonymoustype#1 to int Can someone tell me what i might have done wrong here? Here's what my class looks like: using System; using System.Collections.Generic; using System.Linq; using System.Web; /// <summary> /// Summary description for BasePage /// </summary> public abstract class BasePage : System.Web.UI.Page { protected abstract int NavHighlight { get; } protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (this.Master != null) { //value assignment } } public BasePage() { // // TODO: Add constructor logic here // } } Thanks.

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• Different Linux message queues have the same id?

  - by Halo

  I open a mesage queue in a .c file, and upon success it says the message queue id is 3. While that program is still running, in another terminal I start another program (of another .c file), that creates a new message queue with a different mqd_t. But its id also appears as 3. Is this a problem? server file goes like this: void server(char* req_mq) { struct mq_attr attr; mqd_t mqdes; struct request* msgptr; int n; char *bufptr; int buflen; pid_t apid; //attr.mq_maxmsg = 300; //attr.mq_msgsize = 1024; mqdes = mq_open(req_mq, O_RDWR | O_CREAT, 0666, NULL); if (mqdes == -1) { perror("can not create msg queue\n"); exit(1); } printf("server mq created, mq id = %d\n", (int) mqdes); and the client goes like: void client(char* req_mq, int min, int max, char* dir_path_name, char* outfile) { pid_t pid; /* get the process id */ if ((pid = getpid()) < 0) { perror("unable to get client pid"); } mqd_t mqd, dq; char pfx[50] = DQ_PRFX; char suffix[50]; // sprintf(suffix, "%d", pid); strcat(pfx, suffix); dq = mq_open(pfx, O_RDWR | O_CREAT, 0666, NULL); if (dq == -1) { perror("can not open data queue\n"); exit(1); } printf("data queue created, mq id = %d\n", (int) dq); mqd = mq_open(req_mq, O_RDWR); if (mqd == -1) { perror("can not open msg queue\n"); exit(1); } mqdes and dq seem to share the same id 3.

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• Window Size when SizeToContent is not specified

  - by moogs

  When the following XAML used, the window size is not 5000x5000, but some small window where the button is cropped. <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" > <Button Width="5000" Height="5000">XXX</Button> </Window> From what I can tell, size I did not specify the SizeToContent attribute, the default is "Manual", so it will use *size of a window is determined by other properties, including Width, Height, MaxWidth, MaxHeight, MinWidth, and MinHeight. * From the WPF Windows Overview, it seems those other properties are FrameworkElement::MinHeight/Width, and FrameworkElement::MaxHeight. But since the default for the Mins are 0, the Maxs are Infinity and the Width/Height is Nan....what's going on? Where is WPF getting the window size? Any pointers to the right direction would be appreciated.

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• Intel IA-32 Assembly

  - by Kay

  I'm having a bit of difficulty converting the following java code into Intel IA-32 Assembly: class Person() { char name [8]; int age; void printName() {...} static void printAdults(Person [] list) { for(int k = 0; k < 100; k++){ if (list[k].age >= 18) { list[k].printName(); } } } } My attempt is: Person: push ebp; save callers ebp mov ebp, esp; setup new ebp push esi; esi will hold name push ebx; ebx will hold list push ecx; ecx will hold k init: mov esi, [ebp + 8]; mov ebx, [ebp + 12]; mov ecx, 0; k=0 forloop: cmp ecx, 100; jge end; if k>= 100 then break forloop cmp [ebx + 4 * ecx], 18 ; jl auxloop; if list[k].age < 18 then go to auxloop jmp printName; printName: auxloop: inc ecx; jmp forloop; end: pop ecx; pop ebx; pop esi; pop ebp; Is my code correct? NOTE: I'm not allowed to use global variables.

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• Can't connect to MySql database from server using Devart

  - by annelie

  Hello, I'm having trouble connecting to a MySql database from a server. I'm using Devart to connect, and I'm not sure if I need to do something more than to simply reference the dlls. When I started working on this project it was referencing the CoreLabs dlls, which if I've understood is the previous name for Devart. That didn't work, so I downloaded the new Devart dlls instead. It works on my local machine, but when uploading to the server it crashes. I made a tiny console app to test the connection, and it fails when initialising, before I've even assigned a host etc. Do I need to do anything more than just upload my .exe file to the server? using System; using System.Collections.Generic; using System.Linq; using System.Text; using Devart.Data; using Devart.Data.MySql; namespace TestDatabaseConnection { public class Program { public static void Main(string[] args) { Console.WriteLine("about to connect"); ConnectToDatabase(); Console.ReadLine(); } public static void ConnectToDatabase() { MySqlConnection connection = new MySqlConnection(); } } } UPDATE: I can't see what the error is, I had a try catch around MySqlConnection connection = new MySqlConnection(); but no exception is thrown, it just crashes. Thanks, Annelie

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• Newb Question: passing objects in java?

