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  • Spring MessageSource not being used during validation

    - by Jeremy
    I can't get my messages in messages.properties to be used during Spring validation of my form backing objects. app-config.xml: <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="messages" /> </bean> WEB-INF/classes/messages.properties: NotEmpty=This field should not be empty. Form Backing Object: ... @NotEmpty @Size(min=6, max=25) private String password; ... When I loop through all errors in the BindingResult and output the ObjectError's toString I get this: Field error in object 'settingsForm' on field 'password': rejected value []; codes [NotEmpty.settingsForm.password,NotEmpty.password,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [settingsForm.password,password]; arguments []; default message [password]]; default message [may not be empty] As you can see the default message is "may not be empty" instead of my message "This field should not be empty". I do get my correct message if I inject the messageSource into a controller and output this: messageSource.getMessage("NotEmpty", new Object [] {"password"}, "default empty message", null); So why isn't the validation using my messages.properties? I'm running Spring 3.1.1. Thanks!

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  • C++ class derivation and superconstructor confusion

    - by LukeN
    Hey, in a tutorial C++ code, I found this particular piece of confusion: PlasmaTutorial1::PlasmaTutorial1(QObject *parent, const QVariantList &args) : Plasma::Applet(parent, args), // <- Okay, Plasma = namespace, Applet = class m_svg(this), // <- A member function of class "Applet"? m_icon("document") // <- ditto? { m_svg.setImagePath("widgets/background"); // this will get us the standard applet background, for free! setBackgroundHints(DefaultBackground); resize(200, 200); } I'm not new to object oriented programming, so class derivation and super-classes are nothing complicated, but this syntax here got me confused. The header file defines the class like this: class PlasmaTutorial1 : public Plasma::Applet { Similar to above, namespace Plasma and class Applet. But what's the public doing there? I fear that I already know the concept but don't grasp the C++ syntax/way of doing it. In this question I picked up that these are called "superconstructors", at least that's what stuck in my memory, but I don't get this to the full extend. If we glance back at the first snippet, we see Constructor::Class(...) : NS::SuperClass(...), all fine 'till here. But what are m_svg(this), m_icon("document") doing there? Is this some kind of method to make these particular functions known to the derivated class? Is this part of C++ basics or more immediate? While I'm not completly lost in C++, I feel much more at home in C :) Most of the OOP I have done so far was done in D, Ruby or Python. For example in D I would just define class MyClass : MySuperClass, override what I needed to and call the super class' constructor if I'd need to.

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  • Creating simple calculator with bison & flex in C++ (not C)

    - by ak91
    Hey, I would like to create simple C++ calculator using bison and flex. Please note I'm new to the creating parsers. I already found few examples in bison/flex but they were all written in C. My goal is to create C++ code, where classes would contain nodes of values, operations, funcs - to create AST (evaluation would be done just after creating whole AST - starting from the root and going forward). For example: my_var = sqrt(9 ** 2 - 32) + 4 - 20 / 5 my_var * 3 Would be parsed as: = / \ my_var + / \ sqrt - | / \ - 4 / / \ / \ ** 32 20 5 / \ 9 2 and the second AST would look like: * / \ my_var 3 Then following pseudocode reflects AST: ast_root = create_node('=', new_variable("my_var"), exp) where exp is: exp = create_node(OPERATOR, val1, val2) but NOT like this: $$ = $1 OPERATOR $3 because this way I directly get value of operation instead of creation the Node. I believe the Node should contain type (of operation), val1 (Node), val2 (Node). In some cases val2 would be NULL, like above mentioned sqrt which takes in the end one argument. Right? It will be nice if you can propose me C++ skeleton (without evaluation) for above described problem (including *.y file creating AST) to help me understand the way of creating/holding Nodes in AST. Code can be snipped, just to let me get the idea. I'll also be grateful if you point me to an existing (possibly simple) example if you know any. Thank you all for your time and assistance!

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  • Whether to put method code in a VB.Net data storage class, or put it in a separate class?

