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  • Images in Applet not showing in web page

    - by Leanne C
    I am trying to display a JPEG image and a moving dot on a Java applet which I am using on a web based application. However, when I run the applet it works fine, but when I display the applet from the JSP page, I get the moving dot but not the JPEG image. Is there a specific folder where the JPEG needs to be? These are the 2 methods i use for drawing the picture and the moving dot on the screen. public class mapplet extends Applet implements Runnable { int x_pos = 10; int y_pos = 100; int radius = 20; Image img, img2; Graphics gr; URL base; MediaTracker m; @Override public void init() { mt = new MediaTracker(this); try { //getDocumentbase gets the applet path. base = getCodeBase(); img = getImage(base, "picture.jpg"); m.addImage(img, 1); m.waitForAll(); } catch (InterruptedException ex) { Logger.getLogger(movement.class.getName()).log(Level.SEVERE, null, ex); } public void paint (Graphics g) { g.drawImage(img, 0, 0, this); // set color g.setColor (Color.red); // paint a filled colored circle g.fillOval (x_pos - radius, y_pos - radius, 2 * radius, 2 * radius); } The code one below is the call from the jsp page <applet archive="mapplet.jar" code="myapplets/mapplet.class" width=350 height=200> </applet> The jar file and the picture are in the same folder as the jsp page, and there is also a folder containing the contents of the class and image of the applet in the web section of the application. The applet loads fine however the picture doesn't display. I think it's not the code but the location of the picture that is causing a problem. Thanks

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  • Why do bind1st and bind2nd require constant function objects?

    - by rlbond
    So, I was writing a C++ program which would allow me to take control of the entire world. I was all done writing the final translation unit, but I got an error: error C3848: expression having type 'const `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>' would lose some const-volatile qualifiers in order to call 'void `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>::operator ()(const point::Point &,const int &)' with [ T=SideCounter, BinaryFunction=std::plus<int> ] c:\program files (x86)\microsoft visual studio 9.0\vc\include\functional(324) : while compiling class template member function 'void std::binder2nd<_Fn2>::operator ()(point::Point &) const' with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] c:\users\****\documents\visual studio 2008\projects\TAKE_OVER_THE_WORLD\grid_divider.cpp(361) : see reference to class template instantiation 'std::binder2nd<_Fn2>' being compiled with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] I looked in the specifications of binder2nd and there it was: it took a const AdaptibleBinaryFunction. So, not a big deal, I thought. I just used boost::bind instead, right? Wrong! Now my take-over-the-world program takes too long to compile (bind is used inside a template which is instantiated quite a lot)! At this rate, my nemesis is going to take over the world first! I can't let that happen -- he uses Java! So can someone tell me why this design decision was made? It seems like an odd decision. I guess I'll have to make some of the elements of my class mutable for now...

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  • C# Hiding, overriding and calling function from base class.

    - by Lukasz Lysik
    I'm learning C# and I encountered the following problem. I have two classes: base and derived: class MyBase { public void MyMethod() { Console.WriteLine("MyBase::MyMethod()"); } } class MyDerived: MyBase { public void MyMethod() { Console.WriteLine("MyDerived::MyMethod()"); } } For now, without virtual and override key words. When I compile this I get the warning (which is of course expected) that I try to hide MyMethod from MyBase class. What I want to do is to call the method from the base class having an instance of derived class. I do this like this: MyDerived myDerived = new MyDerived(); ((MyBase)myDerived).MyMethod(); It works fine when I do not specify any virtual, etc. keywords in the methods. I tried to put combination of the keywords and I got the following results: | MyBase::MyMethod | MyDerived::MyMethod | Result printed on the console | | -----------------|---------------------|-------------------------------| | - | - | MyBase::MyMethod() | | - | new | MyBase::MyMethod() | | virtual | new | MyBase::MyMethod() | | virtual | override | MyDerived::MyMethod() | I hope the table is clear to you. I have two questions: Is it the correct way to call the function from the base class (((MyBase)myDerived).MyMethod();)? I know about base keyword, but it can be called only from the inside of the derived class. Is it right? Why in the last case (with virtual and override modifiers) the method which was called came from the derived class? Would you please explain that?

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  • Why my inner class DO see a NON static variable?