  - by Adam Outler

  Hello, I am new at java. I am doing the following: Read from file, then put data into a variable. checkToken = lineToken.nextToken(); processlinetoken() } But then when I try to process it... public static void readFile(String fromFile) throws IOException { BufferedReader reader = new BufferedReader(new FileReader(fromFile)); String line = null; while ((line=reader.readLine()) != null ) { if (line.length() >= 2) { StringTokenizer lineToken = new StringTokenizer (line); checkToken = lineToken.nextToken(); processlinetoken() ...... But here's where I come into a problem. public static void processlinetoken() checkToken=lineToken.nextToken(); } it fails out. Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method nextToken() is undefined for the type String at testread.getEngineLoad(testread.java:243) at testread.readFile(testread.java:149) at testread.main(testread.java:119) so how do I get this to work? It seems to pass the variable, but nothing after the . works.

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• How to use my trackpad for horizontal mousewheel scrolling in a Java AWT ScrollPane

  - by blissapp

  Like many modern mice and trackpads, my laptop supports vertical and horizontal scrolling. It's an addictive feature once you get used to it. I simply want my Java apps to support horizontal scrolling via the trackpad/mousewheel, but everywhere I search it seems that this is not possible in Java. I really want someone to tell me that I'm somehow doing it wrong, this feature is already requested behaviour: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6440198 The inability to do this simple thing is actually a deal breaker for the app I'm working on. In fact, for any app I can envision! I've invested a bit of time in the Java backend, so I'd really like to find a solution for this seemingly simple thing. Question is what could I do to implement this behaviour? Are raw OS level events even exposed to java, would I then need to write this from scratch? import java.awt.*; public class ScrollExample extends Canvas { public void paint(Graphics g) { g.setColor(Color.green); g.fillOval(0,0,400, 400); } public static void main(String[] args) { ScrollExample b = new ScrollExample(); Frame f = new Frame ("Scroll Example"); ScrollPane scroller = new ScrollPane (ScrollPane.SCROLLBARS_ALWAYS); scroller.add(b,"Center"); f.setPreferredSize(new Dimension(500,500)); f.add ("Center",scroller); f.pack(); f.show(); } }

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• Lightweight alternative to Manual/AutoResetEvent in C#

  - by sweetlilmre

  Hi, I have written what I hope is a lightweight alternative to using the ManualResetEvent and AutoResetEvent classes in C#/.NET. The reasoning behind this was to have Event like functionality without the weight of using a kernel locking object. Although the code seems to work well in both testing and production, getting this kind of thing right for all possibilities can be a fraught undertaking and I would humbly request any constructive comments and or criticism from the StackOverflow crowd on this. Hopefully (after review) this will be useful to others. Usage should be similar to the Manual/AutoResetEvent classes with Notify() used for Set(). Here goes: using System; using System.Threading; public class Signal { private readonly object _lock = new object(); private readonly bool _autoResetSignal; private bool _notified; public Signal() : this(false, false) { } public Signal(bool initialState, bool autoReset) { _autoResetSignal = autoReset; _notified = initialState; } public virtual void Notify() { lock (_lock) { // first time? if (!_notified) { // set the flag _notified = true; // unblock a thread which is waiting on this signal Monitor.Pulse(_lock); } } } public void Wait() { Wait(Timeout.Infinite); } public virtual bool Wait(int milliseconds) { lock (_lock) { bool ret = true; // this check needs to be inside the lock otherwise you can get nailed // with a race condition where the notify thread sets the flag AFTER // the waiting thread has checked it and acquires the lock and does the // pulse before the Monitor.Wait below - when this happens the caller // will wait forever as he "just missed" the only pulse which is ever // going to happen if (!_notified) { ret = Monitor.Wait(_lock, milliseconds); } if (_autoResetSignal) { _notified = false; } return (ret); } } }

