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  • Multiple choice test GUI with serialization of Q&A

    - by Bobby
    I'm working on a project for school in Java programming. I need to design a GUI that will take in questions and answers and store them in a file. It should be able to contain an unlimited number of questions. We have covered binary I/O. How do I write the input they give to a file? How would I go about having them add multiple questions from this GUI? package multiplechoice; import java.awt.*; import javax.swing.*; public class MultipleChoice extends JFrame { public MultipleChoice() { /* * Setting Layout */ setLayout(new GridLayout(10,10)); /* * First Question */ add(new JLabel("What is the category of the question?: ")); JTextField category = new JTextField(); add(category); add(new JLabel("Please enter the question you wish to ask: ")); JTextField question = new JTextField(); add(question); add(new JLabel("Please enter the correct answer: ")); JTextField correctAnswer = new JTextField(); add(correctAnswer); add(new JLabel("Please enter a reccomended answer to display: ")); JTextField reccomendedAnswer = new JTextField(); add(reccomendedAnswer); add(new JLabel("Please enter a choice for multiple choice option " + "A")); JTextField A = new JTextField(); add(A); add(new JLabel("Please enter a choice for multiple choice option " + "B")); JTextField B = new JTextField(); add(B); add(new JLabel("Please enter a choice for multiple choice option " + "C")); JTextField C = new JTextField(); add(C); add(new JLabel("Please enter a choice for multiple choice option " + "D")); JTextField D = new JTextField(); add(D); add(new JButton("Compile Questions")); add(new JButton("Next Question")); } public static void main(String[] args) { /* * Creating JFrame to contain questions */ FinalProject frame = new FinalProject(); // FileOutputStream output = new FileOutputStream("Questions.dat"); JPanel panel = new JPanel(); // button.setLayout(); // frame.add(panel); panel.setSize(100,100); // button.setPreferredSize(new Dimension(100,100)); frame.setTitle("FinalProject"); frame.setSize(600, 400); frame.setLocationRelativeTo(null); // Center the frame frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }

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  • Marionette js itemview not defined: then on browser refresh it is defined and all works well - race condition?

    - by Robert
    Yeah it's just the initial browser load or two after a cache clear. Subsequent refreshes clear the problem up. I'm thinking the item views just aren't fully constructed in time to be used in the collection views on the first load. But then they are on a refresh? Don't know. There must be something about the code sequence or loading or the load time itself. Not sure. I'm loading via require.js. Have two collections - users and messages. Each renders in its own list view. Each works, just not the first time or two the browser loads. The first time you load after clearing browser cache the console reports, for instance: "Uncaught ReferenceError: MessageItemView is not defined" A simple browser refresh clears it up. Same goes for the user collection. It's collection view says it doesn't know anything about its item view. But a simple browser refresh and all is well. My views (item and collection) are in separate files. Is that the problem? For instance, here is my message collection view in its own file: messagelistview.js var MessageListView = Marionette.CollectionView.extend({ itemView: MessageItemView, el: $("#messages") }); And the message item view is in a separate file: messageview.js var MessageItemView = Marionette.ItemView.extend({ tagName: "div", template: Handlebars.compile( '<div>{{fromUserName}}:</div>' + '<div>{{message}}</div>' + ) }); Then in my main module file, which references each of those files, the collection view is constructed and displayed: main.js //Define a model MessageModel = Backbone.Model.extend(); //Make an instance of MessageItemView - code in separate file, messagelistview.js MessageView = new MessageItemView(); //Define a message collection var MessageCollection = Backbone.Collection.extend({ model: MessageModel }); //Make an instance of MessageCollection var collMessages = new MessageCollection(); //Make an instance of a MessageListView - code in separate file, messagelistview.js var messageListView = new MessageListView({ collection: collMessages }); App.messageListRegion.show(messageListView); Do I just have things sequenced wrong? I'm thinking it's some kind of race condition only because over 3G to an iPad the item views are always undefined. They never seem to get constructed in time. PC on a hard wired connection does see success after a browser refresh or two.

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  • Is there some way to make variables like $a and $b in regard to strict?

    - by Axeman
    In light of Michael Carman's comment, I have decided to rewrite the question. Note that 11 comments appear before this edit, and give credence to Michael's observation that I did not write the question in a way that made it clear what I was asking. Question: What is the standard--or cleanest way--to fake the special status that $a and $b have in regard to strict by simply importing a module? First of all some setup. The following works: #!/bin/perl use strict; print "\$a=$a\n"; print "\$b=$b\n"; If I add one more line: print "\$c=$c\n"; I get an error at compile time, which means that none of my dazzling print code gets to run. If I comment out use strict; it runs fine. Outside of strictures, $a and $b are mainly special in that sort passes the two values to be compared with those names. my @reverse_order = sort { $b <=> $a } @unsorted; Thus the main functional difference about $a and $b--even though Perl "knows their names"--is that you'd better know this when you sort, or use some of the functions in List::Util. It's only when you use strict, that $a and $b become special variables in a whole new way. They are the only variables that strict will pass over without complaining that they are not declared. : Now, I like strict, but it strikes me that if TIMTOWTDI (There is more than one way to do it) is Rule #1 in Perl, this is not very TIMTOWDI. It says that $a and $b are special and that's it. If you want to use variables you don't have to declare $a and $b are your guys. If you want to have three variables by adding $c, suddenly there's a whole other way to do it. Nevermind that in manipulating hashes $k and $v might make more sense: my %starts_upper_1_to_25 = skim { $k =~ m/^\p{IsUpper}/ && ( 1 <= $v && $v <= 25 ) } %my_hash ;` Now, I use and I like strict. But I just want $k and $v to be visible to skim for the most compact syntax. And I'd like it to be visible simply by use Hash::Helper qw<skim>; I'm not asking this question to know how to black-magic it. My "answer" below, should let you know that I know enough Perl to be dangerous. I'm asking if there is a way to make strict accept other variables, or what is the cleanest solution. The answer could well be no. If that's the case, it simply does not seem very TIMTOWTDI.

