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  • Storing same type but still getting an ArrayStoreException

    - by Firefoxx Pwnass
    I have strange problem. I have three classes. Book ( abstract ), and two subclasses ( Fiction, Nonfiction). I have created array of Book references. That array can hold both subclasse's objects. I'have following code for Fiction class. public class Fiction extends Book{ public Fiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 24.99; } } And the "same" code for Nonfiction class public class Nonfiction extends Book{ public Nonfiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 37.99; } } And this is Main program. import javax.swing.JOptionPane; public class Main { public static void main(String[] args) { Book[] book = new Fiction[6]; for(int i = 0; i<book.length; i++) { if(i<4) { String title = JOptionPane.showInputDialog("Enter fiction book, no "+i); book[i] = new Fiction(title); } else { String title = JOptionPane.showInputDialog("Enter non fiction book, no "+i); book[i] = new Nonfiction(title); } } for(int x = 0; x<book.length; x++) { System.out.println("Book named "+book[x].getTitle()+" costs "+book[x].getPrice()); } } } For any reason i'm getting ArrayStoreException on this line.. book[i] = new Nonfiction(title); But same code works for Fiction class. I checked java documentation and it says that this exception is thrown when i'm trying to store different objects in array ( like String and Int ), but in this case they are all the same objects. Both classes are children of superclass, that means, they are of the same type. I'm confsued. A little help here please?

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  • find nearest match to array of doubles

    - by Scott
    Given the code below, how do I compare a List of objects's values with a test value? I'm building a geolocation application. I'll be passing in longitude and latitude and would like to have the service answer back with the location closest to those values. I started down the path of converting to a string, and formatting the values down to two decimal places, but that seemed a bit too ghetto, and I'm looking for a more elegant solution. public class Location : IEnumerable { public string label { get; set; } public double lat { get; set; } public double lon { get; set; } //Implement IEnumerable public IEnumerator GetEnumerator() { return (IEnumerator)this; } } [HandleError] public class HomeController : Controller { private List<Location> myList = new List<Location> { new Location { label="Atlanta Midtown", lon=33.657674, lat=-84.423130}, new Location { label="Atlanta Airport", lon=33.794151, lat=-84.387228}, new Location { label="Stamford, CT", lon=41.053758, lat=-73.530979}, ... } public static int Main(String[] args) { string inLat = "-80.987654"; double dblInLat = double.Parse(inLat); // here's where I would like to find the closest location to the inLat // once I figure out this, I'll implement the Longitude, and I'll be set }

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  • Get the parent class of a null object (C# Reflection)

    - by Nick
    How would I get the parent class of an object that has a value of null? For example... 'Class A' contains 'int? i' which is not set to any value when the class is created. Then in some other place in the code I want to pass in 'i' as a parameter to some function. Using 'i' as the only info, I want to be able to figure out that 'Class A' "owns" 'i'. The reason for this is because 'Class A' also contains some other object, and I want to call this other object's value from that same function mentioned in the above paragraph. Could also be: public class A { public class B { public int? i; public int? j; } B classBInstance = new B(); public string s; } { ... A someClassAInstance = new A(); ... doSomething(someClassAInstance.classBInstance.i); ... } public static bool doSomething(object theObject) { string s = /* SOMETHING on theObject to get to "s" from Class A */; int someValue = (int)theObject; }

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  • How to proxy calls to the instance of an object

    - by mr.b
    Edit: Changed question title from "Does C# allow method overloading, PHP style (__call)?" - figured out it doesn't have much to do with actual question. Also edited question text. What I want to accomplish is to proxy calls to a an instance of an object methods, so I could log calls to any of its methods. Right now, I have code similar to this: class ProxyClass { static logger; public AnotherClass inner { get; private set; } public ProxyClass() { inner = new AnotherClass(); } } class AnotherClass { public void A() {} public void B() {} public void C() {} // ... } // meanwhile, in happyCodeLandia... ProxyClass pc = new ProxyClass(); pc.inner.A(); // need to write log message like "method A called" pc.inner.B(); // need to write log message like "method B called" // ... So, how can I proxy calls to an object instance in extensible way? Method overloading would be most obvious solution (if it was supported in PHP way). By extensible, meaning that I don't have to modify ProxyClass whenever AnotherClass changes. In my case, AnotherClass can have any number of methods, so it wouldn't be appropriate to overload or wrap all methods to add logging. I am aware that this might not be the best approach for this kind of problem, so if anyone has idea what approach to use, shoot. Thanks!

