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• How do I get a MessageBox like information window to appear in Java?

  - by John McClane

  I'm learning Java and I have no idea how to do this. I dragged a button on the form in Netbeans, double clicked it and it created this event: @Action public void HelloClickMethod() { JOptionPane.showMessageDialog(this, "The message!", "This is supposed to be the MessageBox title."); } This is the exception the IDE brings up. Cannot find symbol. Symbol: showMessageDialog() Edit 1 Now I changed it to this: @Action public void HelloClickMethod() { JOptionPane.showMessageDialog(this, "The message!", "This is supposed to be the MessageBox title.",JOptionPane.ERROR_MESSAGE); } However the IDE is saying I have an error in the word 'this'. "Cannot find symbol". I don't understand. Why is it so dificult and why are the errors so esoteric. :P

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• pyschool is wrong ?

  - by geekkid

  I'm currently learning python and trying to do exercises at pyschools (if anyone knows what it is). Anyway, i have an exercise that asks me to do the following : Write a function percent(value, total) that takes in two numbers as arguments, and returns the percentage value as an integer. Here's my code: def percent(value, total): percent = value / total * 100 return int(percent) It works great in my Python Idle and it gives all the correct answers. however, when i run it in the pyschools website, it says that , for example , when the function is called with parameters 46 and 90 , the function returns 0. However, in my python idle , it correctly returns 51. What might be the problem ? Thank you very much for your help!

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• Is there a 'hello world' website for django? OR (I've installed django, now what) ?

  - by morpheous

  I'm learning Python and decided to start familiarizing myself with the (defacto?) Python web framework - django. I have successfully installed the latest release of django. I want a simple 'hello world' website that will get me up and running quickly. I am already familiar with web frameworks (albeit for different languages) - so I just need a simple 'hello world' example website to help me get going. Ideally, I don't want to mess up with my Apache server settings (as I am still experimenting), so I want to use the lightweight web server that django bundles. I cant seem to find how to do this on the django website though - no doubt someone will post a link and shame me ... So, does anyone know of a link that shows how to get a simple 'hello world' django website up and running with minimal fuss?

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• A way of allocating multidimensional arrays dynamically

  - by C77431

  salute.. I am learning dynamic allocations for multidimensional arrays in a book and I found some ways for that, And now haven't problem in it. But the author of the book shows us a way, but it doesn't work correctly. It is this: pbeans = new double [3][4]; // Allocate memory for a 3x4 array And this is the error: error C2440: '=' : cannot convert from 'int (*)[4]' to 'int *' how should i define pbeans ( if this type of coding is legal)? and what is the problem exactly? Regards.

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• How many real world developers are involved with the Demoscene?

  - by spoulson

  I grew up learning to code based on what I've experienced with the demoscene. It seems to be a pretty sparse subculture in the US. How many developers watch or participate in the scene? Teaser: If you haven't checked out the scene before, take a look at one of my favorites: Debris by Farbrausch. Watch on demoscene.tv or download the app (179k) and run it yourself. No video, all realtime rendering and audio. Think, a small group of guys wrote this for a competition on their free time.

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• How would you use version control for personal data, like a personal website?

  - by nn

  This is more a use-case question, but I generate static files for a personal website using txt2tags. I was thinking of maybe storing this information in a git repository. Normally I use RCS since it's simplest, and I'm only a single user. But there just seems to be a large trend of people using git/svn/cvs/etc. for personal data, and I thought this may also be a good way to at least learn some of the basics of the tool. Obviously most of the learning is done in an environment where you collaborate. So back to the question: how would you use use a version control system such as git, to manage a personal website?