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  • 'Scanner' does not name a type error in g++

    - by Max
    Hi. I'm trying to compile code in g++ and I get the following errors: In file included from scanner.hpp:8, from scanner.cpp:5: parser.hpp:14: error: ‘Scanner’ does not name a type parser.hpp:15: error: ‘Token’ does not name a type Here's my g++ command: g++ parser.cpp scanner.cpp -Wall Here's parser.hpp: #ifndef PARSER_HPP #define PARSER_HPP #include <string> #include <map> #include "scanner.hpp" using std::string; class Parser { // Member Variables private: Scanner lex; // Lexical analyzer Token look; // tracks the current lookahead token // Member Functions <some function declarations> }; #endif and here's scanner.hpp: #ifndef SCANNER_HPP #define SCANNER_HPP #include <iostream> #include <cctype> #include <string> #include <map> #include "parser.hpp" using std::string; using std::map; enum { // reserved words BOOL, ELSE, IF, TRUE, WHILE, DO, FALSE, INT, VOID, // punctuation and operators LPAREN, RPAREN, LBRACK, RBRACK, LBRACE, RBRACE, SEMI, COMMA, PLUS, MINUS, TIMES, DIV, MOD, AND, OR, NOT, IS, ADDR, EQ, NE, LT, GT, LE, GE, // symbolic constants NUM, ID, ENDFILE, ERROR }; class Token { public: int tag; int value; string lexeme; Token() {tag = 0;} Token(int t) {tag = t;} }; class Num : public Token { public: Num(int v) {tag = NUM; value = v;} }; class Word : public Token { public: Word() {tag = 0; lexeme = "default";} Word(int t, string l) {tag = t; lexeme = l;} }; class Scanner { private: int line; // which line the compiler is currently on int depth; // how deep in the parse tree the compiler is map<string,Word> words; // list of reserved words and used identifiers // Member Functions public: Scanner(); Token scan(); string printTag(int); friend class Parser; }; #endif anyone see the problem? I feel like I'm missing something incredibly obvious.

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  • Use multiple inheritance to discriminate useage roles?

    - by Arne
    Hi fellows, it's my flight simulation application again. I am leaving the mere prototyping phase now and start fleshing out the software design now. At least I try.. Each of the aircraft in the simulation have got a flight plan associated to them, the exact nature of which is of no interest for this question. Sufficient to say that the operator way edit the flight plan while the simulation is running. The aircraft model most of the time only needs to read-acess the flight plan object which at first thought calls for simply passing a const reference. But ocassionally the aircraft will need to call AdvanceActiveWayPoint() to indicate a way point has been reached. This will affect the Iterator returned by function ActiveWayPoint(). This implies that the aircraft model indeed needs a non-const reference which in turn would also expose functions like AppendWayPoint() to the aircraft model. I would like to avoid this because I would like to enforce the useage rule described above at compile time. Note that class WayPointIter is equivalent to a STL const iterator, that is the way point can not be mutated by the iterator. class FlightPlan { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) WayPointIter First() const; WayPointIter Last() const; WayPointIter Active() const; void AdvanceActiveWayPoint() const; (...) }; My idea to overcome the issue is this: define an abstract interface class for each usage role and inherit FlightPlan from both. Each user then only gets passed a reference of the appropriate useage role. class IFlightPlanActiveWayPoint { public: WayPointIter Active() const =0; void AdvanceActiveWayPoint() const =0; }; class IFlightPlanEditable { public: void AppendWayPoint(const WayPointIter& at, WayPoint new_wp); void ReplaceWayPoint(const WayPointIter& ar, WayPoint new_wp); void RemoveWayPoint(WayPointIter at); (...) }; Thus the declaration of FlightPlan would only need to be changed to: class FlightPlan : public IFlightPlanActiveWayPoint, IFlightPlanEditable { (...) }; What do you think? Are there any cavecats I might be missing? Is this design clear or should I come up with somethink different for the sake of clarity? Alternatively I could also define a special ActiveWayPoint class which would contain the function AdvanceActiveWayPoint() but feel that this might be unnecessary. Thanks in advance!

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  • C++ Template const char array to int

    - by Levi Schuck
    So, I'm wishing to be able to have a static const compile time struct that holds some value based on a string by using templates. I only desire up to four characters. I know that the type of 'abcd' is int, and so is 'ab','abc', and although 'a' is of type char, it works out for a template<int v> struct What I wish to do is take sizes of 2,3,4,5 of some const char, "abcd" and have the same functionality as if they used 'abcd'. Note that I do not mean 1,2,3, or 4 because I expect the null terminator. cout << typeid("abcd").name() << endl; tells me that the type for this hard coded string is char const [5], which includes the null terminator on the end. I understand that I will need to twiddle the values as characters, so they are represented as an integer. I cannot use constexpr since VS10 does not support it (VS11 doesn't either..) So, for example with somewhere this template defined, and later the last line template <int v> struct something { static const int value = v; }; //Eventually in some method cout << typeid(something<'abcd'>::value).name() << endl; works just fine. I've tried template<char v[5]> struct something2 { static const int value = v[0]; } template<char const v[5]> struct something2 { static const int value = v[0]; } template<const char v[5]> struct something2 { static const int value = v[0]; } All of them build individually, though when I throw in my test, cout << typeid(something2<"abcd">::value).name() << endl; I get 'something2' : invalid expression as a template argument for 'v' 'something2' : use of class template requires template argument list Is this not feasible or am I misunderstanding something?

