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  • Consistent HashCode() and Equals() results, but inconsistent TreeMap.containsKey() result

    - by smessing
    I have the following object Node: private class Node implements Comparable<Node>(){ private String guid(); ... public boolean equals(Node o){ return (this == o); } public int hashCode(){ return guid.hashCode(); } ... } And I use it in the following TreeMap: TreeMap<Node, TreeSet<Edge>> nodes = new TreeMap<Node, TreeSet<Edge>>(); Now, the tree map is used in a class called Graph to store nodes currently in the graph, along with a set of their edges (from the class Edge). My problem is when I try to execute: public containsNode(n){ for (Node x : nodes.keySet()) { System.out.println("HASH CODE: "); System.out.print(x.hashCode() == n.hashCode()); System.out.println("EQUALS: "); System.out.print(x.equals(n)); System.out.println("CONTAINS: "); System.out.print(nodes.containsKey(n)); System.out.println("N: " + n); System.out.println("X: " + x); } } I sometimes get the following: HASHCODE: true EQUALS: true CONTAINS: false N: foo X: foo Anyone have an idea as to what I'm doing wrong? I'm still new to all this, so I apologize in advance if I'm overlooking something simple (I know hashCode() doesn't really matter for TreeMap, but I figured I'd include it).

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  • Is this a correct way to stop Execution Task

    - by Yan Cheng CHEOK
    I came across code to stop execution's task. private final ExecutorService executor = Executors.newSingleThreadExecutor(); public void stop() { executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (!Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; } I realize that, it is possible for Runnable to be in forever loop, as Unknown fun may Thread.sleep, clear the interrupt flag and ignore the InterruptedException Unknown fun may Thread.interrupted, clear the interrupt flag. I was wondering, is the following way correct way to fix the code? private final ExecutorService executor = Executors.newSingleThreadExecutor(); private volatile boolean flag = true; public void stop() { flag = false; executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (flag && !Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; }

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  • Login form validation using javascript and php

    - by ipl
    Hi, I have been trying to create a login form using javascript.My login form needs to do the fllowing using javascript validation 1.login field contains only letters with a minimum of 4 and a maximum of 6 letters 2.password is at least 5 characters long and not more than 7 characters and contains only letters and digits with at least 1 letter and at least 1 digit 3.if the data is incorrect, generate an alert window with an appropriate message and set the cursor to the incorrect input field and the form needs to be submitted to a php file which needs to validate against a text file I tried to use regular expression to check for the login fiels and password in the javascript and i have used a login .php but havent done anything in that till now.However my javascript/html file which i have pasted below doesnt seem to work.Can anyone tell me the issue with my file? Rgds ip function validateFormOnSubmit(theForm) { reason += validateUsername(theForm.username.value) reason += validatePassword (theForm.pwd.value) if (reason == "") return true else { alert(reason); return false } } function validateUsername(fld) { if (fld == "") return "No username entered" else if((fld.length 6) || (fld.length 7 ) { return "length shoild be b/w 4 and 7"; } else if (!/[a-z]/.test(fld) || !/[A-Z]/.test(fld) || !/[0-9]/.test(fld)){ return "passwords rewuire one of the letters or digitys"; } } SignupForm Your user name: Your Password:    

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  • Blackberry: Getting uncaught exception java.lang.securityexception

    - by Maxim Xion
    here is my code to open an image file from SDcard in Blackberry import javax.microedition.midlet.*; import javax.microedition.lcdui.*; import java.io.*; public class DisplayAnImage extends MIDlet { private Display mDisplay; private Form mForm; private Image pngBackground; public void startApp() { try{ pngBackground = Image.createImage("file:///Media Card/test_image.png"); ImageItem img = new ImageItem("bg",pngBackground, ImageItem.LAYOUT_EXPAND,"background",ImageItem.PLAIN); mForm = new Form("MIDlet Developer Guide: Display an image."); mForm.append(img); mDisplay = Display.getDisplay(this); mDisplay.setCurrent(mForm); } catch(IOException e) { mForm.append(e.getMessage()); } } public void pauseApp() { } public void destroyApp(boolean flag) { } } While I am running this app with giving all permission to app it shows me "uncaught exception java.lang.securityexception". Please somebody help me on this. Thanks in advance.. :-)

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  • When should EntityManagerFactory instance be created/opened ?

