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  • Java game design question (graphical objects)

    - by vemalsar
    Hello Guys, I'm beginner in game development, in Java and here on this site too and I have a game design question. Please comment my idea: I have a main loop which call update and draw method. I want to use an ArrayList which store graphical objects, they have coordinate and image or text to draw and my game objects extends this class. In update, I can choose which objects should be put in the array and in draw method I'll display the elements of array on the screen. I'm using a buffer and draw first there, but it is not important now I guess...Here is a simple (not full) code, only the logic: public class GamePanel extends JPanel implements KeyListener { ArrayList<graphicalObjects> graphArray = new ArrayList<graphicalObjects>(); public void update() { //change the game scene, update the graphArray, process input etc. } public void draw() { //draws every element of graphArray to a JPanel } public static main(String[] args) { while(true) { update(); draw(); } } } My questions: Should have I use interface or abstract class for graphicalObjects? graphicalObjects class and the ArrayList really needs or there is some better solution? How to draw objects? They draw themself with their own method or in the draw method I have to draw manually based on graphicalObjects variables (x,y coordinates, image etc.)? If this conception is wrong, please suggest another one! All comments are welcome and sorry if this is dumb question, thanks!

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  • Resource Acquisition is Initialization in C#

    - by codeWithoutFear
    Resource Acquisition Is Initialization (RAII) is a pattern I grew to love when working in C++.  It is perfectly suited for resource management such as matching all those pesky new's and delete's.  One of my goals was to limit the explicit deallocation statements I had to write.  Often these statements became victims of run-time control flow changes (i.e. exceptions, unhappy path) or development-time code refactoring. The beauty of RAII is realized by tying your resource creation (acquisition) to the construction (initialization) of a class instance.  Then bind the resource deallocation to the destruction of that instance.  That is well and good in a language with strong destructor semantics like C++, but languages like C# that run on garbage-collecting runtimes don't provide the same instance lifetime guarantees. Here is a class and sample that combines a few features of C# to provide an RAII-like solution: using System; namespace RAII { public class DisposableDelegate : IDisposable { private Action dispose; public DisposableDelegate(Action dispose) { if (dispose == null) { throw new ArgumentNullException("dispose"); } this.dispose = dispose; } public void Dispose() { if (this.dispose != null) { Action d = this.dispose; this.dispose = null; d(); } } } class Program { static void Main(string[] args) { Console.Out.WriteLine("Some resource allocated here."); using (new DisposableDelegate(() => Console.Out.WriteLine("Resource deallocated here."))) { Console.Out.WriteLine("Resource used here."); throw new InvalidOperationException("Test for resource leaks."); } } } } The output of this program is: Some resource allocated here. Resource used here. Unhandled Exception: System.InvalidOperationException: Test for resource leaks. at RAII.Program.Main(String[] args) in c:\Dev\RAII\RAII\Program.cs:line 40 Resource deallocated here. Code without fear! --Don

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  • Understanding interfaces [closed]

    - by user985482
    Possible Duplicate: When to use abstract classes instead of interfaces and extension methods in C#? Why are interfaces useful? What is the point of an interface? What other reasons are there to write interfaces rather than abstract classes? What is the point of having every service class have an interface? Is it bad habit not using interfaces? I am reading Microsoft Visual C# 2010 Step by Step which I feel it is a very good book on introducing you to the C# language. I have just finished reading a chapter on interfaces and although I understood the syntax of creating and using interfaces I have trouble of understanding the point on why should I use them? Correct me If I am wrong but in an interface you can only declare methods names and parameters.The body of the method should be declared in the class that inherits the interface. So in this case why should I declare an interface if I am going to declare the entire method in the class that inherits that interface? What is the point? Does this have something to do with the fact that a class can inherit multiple interfaces?

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  • How can I design my classes for a calendar based on database events?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCells() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many events stored in a database. My question is: which is the best way to manage these events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • Oracle College Rehire Program -China by Camilla!!