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• Difference between var and Class class in object creation

  - by Divine

  Its a silly question, however shocked to see different behaviors. Learning a lot. Lets say I have two classes below Class A { public void Display() { } } Class B : A { public void Display() { } } Class C : B { public void Display() { } } Class Final { static void Main() { var c = new C(); // B c = new C(); //My doubt is, both of the above gives different results. May I know B c = new C() creates object of B or C? What I understood is, it creates object of B. Then why we say "new C()"? I agree with C c = new C(); But I thought, B b = new C(); creates object of B. Where we use this style? Only when utilizing runtime polymorphism? (Overriding methods)? } }

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• JQuery Ajax returned blank data

  - by kwokwai

  Hi all, I am learning how to use JQuery to help check data availability. I have written a function in a Controller for checking data input, and the URL is like this: http://www.mywebsite.com/controllers/action/avariable but the returned data was blank. <Script language="javascript"> $(document).ready(function(){ $(document).change(function(){ var usr = $("#data\\[User\\]\\[name\\]").val(); $.post{"http://www.mywebsite.com/controllers/action/", usr, function(msg){alert(msg);} } }); }); </Script> <div id="username"> <input type=text name="data[User][name]" id="data[User][name]"> </div> Here is the code of the Action: function action($data=null){ $this->autoRender = false; $result2=$this->__avail($udata); if($result2==1) {return "OK";} else {return "NOT";} }

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• Start diving into large open source projetcs

  - by Vanangamudi

  How to start learning and reading the source of large and complex projects like Blender3D and Gimp, for instance. Since the developers busy improving it and there is no docs exist at present, how do we start developing and customizing these projects. Linux kernel deserve to have several books on its code, also these kind of project do deserve the same. And there are no unit tests available for this kind of projects. Say I'm going to read and understand the source code blender. How do I start. How to setup the development environment for developing the app? If it includes several dependencies, and assume that their source code also available how to setup this kind of inter-related, coherent source code to debug?

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• After C++ - Python or Java?

  - by carleeto

  I'm fast approaching the point in my coding where I would like to quickly write object oriented code in languages other than C++ for a variety of reasons. After a lot of research, my choices have pretty much narrowed down to Python and Java. I'm leaning towards Python because of its relationship to C, but with Java, from what I can see, I get a good introduction to using and creating test suites with Eclipse - there is also Processing which is pulling me towards Java. I'm not the kind of guy to tackle two languages at once, so which one would you recommend and why? What I want at the end is to have an additional language I can use for rapid development. Ease of learning isn't important to me as I'm willing to put in the time regardless. Ability to use the new language widely is.

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• DDD Infrastructure services

  - by Zygimantas

  Hello, I am learning DDD and I am a little bit lost in Infrastructure layer: As I understand, "all good DDD applications" should have 4 layers: Presentation, Application, Domain and Infrastructure. Database should be accessed using Repositories. Repository interfaces should be in Domain layer and repository implementation - in Infrastructure (reference http://stackoverflow.com/questions/693221/ddd-where-to-keep-domain-interfaces-the-infrastructure). Application, Domain and Infrastructure layer should/may have services (reference www.lostechies.com/blogs/jimmy_bogard/archive/2008/08/21/services-in-domain-driven-design.aspx), in example EmailService in Infrastructure layer which sends Email messages. BUT, inside Infrastructure layer we have repository implementations, which are used to access database. So, in this case, repositories are database services? What is the difference between Infrastructure service and repository? Thanks in advance!

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• <= vs < when proving big-o notation

  - by user600197

  We just started learning big-o in class. I understand the general concept that f(x) is big-o of g(x) if there exists two constants c,k such that for all xk |f(x)|<=c|g(x)|. I had a question whether or not it is required that we include the <= to sign or whether it is just sufficient to put the < sign? For example: suppose f(x)=17x+11 and we are to prove that this is O(x^2). Then if we take c=28 and xk=1 we know that 17x+11<=28x^2. So since we know that x will always be greater than 1 this implies that 28x^2 will always be greater than 17x+11. So, do we really need to include the equal sign (<=) or is it okay if we just write (<)? Thanks in advance.

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• Copy a Table's data from a Stored Procedure

  - by Niike2

  I am learning how to use SQL and Stored Procedures. I know the syntax is incorrect: Copy data from one table into another table on another Database with a Stored Procedure. The problem is I don't know what table or what database to copy to. I want it to use parameters and not specify the columns specifically. I have 2 Databases (Master_db and Master_copy) and the same table structure on each DB. I want to quickly select a table in Master_db and copy that table's data into Master_copy table with same name. I have come up with something like this: USE Master_DB CREATE PROCEDURE TransferData DEFINE @tableFrom, @tableTo, @databaseTo; INSERT INTO @databaseTo.dbo.@databaseTo SELECT * FROM Master_DB.dbo.@tableFrom GO;

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• How is the syntax for stl iterators implemented?