    - by Roman
    Earlier I had a problem when an inner anonymous class did not see a field of the "outer" class. I needed to make a final variable to make it visible to the inner class. Now I have an opposite situation. In the "outer" class "ClientListener" I use an inner class "Thread" and the "Thread" class I have the "run" method and does see the "earPort" from the "outer" class! Why? import java.io.IOException; import java.net.*; import java.io.BufferedReader; import java.io.InputStreamReader; public class ClientsListener { private int earPort; // Constructor. public ClientsListener(int earPort) { this.earPort = earPort; } public void starListening() { Thread inputStreamsGenerator = new Thread() { public void run() { System.out.println(earPort); try { System.out.println(earPort); ServerSocket listeningSocket = new ServerSocket(earPort); Socket serverSideSocket = listeningSocket.accept(); BufferedReader in = new BufferedReader(new InputStreamReader(serverSideSocket.getInputStream())); } catch (IOException e) { System.out.println(""); } } }; inputStreamsGenerator.start(); } }

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  • How to implement escape Sequence in SDL

    - by Sa'me Smd
    Im trying to use the STL library inside the SDL. but it gives me the error "undeclared identifier" Is there any way i can use "\n"or even cout<<endl; Can the function SDL_WarpMousewhich places the mouse cursor on a desired location on screen help me with this. Because i want to put a tile on the next line sequence. I hope you get the Question. Its very vague and messed up question though (sorry for that). EDIT: void putMap(SDL_Surface* tile, SDL_Surface* screen) { for(int y = 0; y < 21; y++) { for(int x = 0; x < 60; x++) { if(maze[x][y] != '#') { apply_surface( x*10 , y*10 , tile, screen); } } cout<<endl; } } c:\documents and settings\administrator\my documents\visual studio 2008\projects\craptest\craptest\main.cpp(605) : error C2065: 'cout' : undeclared identifier c:\documents and settings\administrator\my documents\visual studio 2008\projects\craptest\craptest\main.cpp(605) : error C2065: 'endl' : undeclared identifier This is my apply_surface funtion. void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination ) { //Make a temporary rectangle to hold the offsets SDL_Rect offset; //Give the offsets to the rectangle offset.x = x; offset.y = y; //Blit the surface SDL_BlitSurface( source, NULL, destination, &offset ); }

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  • Django : mysql : 1045, "Access denied for user

    - by PlanetUnknown
    I have the whole setup working for months on my local computer. I'm installing on a remote site now. Created a fresh mysql DB, and created a new user ("someuser") and gave it complete grants, like so - GRANT ALL PRIVILEGES ON . TO 'someuser'@'localhost' IDENTIFIED BY 'somepassword' WITH GRANT OPTION; I have sync'd the db, using "python manage.py syncdb" and the correct tables were created. My settings.py has this same user. But when I try to login a user through the application, and it hits the DB, I see the following in the logs - (1045, "Access denied for user 'someuser'@'localhost' (using password: YES)") I logged in through mysql (installed on the same box as django) and checked the grants and it correctly shows - Grants for djangouser@localhost GRANT ALL PRIVILEGES ON * . * TO 'someuser'@'localhost' IDENTIFIED BY PASSWORD '*thesaltedpasswordOverHere' WITH GRANT OPTION I don't want to use the root user/password for django, since it doesn't seem the correct way. Any pointers as to what might be wrong ?

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  • A monkey could do this better - Access to and availability of private member functions in C++

    - by David
    I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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  • lock shared data using c#

    - by menacheb
    Hi, I have a program (C#) with a list of tests to do. Also, I have two thread. one to add task into the list, and one to read and remove from it the performed tasks. I'm using the 'lock' function each time one of the threads want to access to the list. Another thing I want to do is, if the list is empty, the thread who need to read from the list will sleep. and wake up when the first thread add a task to the list. Here is the code I wrote: ... List<String> myList = new List(); Thread writeThread, readThread; writeThread = new Thread(write); writeThread.Start(); readThraed = new Thread(read); readThread.Start(); ... private void write() { while(...) { ... lock(myList) { myList.Add(...); } ... if (!readThread.IsAlive) { readThraed = new Thread(read); readThread.Start(); } ... } ... } private void read() { bool noMoreTasks = false; while (!noMoreTasks) { lock (MyList)//syncronize with the ADD func. { if (dataFromClientList.Count > 0) { String task = myList.First(); myList.Remove(task); } else { noMoreTasks = true; } } ... } readThread.Abort(); } Apparently I did it wrong, and it's not performed as expected (The readTread does't read from the list). Does anyone know what is my problem, and how to make it right? Many thanks,

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  • What does this structure actually do?