    - by Nadiya
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 In China,for the R&D campus hire, we launched a Oracle College Hire Program, all the new graduates in R&D team could join it, the purpose is to let them understand Oracle’s culture and value, get them quickly to be familiar and productive on their new work, provide meaningful events and get them engaged.  They’re divided into classes by location, each class would have around 20 people, and each class would have a monitor, who is in charge of the whole class activity, the program has 3 modules, including social activity, Speaker Series and Career Development. The pictures show one class, which is having the social activity session,exciting isnt it?   /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Add & Show data in Java ArrayList [closed]

    - by Kaidul Islam Sazal
    I have a class inside a main class : static class Graph{ static int u, v, cost; } I have instantiated an arraylist of the class: static List<Graph> g = new ArrayList<Graph>(); And I insert several values into the arraylist like this: Scanner input = new Scanner(System.in); for (int i = 0; i < edge_no; i++) { Graph e = new Graph(); e.u = input.nextInt(); e.v = input.nextInt(); e.cost = input.nextInt(); g.add(e); } And I print it like this: for (int i = 0; i < edge_no; i++) { System.out.println(g.get(i).u + " " + g.get(i).v + " " + g.get(i).cost); } But the problem is that, when I print it, only the last value is shown all the time.It seems that, all the previous values are over-written with it. Input : 1 2 5 1 3 8 2 3 9 Output: 2 3 9 2 3 9 2 3 9 Expected output is just like the input.But I can't fix the problem as I am novice in java.

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  • Using nested public classes to organize constants

    - by FrustratedWithFormsDesigner
    I'm working on an application with many constants. At the last code review it came up that the constants are too scattered and should all be organized into a single "master" constants file. The disagreement is about how to organize them. The majority feel that using the constant name should be good enough, but this will lead to code that looks like this: public static final String CREDITCARD_ACTION_SUBMITDATA = "6767"; public static final String CREDITCARD_UIFIELDID_CARDHOLDER_NAME = "3959854"; public static final String CREDITCARD_UIFIELDID_EXPIRY_MONTH = "3524"; public static final String CREDITCARD_UIFIELDID_ACCOUNT_ID = "3524"; ... public static final String BANKPAYMENT_UIFIELDID_ACCOUNT_ID = "9987"; I find this type of naming convention to be cumbersome. I thought it might be easier to use public nested class, and have something like this: public class IntegrationSystemConstants { public class CreditCard { public static final String UI_EXPIRY_MONTH = "3524"; public static final String UI_ACCOUNT_ID = "3524"; ... } public class BankAccount { public static final String UI_ACCOUNT_ID = "9987"; ... } } This idea wasn't well received because it was "too complicated" (I didn't get much detail as to why this might be too complicated). I think this creates a better division between groups of related constants and the auto-complete makes it easier to find these as well. I've never seen this done though, so I'm wondering if this is an accepted practice or if there's better reasons that it shouldn't be done.

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  • PyQt application architecture

    - by L. De Leo
    I'm trying to give a sound structure to a PyQt application that implements a card game. So far I have the following classes: Ui_Game: this describes the ui of course and is responsible of reacting to the events emitted by my CardWidget instances MainController: this is responsible for managing the whole application: setup and all the subsequent states of the application (like starting a new hand, displaying the notification of state changes on the ui or ending the game) GameEngine: this is a set of classes that implement the whole game logic Now, the way I concretely coded this in Python is the following: class CardWidget(QtGui.QLabel): def __init__(self, filename, *args, **kwargs): QtGui.QLabel.__init__(self, *args, **kwargs) self.setPixmap(QtGui.QPixmap(':/res/res/' + filename)) def mouseReleaseEvent(self, ev): self.emit(QtCore.SIGNAL('card_clicked'), self) class Ui_Game(QtGui.QWidget): def __init__(self, window, *args, **kwargs): QtGui.QWidget.__init__(self, *args, **kwargs) self.setupUi(window) self.controller = None def place_card(self, card): cards_on_table = self.played_cards.count() + 1 print cards_on_table if cards_on_table <= 2: self.played_cards.addWidget(card) if cards_on_table == 2: self.controller.play_hand() class MainController(object): def __init__(self): self.app = QtGui.QApplication(sys.argv) self.window = QtGui.QMainWindow() self.ui = Ui_Game(self.window) self.ui.controller = self self.game_setup() Is there a better way other than injecting the controller into the Ui_Game class in the Ui_Game.controller? Or am I totally off-road?