    - by Alan K
    TLDR summary: (a) Should I include (lengthy) method code in classes which may spawn multiple objects at runtime, (b) does doing so cause memory usage bloat, (c) if so should I "outsource" the code to a class that is loaded only once and have the class methods call that, or alternatively (d) does the code get loaded only once with the object definition anyway and I'm worrying about nothing? ........ I don't know whether there's a good answer to this but if there is I haven't found it yet by searching in the usual places. In my VB.Net (2010 if it matters) WinForms project I have about a dozen or so class objects in an object model. Some of these are pretty simple and do little more than act as data storage repositories. The ones further up the object model, however, have an increasing number of methods. There can be a significant number of higher level objects in use though the exact number will be runtime dependent so I can't be more precise than that. As I was writing the method code for one of the top level ones I noticed that it was starting to get quite lengthy. Memory optimisation is something of a lost art given how much memory the average PC has these days but I don't want to make my application a resource hog. So my questions for anyone who knows .Net way better than I do (of which there will be many) are: Is the code loaded into memory with each instance of the class that's created? Alternatively is it loaded only once with the definition of the class, and all derived objects just refer to that definition? (I'm not really sure how that could be possible given that, for example, event handlers can be assigned dynamically, but no harm asking.) If the answer to the first one is yes, would it be more efficient to write the code in a "utility" object which is loaded only once and called from the real class' methods? Any thoughts appreciated.

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  • Debugging scripts loaded with GroovyShell (in eclipse)

    - by MSh
    I am working with eclipse and groovy plug in. I am building a test harness to debug and test groovy scripts. The scripts are really simple but long, most of them just if/else/return. I figured out that I can call them using GroovyShell and Bindings to pass in the values. The problem is that, while I can call the script and get the results just fine, I CAN NOT step in there with the debugger. Breakpoints in those scripts are not active. Is there a way to debug the scripts? Maybe I should use something other than GroovyShell? I really don't want to modify the scripts by wrapping them into functions, and then calling those functions from my test classes. That's how I am using Binding and GroovyShell: def binding = new Binding(); binding.lineList = [list1]; binding.count = 5; def shell = new GroovyShell(binding); def result = shell.evaluate(new File("src/Rules/checkLimit.groovy"));

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  • Exemplars of large document-centric applications with COM/XPCOM/.NET interfaces.

    - by Warren P
    I am looking for exemplars (design examples) showing the use of interfaces (aka 'protocols' for you smalltalkers) to design a document management architecture in a large Word Processor, Spreadsheet, vector graphic or publishing package, or office-productivity (non-database) application with support for as many of the following as possible: any open source project, will be ideal, and language of implementation is unimportant since I am looking for design examples, however an object oriented language with support for "interfaces" is a must. I know at least a dozen languages, and I'm willing to study any application's source. use of "interface" could loosely be applied to either XPCOM or COM interfaces, or .NET interfaces, or even the use of pure-virtual (virtual+abstract) base-classes for OOP languages that lack the ability to declare an interface distinct from a class. I am mostly looking for a robust, thorough and flexible implementation for a document, IDocument, various document views (IDocumentView), and whatever operations make sense in that case. I am particular interested in cases where the product in question is a real-world product. For example, if anybody familiar with OpenOffice can tell me if the code contains a good sample design. I am looking for design documentation that outlines the design of the interfaces for such an application. So for example, if the openoffice spreadsheet has such an interface design, then that might be the best case, because it is a widely used real-world design, with millions of users, rather than a textbook example, which is minimal, and contrived. I know that the Mozilla platform uses XPCOM, and its design is heavily "interface" oriented, but I am looking more for a "word processor" or "spreadsheet" type of document design, rather than a web-browser. I am particularly interested in the interfaces used to access to data and meta-data such as markup (attributes like bold, and italics, and font size), and the ability to search and look up named entities within a document.

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  • Where should I put validation code?

    - by D Lawson
    I'm creating interfaces and abstract classes that represent a messaging framework for short text-based messages like SMS, email, twitter, xml, etc.. and I was wondering where I should put the message validation code. The thing is that I am only writing the superclasses and interfaces, so I'm not putting the actual implementation in, I'll just put the hooks in that allow others to validate the content of the messages. The way I see it, I could do it several ways: in the abstract superclass "Message", have an abstract method 'isValid'. A variation on this would be to have isValid be called when the Message constructor is called, throwing a MalformedMessageException if the message is formatted incorrectly. in the transport layer, immediately before sending, validate the message. I would have a send(Message) method that calls an isValid(Message) method immediately before it sends. have a singleton message validator with a static method isValid(Message) that is called at some point. I'm sure there are other options that I'm missing. Currently, I'm leaning towards the first one, but it doesn't feel right to me to have validation code in what should be a domain object.

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  • Is Domain Anaemia appropriate in a Service Oriented Architecture?