    - by masato-san
    Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory (EMF) should only be created once preferably in application scope. And also make sure to close the EMF once it's used (?) So I wrote EMF helper class for business methods to use: public class EmProvider { private static final String DB_PU = "KogaAlphaPU"; public static final boolean DEBUG = true; private static final EmProvider singleton = new EmProvider(); private EntityManagerFactory emf; private EmProvider() {} public static EmProvider getInstance() { return singleton; } public EntityManagerFactory getEntityManagerFactory() { if(emf == null) { emf = Persistence.createEntityManagerFactory(DB_PU); } if(DEBUG) { System.out.println("factory created on: " + new Date()); } return emf; } public void closeEmf() { if(emf.isOpen() || emf != null) { emf.close(); } emf = null; if(DEBUG) { System.out.println("EMF closed at: " + new Date()); } } }//end class And my method using EmProvider: public String foo() { EntityManager em = null; List<Object[]> out = null; try { em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager(); Query query = em.createNativeQuery(JPQL_JOIN); //just some random query out = query.getResultList(); } catch(Exception e) { //handle error.... } finally { if(em != null) { em.close(); //make sure to close EntityManager } } I made sure to close EntityManager (em) within method level as suggested. But when should EntityManagerFactory be closed then? And why EMF has to be singleton so bad??? I read about concurrency issues but as I am not experienced multi-thread-grammer, I can't really be clear on this idea.

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  • scheme basic loop

    - by utku
    I'm trying to write a scheme func that behaves in a way similar to a loop. (loop min max func) This loop should perform the func between the range min and max (integers) -- one of an example like this (loop 3 6 (lambda (x) (display (* x x)) (newline))) 9 16 25 36 and I define the function as ( define ( loop min max fn) (cond ((>= max min) ( ( fn min ) ( loop (+ min 1 ) max fn) ) ) ) ) when I run the code I get the result then an error occur. I couldn't handle this error. (loop 3 6 (lambda (x) (display(* x x))(newline))) 9 16 25 36 Backtrace: In standard input: 41: 0* [loop 3 6 #] In utku1.scheme: 9: 1 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 2 [# ... 10: 3* [loop 4 6 #] 9: 4 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 5 [# ... 10: 6* [loop 5 6 #] 9: 7 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 8 [# ... 10: 9* [loop 6 6 #] 9: 10 (cond ((= max min) ((fn min) (loop # max fn)))) 10: 11 [# #] utku1.scheme:10:31: In expression ((fn min) (loop # max ...)): utku1.scheme:10:31: Wrong type to apply: #<unspecified> ABORT: (misc-error)

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  • Algorithm complexity question

    - by Itsik
    During a recent job interview, I was asked to give a solution to the following problem: Given a string s (without spaces) and a dictionary, return the words in the dictionary that compose the string. For example, s= peachpie, dic= {peach, pie}, result={peach, pie}. I will ask the the decision variation of this problem: if s can be composed of words in the dictionary return yes, otherwise return no. My solution to this was in backtracking (written in Java) public static boolean words(String s, Set<String> dictionary) { if ("".equals(s)) return true; for (int i=0; i <= s.length(); i++) { String pre = prefix(s,i); // returns s[0..i-1] String suf = suffix(s,i); // returns s[i..s.len] if (dictionary.contains(pre) && words(suf, dictionary)) return true; } return false; } public static void main(String[] args) { Set<String> dic = new HashSet<String>(); dic.add("peach"); dic.add("pie"); dic.add("1"); System.out.println(words("peachpie1", dic)); // true System.out.println(words("peachpie2", dic)); // false } What is the time complexity of this solution? I'm calling recursively in the for loop, but only for the prefix's that are in the dictionary. Any idea's?

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  • PROLOG - DCG parsing

    - by user2895589
    Hello I am new Prolog and DGC.I want to write a DCG to parse time expressions like 10.20 am or 12 oclock. how can I check 10.20 am is valid expression or not for Olcock I wrote some code. oclock --> digit1,phrase1. digit1 --> [T],{digit1(T)}. digit1(1). digit1(2). digit1(3). digit1(4). digit1(5). digit1(6). digit1(7). digit1(8). digit1(9). digit1(10). digit1(11). digit1(12). phrase1 --> [P],{phrase1(P)}. phrase1(Oclock). i ma checking by query oclock([1,oclock],[]). can someone help me on this.