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  • Integrating Amazon EC2 in Java via NetBeans IDE

    - by Geertjan
    Next, having looked at Amazon Associates services and Amazon S3, let's take a look at Amazon EC2, the elastic compute cloud which provides remote computing services. I started by launching an instance of Ubuntu Server 14.04 on Amazon EC2, which looks a bit like this in the on-line AWS Management Console, though I whitened out most of the details: Now that I have at least one running instance available on Amazon EC2, it makes sense to use the services that are integrated into NetBeans IDE:  I created a new application with one class, named "AmazonEC2Demo". Then I dragged the "describeInstances" service that you see above, with the mouse, into the class. Then the IDE automatically created all the other files you see below, i.e., 4 Java classes and one properties file: In the properties file, register the access ID and secret keys. These are read by the other generated Java classes. Signing and authentication are done automatically by the code that is generated, i.e., there's nothing generic you need to do and you can immediately begin working on your domain-specific code. Finally, you're now able to rewrite the code in "AmazonEC2Demo" to connect to Amazon EC2 and obtain information about your running instance: public class AmazonEC2Demo { public static void main(String[] args) { String instanceId1 = "i-something"; RestResponse result; try { result = AmazonEC2Service.describeInstances(instanceId1); System.out.println(result.getDataAsString()); } catch (IOException ex) { Logger.getLogger(AmazonEC2Demo.class.getName()).log(Level.SEVERE, null, ex); } } } From the above, you'll receive a chunk of XML with data about the running instance, it's name, status, dates, etc. In other words, you're now ready to integrate Amazon EC2 features directly into the applications you're writing, without very much work to get started. Within about 5 minutes, you're working on your business logic, rather than on the generic code that anyone needs when integrating with Amazon EC2.

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  • Authenticate with Django 1.5

    - by gorjuce
    I'm currently testing django 1.5 and a custom User model, but I've some problems. I've created a User class in my account app, which looks like: class User(AbstractBaseUser): email = models.EmailField() activation_key = models.CharField(max_length=255) is_active = models.BooleanField(default=False) is_admin = models.BooleanField(default=False) USERNAME_FIELD = 'email' I can correctly register a user, who is stored in my account_user table. Now, how can I log in? I've tried with: def login(request): form = AuthenticationForm() if request.method == 'POST': form = AuthenticationForm(request.POST) email = request.POST['username'] password = request.POST['password'] user = authenticate(username=email, password=password) if user is not None: if user.is_active: login(user) else: message = 'disabled account, check validation email' return render( request, 'account-login-failed.html', {'message': message} ) return render(request, 'account-login.html', {'form': form}) I can correctly register a new User My forms.py which contains my register form class RegisterForm(forms.ModelForm): """ a form to create user""" password = forms.CharField( label="Password", widget=forms.PasswordInput() ) password_confirm = forms.CharField( label="Password Repeat", widget=forms.PasswordInput() ) class Meta: model = User exclude = ('last_login', 'activation_key') def clean_password_confirm(self): password = self.cleaned_data.get("password") password_confirm = self.cleaned_data.get("password_confirm") if password and password_confirm and password != password_confirm: raise forms.ValidationError("Password don't math") return password_confirm def clean_email(self): if User.objects.filter(email__iexact=self.cleaned_data.get("email")): raise forms.ValidationError("email already exists") return self.cleaned_data['email'] def save(self): user = super(RegisterForm, self).save(commit=False) user.password = self.cleaned_data['password'] user.activation_key = generate_sha1(user.email) user.save() return user My question is: Why does authenticate give me None? I know I'm trying to authenticate() with an email as username but is that not one of the reasons to use a custom User model?

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  • Reasons behind polymorphism related behaviour in java

    - by Shades88
    I read this code somewhere class Foo { public int a; public Foo() { a = 3; } public void addFive() { a += 5; } public int getA() { System.out.println("we are here in base class!"); return a; } } public class Polymorphism extends Foo{ public int a; public Poylmorphism() { a = 5; } public void addFive() { System.out.println("we are here !" + a); a += 5; } public int getA() { System.out.println("we are here in sub class!"); return a; } public static void main(String [] main) { Foo f = new Polymorphism(); f.addFive(); System.out.println(f.getA()); // SOP 1 System.out.println(f.a); // SOP 2 } } For SOP1 we get answer 10 and for SOP2 we get answer 3. Reason for this is that you can't override variables whereas you can do so for methods. This happens because type of the reference variable is checked when a variable is accessed and type of the object is checked when a method is accessed. But I am wondering, just why is it that way? Can anyone explain me what is the reason for this behaviour

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  • Interface (contract), Generics (universality), and extension methods (ease of use). Is it a right design?