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  • JavaFX2: Drag Event start and end coordinates

    - by user
    I have one node(ImageView) that displays an image and another node(rectangle) that resides on top of it. The behavior I need is that when the mouse is dragged(press-drag-release gesture) over the rectangle, both the nodes should move coherently. My thought process goes in the following direction: • Move both the nodes by the same distance in the direction of the drag. For this option(maybe there are more options) I need the distance between the start and end of the mouse drags. I tried capturing the start and end coordinates of the drag but have been unsuccessful. I think I am getting lost in which handlers to implement. The code I have is below: import javafx.event.EventHandler; import javafx.geometry.Rectangle2D; import javafx.scene.image.ImageView; import javafx.scene.input.MouseEvent; public class MyView { double mouseDragStartX; double mouseDragEndX; double mouseDragStartY; double mouseDragEndY; ImageView imageView; public MyView() { imageView = new ImageView("C:\\temp\\test.png"); } private void setRectangleEvents(final MyObject myObject) { myObject.getRectangle().setOnMousePressed(new EventHandler<MouseEvent>() { @Override public void handle(MouseEvent mouseEvent) { mouseDragStartX = mouseEvent.getX(); mouseDragStartY = mouseEvent.getY(); mouseEvent.consume(); } }); myObject.getRectangle().setOnMouseReleased(new EventHandler<MouseEvent>() { public void handle(MouseEvent mouseEvent) { mouseDragEndX = mouseEvent.getX(); mouseDragEndY = mouseEvent.getY(); myObjectDraggedHandler(); } }); } private void myObjectDraggedHandler() { Rectangle2D viewport = this.imageView.getViewport(); double newX = this.imageView.getImage().getWidth() + (mouseDragEndX - mouseDragStartX); double newY = this.imageView.getImage().getHeight() + (mouseDragEndY - mouseDragStartY); this.imageView.setViewport(new Rectangle2D(newX, newY, viewport.getWidth(), viewport .getHeight())); } } P.S: This code is just for indicating what I am trying to implement and will not compile correctly. Or maybe my question should just have been: How to capture the length or span of a mouse drag?

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  • Which work process in my company should I Improve first?

    - by shoren
    I've just started to work in a new place, and I see several things they do that I find really terrible, and I want to know if they are indeed so wrong, or I am just too strict. Please let me know if my criticism is in place, and your opinion on which problem is the worst and should be fixed first. The developement is all in Java. 1) Not using svnignore. This means svn stat can't be used, and developers forget to add files and break the build. 2) Generated files go to same folders as committed files. Can't use simple maven clean, have to find them one by one. Maven clean doesn't remove all of them. 3) Not fixing IDE analyze warnings. Analyze code returns about 5,000 warning, of many different kinds. 4) Not following conventions: spring beans names sometimes start with uppercase and sometimes not, ant properties sometimes with underline and sometimes with dots delimiter, etc. 5) Incremental build takes 6 minutes, even when nothing is changed. 6) Developers only use remote debug, and don't know how to run the Tomcat server internally from the IDE. 7) Developers always restart the server after every compilation, instead of dynamically reloading the class and saving the server's state. It takes them at least 10 minutes to start checking any change in the code. 8) Developers only compile from command line. When there are compilation errors, they manually open the file and go the the problematic line. 9) A complete mess in project dependencies. Over 200 open sources are depended on, and no one knows what is indeed needed and why. They do know that not all dependencies are necessary. 10) Mixing Maven and Ant in a way that disables the benefits of both. In one case, even dependency checks are not done by Maven. 11) Not using generics properly. 12) Developers don't use Subversion integration with IDE (Eclipse, Intellij Idea). What do you think? Where should I start? Is any of the things I mentioned not really a problem?

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  • Template class + virtual function = must implement?

    - by sold
    This code: template <typename T> struct A { T t; void DoSomething() { t.SomeFunction(); } }; struct B { }; A<B> a; is easily compiled without any complaints, as long as I never call a.DoSomething(). However, if I define DoSomething as a virtual function, I will get a compile error saying that B doesn't declare SomeFunction. I can somewhat see why it happens (DoSomething should now have an entry in the vtable), but I can't help feeling that it's not really obligated. Plus it sucks. Is there any way to overcome this? EDIT 2: Okay. I hope this time it makes sence: Let's say I am doing intrusive ref count, so all entities must inherit from base class Object. How can I suuport primitive types too? I can define: template <typename T> class Primitive : public Object { T value; public: Primitive(const T &value=T()); operator T() const; Primitive<T> &operator =(const T &value); Primitive<T> &operator +=(const T &value); Primitive<T> &operator %=(const T &value); // And so on... }; so I can use Primitive<int>, Primitive<char>... But how about Primitive<float>? It seems like a problem, because floats don't have a %= operator. But actually, it isn't, since I'll never call operator %= on Primitive<float>. That's one of the deliberate features of templates. If, for some reason, I would define operator %= as virtual. Or, if i'll pre-export Primitive<float> from a dll to avoid link errors, the compiler will complain even if I never call operator %= on a Primitive<float>. If it would just have fill in a dummy value for operator %= in Primitive<float>'s vtable (that raises an exception?), everything would have been fine.