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• Deserializing JSON in WCF throws xml errors in .Net 4.0

  - by Syg

  Hi there. I'm going slidely mad over here, maybe someone else can figure out what's going on here. I have a WCF service exposing a function using webinvoke, like so: [OperationContract] [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.Wrapped, RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, UriTemplate = "registertokenpost" )] void RegisterDeviceTokenForYoumiePost(test token); The datacontract for the test class looks like this: [DataContract(Namespace="Zooma.Test", Name="test", IsReference=true)] public class test { string waarde; [DataMember(Name="waarde", Order=0)] public string Waarde { get { return waarde; } set { waarde = value; } } } When sending the following json message to the service, { "test": { "waarde": "bla" } } the trace log gives me errors (below). I have tried this with just a string instead of the datatype (void RegisterDeviceTokenForYoumiePost(string token); ) but i get the same error. All help is appreciated, can't figure it out. It looks like it's creating invalid xml from the json message, but i'm not doing any custom serialization here. The formatter threw an exception while trying to deserialize the message: Error in deserializing body of request message for operation 'RegisterDeviceTokenForYoumiePost'. Unexpected end of file. **Following elements are not closed**: waarde, test, root.</Message><StackTrace> at System.ServiceModel.Dispatcher.OperationFormatter.DeserializeRequest(Message message, Object[] parameters)

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• C# Serialization lock out

  - by Greycrow

  When I try to Serialize a class to an xml file I get the exception: The process cannot access the file 'C:\settings.xml' because it is being used by another process. Settings currentSettings = new Settings(); public void LoadSettings() { //Load Settings from XML file try { Stream stream = File.Open("settings.xml", FileMode.Open); XmlSerializer s = new XmlSerializer(typeof(Settings)); currentSettings = (Settings)s.Deserialize(stream); stream.Close(); } catch //Can't read XML - use default settings { currentSettings.Name = GameSelect.Items[0].ToString(); currentSettings.City = MapSelect.Items[0].ToString(); currentSettings.Country = RaceSelect.Items[0].ToString(); } } public void SaveSettings() { //Save Settings to XML file try { Stream stream = File.Open("settings.xml", FileMode.Create); XmlSerializer x = new XmlSerializer(typeof(Settings)); x.Serialize(stream, currentSettings); stream.Close(); } catch { MessageBox.Show("Unable to open XML File - File in use by other process"); } It appears that when I Deserialize it locks the file for writing back, even if I closed the stream. Thanks in advance.

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• Cakephp, i18n, Retrieve translation records for associated models

  - by ion

  Quoting from the cakephp Book (ver 1.3): Note that only fields of the model you are directly doing find on will be translated. Models attached via associations won't be translated because triggering callbacks on associated models is currently not supported. Has anyone come up with a solution for this??? If not could you give me some pointers concerning the following simple scenario. I have 2 models: Project, Category. Project HABTM Category I have properly set up i18n table and I have a few entries in the db, all translated. When I retrieve a project it does retrieve the translation but not the translated category because as it says in the cakephp book models attached via associations won't be translated. Any help would be appreciated

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• help on ejb stateless datagram and message driven beans

  - by Kemmal

  i have a client thats sending a message to the ejbserver using UDP, i want the server(stateless bean) to echo back this message to the client but i cant seem to do this. or can i implement the same logic by using JMS? please help and enlighten. this is just a test, in the end i want a midp to be sending the message to the ejb using datagrams. here is my code. @Stateless public class SessionFacadeBean implements SessionFacadeRemote { public SessionFacadeBean() { } public static void main(String[] args) { DatagramSocket aSocket = null; byte[] buffer = null; try { while(true) { DatagramPacket request = new DatagramPacket(buffer, buffer.length); aSocket.receive(request); DatagramPacket reply = new DatagramPacket(request.getData(), request.getLength(), request.getAddress(), request.getPort()); aSocket.send(reply); } } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } } and the client: public static void main(String[] args) { DatagramSocket aSocket = null; try { aSocket = new DatagramSocket(); byte [] m = "Test message!".getBytes(); InetAddress aHost = InetAddress.getByName("localhost"); int serverPort = 6789; DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort); aSocket.send(request); byte[] buffer = new byte[1000]; DatagramPacket reply = new DatagramPacket(buffer, buffer.length); aSocket.receive(reply); System.out.println("Reply: " + new String(reply.getData())); } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } please help.