    - by Saeed Neamati
    I'm trying to design a simple conversion framework based on these requirements: All developers should follow a predefined set of rules to convert from the source entity to the target entity Some overall policies should be able to be applied in a central place, without interference with developers' code Both the creation of converters and usage of converter classes should be easy To solve these problems in C# language, A thought came to my mind. I'm writing it here, though it doesn't compile at all. But let's assume that C# compiles this code: I'll create a generic interface called IConverter public interface IConverter<TSource, TTarget> where TSource : class, new() where TTarget : class, new() { TTarget Convert(TSource source); List<TTarget> Convert(List<TSource> sourceItems); } Developers would implement this interface to create converters. For example: public class PhoneToCommunicationChannelConverter : IConverter<Phone, CommunicationChannle> { public CommunicationChannel Convert(Phone phone) { // conversion logic } public List<CommunicationChannel> Convert(List<Phone> phones) { // conversion logic } } And to make the usage of this conversion class easier, imagine that we add static and this keywords to methods to turn them into Extension Methods, and use them this way: List<Phone> phones = GetPhones(); List<CommunicationChannel> channels = phones.Convert(); However, this doesn't even compile. With those requirements, I can think of some other designs, but they each lack an aspect. Either the implementation would become more difficult or chaotic and out of control, or the usage would become truly hard. Is this design right at all? What alternatives I might have to achieve those requirements?

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  • Help with design structure choice: Using classes or library of functions

    - by roverred
    So I have GUI Class that will call another class called ImageProcessor that contains a bunch functions that will perform image processing algorithms like edgeDetection, gaussianblur, contourfinding, contour map generations, etc. The GUI passes an image to ImageProcessor, which performs one of those algorithm on it and it returns the image back to the GUI to display. So essentially ImageProcessor is a library of independent image processing functions right now. It is called in the GUI like so Image image = ImageProcessor.EdgeDetection(oldImage); Some of the algorithms procedures require many functions, and some can be done in a single function or even one line. All these functions for the algorithms jam packed into ImageProcessor can be pretty messy, and ImageProcessor doesn't sound it should be a library. So I was thinking about making every algorithm be a class with a shared interface say IAlgorithm. Then I pass the IAlgorithm interface from the GUI to the ImageProcessor. public interface IAlgorithm{ public Image Process(); } public class ImageProcessor{ public Image Process(IAlgorithm TheAlgorithm){ return IAlgorithm.Process(); } } Calling in the GUI like so Image image = ImageProcessor.Process(new EdgeDetection(oldImage)); I think it makes sense in an object point of view, but the problem is I'll end up with some classes that are just one function. What do you think is a better design, or are they both crap and you have a much better idea? Thanks!

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  • Repository query conditions, dependencies and DRY

    - by vFragosop
    To keep it simple, let's suppose an application which has Accounts and Users. Each account may have any number of users. There's also 3 consumers of UserRepository: An admin interface which may list all users Public front-end which may list all users An account authenticated API which should only list it's own users Assuming UserRepository is something like this: class UsersRepository extends DatabaseAbstraction { private function query() { return $this->database()->select('users.*'); } public function getAll() { return $this->query()->exec(); } // IMPORTANT: // Tons of other methods for searching, filtering, // joining of other tables, ordering and such... } Keeping in mind the comment above, and the necessity to abstract user querying conditions, How should I handle querying of users filtering by account_id? I can picture three possible roads: 1. Should I create an AccountUsersRepository? class AccountUsersRepository extends UserRepository { public function __construct(Account $account) { $this->account = $account; } private function query() { return parent::query() ->where('account_id', '=', $this->account->id); } } This has the advantage of reducing the duplication of UsersRepository methods, but doesn't quite fit into anything I've read about DDD so far (I'm rookie by the way) 2. Should I put it as a method on AccountsRepository? class AccountsRepository extends DatabaseAbstraction { public function getAccountUsers(Account $account) { return $this->database() ->select('users.*') ->where('account_id', '=', $account->id) ->exec(); } } This requires the duplication of all UserRepository methods and may need another UserQuery layer, that implements those querying logic on chainable way. 3. Should I query UserRepository from within my account entity? class Account extends Entity { public function getUsers() { return UserRepository::findByAccountId($this->id); } } This feels more like an aggregate root for me, but introduces dependency of UserRepository on Account entity, which may violate a few principles. 4. Or am I missing the point completely? Maybe there's an even better solution? Footnotes: Besides permissions being a Service concern, in my understanding, they shouldn't implement SQL query but leave that to repositories since those may not even be SQL driven.

