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  • Generics List Interface...newb question

    - by newToProgramming
    The List interface is the following: public interface List<E>{ public boolean add(Object e); public boolean remove(Object e); public boolean contains(Object e); ...etc Why aren't the add, remove and contains methods written like the following? public boolean add(E e) public boolean remove(E e) public boolean contains(E e)

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  • What's the scope of a Python variable declared in an if statement?

    - by froadie
    I'm new to Python, so this is probably a simple scoping question. The following code in a Python file (module) is confusing me slightly: if __name__ == '__main__': x = 1 print x In other languages I've worked in, this code would throw an exception, as the x variable is local to the if statement and should not exist outside of it. But this code executes, and prints 1. Can anyone explain this behavior? Are all variables declared in a module global/available to the entire module?

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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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  • jQuery click event not working when mouse moves from one div to another with button held down

    - by Acorn
    I've made a page that uses jQuery to allow you to place <div>s on the page based on your mouse coordinates when you click. The page And here's the javascript: $('document').ready(function() { $("#canvas").click(function(e){ var x = e.pageX - this.offsetLeft; var y = e.pageY - this.offsetTop; $(document.createElement('div')).css({'left':x + 'px', 'top':y + 'px'}).addClass('tile').appendTo('#canvas'); }); }); I've found that if you mousedown in the div#canvas and mouseup with your pointer over a placed <div> (or vice versa) then a new <div> doesn't get placed. Why is this?

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  • How do Arrays work in C#?

    - by Slateboard
    I know that they are used to store data, but I have a difficult time understanding exactly how to use them in a program. In addition, I found this site with a tetris clone tutorial (the actual tutorial is missing). It uses arrays, but I can't really make sense of how it works. Here's an example of the code - public int[, ,] TShape = new int[4, 4, 2] { {{1, 0}, {0, 1}, {1, 1}, {2, 1}}, {{1, 0}, {0, 1}, {1, 1}, {1, 2}}, {{0, 0}, {1, 0}, {2, 0}, {1, 1}}, {{0, 0}, {0, 1}, {1, 1}, {0, 2}}}; Could it be that I'm looking too hard into this, or perhaps there's something I'm not grasping about it?

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  • Deleting an element from an array in perl

    - by Flamewires
    Hey I'm wondering how i can get this code to work, basically i want to keep the lines of $filename as long as they contain the $user in the path. Sry, perl noob. open STDERR, ">/dev/null"; $filename=`find -H /home | grep $file`; @filenames = split(/\n/, $filename); for $i (@filenames) { if ($i =~ m/$user/) { #keep results } else { delete $i; # does not work. } } $filename = join ("\n", @filenames); close STDERR; I know you can delete like delete $array[index] but I don't have an index with this kind of loop that I know of.

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  • Newbie programmer looking for a fun, small project (pref. C++/Python)

    - by Francisco P.
    Hello everyone, I have some experience in Scheme and C++ (read: a semester of each) I know the very basics of Python (used it for physics simulations with the Visual Python module). Can you recommend me some fun and small (i.e. don't take much time) projects on either Python or C++? I have no real preferences, just that it is fun :P Thanks for your time! PS: I've tried projecteuler and python challenge. Euler is good, but more about math than coding, and py challenge just didn't work for me.

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  • How do I create a new AnyType[] array?

    - by cb
    Which is the best practice in this situation? I would like an un-initialized array of the same type and length as the original. public static <AnyType extends Comparable<? super AnyType>> void someFunction(AnyType[] someArray) { AnyType[] anotherArray = (AnyType[]) new Comparable[someArray.length]; ...or... AnyType[] anotherArray = (AnyType[]) new Object[someArray.length]; ...some other code... } Thanks, CB

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  • In what order should the Python concepts be explained to absolute beginners?