    - by LGTrader
    I found this structure code in a Julia Set example from a book on CUDA. I'm a newbie C programmer and cannot get my head around what it's doing, nor have I found the right thing to read on the web to clear it up. Here's the structure: struct cuComplex { float r; float i; cuComplex( float a, float b ) : r(a), i(b) {} float magnitude2( void ) { return r * r + i * i; } cuComplex operator*(const cuComplex& a) { return cuComplex(r*a.r - i*a.i, i*a.r + r*a.i); } cuComplex operator+(const cuComplex& a) { return cuComplex(r+a.r, i+a.i); } }; and it's called very simply like this: cuComplex c(-0.8, 0.156); cuComplex a(jx, jy); int i = 0; for (i=0; i<200; i++) { a = a * a + c; if (a.magnitude2() > 1000) return 0; } return 1; So, the code did what? Defined something of structure type 'cuComplex' giving the real and imaginary parts of a number. (-0.8 & 0.156) What is getting returned? (Or placed in the structure?) How do I work through the logic of the operator stuff in the struct to understand what is actually calculated and held there? I think that it's probably doing recursive calls back into the stucture float magnitude2 (void) { return return r * r + i * i; } probably calls the '*' operator for r and again for i, and then the results of those two operations call the '+' operator? Is this correct and what gets returned at each step? Just plain confused. Thanks!

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  • String Length Evaluating Incorrectly

    - by Justin R.
    My coworker and I are debugging an issue in a WCF service he's working on where a string's length isn't being evaluated correctly. He is running this method to unit test a method in his WCF service: // Unit test method public void RemoveAppGroupTest() { string addGroup = "TestGroup"; string status = string.Empty; string message = string.Empty; appActiveDirectoryServicesClient.RemoveAppGroup("AOD", addGroup, ref status, ref message); } // Inside the WCF service [OperationBehavior(Impersonation = ImpersonationOption.Required)] public void RemoveAppGroup(string AppName, string GroupName, ref string Status, ref string Message) { string accessOnDemandDomain = "MyDomain"; RemoveAppGroupFromDomain(AppName, accessOnDemandDomain, GroupName, ref Status, ref Message); } public AppActiveDirectoryDomain(string AppName, string DomainName) { if (string.IsNullOrEmpty(AppName)) { throw new ArgumentNullException("AppName", "You must specify an application name"); } } We tried to step into the .NET source code to see what value string.IsNullOrEmpty was receiving, but the IDE printed this message when we attempted to evaluate the variable: 'Cannot obtain value of local or argument 'value' as it is not available at this instruction pointer, possibly because it has been optimized away.' (None of the projects involved have optimizations enabled). So, we decided to try explicitly setting the value of the variable inside the method itself, immediately before the length check -- but that didn't help. // Lets try this again. public AppActiveDirectoryDomain(string AppName, string DomainName) { // Explicitly set the value for testing purposes. AppName = "AOD"; if (AppName == null) { throw new ArgumentNullException("AppName", "You must specify an application name"); } if (AppName.Length == 0) { // This exception gets thrown, even though it obviously isn't a zero length string. throw new ArgumentNullException("AppName", "You must specify an application name"); } } We're really pulling our hair out on this one. Has anyone else experienced behavior like this? Any tips on debugging it?

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  • MVVM using Page Navigation On Windows Mobile 7

    - by anon
    The Navigation framework in Windows Mobile 7 is a cut down version of what is in Silverlight. You can only navigate to a Uri and not pass in a view. Since the NavigationService is tied to the View, how do people get this to fit into MVVM. For example: public class ViewModel : IViewModel { private IUnityContainer container; private IView view; public ViewModel(IUnityContainer container, IView view) { this.container = container; this.view = view; } public ICommand GoToNextPageCommand { get { ... } } public IView { get { return this.view; } } public void GoToNextPage() { // What do I put here. } } public class View : PhoneApplicationPage, IView { ... public void SetModel(IViewModel model) { ... } } I am using the Unity IOC container. I have to resolve my view model first and then use the View property to get hold of the view and then show it. However using the NavigationService, I have to pass in a view Uri. There is no way for me to create the view model first. Is there a way to get around this.