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  • Get name mangling when I try to use exceptions [CodeBlocks, C++]

    - by Beetroot
    I am trying to use exceptions for the first time but even though it is quite a simple example I just cannot get it to compile, I have looked at several examples and tried coding it in many, many different ways but I am still not even sure exactly where the problem is because I get namemangling when I introduce the catch/try/throw anyway here is my code hopefully it is something really stupid :) #include "Surface.h" #include "SDL_Image.h" using namespace std; SDL_Surface* surface::Load(string fileName){ SDL_Surface* loadedSurface = IMG_Load(fileName.c_str()); if(loadedSurface == 0) throw 0; //Convert surface to same format as display loadedSurface = SDL_DisplayFormatAlpha(loadedSurface); return loadedSurface; } #include "GameState.h" #include "Surface.h" #include<iostream> using namespace std; GameState::GameState(string fileName){ try{ stateWallpaper_ = surface::Load(fileName); } catch(int& e){ cerr << "Could not load " << fileName << endl; } } Thanks in advance for any help! EDIT: Sorry I forgot to post the error message: It is In function `ZN14GameStateIntroC1Ev':| -undefined reference to `__gxx_personality_sj0'| -undefined reference to `_Unwind_SjLj_Register'| -undefined reference to `_Unwind_SjLj_Unregister'| In function `ZN14GameStateIntroC1Ev':| undefined reference to `_Unwind_SjLj_Resume'| In function `ZN14GameStateIntroC2Ev':| -undefined reference to `__gxx_personality_sj0'| -undefined reference to `_Unwind_SjLj_Register'| -undefined reference to `_Unwind_SjLj_Unregister'| obj\Release\GameStateIntro.o||In function `ZN14GameStateIntroC2Ev':| C:\Program Files (x86)\CodeBlocks\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\include\c++\3.4.5\ext\new_allocator.h|69|undefined reference to `_Unwind_SjLj_Resume'| C:\MinGW\lib\libSDLmain.a(SDL_win32_main.o)||In function `redirect_output':| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|219|undefined reference to `SDL_strlcpy'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|220|undefined reference to `SDL_strlcat'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|243|undefined reference to `SDL_strlcpy'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|244|undefined reference to `SDL_strlcat'| C:\MinGW\lib\libSDLmain.a(SDL_win32_main.o)||In function `console_main':| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|296|undefined reference to `SDL_strlcpy'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|301|undefined reference to `SDL_GetError'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|312|undefined reference to `SDL_SetModuleHandle'| C:\MinGW\lib\libSDLmain.a(SDL_win32_main.o)||In function `WinMain@16':| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|354|undefined reference to `SDL_getenv'| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|386|undefined reference to `SDL_strlcpy'| C:\MinGW\lib\libSDLmain.a(SDL_win32_main.o)||In function `cleanup':| \Users\slouken\release\SDL\SDL-1.2.15\.\src\main\win32\SDL_win32_main.c|158|undefined reference to `SDL_Quit'| **

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  • c++ property class structure

    - by Without me Its just Aweso
    I have a c++ project being developed in QT. The problem I'm running in to is I am wanting to have a single base class that all my property classes inherit from so that I can store them all together. Right now I have: class AbstractProperty { public: AbstractProperty(QString propertyName); virtual QString toString() const = 0; virtual QString getName() = 0; virtual void fromString(QString str) = 0; virtual int toInteger() = 0; virtual bool operator==(const AbstractProperty &rightHand) = 0; virtual bool operator!=(const AbstractProperty &rightHand) = 0; virtual bool operator<(const AbstractProperty &rightHand) = 0; virtual bool operator>(const AbstractProperty &rightHand) = 0; virtual bool operator>=(const AbstractProperty &rightHand) = 0; virtual bool operator<=(const AbstractProperty &rightHand) = 0; protected: QString name; }; then I am implementing classes such as PropertyFloat and PropertyString and providing implementation for the comparator operators based on the assumption that only strings are being compared with strings and so on. However the problem with this is there would be no compiletime error thrown if i did if(propertyfloat a < propertystring b) however my implementation of the operators for each derived class relies on them both being the same derived class. So my problem is I cant figure out how to implement a property structure so that I can have them all inherit from some base type but code like what I have above would throw a compile time error. Any ideas on how this can be done? For those familiar with QT I tried using also a implementation with QVariant however QVariant doesn't have operators < and defined in itself only in some of its derived classes so it didn't work out. What my end goal is, is to be able to generically refer to properties. I have an element class that holds a hashmap of properties with string 'name' as key and the AbstractProperty as value. I want to be able to generically operate on the properties. i.e. if I want to get the max and min values of a property given its string name I have methods that are completely generic that will pull out the associated AbstactProperty from each element and find the max/min no matter what the type is. so properties although initially declared as PropertyFloat/PropertyString they will be held generically.

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  • Accesing server control from withing app_code class

    - by OverSeven
    My question is about how to acces a server control (listbox) that is located in default.aspx. I wish to acces this control in Functions.cs (this class is located in the App_Code folder). My page structures: - 1 masterpage with 1 content holder - Default.aspx (all the controls are within the content place holder) - Functions.cs (located in App_Code) Now when i try to fill up the listbox elements i get the error "object reference not set to an instance of an object." What i have tried to gain acces to this control: (this code is located in Functions.cs in App_Code). This is basicly showing some items in the listbox that are located in the xml file private static string file = HttpContext.Current.Server.MapPath("~/App_Data/Questions.xml"); public static void ListItems() { XmlDocument XMLDoc = new XmlDocument(); XMLDoc.Load(file); XPathNavigator nav = XMLDoc.CreateNavigator(); XPathExpression expr; expr = nav.Compile("/root/file/naam"); XPathNodeIterator iterator = nav.Select(expr); //ATTEMPT to get acces to ServerControl(listbox) Page page = (Page)HttpContext.Current.Handler; ListBox test = (ListBox)page.FindControl("lbTest"); //control is called lbTest in Default.aspx test.Items.Clear(); while (iterator.MoveNext()) { test.Items.Add(iterator.Current.Value); } } Code from the default.apx file <%@ Page Title="" Language="C#" MasterPageFile="~/MasterFile.master" AutoEventWireup="true" CodeFile="default.aspx.cs" Inherits="default" Debug="true" %> <%@ MasterType TypeName="Master" %> <asp:Content ID="Content1" ContentPlaceHolderID="cphContent" Runat="Server" > <asp:MultiView ID="mvTest" runat="server" > <asp:View ID="vCollection" runat="server"> <asp:ListBox ID="lbTest" runat="server" CssClass="listbox" ></asp:ListBox> </asp:View> </asp:MultiView> </asp:Content> The masterfile itself just has 1 placeholder. Then i call upon the funcion ListItems in the Default.aspx.cs file protected void Page_Load(object sender, EventArgs e) { Functions.ListItems(); } Regards.