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  • Generic Pop and Push for List<T>

    - by Bil Simser
    Here's a little snippet I use to extend a generic List class to have similar capabilites to the Stack class. The Stack<T> class is great but it lives in its own world under System.Object. Wouldn't it be nice to have a List<T> that could do the same? Here's the code: .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public static class ExtensionMethods 2: { 3: public static T Pop<T>(this List<T> theList) 4: { 5: var local = theList[theList.Count - 1]; 6: theList.RemoveAt(theList.Count - 1); 7: return local; 8: } 9:   10: public static void Push<T>(this List<T> theList, T item) 11: { 12: theList.Add(item); 13: } 14: } It's a simple extension but I've found it useful, hopefully you will too! Enjoy.

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  • In C++ Good reasons for NOT using symmetrical memory management (i.e. new and delete)

    - by Jim G
    I try to learn C++ and programming in general. Currently I am studying open source with help of UML. Learning is my hobby and great one too. My understanding of memory allocation in C++ is that it should be symmetrical. A class is responsible for its resources. If memory is allocated using new it should be returned using delete in the same class. It is like in a library you, the class, are responsibility for the books you have borrowed and you return them then you are done. This, in my mind, makes sense. It makes memory management more manageable so to speak. So far so good. The problem is that this is not how it works in the real world. In Qt for instance, you create QtObjects with new and then hand over the ownership of the object to Qt. In other words you create QtObjects and Qt destroys them for you. Thus unsymmetrical memory management. Obviously the people behind Qt must have a good reason for doing this. It must be beneficial in some kind of way, My questions is: What is the problem with Bjarne Stroustrups idea about a symmetrical memory management contained within a class? What do you gain by splitting new and delete so you create an object and destroy it in different classes like you do in Qt. Is it common to split new and delete and why in such case, in other projects not involving Qt? Thanks for any help shedding light on this mystery!

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  • OOP Structure for web application

    - by Query
    Ok so I have a website in which users complete tasks to earn points. When they earn enough points, they rise in rank. The site from my understanding is very basic and only executes one query or two queries at most a page. There is a user table, a support ticket table, and an orders table. All of these contain a relational row for username. Our class was familiarized with OOP back in highschool with Java but that was for video games and I could grasp the concept on why you would need a class player and class enemy. However I don't understand it's web application. At least not in my situation. I understand the user class might contain stuff like: getUsername getPoints getEmail setEmail addPoints (does this belong here? OR only things the user can manipulate should be here?) etc.. But I'm at a loss with everything else such as user registration. Can you help give me a wire framework that I could wrap my head around? Pointing me to a good eBook would help greatly

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  • Rowspan not using top row

    - by DaAwesomeP
    I don't understand why my column won't span to the top and bottom rows I created. It is supposed to look like the "Today" column is taller on the top and bottom then the other columns. I tried accomplishing this by adding rows above and below it and then using rowspan. For some reason, it only works on the bottom row. It's a lot of code, and I wasn't sure what I should cut without deforming it all or adding a new variable (it needs a fluid height). JSFiddle: http://jsfiddle.net/DaAwesomeP/aU9Le/ Basic HTML Layout (the full fiddle has the css: <table id="weatherForecast"> <tr class="weatherForecast-row-outer"> <td></td> </tr> <tr id="weatherForecast-row"> <td id="weatherForecast-DATE" class="weatherForecast-day weatherForecast-day-today" rowspan="2"> <!-- Cell Content for "Today" Here --> <td id="weatherForecast-DATE" class="weatherForecast-day "> <!-- Cell Content Here. There are 4 of these --> </td> </tr> <tr class="weatherForecast-row-outer"> <td></td> </tr> </table> An image showing what I am trying to accomplish: http://s14.postimg.org/ba3xwcm75/Rowspan_not_using_top_row.png

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  • How to handle notifications to several partial views of the same model?

    - by Seki
    I am working on refactoring an old simulation of a Turing machine. The application uses a class that contains the state and the logic of program execution, and several panels to display the tape representation and show the state, messages, and the GUI controls (start, stop, program listing, ...). I would like to refactor it using the MVC architecture that was not used originaly: the Frame is the only way to get access to the different panels and there is also a strong coupling between the "engine" class and the GUI updates in the way of frame.displayPanel.state.setText("halted"); or frame.outputPanel.messages.append("some thing"); It looks to me that I should put the state related code into an observable model class and make the different panels observers. My problem is that the java Observable class only provides a global notification to the Observers, while I would prefer not to refresh every Observers everytime, but only when the part that specificaly observe has changed. I am thinking of implementing myself several vectors of listeners (for the state / position, for the output messages, ...) but I feel like reinventing the wheel. I though also about adding some flags that the observers could check like isNewMessageAvailable(), hasTapeMoved(), etc but it sounds also approximative design. BTW, is it ok to keep the fetch / execute loop into the model or should I move it in another place? We can think in a theorical ideal way as I am completely revamping this small application.