  - by Liberalkid

  I've been working on writing a library in my spare time to familiarize myself more with c++ and singular value decomposition. I've been working on writing an Iterator class and I'm entirely capable of writing the functionality and I have already for my own currently MatrixIterator class. I'm guessing that it involves namespaces because: vector<int>::iterator Would appear to be an iterator from the namespace vector, but namespaces are another topic which I'm not familiar with. Mainly I'm asking what would it involve to implement an iterator such that it could be referenced in a similar way to the stl iterators. I'm also aware that I could use boost.iterators or something similar to save myself a lot of work, but I'm more interested in learning all of the details that go into something like this.

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• c# how to get keydown and button click to do the same thing??

  - by myax

  I am new to C#.I am learning to make a calculator just like ms windows calculator.the buttons work when i click it, but I want the numpad to work too. Suppose the user types '0', it should be the same as if he clicked the 0 button on my gui. here is my button click event for 0. private void button0_Click(object sender, EventArgs e) { checkifequa(); textBox1.Text = textBox1.Text + "0"; } how do i get the keydown to work?

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• What Should be the Structure of a C++ Project?

  - by Ell

  I have recently started learning C++ and coming from a Ruby environment I have found it very hard to structure a project in a way that it still compiles correctly, I have been using Code::Blocks which is brilliant but a downside is that when I add a new header file or c++ source file, it will generate some code and even though it is only a mere 3 or 4 lines, I do not know what these lines do. First of all I would like to ask this question: What do these lines do? #ifndef TEXTGAME_H_INCLUDED #define TEXTGAME_H_INCLUDED #endif // TEXTGAME_H_INCLUDED My second question is, do I need to #include both the .h file and the .cpp file, and in which order. My third question is where can I find the GNU GCC Compiler that, I beleive, was packaged with Code::Blocks and how do I use it without Code::Blocks? I would rather develop in a notepad++ sort of way because that is what I'm used to in Ruby but since C++ is compiled, you may think differently (please give advice and views on that as well) Thanks in advance, ell.

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• Splitting string to integer from single-line user input?

  - by pootzko

  I just started learning some ruby, and I want to do something like this: print "Insert two numbers: " a, b = gets.split(" ") but I want to make a and b to be integers at the same time (in the same line).. If I add .to_i to the second line (before or after split(" ")), it doesn't work... so, how should I approach this? mapping, splitting, slicing? ok, I know I could use scanf, but other than scanf, how would I do this? sorry for such a noobish question, but I just couldn't find a good enough answer only googling...

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• Assistance with regular expressions in Python

  - by da5id

  I am still learning REGEX, and I've run into an issue ... I am trying to separate a string that is composed of a mixture of letters and numbers that are in decimal format: AB0.500CD1.05EF2.29 Into something like this: list1 = AB,CD,EF list2 = 0.500,1.05,2.29 A complication to all this is that I also have strings that look like this: AB1CD2EF3 Which I'd also like to separate into this: list1 = AB,CD,EF list2 = 1,2,3 A previous inquiry yielded the following snippet, import re pattern = re.compile(r'([a-zA-Z]+)([0-9]+)') for (letters, numbers) in re.findall(pattern,cmpnd): print numbers print letters This example works fine for strings of the 2nd kind, but only "finds" the leading digit in the numbers that contain decimal places in the strings of the first kind. I've attempted an approach using the following line: pattern = re.compile(r'([a-zA-Z]+)([0-9]+(\.[0-9]))') But this results in an error: "ValueError: too many values to unpack" Thanks for any and all assistance!

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• is counter has certain value inside a class in python

  - by mazlor

  i am learning classes in python and when i was reading the documentation i found this example that i didn't understand : class MyClass: """A simple example class""" def __init__(self): self.data = [] i = 12345 def f(self): return 'hello world' then if we assign : x = MyClass() x.counter = 1 now if we implement while loop : while x.counter < 10: x.counter = x.counter * 2 so the value of x.counter will be : 16 while for example if we have a variable y : y = 1 while y < 1 : y = y *2 then if we look for the value of y we find it 1 so i don't know how is the value of counter became 16 . thanks

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• What is the most efficient algorithm for reversing a String in Java?