    - by Tomaž Pisanski
    I am teaching Python to undergraduate math majors. I am interested in the optimal order in which students should be introduced to various Python concepts. In my view, at each stage the students should be able to solve a non-trivial programming problem using only the tools available at that time. Each new tool should enable a simpler solution to a familiar problem. A selection of numerous concepts available in Python is essential in order to keep students focused. They should also motivated and should appreciate each newly mastered tool without too much memorization. Here are some specific questions: For instance, my predecessor introduced lists before strings. I think the opposite is a better solution. Should function definitions be introduced at the very beginning or after mastering basic structured programming ideas, such as decisions (if) and loops (while)? Should sets be introduced before dictionaries? Is it better to introduce reading and writing files early in the course or should one use input and print for most of the course? Any suggestions with explanations are most welcome.

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  • Returning currently displayed index of an array Javascript...

    - by Jeff Kindred
    I have a simple array with x number of items. I am displaying them individually via a link click... I want to update a number that say 1 of 10. when the next one is displayed i want it to display 2 of 10 etc... I have looked all around and my brain is fried right now... I know its simple I just cant get it out. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>Page Title</title> <link rel="stylesheet" href="style.css" type="text/css" media="screen" charset="utf-8"/> <script type="text/javascript"> var quotations = new Array() quotations[0]= "1" quotations[1]= "2" quotations[2]= "3" quotations[3]= "4" quotations[4]= "5" quotations[5]= "6" quotations[6]= "7" numQuotes = quotations.length; curQuote = 1; function move( xflip ) { curQuote = curQuote + xflip; if (curQuote > numQuotes) { curQuote = 1 ; } if (curQuote == 0) { curQuote = numQuotes ; } document.getElementById('quotation').innerHTML=quotations[curQuote - 1]; } var curPage = //this is where the current index should go </script> </head> <body> <div id="quotation"> <script type="text/javascript">document.write(quotations[0]);</script> </div> <div> <p><a href="javascript();" onclick="move(-1)">GO back</a> <script type="text/javascript">document.write(curPage + " of " + numQuotes)</script> <a href="javascript();" onclick="move(1)">GO FORTH</a></p> </div> </body> </html>

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  • How do I splice a python string programmatically?

    - by Robin Welch
    Very simple question, hopefully. So, in Python you can split up strings using indices as follows: >>> a="abcdefg" >>> print a[2:4] cd but how do you do this if the indices are based on variables? E.g. >>> j=2 >>> h=4 >>> print a[j,h] Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: string indices must be integers

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  • Regex, replace path to resource, modify resource name

    - by jerome
    Hi all, I'd like to use a JS regex to take a string such as the following: 'http://www.somedomain.com/some_directory/some_other_directory/some_image.jpg' And turn it into this: 'http://www.some_other_domain.com/another_directory/yet_another_directory/size1_some_image.jpg' Any hints? Additionally, any pointers for books or other resources that give a gentle introduction to mastering regexes in JS and other languages?

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  • Jquery toggle event is messing with checkbox value

    - by John McCollum
    Hi all, I'm using Jquery's toggle event to do some stuff when a user clicks a checkbox, like this: $('input#myId').toggle( function(){ //do stuff }, function(){ //do other stuff } ); The problem is that the checkbox isn't being ticked when I click on the checkbox. (All the stuff I've put into the toggle event is working properly.) I've tried the following: $('input#myId').attr('checked', 'checked'); and $(this).attr('checked', 'checked'); and even simply return true; But nothing is working. Can anyone tell me where I'm going wrong? Edit - thanks to all who replied. Dreas' answer very nearly worked for me, except for the part that checked the attribute. This works perfectly (although it's a bit hacky) $('input#myInput').change(function () { if(!$(this).hasClass("checked")) { //do stuff if the checkbox isn't checked $(this).addClass("checked"); return; } //do stuff if the checkbox isn't checked $(this).removeClass('checked'); }); Thanks again to all who replied.

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  • What are good resources for computer graphics basics?

    - by Hanno Fietz
    During Flex programming, I recently ran into several questions (about box models, ways to join lines and misaligning pixels [on doctype]) regarding computer graphics and layout, where I felt that I lacked some basic background on things like concepts like the box model approaches mapping real numbers to a pixel raster (like font anti-aliasing) conventions found across drawing engines, like do you count y coordinates from top or bottom, and why I feel that reading some basic Wikipedia articles, books or tutorials on these subjects might help in phrasing my questions more specifically and debugging my code more systematically. I have repeatedly found myself writing tiny test apps in Flex, just to find out how the APIs do very basic stuff. My assumption would be that if I knew the right vocabulary and some general concepts, I could solve these questions much faster.