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  • Iterating over a String to check for a number and printing out the String value if it doesn't have a number

    - by wheelerlc64
    I have set up my function for checking for a number in a String, and printing out that String if it has no numbers, and putting up an error message if it does. Here is my code: public class NumberFunction { public boolean containsNbr(String str) { boolean containsNbr = false; if(str != null && !str.isEmpty()) { for(char c : str.toCharArray()) { if(containsNbr = Character.isDigit(c)) { System.out.println("Can't contain numbers in the word."); break; } else { System.out.println(str); } } } return containsNbr; } } import com.imports.validationexample.function.NumberFunction; public class Main { public static void main(String[] args) { NumberFunction nf = new NumberFunction(); System.out.println(nf.containsNbr("bill4")); } } I am trying to get it to print out the result to the console, but the result keeps printing multiple times and prints the boolean value, which I do not want, something like this: bill4 bill4 bill4 bill4 Can't contain numbers in the word. true Why is this happening? I've tried casting but that hasn't worked out either. Any help would be much appreciated.

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  • Is it possible to limit outside connections to a subdomain with .htaccess or similar?

    - by digidave0205
    I host a web application. This application serves static html pages that are refreshed at various intervals. Some as often as every 30 secs. At this time I have about 300 unique pages that are accessed via 300 unique subdomains. Some clients have at most 50 visitors to their unique page and it refreshes every 30 secs, no problem. Other clients have up to 1000 or more visitors to their page. These clients are killing my server. There was no predefined limit upon signup but now I have to impose such a limit to remain afloat financially. I would like to define a finite number of connections allowed for each individual subdomain in my hosting account. Connections attempted out of range of this finite value would either be rejected or redirected. I have access to .htaccess and php.ini. Is something of this nature possible? Oh, I have a dedicated/managed server at 1and1.

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  • How to set only the first cell of a UITableView to a different color?

    - by Ted
    I use cellForRowAtIndexPath like here: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if(cell == nil) cell = [self getCellContentView:CellIdentifier]; UILabel *lbl = (UILabel*)[cell.contentView viewWithTag:1]; for (UITableViewCell *c in [tbl visibleCells]) { // UITableViewCell *cell2 = [tbl cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]]; UILabel *lbl = (UILabel*)[c.contentView viewWithTag:1]; lbl.textColor = [UIColor redColor]; } if([tbl indexPathForCell:cell].section==0) lbl.textColor = [UIColor whiteColor]; UILabel *lblTemp1 = (UILabel *)[cell viewWithTag:1]; UILabel *lblTemp2 = (UILabel *)[cell viewWithTag:2]; //First get the dictionary object lblTemp1.text = @"test!"; lblTemp2.text = @"testing more"; NSLog(@"%@",[tbl indexPathForCell:cell]); return cell; } But is still makes some of my cells white instead of gray. How can I change only the first item in the row to white?

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  • How to connect SQLite with Java?

    - by Rajapandian
    Hi, I am using one simple code to access the SQLite database from Java application . My code is import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; public class ConnectSQLite { public static void main(String[] args) { Connection connection = null; ResultSet resultSet = null; Statement statement = null; try { Class.forName("org.sqlite.JDBC"); connection = DriverManager.getConnection("jdbc:sqlite:D:\\testdb.db"); statement = connection.createStatement(); resultSet = statement .executeQuery("SELECT EMPNAME FROM EMPLOYEEDETAILS"); while (resultSet.next()) { System.out.println("EMPLOYEE NAME:" + resultSet.getString("EMPNAME")); } } catch (Exception e) { e.printStackTrace(); } finally { try { resultSet.close(); statement.close(); connection.close(); } catch (Exception e) { e.printStackTrace(); } } } } But this code gives one exception like java.lang.ClassNotFoundException: org.sqlite.JDBC Any body knows how to slove it,please help me.

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  • Please help with my twodimensional array source code

    - by Baiba
    Here is what i have done but i have some questions: class masivins { public static void main (String args[]) { int mas[][] = {{0, 2, 7, 0, 8, 5, 3}, {0, 4, 0, 6, 0, 0, 0}, {0, 0, 0, 0, 3, 0, 0}, {7, 0, 0, 9, 1, 0, 7}, {5, 0, 4, 0, 0, 2, 0}}; int nulmas[] = new int [7]; int nul=0; for(int j=0; j<7; j++) { nul=0; for(int i=0; i<5; i++) { if(mas[i][j]==0) { nul++; } } nulmas[j]=nul; } for(int i=0; i<5; i++) { for(int j=0; j<7; j++) { System.out.println(mas[i][j]); } System.out.println(); } System.out.println(); for(int i=0; i<5; i++) { System.out.println("Zeros in each array column: " + nulmas[i]); } System.out.println(); } } so my questions are: 1) why after running project there are only 5 "Zeros in each array column....." shown? 2) what and where i need to change in this code to get out the number of column in which zeros are least?