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  • Is it possible to create an Android Service that listens for hardware key presses?

    - by VoteBrian
    I'd like to run an Android background service that will act as a keylistener from the home screen or when the phone is asleep. Is this possible? From semi-related examples online, I put together the following service, but get the error, "onKeyDown is undefined for the type Service". Does this mean it can't be done without rewriting Launcher, or is there something obvious I'm missing? public class ServiceName extends Service { @Override public void onCreate() { //Stuff } public IBinder onBind(Intent intent) { //Stuff return null; } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if(event.getAction() == KeyEvent.ACTION_DOWN) { switch(keyCode) { case KeyEvent.KEYCODE_A: //Stuff return true; case KeyEvent.KEYCODE_B: //Stuff return true; //etc. } } return super.onKeyDown(keyCode, event); } } I realize Android defaults to the search bar when you type from the home screen, but this really is just for a very particular use. I don't really expect anyone but me to want this. I just think it'd be nice, for example, to use the camera button to wake the phone.

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  • JTree TreePath casting problem

    - by newbie123
    I got this casting problem java.lang.String cannot be cast to java.io.File, when I trying to do this TreePath p = new TreePath(new Object[] {"src","file","My Diary" }); This is my jtree file model class FileTreeModel implements TreeModel { private FileNode root; public FileTreeModel(String directory) { root = new FileNode(directory); } public Object getRoot() { return root; } public Object getChild(Object parent, int index) { FileNode parentNode = (FileNode) parent; return new FileNode(parentNode, parentNode.listFiles()[index].getName()); } public int getChildCount(Object parent) { FileNode parentNode = (FileNode) parent; if (parent == null || !parentNode.isDirectory() || parentNode.listFiles() == null) { return 0; } return parentNode.listFiles().length; } public boolean isLeaf(Object node) { return (getChildCount(node) == 0); } public int getIndexOfChild(Object parent, Object child) { FileNode parentNode = (FileNode) parent; FileNode childNode = (FileNode) child; return Arrays.asList(parentNode.list()).indexOf(childNode.getName()); } public void valueForPathChanged(TreePath path, Object newValue) { } public void addTreeModelListener(TreeModelListener l) { } public void removeTreeModelListener(TreeModelListener l) { } } class FileNode extends java.io.File { public FileNode(String directory) { super(directory); } public FileNode(FileNode parent, String child) { super(parent, child); } @Override public String toString() { return getName(); } }

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  • Entity Filter child without include

    - by Lic
    i'm a C# developer and i have a trouble with Entity Framework 5. I have mapped my database with Entity using the default code generation strategy. In particolar there are three classes: menus, submenus and submenuitems. The relationships about three classes are: one menu - to many submenus one submenu - to many submenuitems. All classes have a boolean attribute called "Active". Now, i want to filter all the Menus with the SubMenus active, and the SubMenus with the SubMenuItems active. To get this i've tried this: var tmp = _model.Menus.Where(m => m.Active) .Select => new { Menu = x, SubMenu = x.SubMenus.Where(sb => sb.Active) .Select(y => new { SubMenu = y, SubMenuItem = y.SubMenuItems.Where(sbi => sbi.Active) }) }) .Select(x => x.Menu).ToList(); But didn't work. Someone can help me? Thank you for your help!

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  • String comparison in Python: is vs. ==

    - by Coquelicot
    I noticed a Python script I was writing was acting squirrelly, and traced it to an infinite loop, where the loop condition was "while line is not ''". Running through it in the debugger, it turned out that line was in fact ''. When I changed it to != rather than 'is not', it worked fine. I did some searching, and found this question, the top answer to which seemed to be just what I needed. Except the answer it gave was counter to my experience. Specifically, the answerer wrote: For all built-in Python objects (like strings, lists, dicts, functions, etc.), if x is y, then x==y is also True. I double-checked the type of the variable, and it was in fact of type str (not unicode or something). Is his answer just wrong, or is there something else afoot? Also, is it generally considered better to just use '==' by default, even when comparing int or Boolean values? I've always liked to use 'is' because I find it more aesthetically pleasing and pythonic (which is how I fell into this trap...), but I wonder if it's intended to just be reserved for when you care about finding two objects with the same id.