    - by Stimul8d
    I want to be clear on this. When I say domain anaemia, I mean intentional domain anaemia, not accidental. In a world where most of our business logic is hidden away behind a bunch of services, is a full domain model really necessary? This is the question I've had to ask myself recently since working on a project where the "domain" model is in reality a persistence model; none of the domain objects contain any methods and this is a very intentional decision. Initially, I shuddered when I saw a library full of what are essentially type-safe data containers but after some thought it struck me that this particular system doesn't do much but basic CRUD operations, so maybe in this case this is a good choice. My problem I guess is that my experience so far has been very much focussed on a rich domain model so it threw me a little. The remainder of the domain logic is hidden away in a group of helpers, facades and factories which live in a separate assembly. I'm keen to hear what people's thoughts are on this. Obviously, the considerations for reuse of these classes are much simpler but is really that great a benefit?

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  • How do I access abstract private data from derived class without friend or 'getter' functions in C++?

    - by John
    So, I am caught up in a dilemma right now. How am I suppose to access a pure abstract base class private member variable from a derived class? I have heard from a friend that it is possible to access it through the base constructor, but he didn't explain. How is it possible? There are some inherited classes from base class. Is there any way to gain access to the private variables ? class Base_button { private: bool is_vis; Rect rButton; public: // Constructors Base_button(); Base_button( const Point &corner, double height, double width ); // Destructor virtual ~ Base_button(); // Accessors virtual void draw() const = 0; bool clicked( const Point &click ) const; bool is_visible() const; // Mutators virtual void show(); virtual void hide(); void move( const Point &loc ); }; class Button : public Base_button { private: Message mButton; public: // Constructors Button(); Button( const Point &corner, const string &label ); // Acessors virtual void draw() const; // Mutators virtual void show(); virtual void hide(); }; I want to be able access Rect and bool in the base class from the subclass

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  • Alternate colors on click with jQuery

    - by Jace Cotton
    I'm sure there is a simple solution to this, and I'm sure this is a duplicate question, though I have been unable to solve my solution particularly because I don't really know how to phrase it in order to search for other questions/solutions, so I'm coming here hoping for some help. Basically, I have spans with classes that assigns a background-color property, and inside those spans are words. I have three of these spans, and each time a user clicks on a span I want the class to change (thus changing the background color and inner text). HTML: <span class="alternate"> <span class="blue showing">Lorem</span> <span class="green">Ipsum</span> <span class="red">Dolor</span> </span> CSS: .alternate span { display : none } .alternate .showing { display : inline } .blue { background : blue } .green { background : green } .red { background : red } jQuery: $(".alternate span").each(function() { $(this).on("click", function() { $(this).removeClass("showing"); $(this).next().addClass("showing"); }); }); This solution works great using $.next until I get to the third click, whereafter .showing is removed, and is not added since there are no more $.next options. How do I, after getting to the last-child, add .showing to the first-child and then start over? I have tried various options including if($(".alternate span:last-child").hasClass("showing")) { etc. etc. }, and I attempted to use an array and for loop though I failed to make it work. Newb question, I know, but I can't seem to solve this so as a last resort I'm coming here.

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  • C++ and Dependency Injection in unit testing

    - by lhumongous
    Suppose I have a C++ class like so: class A { public: A() { } void SetNewB( const B& _b ) { m_B = _b; } private: B m_B; } In order to unit test something like this, I would have to break A's dependency on B. Since class A holds onto an actual object and not a pointer, I would have to refactor this code to take a pointer. Additionally, I would need to create a parent interface class for B so I can pass in my own fake of B when I test SetNewB. In this case, doesn't unit testing with dependency injection further complicate the existing code? If I make B a pointer, I'm now introducing heap allocation, and some piece of code is now responsible for cleaning it up (unless I use ref counted pointers). Additionally, if B is a rather trivial class with only a couple of member variables and functions, why introduce a whole new interface for it instead of just testing with an instance of B? I suppose you could make the argument that it would be easier to refactor A by using an interface. But are there some cases where two classes might need to be tightly coupled?

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  • I have a bunch of template parameters that I want to hide from my users. How can I do this?