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  • Representing a world in memory

    - by user9993
    I'm attempting to write a chunk based map system for a game, where as the player moves around chunks are loaded/unloaded, so that the program doesn't run out of memory by having the whole map in memory. I have this part mostly working, however I've hit a wall regarding how to represent the contents of each chunk in memory because of my so far limited understanding of OOP languages. The design I have currently has a ChunkManager class that uses a .NET List type to store instances of Chunk classes. The "chunks" consist of "blocks". It's similar to a Minecraft style game. Inside the Chunk classes, I have some information such as the chunk's X/Y coordinate etc, and I also have a three dimensional array of Block objects. (Three dimensional because I need XYZ values) Here's the problem: The Block class has some basic properties, and I had planned on making different types of blocks inherit from this "base" class. So for example, I would have "StoneBlock", "WaterBlock" etc. So because I have blocks of many different types, I don't know how I would create an array with different object types in each cell. This is how I currently have the three dimensional array declared in my Chunk class: private Block[][][] ArrayOfBlocks; But obviously this will only accept Block objects, not any of the other classes that inherit from Block. How would I go about creating this? Or am I doing it completely wrong and there's a better way?

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  • knowing all available entity types

    - by plofplof
    I'm making a game where at some point the game will create enemies of random types. Each type of enemy available is defined on its own class derived from an enemy superclass. To do this, obviously the different types of enemies should be known. This is what I have thought of: Just make a list manually. Very simple to do, but I don't like it because I'll be adding more enemy types over time, so any time I add a new class I have to remember to update this (same if I remove an enemy). I would like some kind of auto-updating list. A completely component based system. There are no different classes for each enemy, but definitions of enemies in some file where all enemy types can be found. I really don't need that level of complexity for my game. I'm still using a component based model to some degree, but each Enemy type gets defined on its own class. Java Annotation processing. Give each enemy subclass an annotation like @EnemyType("whatever"), then code an annotation processor that writes in a file all available enemy types. Any time a new class is added the file gets updated after compilation.This gives me a feeling of failure even if its a good solution, it's very dependant on Java, so it means I cant think of a general design good for any kind of language. Also I think that this would be too much work for something so simple. I would like to see comments on these ideas and other possible solutions Thanks

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  • [LINQ] Master&ndash;Detail Same Record (I)

    - by JTorrecilla
    PROBLEM Firstly, I am working on a project based on LINQ, EF, and C# with VS2010. The following Table shows what I have and what I want to show. Header C1 C2 C3 1 P1 01/01/2011 2 P2 01/02/2011 Details 1 1 D1 2 1 D2 3 1 D3 4 2 D1 5 2 D4 Expected Results 1 P1 01/01/2011 D1, D2, D3 2 P2 01/02/2011 D1,D4   IDEAS At the begin I got 3 possible ways: - Doing inside the DB:  It could be achieved from DB with a CURSOR in a Stored Procedure. - Doing from .NET with LOOPS. - Doing with LINQ (I love it!!) FIRST APROX Example with a simple CLASS with a LIST: With and Employee Class that acts as Header Table: 1: public class Employee 2: { 3: public Employee () { } 4: public Int32 ID { get; set; } 5: public String FirstName{ get; set; } 6: public String LastName{ get; set; } 7: public List<string> Numbers{ get; set; } // Acts as Details Table 8: } We can show all numbers contained by Employee: 1: List<Employee > listado = new List<Employee >(); 2: //Fill Listado 3: var query= from Employee em in listado 4: let Nums= string.Join(";", em.Numbers) 5: select new { 6: em.Name, 7: Nums 8: }; The “LET” operator allows us to host the results of “Join” of the Numbers List of the Employee Class. A little example. ASAP I will post the second part to achieve the same with Entity Framework. Best Regards

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  • CSS issue with elements spanning columns