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  • Passing mix of T and T[] to a Java varargs method

    - by rfalke
    Suppose you have a Java method void foobar(int id, String ... args) and want to pass both String arrays and Strings into the method. Like this String arr1[]={"adas", "adasda"}; String arr2[]={"adas", "adasda"}; foobar(0, "adsa", "asdas"); foobar(1, arr1); foobar(2, arr1, arr2); foobar(3, arr1, "asdas", arr2); In Python there is "*" for this. Is there some way better than such rather ugly helper method: static String[] concat(Object... args) { List<String> result = new ArrayList<String>(); for (Object arg : args) { if (arg instanceof String) { String s = (String) arg; result.add(s); } else if (arg.getClass().isArray() && arg.getClass().getComponentType().equals(String.class)) { String arr[] = (String[]) arg; for (String s : arr) { result.add(s); } } else { throw new RuntimeException(); } } return result.toArray(new String[result.size()]); } which allows foobar(4, concat(arr1, "asdas", arr2));

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  • Looping through a method without for/foreach/while

    - by RichK
    Is there a way of calling a method/lines of code multiple times not using a for/foreach/while loop? For example, if I were to use to for loop: int numberOfIterations = 6; for(int i = 0; i < numberOfIterations; i++) { DoSomething(); SomeProperty = true; } The lines of code I'm calling don't use 'i' and in my opinion the whole loop declaration hides what I'm trying to do. This is the same for a foreach. I was wondering if there's a looping statement I can use that looks something like: do(6) { DoSomething(); SomeProperty = true; } It's really clear that I just want to execute that code 6 times and there's no noise involving index instantiating and adding 1 to some arbitrary variable. As a learning exercise I have written a static class and method: Do.Multiple(int iterations, Action action) Which works but scores very highly on the pretentious scale and I'm sure my peers wouldn't approve. I'm probably just being picky and a for loop is certainly the most recognisable, but as a learning point I was just wondering if there (cleaner) alternatives. Thanks. (I've had a look at this thread, but it's not quite the same) http://stackoverflow.com/questions/2248985/using-ienumerable-without-foreach-loop

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  • OnClickListener on Tabs not working

    - by Aracos
    Greetings, I am trying to get the Click - event when clicking on the currently selected tab of my TabActivity. The onTabChangedHandler is only called whenever the tab is changed, not if the currently active Tab is clicked. The debugger tells me i have the onClickListener Registered for the TabWidget within my TabHost. Am i registering for the wrong View? Also, I am unable to create a Context Menu for the Tabs, only for its content, is this problem related? public class TestDroidViewTab extends TabActivity implements TabContentFactory , OnTabChangeListener, OnClickListener { private static final String LOG_KEY = "TEST"; ListView listView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); final TabHost tabHost = getTabHost(); TabHost.TabSpec ts = tabHost.newTabSpec("ID_1"); ts.setIndicator("1"); ts.setContent(this); tabHost.addTab(ts); ts = tabHost.newTabSpec("ID_2"); ts.setIndicator("2"); ts.setContent(this); tabHost.addTab(ts); ts = tabHost.newTabSpec("ID_3"); ts.setIndicator("3"); ts.setContent(this); tabHost.addTab(ts); tabHost.setOnClickListener(this); tabHost.setOnTabChangedListener(this); } public void onClick(View v) { Log.d(LOG_KEY, "OnClick"); } public void onTabChanged(String tabId) { Log.d(LOG_KEY, "OnTabChanged"); }

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  • Python: Sorting array with custom pattern