    - by Alex
    I have a superclass which is defined in terms of a few internal types it uses. Subclassing is performed as so: template <class InternalType1, class InternalType2> class Super { ... } class Sub : Super <interalTypeClass1, interalTypeClass2> { ... } But when I want to write a function that takes a pointer to the superclass, this happens : template <class InternalType1, class InternalType2> void function(Super<InternalType1, InternalType2>* in) { ... } The user really shouldn't know anything about the inside classes, and should really just concern himself with the use of the function. Some of these template lists become very very large, and expecting the user to pass them every time is wasteful, in my opinion. Any suggestions? EDIT: The function needs to know the internal types in use, so unless there is a way to access template types at compile time, I think there is no solution? Potential solution: Have each class do the following: #define SubTemplateArgs <SubTypeName, SubInternalType1, SubInternalType2> ?

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  • I cant put a string in a switch nor an array in a class

    - by TimothyTech
    Okay, im making a pretty big file in my opinion, so i wanted to separate it into several files for cleaner code. so i have my main .cpp file and two header files holding my classes. well the header files dont hold strings, it aboslutely wont budge. i call the library in both my .cpp file and even tried it in my header file. another issue i ran into is using strings to make switches function, reason being if i use integers in a switch if the user inputs a alphabetical character the program goes into an endless loop. string choice; switch (choice) { case "1" : //... break; case "2" : //... break; } and my last issue is when i create an object in a case it gives an error. says cross initialization of object. string choice; switch (choice) { case "1" : Class object; break; case "2" : //... break; }

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  • jQuery script works in Firefox but not in IE. Why am I not surprised?

    - by Ben Tew
    I'm working with the context of a CMS system and trying to turn seperate div's into tabs. You can see it at http://www.wtvynews4.com/test I've kludged together some code from a tutorial site. <script charset="utf-8" type="text/javascript"> jQuery(function() { //When page loads... $("div[ondblclick$='87119417']").attr("id", "87119417"); $("div[ondblclick$='87119482']").attr("id", "87119482"); $("div[ondblclick$='87119672']").attr("id", "87119672"); $("div[ondblclick$='87119727']").attr("id", "87119727"); $("div[ondblclick$='87119812']").attr("id", "87119812"); $("div[ondblclick$='87119417']").addClass("tab_content"); $("div[ondblclick$='87119482']").addClass("tab_content"); $("div[ondblclick$='87119672']").addClass("tab_content"); $("div[ondblclick$='87119727']").addClass("tab_content"); $("div[ondblclick$='87119812']").addClass("tab_content"); $(".tab_content").hide(); //Hide all content $("ul.morenewstabs li:first").addClass("active").show(); //Activate first tab $(".tab_content:first").show(); //Show first tab content //On Click Event $("ul.morenewstabs li").click(function() { $("ul.morenewstabs li").removeClass("active"); //Remove any "active" class $(this).addClass("active"); //Add "active" class to selected tab $(".tab_content").hide(); //Hide all tab content var activeTab = $(this).find("a").attr("href"); //Find the href attribute value to identify the active tab + content $(activeTab).show(); //Fade in the active ID content return false; }); }); </script> Everything works fine in Firefox but not IE. can you provide any assistance? When the page loads the attribute ID's and classes aren't assigned. I tried changing jQuery(function() { to $(document).ready(function() still no luck.

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  • Generics in a bidirectional association

    - by Verhoevenv
    Let's say I have two classes A and B, with B a subtype of A. This is only part of a richer type hierarchy, obviously, but I don't think that's relevant. Assume A is the root of the hierarchy. There is a collection class C that keeps track of a list of A's. However, I want to make C generic, so that it is possible to make an instance that only keeps B's and won't accept A's. class A(val c: C[A]) { c.addEntry(this) } class B(c: C[A]) extends A(c) class C[T <: A]{ val entries = new ArrayBuffer[T]() def addEntry(e: T) { entries += e } } object Generic { def main(args : Array[String]) { val c = new C[B]() new B(c) } } The code above obviously give the error 'type mismatch: found C[B], required C[A]' on the new B(c) line. I'm not sure how this can be fixed. It's not possible to make C covariant in T (like C[+T <: A]) because the ArrayBuffer is non-variantly typed in T. It's not possible to make the constructor of B require a C[B] because C can't be covariant. Am I barking up the wrong tree here? I'm a complete Scala newbie, so any ideas and tips might be helpful. Thank you! EDIT: Basically, what I'd like to have is that the compiler accepts both val c = new C[B]() new B(c) and val c = new C[A]() new B(c) but would reject val c = new C[B]() new A(c) It's probably possible to relax the typing of the ArrayBuffer in C to be A instead of T, and thus in the addEntry method as well, if that helps.