    - by bigFoot
    Hi folks. Overview: I'm trying to create a relatively simple page layout detailed below and running into problems no matter how I try to approach it. Concept: - A standard-size-block layout. I'll quote unit widths: each content block is 240px square with 5px of margin around it. - A left column of fixed width of 1 unit (245px - 1 block + margin to left). No problems here. - A right column of variable width to fill the remaining space. No problems here either. - In the left column, a number of 1unit x 1unit blocks fixed down the column. Also some blank space at the top - again, not a problem. - In the right column: a number of free-floating blocks of standard unit-sizes which float around and fill the space given to them by the browser window. No problems here. - Lastly, a single element, 2 units wide, which sits half in the left column and half in the right column, and which the blocks in the right column still float around. Here be dragons. Please see here for a diagram: http://is.gd/bPUGI Problem: No matter how I approach this, it goes wrong. Below is code for my existing attempt at a solution. My current problem is that the 1x1 blocks on the right do not respect the 2x1 block, and as a result half of the 2x1 block is overwritten by a 1x1 block in the right-hand column. I'm aware that this is almost certainly an issue with position: absolute taking things out of flow. However, can't really find a way round that which doesn't just throw up another problem instead. Code: <html> <head> <title>wat</title> <style type="text/css"> body { background: #ccc; color: #000; padding: 0px 5px 5px 0px; margin: 0px; } #leftcol { width: 245px; margin-top: 490px; position: absolute; } #rightcol { left: 245px; position: absolute; } #bigblock { float: left; position: relative; margin-top: -240px; background: red; } .cblock { margin: 5px 0px 0px 5px; float: left; overflow: hidden; display: block; background: #fff; } .w1 { width: 240px; } .w2 { width: 485px; } .l1 { height: 240px; } </head> <body> <div class="cblock w2 l1" id="bigblock"> <h1>DRAGONS</h1> <p>Here be they</p> </div> <div id="leftcol"> <div class="cblock w1 l1"> <h1>Left 1</h1> <p>1x1 block</p> </div> </div> <div id="rightcol"> <div class="cblock w1 l1"> <h1>Right 1</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 2</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 3</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 4</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 5</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 6</h1> <p>1x1 block</p> </div> <div class="cblock w1 l1"> <h1>Right 7</h1> <p>1x1 block</p> </div> </div> </body> </html> Constraints: One final note that I need cross-browser compatibility, though I'm more than happy to enforce this with JS if necessary. That said, if a CSS-only solution exists, I'd be extremely happy. Thanks in advance!

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  • org.apache.struts2.dispatcher.Dispatcher: Could not find action or result Error

    - by peterwkc
    i tried to code the following simple struts but encounter this error during run time. [org.apache.struts2.dispatcher.Dispatcher] Could not find action or result: No result defined for action com.peter.action.LoginAction and result success index.jsp <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@ taglib prefix="s" uri="/struts-tags" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Struts Tutorial</title> </head> <body> <h2>Hello Struts</h2> <s:form action="login" > <s:textfield name="username" label="Username:" /> <s:password name="password" label="Password:"/> <s:submit /> </s:form> </body> </html> LoginAction.java /** * */ package com.peter.action; //import org.apache.struts2.convention.annotation.Namespace; import org.apache.struts2.convention.annotation.ResultPath; import org.apache.struts2.convention.annotation.Result; import org.apache.struts2.convention.annotation.Action; import com.opensymphony.xwork2.ActionSupport; /** * @author nicholas_tse * */ //@Namespace("/") To define URL namespace @ResultPath("/") // To instruct Struts where to search result page(jsp) public class LoginAction extends ActionSupport { private String username, password; /** * */ private static final long serialVersionUID = -8992836566328180883L; /** * */ public LoginAction() { // TODO Auto-generated constructor stub } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } @Override @Action(value = "login", results = {@Result(name="success", location="welcome.jsp")}) public String execute() { return SUCCESS; } } /* Remove * struts2-gxp-plugin * struts2-portlet-plugin * struts2-jsf-plugin * struts2-osgi-plugin and its related osgi-plugin * struts-rest-plugin * * Add * velocity-tools-view * * */ web.xml <?xml version="1.0" encoding="UTF-8"?> <web-app id="WebApp_ID" version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name>Struts</display-name> <!-- org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter org.apache.struts2.dispatcher.FilterDispatcher --> <filter> <filter-name>Struts_Filter</filter-name> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> <init-param> <param-name>actionPackages</param-name> <param-value>com.peter.action</param-value> </init-param> </filter> <filter-mapping> <filter-name>Struts_Filter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app> Besides the runtime error, there is deployment error which is ERROR [com.opensymphony.xwork2.util.finder.ClassFinder] (MSC service thread 1-2) Unable to read class [WEB-INF.classes.com.peter.action.LoginAction]: Could not load WEB-INF/classes/com/peter/action/LoginAction.class - [unknown location] at com.opensymphony.xwork2.util.finder.ClassFinder.readClassDef(ClassFinder.java:785) [xwork-core-2.3.1.2.jar:2.3.1.2] AFAIK, the scanning methodology of struts will scan the default packages named struts2 for any annotated class but i have instructed struts2 to scan in com.peter.action using init-param but still unable to find the class. It is pretty weird. Please help. Thanks.