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  • Why am I getting ClassNotFoundExpection when I have properly imported said class and am looking at it in its directory?

    - by Strider
    This is my Javac compiling statement: javac -cp "C:\java\code\j3D\j3dcore.jar;C:\java\code\j3D\j3dutils.jar;C:\java\code\j3D\vecmath.jar" Simple.java compiles with no problems. The three jar files (j3dcore, j3dutils, and vecmath) are the essential jar's for my program (or at least I am led to believe according to this official tutorial on J3D For the record I ripped this code almost line from line from this pdf file. jar files are correctly located in referenced locations When I run my Simple program, (java Simple) I am greeted with Exception in thread "main" java.lang.NoClassDefFoundError: javax/media/j3d/Cavas3d Caused by: java.lang.ClassNotFoundExpection: javax.media.j3d.Canvas3D Currently I am staring directly at this Canvas3D.class that is located within j3dcore.jar\javax\media\j3d\ wtfisthis.jpg Here is the source code: //First java3D Program import java.applet.Applet; import java.awt.BorderLayout; import java.awt.Frame; import java.awt.event.*; import com.sun.j3d.utils.applet.MainFrame; import com.sun.j3d.utils.universe.*; import com.sun.j3d.utils.geometry.ColorCube; import javax.media.j3d.*; import javax.vecmath.*; import java.awt.GraphicsConfiguration; public class Simple extends Applet { public Simple() { setLayout(new BorderLayout()); GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration(); Canvas3D canvas3D = new Canvas3D(config); add("Center", canvas3D); BranchGroup scene = createSceneGraph(); scene.compile(); // SimpleUniverse is a Convenience Utility class SimpleUniverse simpleU = new SimpleUniverse(canvas3D); // This moves the ViewPlatform back a bit so the // objects in the scene can be viewed. simpleU.getViewingPlatform().setNominalViewingTransform(); simpleU.addBranchGraph(scene); } // end of HelloJava3Da (constructor) public BranchGroup createSceneGraph() { // Create the root of the branch graph BranchGroup objRoot = new BranchGroup(); // Create a simple shape leaf node, add it to the scene graph. // ColorCube is a Convenience Utility class objRoot.addChild(new ColorCube(0.4)); return objRoot; } public static void main(String args[]){ Simple world = new Simple(); } }` Did I import correctly? Did I incorrectly reference my jar files in my Javac statement? If I clearly see Canvas3D within its correct directory why cant java find it? The first folder in both j3dcore.jar and vecmath.jar is "javax". Is the compiler getting confused? If the compiler is getting confused how do I specify where to find that exact class when referencing it within my source code?

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  • C++ stream as a parameter when overloading operator<<

    - by TheOm3ga
    I'm trying to write my own logging class and use it as a stream: logger L; L << "whatever" << std::endl; This is the code I started with: #include <iostream> using namespace std; class logger{ public: template <typename T> friend logger& operator <<(logger& log, const T& value); }; template <typename T> logger& operator <<(logger& log, T const & value) { // Here I'd output the values to a file and stdout, etc. cout << value; return log; } int main(int argc, char *argv[]) { logger L; L << "hello" << '\n' ; // This works L << "bye" << "alo" << endl; // This doesn't work return 0; } But I was getting an error when trying to compile, saying that there was no definition for operator<<: pruebaLog.cpp:31: error: no match for ‘operator<<’ in ‘operator<< [with T = char [4]](((logger&)((logger*)operator<< [with T = char [4]](((logger&)(& L)), ((const char (&)[4])"bye")))), ((const char (&)[4])"alo")) << std::endl’ So, I've been trying to overload operator<< to accept this kind of streams, but it's driving me mad. I don't know how to do it. I've been loking at, for instance, the definition of std::endl at the ostream header file and written a function with this header: logger& operator <<(logger& log, const basic_ostream<char,char_traits<char> >& (*s)(basic_ostream<char,char_traits<char> >&)) But no luck. I've tried the same using templates instead of directly using char, and also tried simply using "const ostream& os", and nothing. Another thing that bugs me is that, in the error output, the first argument for operator<< changes, sometimes it's a reference to a pointer, sometimes looks like a double reference...

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  • Trouble with abstract generic methods