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  • Windows XP: RegSvr32 /i:[cmdline]: What exactly is "Command line" in this case?

    - by Kim
    I am trying to register a dll using regsvr32 in a cmd window. I do this on an administrator account, but I need this dll to be registered for all the users. Turns out regsvr32 does not do that, it only registers for your current user. Well, when you use it this way anyways: "regsvr32 /i "C:\MyDll.dll"" What happens; The entry is added to Local_User, and Classes in the registry, but not Local_Machine. The msdn article on regsvr32 says it also takes a [cmdline] when using the /i option. But the article fails to specify what I can put in place of [cmdline]. Google is refusing to help me as well, so I'm a bit stuck on this. I realize this is not exactly on the topic of programming, but this is something programmers might know, so... Has anyone run into this before? Perhaps someone knows how this [cmdline] tag works? Are there any other ways to add this dll to all users? (Apart from editing the registry manually that is.) Any insight would be greatly appreciated!

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  • Best practice on structuring asynchronous mailers (using Sidekiq)

    - by gbdev
    Just wondering what's the best way to go about structuring asynchronous mailers in my Rails app (using Sidekiq)? I have one ActionMailer class with multiple methods/emails... notifier.rb: class Notifier < ActionMailer::Base default from: "\"Company Name\" <[email protected]>" default_url_options[:host] = Rails.env.production? ? 'domain.com' : 'localhost:5000' def welcome_email(user) @user = user mail to: @user.email, subject: "Thanks for signing up!" end ... def password_reset(user) @user = user @edit_password_reset_url = edit_password_reset_url(user.perishable_token) mail to: @user.email, subject: "Password Reset" end end Then for example, the password_reset mail is sent in my User model by doing... user.rb: def deliver_password_reset_instructions! reset_perishable_token! NotifierWorker.perform_async(self) end notifier_worker.rb: class NotifierWorker include Sidekiq::Worker sidekiq_options queue: "mail" def perform(user) Notifier.password_reset(user).deliver end end So I guess I'm wondering a couple things here... Is it possible to define many "perform" actions in one single worker? By doing so I could keep things simple (one notifier/mail worker) as I have it and send many different emails through it. Or should I create many workers? One for each mailer (e.g. WelcomeEmailWorker, PasswordResetWorker, etc) and just assign them all to use the same "mail" queue with Sidekiq. I know it works as it is, but should I break out each of those mail methods (welcome_email, password_reset, etc) into individually mailer classes or is it ok to have them all under one class like Notifier? Really appreciate any advice here. Thanks!

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  • Implicit linking vs. explicit linking of DLL in Delphi

    - by Tom
    I'm having trouble getting my dll to work when using explicit linking. Using implicit linking it works fine. Would someone google me a solution? :) No, just kidding, here's my code: This code works fine: function CountChars(_s: Pchar): integer; StdCall; external 'sample_dll.dll'; procedure TForm1.Button1Click(Sender: TObject); begin ShowMessage(IntToStr(CountChars('Hello world'))); end; This code doesn't work (I get an access violation): procedure TForm1.Button1Click(Sender: TObject); var LibHandle: HMODULE; CountChars: function(_s: PChar): integer; begin LibHandle := LoadLibrary('sample_dll.dll'); ShowMessage(IntToStr(CountChars('Hello world'))); // Access violation FreeLibrary(LibHandle); end; This is the DLL code: library sample_dll; uses FastMM4, FastMM4Messages, SysUtils, Classes; {$R *.res} function CountChars(_s: PChar): integer; stdcall; begin Result := Length(_s); end; exports CountChars; begin end.

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  • Large Switch statements: Bad OOP?

    - by Mystere Man
    I've always been of the opinion that large switch statements are a symptom of bad OOP design. In the past, I've read articles that discuss this topic and they have provided altnerative OOP based approaches, typically based on polymorphism to instantiate the right object to handle the case. I'm now in a situation that has a monsterous switch statement based on a stream of data from a TCP socket in which the protocol consists of basically newline terminated command, followed by lines of data, followed by an end marker. The command can be one of 100 different commands, so I'd like to find a way to reduce this monster switch statement to something more manageable. I've done some googling to find the solutions I recall, but sadly, Google has become a wasteland of irrelevant results for many kinds of queries these days. Are there any patterns for this sort of problem? Any suggestions on possible implementations? One thought I had was to use a dictionary lookup, matching the command text to the object type to instantiate. This has the nice advantage of merely creating a new object and inserting a new command/type in the table for any new commands. However, this also has the problem of type explosion. I now need 100 new classes, plus I have to find a way to interface them cleanly to the data model. Is the "one true switch statement" really the way to go? I'd appreciate your thoughts, opinions, or comments.