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  • populatin jComBobox with data from a db tbl(table) column

    - by mnmyles
    Hi guyz? I have a JComboBox which i have named "venue_JCB" i want to load details from a tbl column on form load at the initcomponets() i have declared the method "accessDBinit() ;" and after the initComponets() i have implemented the accessDBinit(); method as follows: ================================code============================ void accessDBinit() //Get Student List in the List Box { try { sql = "SELECT classLevel FROM class_session ORDER BY classLevel"; java.lang.Class.forName("com.mysql.jdbc.Driver"); Connection con2=DriverManager.getConnection("jdbc:mysql:///coast","root",""); Statement stmt2 = (Statement)con2.createStatement(); boolean hasResults = stmt2.execute(sql); if(hasResults) { ResultSet rs2 = stmt2.getResultSet(); if(rs2!=null) { displayResultsinit(rs2); } db.stmt.close(); } } catch(Exception e) { System.out.println(e+"Error in connection"); } } void displayResultsinit(ResultSet r) throws SQLException { ResultSetMetaData rmeta = r.getMetaData(); int numColumns=rmeta.getColumnCount(); while(r.next()) { for(int i=1;i<=numColumns;++i) { if(i<=numColumns) { venue_JCB.addItem(r.getString(i)); } } } } ====================================end of code=================================== the method works (Populate the combobox) but at the output bar i get the following on form load and also whenever i select a component from the combobox ======= error===== java.lang.NullPointerExceptionError in connection could some one please tell me where i am going wrong with the method? Thanks in advance regards Malachi

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  • Oracle global lock across process

    - by Jimm
    I would like to synchronize access to a particular insert. Hence, if multiple applications execute this "one" insert, the inserts should happen one at a time. The reason behind synchronization is that there should only be ONE instance of this entity. If multiple applications try to insert the same entity,only one should succeed and others should fail. One option considered was to create a composite unique key, that would uniquely identify the entity and rely on unique constraint. For some reasons, the dba department rejected this idea. Other option that came to my mind was to create a stored proc for the insert and if the stored proc can obtain a global lock, then multiple applications invoking the same stored proc, though in their seperate database sessions, it is expected that the stored proc can obtain a global lock and hence serialize the inserts. My question is it possible to for a stored proc in oracle version 10/11, to obtain such a lock and any pointers to documentation would be helpful.

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  • What's the best NAME for "quick" Category you add to a file?

    - by Joe Blow
    So the other day I was sick of typing out repetetive addTarget:action:forControlEvents:s, and macros are only entertaining for so long, so I did this: @implementation UIControl (xx) -(void)addTarget:(id)target action:(SEL)action { [self addTarget:target action:action forControlEvents:UIControlEventTouchUpInside]; } @end *and simply added it at the top of the .m file in question. Works great of course, but notice the "xx".* What's the best thing to NAME a "quick" Category like this? Annoyingly, it appears you can not leave the xx blank - it would then become an "Extension" (which, incidentally, I don't understand at all). I was thinking maybe: a single underscore the name of the class again identically "quick" perhaps the name of the class in this file (as in "quick extra routines for UIControl in CherryBomb") - so it would be UIControl(CherryBomb), ie, remind you that these extra routines are handy for CherryBomb "x" your or your company's initials (use the same "quick" Category name everywhere) "ThisTextNeverUsedAnywhere" By the way, I've been assuming that Categories only happen in the files that see them (CherryBomb.m in the example) - they do not from then on apply app-wide. ie they only apply where you include the header file (UIControl+NattyStuff) or in the "quick" case only in the file to which one adds the text. (By the way ... it appears you do not actually need to include an interface for such a Category, i.e. you can omit... //you can actually get away without these lines... //#import <UIKit/UIControl.h> //@interface UIControl (x) //-(void)addTarget:(id)target action:(SEL)action; //@end ... that part and it works fine.) For people who love Categories, and who doesn't, what's the answer to this troubling question? What should you name a "quick" Category where the name is never going to be referenced again and is irrelevant? Is "_" a solution?

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  • Java Code for calculating Leap Year, is this code correct ?