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  • Writing functions of tuples conveniently in Scala

    - by Alexey Romanov
    Quite a few functions on Map take a function on a key-value tuple as the argument. E.g. def foreach(f: ((A, B)) ? Unit): Unit. So I looked for a short way to write an argument to foreach: > val map = Map(1 -> 2, 3 -> 4) map: scala.collection.immutable.Map[Int,Int] = Map(1 -> 2, 3 -> 4) > map.foreach((k, v) => println(k)) error: wrong number of parameters; expected = 1 map.foreach((k, v) => println(k)) ^ > map.foreach({(k, v) => println(k)}) error: wrong number of parameters; expected = 1 map.foreach({(k, v) => println(k)}) ^ > map.foreach(case (k, v) => println(k)) error: illegal start of simple expression map.foreach(case (k, v) => println(k)) ^ I can do > map.foreach(_ match {case (k, v) => println(k)}) 1 3 Any better alternatives?

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  • Using an element against an entire list in Haskell

    - by Snick
    I have an assignment and am currently caught in one section of what I'm trying to do. Without going in to specific detail here is the basic layout: I'm given a data element, f, that holds four different types inside (each with their own purpose): data F = F Float Int, Int a function: func :: F -> F-> Q Which takes two data elements and (by simple calculations) returns a type that is now an updated version of one of the types in the first f. I now have an entire list of these elements and need to run the given function using one data element and return the type's value (not the data element). My first analysis was to use a foldl function: myfunc :: F -> [F] -> Q myfunc y [] = func y y -- func deals with the same data element calls myfunc y (x:xs) = foldl func y (x:xs) however I keep getting the same error: "Couldn't match expected type 'F' against inferred type 'Q'. In the first argument of 'foldl', namely 'myfunc' In the expression: foldl func y (x:xs) I apologise for such an abstract analysis on my problem but could anyone give me an idea as to what I should do? Should I even use a fold function or is there recursion I'm not thinking about?

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  • Problem with mouse event on a user control (wpf).

    - by csciguy
    All, I have a user control, defined as follows. <UserControl x:Class="IDOView.AnimatedCharacter" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:IDOView" mc:Ignorable="d" Background="Transparent" > <Image Name="displayImage" Height="Auto" Width="Auto" Stretch="Fill" IsHitTestVisible="True"/> The control is added to a main page twice, as follows. <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="circle.png" Canvas.Left="-279" Canvas.Top="-56" MouseLeftButtonUp="DoA1"> <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="square.png" Canvas.Left="-209" Canvas.Top="-56" MouseLeftButtonUp="DoA2"> Essentially, about half of the circle is behind the square. I need the square image in this case to pass through events to the circle behind it. The square has an element cut out of it (transparent). What is happening now is that the circle event only registers if I click on the region that is not covered by the square. Surely there has to be a way to bubble this event, or click-through?

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  • Why does this threading approach not work?

    - by Tomas Lycken
    I have a wierd problem with threading in an ASP.NET application. For some reason, when I run the code in the request thread, everything works as expected. But when I run it in a separate thread, nothing happens. This is verified by calling the below handler with the three flags "on", "off" and "larma" respectively - in the two first cases everything works, but in the latter nothing happens. What am I doing wrong here? In the web project I have a generic handler with the following code: If task = "on" Then Alarm.StartaLarm(personId) context.Response.Write("Larmet är PÅ") ElseIf task = "off" Then Alarm.StoppaLarm(personId) context.Response.Write("Larmet är AV") ElseIf task = "larma" Then Alarm.Larma(personId) context.Response.Write("Larmar... (stängs av automagiskt)") Else context.Response.Write("inget hände - task: " & task) End If The Alarm class has the following methods: Private Shared Sub Larma_Thread(ByVal personId As Integer) StartaLarm(personId) Thread.Sleep(1000 * 30) StoppaLarm(personId) End Sub Public Shared Sub StartaLarm(ByVal personId As Integer) SandSMS(True, personId) End Sub Public Shared Sub StoppaLarm(ByVal personId As Integer) SandSMS(False, personId) End Sub Public Shared Sub SandSMS(ByVal setOn As Boolean, ByVal personId As Integer) ... End Sub