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  • How to call a method in another class in Java?

    - by Puchatek
    Currently I have two classes. a classroom class and a School class. I would like to write a method in the School class to call public void setTeacherName(String newTeacherName) from the classroom class. public class classroom { private String classRoomName; private String teacherName; public void setClassRoomName(String newClassRoomName) { classRoomName = newClassRoomName; } public String returnClassRoomName() { return classRoomName; } public void setTeacherName(String newTeacherName) { teacherName = newTeacherName; } public String returnTeacherName() { return teacherName; } } import java.util.ArrayList; public class School { private ArrayList<classroom> classrooms; private String classRoomName; private String teacherName; public School() { classrooms = new ArrayList<classroom>(); } public void addClassRoom(classroom newClassRoom, String theClassRoomName) { classrooms.add(newClassRoom); classRoomName = theClassRoomName; } // how to write a method to add a teacher to the classroom by using the classroom parameter // and the teachers name }

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  • Why should I abstract my data layer?

    - by Gazillion
    OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more. The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of: $sql = 'SELECT * FROM table WHERE type = "type1"';' $result = mysql_query($sql); while($row = mysql_fetch_assoc($result)) { echo '<li>'.$row['name'].'</li>'; } I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements. I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :) I would really appreciate any advice, links, or concrete real-life examples on the subject!

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  • Casting pointer to object to void * in C++

    - by JB
    I've been reading StackOverflow too much and started doubting all the code I've ever written, I keep thinking "Is that undefined behavour?" even in code that has been working for ages. So my question - Is it safe and well defined behavour to cast a pointer to an object (In this case abstract interface classes) to a void* and then later on cast them back to the original class and call method using them? I'm fully aware that the code that does this is probably awful. I wouldn't even consider writing it like this now (this is old code which I don't really want to change), so I'm not looking for a discussion of better ways to do this. I already know how to write it better if I ever did this again. But if it's actually broken to rely on this in C++ then I'll have to look at changing the code, if it's merely awful code then changing it won't be a priority. I would have had no doubts about something this simple a year or two ago but as my understanding of C++ increases I actually find I have more and more worries about code being safe under the standards even if it works perfectly well. Perhaps reading too much stack overflow is a bad thing for productivity sometimes :P

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  • GUI for server-client program

    - by sksingh73
    I am making a server-client application in c++. In this i am also using shared memory & file read-write operations. my program is completely ready & i now wants to make a gui for it. someone suggested me to go for QT4, but when i tried it, i found i have to re-write 80% of the code because QT has got its own classes & variable. i don't want to do it. i want suggestions from you on this regard. my requirements for gui are very simple i.e there will be a main form, which will have two text boxes in which all messages being sent & received by client & server should be shown. there should be another lineedit box, through which i can send the messages to the other end server. I don't know how to make this gui. someone suggested tcl/tk, other suggested me use php/swig. i am not sure how to go about this. my only requirement is that i want to make this simple gui with minimum of changes in my code. THANX

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  • Switching Between Cards in a CardLayout using getParent()

    - by plutoisaplanet
    Hey everyone, I am writing an application where I am using the CardLayout to swap between two panels that are placed right on top of one another. There's a JPanel called Top, and it's layout is the CardLayout. Inside this JPanel is a JPanel called CMatch. Whenever the user clicks the submit button in the CMatch panel, I want a new JPanel added to Top that is custom built based on what the user types in, and it will be shown instead of the original CMatch panel. All of this done using the CardLayout. These are all different classes in different files, however (the panel Top with CardLayout, the panel CMatch that is inside the Top panel, and the custom built panel). So i tried using the following to add the new panel to the Top panel and then have it shown: (this code takes place in the CMatch class): private void submitButtionActionPerformed(ActionEvent e) { CardLayout cl = (CardLayout)(this.getParent().getLayout()); cl.addLayoutComponent(new CChoice(), "college_choices"); cl.show(this.getParent(), "college_choices"); } However, this didn't work. So i was wondering, what am I doing wrong? Any advice is greatly appreciated, thanks!

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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