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  • Sending an Activation Email when a New User Registers

    - by John
    Hello, The code below is a login system that I am using. It is supposed to allow a new user to register and then send the new user an activation email. It is inserting the new user into the MySQL database, but it is not sending the activation email. Any ideas why it's not sending the activation email? Thanks in advance, John header.php: <?php //error_reporting(0); session_start(); require_once ('db_connect.inc.php'); require_once ("function.inc.php"); $seed="0dAfghRqSTgx"; $domain = "...com"; ?> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>The Sandbox - <?php echo $domain; ?></title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" type="text/css" href="sandbox.css"> <div class="hslogo"><a href="http://www...com/sandbox/"><img src="images/hslogo.png" alt="Example" border="0"/></a></div> </head> <body> login.php: <?php if (!isLoggedIn()) { // user is not logged in. if (isset($_POST['cmdlogin'])) { // retrieve the username and password sent from login form & check the login. if (checkLogin($_POST['username'], $_POST['password'])) { show_userbox(); } else { echo "Incorrect Login information !"; show_loginform(); } } else { // User is not logged in and has not pressed the login button // so we show him the loginform show_loginform(); } } else { // The user is already loggedin, so we show the userbox. show_userbox(); } ?> function show_loginform($disabled = false) { echo '<form name="login-form" id="login-form" method="post" action="./index.php?'.$_SERVER['QUERY_STRING'].'"> <div class="usernameformtext"><label title="Username">Username: </label></div> <div class="usernameformfield"><input tabindex="1" accesskey="u" name="username" type="text" maxlength="30" id="username" /></div> <div class="passwordformtext"><label title="Password">Password: </label></div> <div class="passwordformfield"><input tabindex="2" accesskey="p" name="password" type="password" maxlength="15" id="password" /></div> <div class="registertext"><a href="http://www...com/sandbox/register.php" title="Register">Register</a></div> <div class="lostpasswordtext"><a href="http://www...com/sandbox/lostpassword.php" title="Lost Password">Lost password?</a></div> <p class="loginbutton"><input tabindex="3" accesskey="l" type="submit" name="cmdlogin" value="Login" '; if ($disabled == true) { echo 'disabled="disabled"'; } echo ' /></p></form>'; } register.php: <?php require_once "header.php"; if (isset($_POST['register'])){ if (registerNewUser($_POST['username'], $_POST['password'], $_POST['password2'], $_POST['email'])){ echo "<div class='registration'>Thank you for registering, an email has been sent to your inbox, Please activate your account. <a href='http://www...com/sandbox/index.php'>Click here to login.</a> </div>"; }else { echo "Registration failed! Please try again."; show_registration_form(); } } else { // has not pressed the register button show_registration_form(); } ?> New User Function: function registerNewUser($username, $password, $password2, $email) { global $seed; if (!valid_username($username) || !valid_password($password) || !valid_email($email) || $password != $password2 || user_exists($username)) { return false; } $code = generate_code(20); $sql = sprintf("insert into login (username,password,email,actcode) value ('%s','%s','%s','%s')", mysql_real_escape_string($username), mysql_real_escape_string(sha1($password . $seed)) , mysql_real_escape_string($email), mysql_real_escape_string($code)); if (mysql_query($sql)) { $id = mysql_insert_id(); if (sendActivationEmail($username, $password, $id, $email, $code)) { return true; } else { return false; } } else { return false; } return false; } Send Activation Email function: function sendActivationEmail($username, $password, $uid, $email, $actcode) { global $domain; $link = "http://www.$domain/sandbox/activate.php?uid=$uid&actcode=$actcode"; $message = " Thank you for registering on http://www.$domain/, Your account information: username: $username password: $password Please click the link below to activate your account. $link Regards $domain Administration "; if (sendMail($email, "Please activate your account.", $message, "no-reply@$domain")) { return true; } else { return false; } }

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