    - by DanM
    Let's say I have a class library that defines a couple entity interfaces: public interface ISomeEntity { /* ... */ } public interface ISomeOtherEntity { /* ... */ } This library also defines an IRepository interface: public interface IRepository<TEntity> { /* ... */ } And finally, the library has an abstract class called RepositorySourceBase (see below), which the main project needs to implement. The goal of this class is to allow the base class to grab new Repository objects at runtime. Because certain repositories are needed (in this example a repository for ISomeEntity and ISomeOtherEntity), I'm trying to write generic overloads of the GetNew<TEntity>() method. The following implementation doesn't compile (the second GetNew() method gets flagged as "already defined" even though the where clause is different), but it gets at what I'm trying to accomplish: public abstract class RepositorySourceBase // This doesn't work! { public abstract Repository<TEntity> GetNew<TEntity>() where TEntity : SomeEntity; public abstract Repository<TEntity> GetNew<TEntity>() where TEntity : SomeOtherEntity; } The intended usage of this class would be something like this: public class RepositorySourceTester { public RepositorySourceTester(RepositorySourceBase repositorySource) { var someRepository = repositorySource.GetNew<ISomeEntity>(); var someOtherRepository = repositorySource.GetNew<ISomeOtherEntity>(); } } Meanwhile, over in my main project (which references the library project), I have implementations of ISomeEntity and ISomeOtherEntity: public class SomeEntity : ISomeEntity { /* ... */ } public class SomeOtherEntity : ISomeOtherEntity { /* ... */ } The main project also has an implementation for IRepository<TEntity>: public class Repository<TEntity> : IRepository<TEntity> { public Repository(string message) { } } And most importantly, it has an implementation of the abstract RepositorySourceBase: public class RepositorySource : RepositorySourceBase { public override Repository<SomeEntity> GetNew() { return new Repository<SomeEntity>("stuff only I know"); } public override Repository<SomeOtherEntity> GetNew() { return new Repository<SomeOtherEntity>("other stuff only I know"); } } Just as with RepositorySourceBase, the second GetNew() method gets flagged as "already defined". So, C# basically think I'm repeating the same method because there's no way to distinguish the methods from parameters, but if you look at my usage example, it seems like I should be able to distinguish which GetNew() I want from the generic type parameter, e.g, <ISomeEntity> or <ISomeOtherEntity>. What do I need to do to get this to work?

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  • Inlining an array of non-default constructible objects in a C++ class

    - by porgarmingduod
    C++ doesn't allow a class containing an array of items that are not default constructible: class Gordian { public: int member; Gordian(int must_have_variable) : member(must_have_variable) {} }; class Knot { Gordian* pointer_array[8]; // Sure, this works. Gordian inlined_array[8]; // Won't compile. Can't be initialized. }; As even beginner C++ users know, the language guarantees that all members are initialized when constructing a class. And it doesn't trust the user to initialize everything in the constructor - one has to provide valid arguments to the constructors of all members before the body of the constructor even starts. Generally, that's a great idea as far as I'm concerned, but I've come across a situation where it would be a lot easier if I could actually have an array of non-default constructible objects. The obvious solution: Have an array of pointers to the objects. This is not optimal in my case, as I am using shared memory. It would force me to do extra allocation from an already contended resource (that is, the shared memory). The entire reason I want to have the array inlined in the object is to reduce the number of allocations. This is a situation where I would be willing to use a hack, even an ugly one, provided it works. One possible hack I am thinking about would be: class Knot { public: struct dummy { char padding[sizeof(Gordian)]; }; dummy inlined_array[8]; Gordian* get(int index) { return reinterpret_cast<Gordian*>(&inlined_array[index]); } Knot() { for (int x = 0; x != 8; x++) { new (get(x)) Gordian(x*x); } } }; Sure, it compiles, but I'm not exactly an experienced C++ programmer. That is, I couldn't possibly trust my hacks less. So, the questions: 1) Does the hack I came up with seem workable? What are the issues? (I'm mainly concerned with C++0x on newer versions of GCC). 2) Is there a better way to inline an array of non-default constructible objects in a class?

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  • What is the best way to connect to an Oracle database to build my own IDE? [closed]

    - by rima
    before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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  • How to get all captures of subgroup matches with preg_match_all()?

    - by hakre
    Update/Note: I think what I'm probably looking for is to get the captures of a group in PHP. Referenced: PCRE regular expressions using named pattern subroutines. (Read carefully:) I have a string that contains a variable number of segments (simplified): $subject = 'AA BB DD '; // could be 'AA BB DD CC EE ' as well I would like now to match the segments and return them via the matches array: $pattern = '/^(([a-z]+) )+$/i'; $result = preg_match_all($pattern, $subject, $matches); This will only return the last match for the capture group 2: DD. Is there a way that I can retrieve all subpattern captures (AA, BB, DD) with one regex execution? Isn't preg_match_all suitable for this? This question is a generalization. Both the $subject and $pattern are simplified. Naturally with such the general list of AA, BB, .. is much more easy to extract with other functions (e.g. explode) or with a variation of the $pattern. But I'm specifically asking how to return all of the subgroup matches with the preg_...-family of functions. For a real life case imagine you have multiple (nested) level of a variant amount of subpattern matches. Example This is an example in pseudo code to describe a bit of the background. Imagine the following: Regular definitions of tokens: CHARS := [a-z]+ PUNCT := [.,!?] WS := [ ] $subject get's tokenized based on these. The tokenization is stored inside an array of tokens (type, offset, ...). That array is then transformed into a string, containing one character per token: CHARS -> "c" PUNCT -> "p" WS -> "s" So that it's now possible to run regular expressions based on tokens (and not character classes etc.) on the token stream string index. E.g. regex: (cs)?cp to express one or more group of chars followed by a punctuation. As I now can express self-defined tokens as regex, the next step was to build the grammar. This is only an example, this is sort of ABNF style: words = word | (word space)+ word word = CHARS+ space = WS punctuation = PUNCT If I now compile the grammar for words into a (token) regex I would like to have naturally all subgroup matches of each word. words = (CHARS+) | ( (CHARS+) WS )+ (CHARS+) # words resolved to tokens words = (c+)|((c+)s)+c+ # words resolved to regex I could code until this point. Then I ran into the problem that the sub-group matches did only contain their last match. So I have the option to either create an automata for the grammar on my own (which I would like to prevent to keep the grammar expressions generic) or to somewhat make preg_match working for me somehow so I can spare that. That's basically all. Probably now it's understandable why I simplified the question. Related: pcrepattern man page Get repeated matches with preg_match_all()