    - by Binka
    In my little project here I have sorted a list in decending order, however, my goal is to sort it in this custom pattern. (largest - smallest - next largest - next smallest -)etc. In java I was able to do this like this... My goal is to do the same thing but in python, except backwards. Any ideas on how to convert that last for loop that does the wackysort into python and make it go backwards? public static void wackySort(int[] nums){ //first, this simply sorts the array by ascending order. int sign = 0; int temp = 0; int temp2 = 0; for (int i = 0; i < nums.length; i++){ for (int j = 0; j < nums.length -1; j++){ if (nums[j] > nums[j+1]){ temp = nums[j]; nums[j] = nums[j+1]; nums[j+1] = temp; } } } //prepare for new array to actually do the wacky sort. System.out.println(); int firstPointer = 0; int secondPointer = nums.length -1; int[] newarray = new int[nums.length]; int size = nums.length; //for loop that increments by two taking second slot replacing the last (n-1) term for (int i = 0; i < nums.length -1; i+=2){ newarray[i] = nums[firstPointer++]; newarray[i+1] = nums[secondPointer--]; } //storing those values back in the nums array for (int i = 0; i < nums.length; i++){ nums[i] = newarray[i]; } }

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  • Memory usage of strings (or any other objects) in .Net

    - by ava
    I wrote this little test program: using System; namespace GCMemTest { class Program { static void Main(string[] args) { System.GC.Collect(); System.Diagnostics.Process pmCurrentProcess = System.Diagnostics.Process.GetCurrentProcess(); long startBytes = pmCurrentProcess.PrivateMemorySize64; double kbStart = (double)(startBytes) / 1024.0; System.Console.WriteLine("Currently using " + kbStart + "KB."); { int size = 2000000; string[] strings = new string[size]; for(int i = 0; i < size; i++) { strings[i] = "blabla" + i; } } System.GC.Collect(); pmCurrentProcess = System.Diagnostics.Process.GetCurrentProcess(); long endBytes = pmCurrentProcess.PrivateMemorySize64; double kbEnd = (double)(endBytes) / 1024.0; System.Console.WriteLine("Currently using " + kbEnd + "KB."); System.Console.WriteLine("Leaked " + (kbEnd - kbStart) + "KB."); System.Console.ReadKey(); } } } The output in Release build is: Currently using 18800KB. Currently using 118664KB. Leaked 99864KB. I assume that the GC.collect call will remove the allocated strings since they go out of scope, but it appears it does not. I do not understand nor can I find an explanation for it. Maybe anyone here? Thanks, Alex

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  • Bizzare Java invalid Assignment Operator Error

    - by Kay
    public class MaxHeap<T extends Comparable<T>> implements Heap<T>{ private T[] heap; private int lastIndex; private static final int defaultInitialCapacity = 25; public void add(T newItem) throws HeapException{ if (lastIndex < Max_Heap){ heap[lastIndex] = newItem; int place = lastIndex; int parent = (place – 1)/2; //ERROR HERE********** while ( (parent >=0) && (heap[place].compareTo(heap[parent])>0)){ T temp = heap[place]; heap[place] = heap[parent]; heap[parent] = temp; place = parent; parent = (place-1)/2; }else { throw new HeapException(“HeapException: Heap full”); } } } Eclipse complains that there is a: "Syntax error on token "Invalid Character", invalid AssignmentOperator" With the red line beneath the '(place-1)' There shouldn't be an error at all since it's just straight-forward arithmetic. Or is it not that simple?

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  • Confusion with a while statement evaluating if a number is triangular

    - by Darkkurama
    I've been having troubles trying to figure out how to solve a function. I've been assigned the development of a little programme which tells if a number is "triangular" (a number is triangular when the addition of certain consecutive numbers in the [1,n] interval is n. Following the definition, the number 10 is triangular, because in the [1,10] interval, 1+2+3+4=10). I've coded this so far: class TriangularNumber{ boolean numTriangular(int n) { boolean triangular = false; int i = n; while(n>=0 && triangular){ //UE06 is a class which contains the function "f0", which makes the addition of all the numbers in a determined interval UE06 p = new UE06(); if ((p.f0(1, i))==n) triangular = true; else i=i-1; } return triangular; } boolean testTriangular = numTriangular(10) == true && numTriangular(7) == false && numTriangular(6) == true; public static void main(String[] args){ TriangularNumber p = new TriangularNumber(); System.out.println("testTriangular = " + p.testTriangular); } } According to those boolean tests I made, the function is wrong. As I see the function, it goes like this: I state that the input number in the initial state isn't triangular (triangular=false) and i=n (determining the interval [1,i] where the function is going to be evaluated While n is greater or equals 0 and the number isn't triangular, the loop starts The loop goes like this: if the addition of all the numbers in the [1,i] interval is n, the number is triangular, causing the loop to end. If that statement is false, i goes from i to (i-1), starting the loop again with that particular interval, and so on till the addition is n. I can't spot the error in my "algorithm", any advice? Thanks!