  - by Hultner

  I am wondering which way to reverse a string in Java that is most efficient. Should I use some sort of xor method? The easy way would be to put all the chars in a stack and put them back into a string again but I doubt that's a very efficient way to do it. And please do not tell me to use some built in function in Java. I am interested in learning how to do it not to use an efficient function but not knowing why it's efficient or how it's built up.

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• Hibernate - One design problem

  - by Yatendra Goel

  I am learning Hibernate from the tutorial on JBoss website. I have a confusion in a code example located here. There is a Cat class code at 4.1. A simple POJO example. This Cat class has a reference to his mother as private Cat mother; Q1. If the class has an identifier property as id, then wouldn't it be better to store the cat's mother's id instead of cat's mother object. means instead of private Cat mother; wouldn't it be better to have private long motherId; `

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• Tkinter mouse event initially triggered

  - by user3714884

  I'm currently learning Tkinter and I cannot find a solution for my problem here nor outside Stackoverflow. In a nutshell, all events that I bind to my widgets are triggered initialy and don't respond to my actions. In this example, the red rectangle appears on the canvas when I run the code, and color=random.choice(['red', 'blue']) revealed that the event binding doesn't work after that: import Tkinter as tk class application(tk.Frame): def __init__(self, master=None): tk.Frame.__init__(self, master) self.can = tk.Canvas(master, width=200, height=200) self.can.bind('<Button-2>', self.draw()) self.can.grid() def draw(self): self.can.create_rectangle(50, 50, 100, 100, fill='red') app = application() app.mainloop() I use a Mac platform, but I haven't got a clue about its role in the problem. Could anyone please point me at the mistake i did here?

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• Creating custom ribbon with SQL Server linked Access application

  - by andy

  I'm just learning about creating custom ribbons in Access 2010, but I'm running into an issue. The Access application I'm working with is connected to a SQL Server backend (connected, not just linked tables). As I understand it, the USysRibbons table needs to exist in the Access application itself, and not in a connected SQL Server. How does one go about creating a table in an Access application that is already linked to a SQL Server? I tried creating the table in a blank database and then importing it into the Access application without any luck.

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• C# How to place a comma after each word but the last in the list

  - by user576712

  I totally new to C# and learning as I go. I am stuck on issue which I'm hoping an experienced programmer can help. I have added a CheckedListBox to my form and added a collection of 6 items to it. I need all but the last item selected to have a comma placed beside it, so my question is: how can I tell C# NOT to place a comma beside the last item selected? foreach (object itemChecked in RolesCheckedListBox.CheckedItems) { sw.Write(itemChecked.ToString() + ","); } Thanks for any help received! Dan

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• I can't Distinct, Sum, or Count from 3 tables with group clauses

  - by Rio Inggit Dharmawangsa

  I'm still learning linq, now i'm getting confused. I need data for report from 3 tables, I get the result, but it's duplicate. I have used distinct but it's not working, n I need data to be sum still not working. Here is my query, can somebody explain what's wrong? var report= (from u in myDb.TBL_TRANSAKSI_MKN_MNMs.AsEnumerable() where u.TGL_TRANSAKSI.Value.Date.Equals(dateTimePicker1.Value.Date) join l in myDb.TBL_DETAIL_TRANSAKSIs.AsEnumerable() on u.ID_NOTA equals l.ID_NOTA join m in myDb.TBL_MKN_MNMs.AsEnumerable() on l.ID_MKN_MNM equals m.ID_MKN_MNM group new { u, l, m } by new { m.NAMA_MKN_MNM, m.HARGA_JUAL, u.TGL_TRANSAKSI, l.ID_MKN_MNM, u.USERNAME, l.Jumlah } into grp select new { MakanMinum = grp.Key.NAMA_MKN_MNM, HargaJual = grp.Key.HARGA_JUAL, Stok = grp.Sum(groupedthing => groupedthing.l.Jumlah), Tanggal = grp.Key.TGL_TRANSAKSI, Jumlah =(grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Total = grp.Sum(grouptotal => grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Username = grp.Key.USERNAME }).Distinct();

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