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  • sigwait in Linux (Fedora 13) vs OS X

    - by Silas
    So I'm trying to create a signal handler using pthreads which works on both OS X and Linux. The code below works on OS X but doesn't work on Fedora 13. The application is fairly simple. It spawns a pthread, registers SIGHUP and waits for a signal. After spawning the signal handler I block SIGHUP in the main thread so the signal should only be sent to the signal_handler thread. On OS X this works fine, if I compile, run and send SIGHUP to the process it prints "Got SIGHUP". On Linux it just kills the process (and prints Hangup). If I comment out the signal_handler pthread_create the application doesn't die. I know the application gets to the sigwait and blocks but instead of return the signal code it just kills the application. I ran the test using the following commands: g++ test.cc -lpthread -o test ./test & PID="$!" sleep 1 kill -1 "$PID" test.cc #include <pthread.h> #include <signal.h> #include <iostream> using namespace std; void *signal_handler(void *arg) { int sig; sigset_t set; sigemptyset(&set); sigaddset(&set, SIGHUP); while (true) { cout << "Wait for signal" << endl; sigwait(&set, &sig); if (sig == SIGHUP) { cout << "Got SIGHUP" << endl; } } } int main() { pthread_t handler; sigset_t set; // Create signal handler pthread_create(&handler, NULL, signal_handler, NULL); // Ignore SIGHUP in main thread sigfillset(&set); sigaddset(&set, SIGHUP); pthread_sigmask(SIG_BLOCK, &set, NULL); for (int i = 1; i < 5; i++) { cout << "Sleeping..." << endl; sleep(1); } pthread_join(handler, NULL); return 0; }

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  • Class Template Instantiation: any way round this circular reference?

    - by TimYorke34
    I have two classes that I'm using to represent some hardware: A Button and an InputPin class which represent a button that will change the value of an IC's input pin when it's pressed down. A simple example of them is: template <int pinNumber> class InputPin { static bool IsHigh() { return ( (*portAddress) & (1<<pinNumber) ); } }; template <typename InputPin> class Button { static bool IsPressed() { return !InputPin::IsHigh(); } }; This works beautifully and by using class templates, the condition below will compile as tightly as if I'd handwritten it in assembly (a single instruction). Button < InputPin<1> > powerButton; if (powerButton.IsPressed()) ........; However, I am extending it to deal with interrupts and have got a problem with circular references. Compared to the original InputPin, a new InputPinIRQ class has an extra static member function that will be called automatically by the hardware when the pin value changes. I'd like it to be able to notify the Button class of this, so that the Button class can then notify the main application that it has been pressed/released. I am currently doing this with function pointers to callbacks. In order for the callback code to be inlined by the compiler, I need to pass the function pointers as template parameters. So now, both of the new classes have an extra template parameter that is a pointer to a callback function. Unfortunately this gives me a circular reference because to instantiate a ButtonIRQ class I now have to do something like this: ButtonIRQ< InputPinIRQ< A1, ButtonIRQ<....>::OnPinChange, OnButtonChange > pB; where the <...... represents the circular reference. Does anyone know how I can avoid this circular reference? I am new to templates, so might be missing something really simple. It's important that the compiler knows exactly what code will be run when the interrupt occurs as it then does some very useful optimisation - it is able to inline the callback function and literally inserts the callback function's code at the exact address that is called on a h/w interrupt.

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  • No warning from gcc when function definition in linked source different from function prototype in h

    - by c_c
    Hi, I had a problem with a part of my code, which after some iterations seemed to read NaN as value of a int of a struct. I think I found the error, but am still wondering why gcc (version 3.2.3 on a embedded Linux with busybox) did not warn me. Here are the important parts of the code: A c file and its header for functions to acquire data over USB: // usb_control.h typedef struct{ double mean; short *values; } DATA_POINTS; typedef struct{ int size; DATA_POINTS *channel1; //....7 more channels } DATA_STRUCT; DATA_STRUCT *create_data_struct(int N); // N values per channel int free_data_struct(DATA_STRUCT *data); int aqcu_data(DATA_STRUCT *data, int N); A c and header file with helper function (math, bitshift,etc...): // helper.h int mean(DATA_STRUCT *data); // helper.c (this is where the error is obviously) double mean(DATA_STRUCT *data) { // sum in for loop data->channel1->mean = sum/data->N; // ...7 more channels // a printf here displayed the mean values corretly } The main file // main.c #include "helper.h" #include "usb_control.h" // Allocate space for data struct DATA_STRUCT *data = create_data_struct(N); // get data for different delays for (delay = 0; delay < 500; delay += pw){ acqu_data(data, N); mean(data); // printf of the mean values first is correct. Than after 5 iterations // it is always NaN for channel1. The other channels are displayed correctly; } There were no segfaults nor any other missbehavior, just the NaN for channel1 in the main file. After finding the error, which was not easy, it was of course east to fix. The return type of mean(){} was wrong in the definition. Instead of double mean() it has to be int mean() as the prototype defines. When all the functions are put into one file, gcc warns me that there is a redefinition of the function mean(). But as I compile each c file seperately and link them afterwards gcc seems to miss that. So my questions would be. Why didn't I get any warnings, even non with gcc -Wall? Or is there still another error hidden which is just not causing problems now? Regards, christian

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  • How to give properties to c++ classes (interfaces)