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  • Creating object/array to method in request based on __gettypes in PHP

    - by LochNess
    I'm having trouble with the array or object that should be passed based on the response from __gettypes. The __gettypes response: [0] => struct CDataWrapper { schema;any; } [1] => struct NewMember { MemberDetail MemberDetails;ArrayOfHobby Hobbies; } [2] => struct MemberDetail { string Name; string Age; string Sex; } [3] => struct ArrayOfHobby { Hobby Hobby; } [4] => struct Hobby { string Name; string HoursUsedOnHobbyWeekly;boolean Favourite; } ... etc. The methods are: [0] => ReceiveMemberResponse ReceiveMember(ReceiveMember $parameters) [1] => ReturnMemberResponse ReturnMember(ReturnMember $parameters) So far I have this PHP: $client = new SoapClient('http://domain.com?wsdl'); class MemberDetail { public $Name = ''; public $Age = ''; public $Sex = ''; } $mc = new MemberDetail(); $mc->Name= 'Bob'; $mc->Age= '14'; $mc->Sex= 'Male'; $myParam = array('ReceiveMember'=>$mc); $wcf = $client->ReceiveMember($myParam); $wcfResult = $wcf->ReturnMember; print_r($wcfResult) when i call the page it returns: Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error. I'm not really sure how to create the array or object to pass on as $myParam since im no expert with PHP either.

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  • Removing a pattern from the beggining and end of a string in ruby

    - by seaneshbaugh
    So I found myself needing to remove <br /> tags from the beginning and end of strings in a project I'm working on. I made a quick little method that does what I need it to do but I'm not convinced it's the best way to go about doing this sort of thing. I suspect there's probably a handy regular expression I can use to do it in only a couple of lines. Here's what I got: def remove_breaks(text) if text != nil and text != "" text.strip! index = text.rindex("<br />") while index != nil and index == text.length - 6 text = text[0, text.length - 6] text.strip! index = text.rindex("<br />") end text.strip! index = text.index("<br />") while index != nil and index == 0 text = test[6, text.length] text.strip! index = text.index("<br />") end end return text end Now the "<br />" could really be anything, and it'd probably be more useful to make a general use function that takes as an argument the string that needs to be stripped from the beginning and end. I'm open to any suggestions on how to make this cleaner because this just seems like it can be improved.

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  • Can I get an XPathNodeIterator directly from an XPath?

    - by Val
    I hope I'm just missing something obvious. I have a number of repeating nodes in an XML document: <root> <parent> <child/> <child/> </parent> </root> I need to examine the contents of each of the <child> elements in turn, so I need an XPathNodeIterator containing the nodeset of all the <child> nodes. If I have an XPath that would select the child nodes, e.g. /root/parent/child, is there any way to feed that directly to a new XPathNodeIterator? Everything I see in the docs and examples indicates I have to first get an XPathNavigator to the <parent>, then Select the child nodes, like: XPathNavigator nav = datasource.CreateNavigator().SelectSingleNode( "/root/parent" ); XPathNodeIterator it = nav.Select( "./child" ); foreach ( child in it ) { /* do something */ } I was hoping to skip the XPathNavigator, and intialize the XPathNodeIterator with XPath to the child nodes directly, something like: XpathNodeIterator it = new XpathNodeIterator("/root/parent/child"); foreach ( child in it ) { /* do something */ } Possible? The benefit is not only saving a line of code, but I can use a single XPath expression, rather than splitting the path to the <child> nodes in two, first to get the parent element, then to select its children.

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  • Instrumenting a string

    - by George Polevoy
    Somewhere in C++ era i have crafted a library, which enabled string representation of the computation history. Having a math expression like: TScalar Compute(TScalar a, TScalar b, TScalar c) { return ( a + b ) * c; } I could render it's string representation: r = Compute(VerbalScalar("a", 1), VerbalScalar("b", 2), VerbalScalar("c", 3)); Assert.AreEqual(9, r.Value); Assert.AreEqual("(a+b)*c==(1+2)*3", r.History ); C++ operator overloading allowed for substitution of a simple type with a complex self-tracking entity with an internal tree representation of everything happening with the objects. Now i would like to have the same possibility for NET strings, only instead of variable names i would like to see a stack traces of all the places in code which affected a string. And i want it to work with existing code, and existing compiled assemblies. Also i want all this to hook into visual studio debugger, so i could set a breakpoint, and see everything that happened with a string. Which technology would allow this kind of things? I know it sound like an utopia, but I think visual studio code coverage tools actually do the same kind of job while instrumenting the assemblies.