    - by Ibn Saeed
    Hello I am following "The Art and Science of Java" book and it shows how to calculate a leap year. The book uses ACM Java Task Force's library. Here is the code the books uses: import acm.program.*; public class LeapYear extends ConsoleProgram { public void run() { println("This program calculates leap year."); int year = readInt("Enter the year: "); boolean isLeapYear = ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0)); if (isLeapYear) { println(year + " is a leap year."); } else println(year + " is not a leap year."); } } Now, this is how I calculated the leap year. import acm.program.*; public class LeapYear extends ConsoleProgram { public void run() { println("This program calculates leap year."); int year = readInt("Enter the year: "); if ((year % 4 == 0) && year % 100 != 0) { println(year + " is a leap year."); } else if ((year % 4 == 0) && (year % 100 == 0) && (year % 400 == 0)) { println(year + " is a leap year."); } else { println(year + " is not a leap year."); } } } Is there anything wrong with my code or should i use the one provided by the book ? EDIT :: Both of the above code works fine, What i want to ask is which code is the best way to calculate the leap year.

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  • BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding

    - by Tim
    Mr. Ayende wrote in his latest blog post about an implementation of a queue. In the post he's using two magical files: BinaryWriterWith7BitEncoding & BinaryReaderWith7BitEncoding BinaryWriterWith7BitEncoding can write both int and long? using the following method signatures: void WriteBitEncodedNullableInt64(long? value) & void Write7BitEncodedInt(int value) and BinaryReaderWith7BitEncoding can read the values written using the following method signatures: long? ReadBitEncodedNullableInt64() and int Read7BitEncodedInt() So far I've only managed to find a way to read the 7BitEncodedInt: protected int Read7BitEncodedInt() { int value = 0; int byteval; int shift = 0; while(((byteval = ReadByte()) & 0x80) != 0) { value |= ((byteval & 0x7F) << shift); shift += 7; } return (value | (byteval << shift)); } I'm not too good with byte shifting - does anybody know how to read and write the 7BitEncoded long? and write the int ?

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  • iOS MapKit: Selected MKAnnotation coordinates.

    - by Oh Danny Boy
    Using the code at the following tutorial, http://www.zenbrains.com/blog/en/2010/05/detectar-cuando-se-selecciona-una-anotacion-mkannotation-en-mapa-mkmapview/, I was able to add an observer to each MKAnnotation and receive a notification of selected/deselected states. I am attempting to add a UIView on top of the selection annotation to display relevant information about the location. This information cannot be conveyed in the 2 lines allowed (Title/Subtitle) for the pin's callout. - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { Annotation *a = (Annotation *)object; // Alternatively attempted using: //Annotation *a = (Annotation *)[mapView.selectedAnnotations objectAtIndex:0]; NSString *action = (NSString *)context; if ([action isEqualToString:ANNOTATION_SELECTED_DESELECTED]) { BOOL annotationSelected = [[change valueForKey:@"new"] boolValue]; if (annotationSelected) { // Actions when annotation selected CGPoint origin = a.frame.origin; NSLog(@"origin (%f, %f) ", origin.x, origin.y); // Test UIView *v = [[UIView alloc] init]; [v setBackgroundColor:[UIColor orangeColor]]; [v setFrame:CGRectMake(origin.x, origin.y , 300, 300)]; [self.view addSubview:v]; [v release]; }else { // Accions when annotation deselected } } } Results using Annotation *a = (Annotation *)object origin (154373.000000, 197135.000000) origin (154394.000000, 197152.000000) origin (154445.000000, 197011.000000) Results using Annotation *a = (Annotation *)[mapView.selectedAnnotations objectAtIndex:0]; origin (0.000000, 0.000000) origin (0.000000, 0.000000) origin (0.000000, 0.000000) The numbers are large. They are not relative to the view (1024 x 768). I believe they are relative to the entire map. How would I be able to detect the exact coordinates relative to the entire view so that I can appropriately position my view?

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  • Problem with setVisible (true)

    - by Jessy
    The two examples shown below are same. Both are supposed to produce same result e.g. generate the coordinates of images displayed on JPanel. Example 1, works perfectly (print the coordinates of images), however example 2 returning 0 for the coordinate. I was wondering why because, I have put the setvisible (true) after adding the panel, in both examples. The only difference is that example 1 used extends JPanel and example 2 extends JFrame EXAMPLE 1: public class Grid extends JPanel{ public static void main(String[] args){ JFrame jf=new JFrame(); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final Grid grid = new Grid(); jf.add(grid); jf.pack(); Component[] components = grid.getComponents(); for (Component component : components) { System.out.println("Coordinate: "+ component.getBounds()); } jf.setVisible(true); } } EXAMPLE 2: public class Grid extends JFrame { public Grid () { setLayout(new GridBagLayout()); GridBagLayout m = new GridBagLayout(); Container c = getContentPane(); c.setLayout (m); GridBagConstraints con = new GridBagConstraints(); //construct the JPanel pDraw = new JPanel(); ... m.setConstraints(pDraw, con); pDraw.add (new GetCoordinate ()); // call new class to generate the coordinate c.add(pDraw); pack(); setVisible(true); } public static void main(String[] args) { new Grid(); } }