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• Removing NSLog breaks compiler

  - by DVG

  Okay, so this is weird I have this code - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.row) { case 1: NSLog(@"Platform Cell Selected"); AddGamePlatformSelectionViewController *platformVC = [[AddGamePlatformSelectionViewController alloc] initWithNibName:@"AddGamePlatformSelectionViewController" bundle:nil]; platformVC.context = context; platformVC.game = newGame; [self.navigationController pushViewController:platformVC animated:YES]; [platformVC release]; break; default: break; } } Which works fine. When I remove the NSLog Statement, like so: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.row) { case 1: //NSLog(@"Platform Cell Selected"); AddGamePlatformSelectionViewController *platformVC = [[AddGamePlatformSelectionViewController alloc] initWithNibName:@"AddGamePlatformSelectionViewController" bundle:nil]; platformVC.context = context; platformVC.game = newGame; [self.navigationController pushViewController:platformVC animated:YES]; [platformVC release]; break; default: break; } } I get the following compiler errors /Users/DVG/Development/iPhone/Backlog/Classes/AddGameTableViewController.m:102:0 /Users/DVG/Development/iPhone/Backlog/Classes/AddGameTableViewController.m:102: error: expected expression before 'AddGamePlatformSelectionViewController' /Users/DVG/Development/iPhone/Backlog/Classes/AddGameTableViewController.m:103:0 /Users/DVG/Development/iPhone/Backlog/Classes/AddGameTableViewController.m:103: error: 'platformVC' undeclared (first use in this function) If I just edit out the two // for commenting out that line, everything works swimingly.

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• Java assignment issues - Is this atomic?

  - by Bob

  Hi, I've got some questions about Java's assigment. Strings I've got a class: public class Test { private String s; public synchronized void setS(String str){ s = s + " - " + str; } public String getS(){ return s; } } I'm using "synchronized" in my setter, and avoiding it in my getter, because in my app, there are a tons of data gettings, and very few settings. Settings must be synchronized to avoid inconsistency. My question is: is getting and setting a variable atomic? I mean, in a multithreaded environment, Thread1 is about to set variable s, while Thread2 is about to get "s". Is there any way the getter method could get something different than the s's old value or the s's new value (suppose we've got only two threads)? In my app it is not a problem to get the new value, and it is not a problem to get the old one. But could I get something else? What about HashMap's getting and putting? considering this: public class Test { private Map<Integer, String> map = Collections.synchronizedMap(new HashMap<Integer, String>()); public synchronized void setMapElement(Integer key, String value){ map.put(key, value); } public String getValue(Integer key){ return map.get(key); } } Is putting and getting atomic? How does HashMap handle putting an element into it? Does it first remove the old value and put the now one? Could I get other than the old value or the new value? Thanks in advance!

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• Getting started with silverlight 3 mvvm

  - by bplus

  I've just written my first silverlight 3 app. It's written using the code behind in a rater messy way. I want to refactor into mvvm. I'm finding it extremely difficult to find any tutorials on this. So far from what I can gather I'll probably need a mvvm framework. Mvvm-light toolkit sounds like it might be what I want, but I can't find a beginners tutorial. This is actually more frustrating than I thought - do I actually need a framework? Would I maybe be better just trying to do this from scratch with out a framework? How did you get started with silverlight and mvvm? Also I'm using vs2008 so silverlight 4 is a non starter for me. Thanks in advance for any pointers.

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• proper use of volatile keyword

  - by luke

  I think i have a pretty good idea about the volatile keyword in java, but i'm thinking about re-factoring some code and i thought it would be a good idea to use it. i have a class that is basically working as a DB Cache. it holds a bunch of objects that it has read from a database, serves requests for those objects, and then occasionally refreshes the database (based on a timeout). Heres the skeleton public class Cache { private HashMap mappings =....; private long last_update_time; private void loadMappingsFromDB() { //.... } private void checkLoad() { if(System.currentTimeMillis() - last_update_time > TIMEOUT) loadMappingsFromDB(); } public Data get(ID id) { checkLoad(); //.. look it up } } So the concern is that loadMappingsFromDB could be a high latency operation and thats not acceptable, So initially i thought that i could spin up a thread on cache startup and then just have it sleep and then update the cache in the background. But then i would need to synchronize my class (or the map). and then i would just be trading an occasional big pause for making every cache access slower. Then i thought why not use volatile i could define the map reference as volatile private volatile HashMap mappings =....; and then in get (or anywhere else that uses the mappings variable) i would just make a local copy of the reference: public Data get(ID id) { HashMap local = mappings; //.. look it up using local } and then the background thread would just load into a temp table and then swap the references in the class HashMap tmp; //load tmp from DB mappings = tmp;//swap variables forcing write barrier Does this approach make sense? and is it actually thread-safe?