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  • Gridview column right click issue

    - by peter
    I have grid named 'GridView1' and displaying columns like this <asp:GridView ID="GridView1" OnRowCommand="ScheduleGridView_RowCommand" runat="server" AutoGenerateColumns="False" Height="60px" Style="text-align: center" Width="869px" EnableViewState="False"> <Columns> <asp:BoundField HeaderText="Topic" DataField="Topic" /> <asp:BoundField DataField="Moderator" HeaderText="Moderator" /> <asp:BoundField DataField="Expert" HeaderText="Expert" /> <asp:BoundField DataField="StartTime" HeaderText="Start" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:BoundField DataField="EndTime" HeaderText="End" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:TemplateField HeaderText="Join" ShowHeader="False"> <ItemTemplate> <asp:Button ID="JoinBT" runat="server" CommandArgument="<%# Container.DataItemIndex %>" CommandName="Join" Text="Join" Width="52px" /> </ItemTemplate> <HeaderStyle Height="15px" /> </asp:TemplateField> </Columns> </asp:GridView> Here what is my requirement is whenever we right click on each row in gridview ,it should display three option join meeting(if we click it will go to meeting.aspx),,view details(will go to detail.aspx),,Subscribe(subscribe.aspx) just like when we click right any where we can see view,sortby,refresh like that..Do we need to implement javascript here

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  • How can I "override" deepcopy in Python?

    - by Az
    Hi there, I'd like to override __deepcopy__ for a given SQLAlchemy-mapped class such that it ignores any SQLA attributes but deepcopies everything else that's part of the class. I'm not particularly familiar with overriding any of Python's built-in objects in particular but I've got some idea as to what I want. Let's just make a very simple class User that's mapped using SQLA. class User(object): def __init__(self, user_id, name): self.user_id = user_id self.name = name I've used dir() to see, before and after mapping, what SQLAlchemy-specific attributes there are and I've found _sa_class_manager and _sa_instance_state. Provided those are the only ones how would I ignore that when defining __deepcopy__? Also, are there any attributes the SQLA injects into the mapped object? (I asked this in a previous question (as an edit a few days after I selected an answer to the main question, though) but I think I missed the train there. Apologies for that.)

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  • want to start programming

    - by Dan
    I really want to learn how to program. A friend suggested I buy vs 2005 or a newer version if I'm serious about it. Is there a cheaper route? I would like to start with c#.

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  • Java: calculate linenumber from charwise position according to the number of "\n"

    - by HH
    I know charwise positions of matches like 1 3 7 8. I need to know their corresponding line number. Example: file.txt Match: X Mathes: 1 3 7 8. Want: 1 2 4 4 $ cat file.txt X2 X 4 56XX [Added: does not notice many linewise matches, there is probably easier way to do it with stacks] $ java testt 1 2 4 $ cat testt.java import java.io.*; import java.util.*; public class testt { public static String data ="X2\nX\n4\n56XX"; public static String[] ar = data.split("\n"); public static void main(String[] args){ HashSet<Integer> hs = new HashSet<Integer>(); Integer numb = 1; for(String s : ar){ if(s.contains("X")){ hs.add(numb); numb++; }else{ numb++; } } for (Integer i : hs){ System.out.println(i); } } }

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  • In c++ is there any Events/delegates/interfaces/notifications! anything?

    - by Bach
    Say i have these classes ViewA and ViewB In objective C using the delegate pattern I could do @protocol ViewBDelegate{ - (void) doSomething(); } then in ViewB interface: id<ViewBDelegate> delegate; then in ViewA implementation i set the delegate: viewB.delegate = self; and now I can call in doSomething from viewB onto any that unknown type delegate. [delegate doSomething]; "C++ How to Program" has been the worse read an can't find simple examples that demonstrates basic design patterns. What i'm looking for in C++ is: events ActionScript and java either delegates or notifications in Objective C anything that allows class A, Class B and Class C to know that ClassX didSomething()!!! thanks

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