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  • Serializing QGraphicsScene contents

    - by Rob
    I am using the Qt QGraphicsScene class, adding pre-defined items such as QGraphicsRectItem, QGraphicsLineItem, etc. and I want to serialize the scene contents to disk. However, the base QGraphicsItem class (that the other items I use derive from) doesn't support serialization so I need to roll my own code. The problem is that all access to these objects is via a base QGraphicsItem pointer, so the serialization code I have is horrible: QGraphicsScene* scene = new QGraphicsScene; scene->addRect(QRectF(0, 0, 100, 100)); scene->addLine(QLineF(0, 0, 100, 100)); ... QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { if (item->type() == QGraphicsRectItem::Type) { QGraphicsRectItem* rect = qgraphicsitem_cast<QGraphicsRectItem*>(item); // Access QGraphicsRectItem members here } else if (item->type() == QGraphicsLineItem::Type) { QGraphicsLineItem* line = qgraphicsitem_cast<QGraphicsLineItem*>(item); // Access QGraphicsLineItem members here } ... } This is not good code IMHO. So, instead I could create an ABC class like this: class Item { public: virtual void serialize(QDataStream& strm, int version) = 0; }; class Rect : public QGraphicsRectItem, public Item { public: void serialize(QDataStream& strm, int version) { // Serialize this object } ... }; I can then add Rect objects using QGraphicsScene::addItem(new Rect(,,,)); But this doesn't really help me as the following will crash: QList<QGraphicsItem*> list = scene->items(); foreach (QGraphicsItem* item, items) { Item* myitem = reinterpret_class<Item*>(item); myitem->serialize(...) // FAIL } Any way I can make this work?

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  • Java Process.waitFor() and IO streams

    - by lynks
    I have the following code; String[] cmd = { "bash", "-c", "~/path/to/script.sh" }; Process p = Runtime.getRuntime().exec(cmd); PipeThread a = new PipeThread(p.getInputStream(), System.out); PipeThread b = new PipeThread(p.getErrorStream(), System.err); p.waitFor(); a.die(); b.die(); The PipeThread class is quite simple so I will include it in full; public class PipeThread implements Runnable { private BufferedInputStream in; private BufferedOutputStream out; public Thread thread; private boolean die = false; public PipeThread(InputStream i, OutputStream o) { in = new BufferedInputStream(i); out = new BufferedOutputStream(o); thread = new Thread(this); thread.start(); } public void die() { die = true; } public void run() { try { byte[] b = new byte[1024]; while(!die) { int x = in.read(b, 0, 1024); if(x > 0) out.write(b, 0, x); else die(); out.flush(); } } catch(Exception e) { e.printStackTrace(); } try { in.close(); out.close(); } catch(Exception e) { } } } My problem is this; p.waitFor() blocks endlessly, even after the subprocess has terminated. If I do not create the pair of PipeThread instances, then p.waitFor() works perfectly. What is it about the piping of io streams that is causing p.waitFor() to continue blocking? I'm confused as I thought the IO streams would be passive, unable to keep a process alive, or to make Java think the process is still alive.

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  • Design of std::ifstream class

    - by Nawaz
    Those of us who have seen the beauty of STL try to use it as much as possible, and also encourage others to use it wherever we see them using raw pointers and arrays. Scott Meyers have written a whole book on STL, with title Effective STL. Yet what happened to the developers of ifstream that they preferred char* over std::string. I wonder why the first parameter of ifstream::open() is of type const char*, instead of const std::string &. Please have a look at it's signature: void open(const char * filename, ios_base::openmode mode = ios_base::in ); Why this? Why not this: void open(const string & filename, ios_base::openmode mode = ios_base::in ); Is this a serious mistake with the design? Or this design is deliberate? What could be the reason? I don't see any reason why they have preferred char* over std::string. Note we could still pass char* to the latter function that takes std::string. That's not a problem! By the way, I'm aware that ifstream is a typedef, so no comment on my title.:P. It looks short that is why I used it. The actual class template is : template<class _Elem,class _Traits> class basic_ifstream;

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  • Node.js for lua?