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• Why aren't my coordinates matching my JFrame size?

  - by AsLanFromNarnia

  I want to do some drawing in a JPanel but the enclosing JFrame size doesn't seem to match where I've asked the coordinates to be drawn. In my example code, the JFrame size is set to (700, 700) and the last point is drawn at (600, 600). I would expect this point to be drawn 100 pixels away from the right and bottom edges but it isn't (please see screenshot). Here's the code I'm using: import java.awt.Graphics; import javax.swing.JFrame; import javax.swing.JPanel; public class Scratch extends JPanel { static int frameWidth = 700; static int frameHeight = 700; public static void main(String[] args) { JFrame frame = new JFrame(); frame.setSize(frameWidth, frameHeight); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); Scratch scratch = new Scratch(); frame.getContentPane().add(scratch); frame.setVisible(true); } @Override public void paintComponent(Graphics g) { g.drawRect(100, 100, 1, 1); g.drawString("100", 100, 100); g.drawRect(200, 200, 1, 1); g.drawString("200", 200, 200); g.drawRect(300, 300, 1, 1); g.drawString("300", 300, 300); g.drawRect(400, 400, 1, 1); g.drawString("400", 400, 400); g.drawRect(500, 500, 1, 1); g.drawString("500", 500, 500); g.drawRect(600, 600, 1, 1); g.drawString("600", 600, 600); } }

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• Reading Certificates on iOS Problem

  - by David Schiefer

  I am trying to read certificates from various URLs in iOS. My code however is not working well - the array that should return the information I need always returns null. What am I missing? - (void)findCertificate:(NSString *)url { NSInputStream*input = [[NSInputStream inputStreamWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"https://store.writeitstudios.com"]]] retain]; [input setDelegate:self]; [input scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode]; [input open]; NSLog(@"Status: %i",[input streamStatus]); } - (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode { NSLog(@"handle Event: %i",eventCode); if (eventCode == NSStreamStatusOpen) { NSArray *certificates = (NSArray*)CFReadStreamCopyProperty((CFReadStreamRef)aStream, kCFStreamPropertySSLPeerCertificates); NSLog(@"Certs: %@",CFReadStreamCopyProperty((CFReadStreamRef)aStream, kCFStreamPropertySSLPeerCertificates)); if ([certificates count] > 0) { SecCertificateRef certificate = (SecCertificateRef)[certificates objectAtIndex:0]; NSString *description = (NSString*)SecCertificateCopySubjectSummary(certificate); NSData *data = (NSData *)SecCertificateCopyData(certificate); NSLog(@"Description: %@",description); } } } And yes, I am aware that I am leaking memory. This is just a snippet.

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• What do I name this class whose sole purpose is to report failure?

  - by Blair Holloway

  In our system, we have a number of classes whose construction must happen asynchronously. We wrap the construction process in another class that derives from an IConstructor class: class IConstructor { public: virtual void Update() = 0; virtual Status GetStatus() = 0; virtual int GetLastError() = 0; }; There's an issue with the design of the current system - the functions that create the IConstructor-derived classes are often doing additional work which can also fail. At that point, instead of getting a constructor which can be queried for an error, a NULL pointer is returned. Restructuring the code to avoid this is possible, but time-consuming. In the meantime, I decided to create a constructor class which we create and return in case of error, instead of a NULL pointer: class FailedConstructor : public IConstructor public: virtual void Update() {} virtual Status GetStatus() { return STATUS_ERROR; } virtual int GetLastError() { return m_errorCode; } private: int m_errorCode; }; All of the above this the setup for a mundane question: what do I name the FailedConstructor class? In our current system, FailedConstructor would indicate "a class which constructs an instance of Failed", not "a class which represents a failed attempt to construct another class". I feel like it should be named for one of the design patterns, like Proxy or Adapter, but I'm not sure which.

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