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  • How to use linux csplit to chop up massive XML file?

    - by Fred
    Hi everyone, I have a gigantic (4GB) XML file that I am currently breaking into chunks with linux "split" function (every 25,000 lines - not by bytes). This usually works great (I end up with about 50 files), except some of the data descriptions have line breaks, and so frequently the chunk files do not have the proper closing tags - and my parser chokes halfway through processing. Example file: (note: normally each "listing" xml node is supposed to be on its own line) <?xml version="1.0" encoding="UTF-8"?> <listings> <listing><date>2009-09-22</date><desc>This is a description WITHOUT line breaks and works fine with split</desc><more_tags>stuff</more_tags></listing> <listing><date>2009-09-22</date><desc>This is a really annoying description field WITH line breaks that screw the split function</desc><more_tags>stuff</more_tags></listing> </listings> Then sometimes my split ends up like <?xml version="1.0" encoding="UTF-8"?> <listings> <listing><date>2009-09-22</date><desc>This is a description WITHOUT line breaks and works fine with split</desc><more_tags>stuff</more_tags></listing> <listing><date>2009-09-22</date><desc>This is a really annoying description field WITH line breaks ... EOF So - I have been reading about "csplit" and it sounds like it might work to solve this issue. I cant seem to get the regular expression right... Basically I want the same output of ~50ish files Something like: *csplit -k myfile.xml '/</listing>/' 25000 {50} Any help would be great Thanks!

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  • Project Euler, Problem 10 java solution now working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • How to speed up a slow UPDATE query

    - by Mike Christensen
    I have the following UPDATE query: UPDATE Indexer.Pages SET LastError=NULL where LastError is not null; Right now, this query takes about 93 minutes to complete. I'd like to find ways to make this a bit faster. The Indexer.Pages table has around 506,000 rows, and about 490,000 of them contain a value for LastError, so I doubt I can take advantage of any indexes here. The table (when uncompressed) has about 46 gigs of data in it, however the majority of that data is in a text field called html. I believe simply loading and unloading that many pages is causing the slowdown. One idea would be to make a new table with just the Id and the html field, and keep Indexer.Pages as small as possible. However, testing this theory would be a decent amount of work since I actually don't have the hard disk space to create a copy of the table. I'd have to copy it over to another machine, drop the table, then copy the data back which would probably take all evening. Ideas? I'm using Postgres 9.0.0. UPDATE: Here's the schema: CREATE TABLE indexer.pages ( id uuid NOT NULL, url character varying(1024) NOT NULL, firstcrawled timestamp with time zone NOT NULL, lastcrawled timestamp with time zone NOT NULL, recipeid uuid, html text NOT NULL, lasterror character varying(1024), missingings smallint, CONSTRAINT pages_pkey PRIMARY KEY (id ), CONSTRAINT indexer_pages_uniqueurl UNIQUE (url ) ); I also have two indexes: CREATE INDEX idx_indexer_pages_missingings ON indexer.pages USING btree (missingings ) WHERE missingings > 0; and CREATE INDEX idx_indexer_pages_null ON indexer.pages USING btree (recipeid ) WHERE NULL::boolean; There are no triggers on this table, and there is one other table that has a FK constraint on Pages.PageId.

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  • Java: Comparing a class with another within that class using a my own .equals

    - by user1670252
    I am making a method .equals replacing the equals method used. It accepts a object. I want it to check if that object equals the class that runs the .equals class. I know I want to compare all the private methods I have to that object. Is there a way to do this without making another private class to get the private variables from the object? How do I do this to compare equality not identity? I am stuck on this. Do i have to use == to compare? Also looking online i see others use recursion. If this is the way i have to do it can you show and explain it to me? so an example i have public boolean equals(Object o) { this is in a class we will call bobtheBuilder (first thing to pop in my head) I want to check if the object o is equal to the class he has private object array and a private int. I assume I want to check if the array and int of this class equal the array and int of the object.

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  • How can I use a compound condition in a join in Linq?

    - by Gary McGill
    Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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