    - by Shahbaz
    I've been playing around with node.js (nodejs) for the past few day and it is fantastic. As far as I can tell, lua doesn't have a similar integration of libev and libio which let's one avoid almost any blocking calls and interact with the network and the filesystem in an asynchronous manner. I'm slowly porting my java implementation to nodejs, but I'm shocked that luajit is much faster than v8 JavaScript AND uses far less memory! I imagine writing my server in such an environment (very fast and responsive, very low memory usage, very expressive) will improve my project immensly. Being new to lua, I'm just not sure if such a thing exists. I'll appreciate any pointers. Thanks

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  • How to open the download window when a dynamically created link is clicked in asp.net

    - by Ranjana
    i have stored the txtfile in the database.i need to show the txtfile when i clik the link. and this link has to be created dynamically. my code below: aspx code: aspx.cs protected void Page_Load(object sender, EventArgs e) { if(!Page.IsPostBack) { DataTable dtassignment = new DataTable(); dtassignment = serviceobj.DisplayAssignment(Session["staffname"].ToString()); if (dtassignment != null) { Byte[] bytes = (Byte[])dtassignment.Rows[0]["Data"]; //download(dtassignment); } divlink.InnerHtml = ""; divlink.Visible = true; foreach (DataRow r in dtassignment.Rows) { divlink.InnerHtml += "<a href='" + "'onclick='download(dtassignment)'>" + r["Filename"].ToString() + "</a>" + "<br/>"; } } } - public void download(DataTable dtassignment) { System.Diagnostics.Debugger.Break(); Byte[] bytes = (Byte[])dtassignment.Rows[0]["Data"]; Response.Buffer = true; Response.Charset = ""; Response.Cache.SetCacheability(HttpCacheability.NoCache); Response.ContentType = dtassignment.Rows[0]["ContentType"].ToString(); Response.AddHeader("content-disposition", "attachment;filename=" + dtassignment.Rows[0]["FileName"].ToString()); Response.BinaryWrite(bytes); Response.Flush(); Response.End(); } i have got the link dynamically, but i did not able to download the txtfile when i clik the link. how to carry out this. pls help me out...

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  • How can a link within a WebView load another layout using javascript?

    - by huffmaster
    So I have 2 layout files (main.xml, featured.xml) and both each have a single WebView. When the application starts "main.xml" loads a html file into it's WebView. In this html file I have a link that calls javascript that runs code in the Activity that loaded the html. Once back in this Activity code though I try running setContentView(R.layout.featured) but it just bombs out on me. If I debug it just dies without any real error and if I run it the application just Force closes. Am I going about this correctly or should I be doing something differently? final private int MAIN = 1; final private int FEATURED = 2; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); webview = (WebView) findViewById(R.id.wvMain); webview.getSettings().setJavaScriptEnabled(true); webview.getSettings().setSupportZoom(false); webview.addJavascriptInterface(new EHJavaScriptInterface(), "eh"); webview.loadUrl("file:///android_asset/default.html"); } final class EHJavaScriptInterface { EHJavaScriptInterface() { } public void loadLayout(final String lo) { int i = Integer.parseInt(lo.trim()); switch (i) { /****** THIS IS WHERE I'M BOMBING OUT *********/ case FEATURED: setContentView(R.layout.featured);break; case MAIN: setContentView(R.layout.main);break; } } }

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  • Prevent default on a click within a JQuery tabs in Google Chrome.

    - by Sydney
    I would like to prevent the default behaviour of a click on a link. I tried the return false; also javascript:void(0); in the href attribute but it doesn’t seem to work. It works fine in Firefox, but not in Chrome and IE. I have a single tab that loads via AJAX the content which is a simple link. <script type="text/javascript"> $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, success: function() { alert('hello'); $('#lk').click(function() { alert('Click Me'); return false; }); } }, load: function(event, ui) { $('a', ui.panel).click(function() { $(ui.panel).load(this.href); return false; }); } }); }); </script> <body> <div id="tabs"> <ul> <li><a href="linkChild.htm">Link</a></li> </ul> </div> </body> The content of linkChild.htm is <a href="javascript:void(0)" id="lk">Click Me</a> So basically when the tab content is loaded with success, a click event is attached to the link “lk”. When I click on the link, the alert is displayed but then link disappears. I check the HTML and the element is actually removed from the DOM.

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