    - by caas
    Hello, I have built several classes (A, B, C...) which perform operations on the same BaseClass. Example: struct BaseClass { int method1(); int method2(); int method3(); } struct A { int methodA(BaseClass& bc) { return bc.method1(); } } struct B { int methodB(BaseClass& bc) { return bc.method2()+bc.method1(); } } struct C { int methodC(BaseClass& bc) { return bc.method3()+bc.method2(); } } But as you can see, each class A, B, C... only uses a subset of the available methods of the BaseClass and I'd like to split the BaseClass into several chunks such that it is clear what it used and what is not. For example a solution could be to use multiple inheritance: // A uses only method1() struct InterfaceA { virtual int method1() = 0; } struct A { int methodA(InterfaceA&); } // B uses method1() and method2() struct InterfaceB { virtual int method1() = 0; virtual int method2() = 0; } struct B { int methodB(InterfaceB&); } // C uses method2() and method3() struct InterfaceC { virtual int method2() = 0; virtual int method3() = 0; } struct C { int methodC(InterfaceC&); } The problem is that each time I add a new type of operation, I need to change the implementation of BaseClass. For example: // D uses method1() and method3() struct InterfaceD { virtual int method1() = 0; virtual int method3() = 0; } struct D { int methodD(InterfaceD&); } struct BaseClass : public A, B, C // here I need to add class D { ... } Do you know a clean way I can do this? Thanks for your help edit: I forgot to mention that it can also be done with templates. But I don't like this solution either because the required interface does not appear explicitly in the code. You have to try to compile the code to verify that all required methods are implemented correctly. Plus, it would require to instantiate different versions of the classes (one for each BaseClass type template parameter) and this is not always possible nor desired.

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  • How to ensure structures are completly initialized (by name) in GCC?

    - by Steven Spark
    How do I ensure each and every field of my structures are initialized in GCC when using designated initializers? (I'm especially interested in function pointers.) (I'm using C not C++.) Here is an example: typedef struct { int a; int b; } foo_t; typedef struct { void (*Start)(void); void (*Stop)(void); } bar_t; foo_t fooo = { 5 }; foo_t food = { .b=4 }; bar_t baro = { NULL }; bar_t bard = { .Start = NULL }; -Wmissing-field-initializers does not help at all. It works for fooo only in GCC (mingw 4.7.3, 4.8.1), and clang does only marginally better (no warnings for food and bard). I'm sure there is a reason for not producing warnings for designated initializer (even when I explicitly ask for them) but I want/need them. I do not want to initialize structures based on order/position because that is more error prone (for example swapping Start and Stop won't even give any warning). And neither gcc nor clang will give any warning that I failed to explicitly initialize a field (when initializing by name). I also don't want to litter my code with if(x.y==NULL) lines for multiple reasons, one of which is I want compile time warnings and not runtime errors. At least splint will give me warnings on all 4 cases, but unfortunately I cannot use splint all the time (it chokes on some of the code (fails to parse some C99, GCC extensions)). Note: If I'm using a real function instead of NULL GCC will also show a warning for baro (but not bard). I searched google and stack overflow but only found related questions and have not found answer for this specific problem. The best match I have found is 'Ensure that all elements in a structure are initialized' Ensure that all elements in a structure are initialized Which asks pretty much the same question, but has no satisfying answer. Is there a better way dealing with this that I have not mentioned? (Maybe other code analysis tool? Preferably something (free) that can be integrated into Eclipse or Visual Studio...)

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  • Is it OK to put a standard, pure C header #include directive inside a namespace?

    - by mic_e
    I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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  • Java error - not a statement, what does this mean?

    - by user2898828
    I am trying to get my code to create the new constructor objects which I require to create a mobile phone object. I have tried naming the constuctor fields to create the object. when I compile my code on this line this.Mobile samsungPhone = new Mobile("Samsung", 1, 2, "verizon", 3 "GPS"); I get this error: not a statement, what does this mean?? UPDATED CODE! my code: /** * to write a simple java class Mobile that models a mobile phone. * * @author (Lewis Burte-Clarke) * @version (14/10/13) */ public class Mobile { // type of phone private String phonetype; // size of screen in inches private int screensize; // menory card capacity private int memorycardcapacity; // name of present service provider private String serviceprovider; // type of contract with service provider private int typeofcontract; // camera resolution in megapixels private int cameraresolution; // the percentage of charge left on the phone private int checkcharge; // wether the phone has GPS or not private String GPS; // instance variables - replace the example below with your own private int x; // The constructor method public Mobile(String mobilephonetype, int mobilescreensize, int mobilememorycardcapacity,int mobilecameraresolution,String mobileGPS, String newserviceprovider) { this.phonetype = mobilephonetype; this.screensize = mobilescreensize; this.memorycardcapacity = mobilememorycardcapacity; this.cameraresolution = mobilecameraresolution; this.GPS = mobileGPS; this.serviceprovider = newserviceprovider; this.typeofcontract = 12; this.checkcharge = checkcharge; // you do not use this ones during instantiation,you can remove them if you do not need or assign them some default values Mobile samsungPhone = new Mobile("Samsung", 1, 2, "verizon", 3, "GPS"); 1024 = screen size; 2 = memory card capacity; 3=resolution; GPS = gps; "verizon"=service provider; typeofcontract = 12; checkcharge = checkcharge; } } // A method to display the state of the object to the screen public void displayMobileDetails() { System.out.println("phonetype: " + phonetype); System.out.println("screensize: " + screensize); System.out.println("memorycardcapacity: " + memorycardcapacity); System.out.println("cameraresolution: " + cameraresolution); System.out.println("GPS: " + GPS); System.out.println("serviceprovider: " + serviceprovider); System.out.println("typeofcontract: " + typeofcontract); } } class mymobile { public static void) { Mobile Samsung = new Mobile("Samsung", 1, 2, "verizon", 3, "GPS"); Mobile Blackberry = new Mobile("Blackberry", "3.", "4","8", "GPS"); Samsung.displayMobileDetails(); Blackberry.displayMobileDetails(); } } any answers and replies would be greatly appreciated!

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