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  • how to read string part in java

    - by Gandalf StormCrow
    Hello everyone, I have this string : <meis xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" uri="localhost/naro-nei" onded="flpSW531213" identi="lemenia" id="75" lastStop="bendi" xsi:noNamespaceSchemaLocation="http://localhost/xsd/postat.xsd xsd/postat.xsd"> How can I get lastStop property value in JAVA? This regex worked when tested on http://www.myregexp.com/ But when I try it in java I don't see the matched text, here is how I tried : import java.util.regex.Pattern; import java.util.regex.Matcher; public class SimpleRegexTest { public static void main(String[] args) { String sampleText = <meis xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" uri=\"localhost/naro-nei\" onded=\"flpSW531213\" identi=\"lemenia\" id=\"75\" lastStop=\"bendi\" xsi:noNamespaceSchemaLocation=\"http://localhost/xsd/postat.xsd xsd/postat.xsd\">"; String sampleRegex = "(?<=lastStop=[\"']?)[^\"']*"; Pattern p = Pattern.compile(sampleRegex); Matcher m = p.matcher(sampleText); if (m.find()) { String matchedText = m.group(); System.out.println("matched [" + matchedText + "]"); } else { System.out.println("didn’t match"); } } }

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  • Drawing line graphics leads Flash to spiral out of control!

    - by drpepper
    Hi, I'm having problems with some AS3 code that simply draws on a Sprite's Graphics object. The drawing happens as part of a larger procedure called on every ENTER_FRAME event of the stage. Flash neither crashes nor returns an error. Instead, it starts running at 100% CPU and grabs all the memory that it can, until I kill the process manually or my computer buckles under the pressure when it gets up to around 2-3 GB. This will happen at a random time, and without any noticiple slowdown beforehand. WTF? Has anyone seen anything like this? PS: I used to do the drawing within a MOUSE_MOVE event handler, which brought this problem on even faster. PPS: I'm developing on Linux, but reproduced the same problem on Windows. UPDATE: You asked for some code, so here we are. The drawing function looks like this: public static function drawDashedLine(i_graphics : Graphics, i_from : Point, i_to : Point, i_on : Number, i_off : Number) : void { const vecLength : Number = Point.distance(i_from, i_to); i_graphics.moveTo(i_from.x, i_from.y); var dist : Number = 0; var lineIsOn : Boolean = true; while(dist < vecLength) { dist = Math.min(vecLength, dist + (lineIsOn ? i_on : i_off)); const p : Point = Point.interpolate(i_from, i_to, 1 - dist / vecLength); if(lineIsOn) i_graphics.lineTo(p.x, p.y); else i_graphics.moveTo(p.x, p.y); lineIsOn = !lineIsOn; } } and is called like this (m_graphicsLayer is a Sprite): m_graphicsLayer.graphics.clear(); if (m_destinationPoint) { m_graphicsLayer.graphics.lineStyle(2, m_fixedAim ? 0xff0000 : 0x333333, 1); drawDashedLine(m_graphicsLayer.graphics, m_initialPos, m_destinationPoint, 10, 10); }

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  • How can I split abstract testcases in JUnit?

    - by Willi Schönborn
    I have an abstract testcase "AbstractATest" for an interface "A". It has several test methods (@Test) and one abstract method: protected abstract A unit(); which provides the unit under testing. No i have multiple implementations of "A", e.g. "DefaultA", "ConcurrentA", etc. My problem: The testcase is huge (~1500 loc) and it's growing. So i wanted to split it into multiple testcases. How can organize/structure this in Junit 4 without the need to have a concrete testcase for every implementation and abstract testcase. I want e.g. "AInitializeTest", "AExectueTest" and "AStopTest". Each being abstract and containing multiple tests. But for my concrete "ConcurrentA", i only want to have one concrete testcase "ConcurrentATest". I hope my "problem" is clear. EDIT Looks like my description was not that clear. Is it possible to pass a reference to a test? I know parameterized tests, but these require static methods, which is not applicable to my setup. Subclasses of an abstract testcase decide about the parameter.

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  • Setting Cursor property has no effect (C#)

    - by Knarf Navillus
    Hello, I have a class that I've derived from System.Windows.Forms.Panel, and my application has a main form with one of these panels. On the whole, the panel works great! The only thing I'm having trouble with is setting the cursor. Whether I'm setting it to one of the static members of the Cursors class (Default, WaitCursor, etc.) or setting it to a custom cursor that I've loaded from a resource, the end result is the same: it does nothing. I still see the default mouse pointer, no matter what. This line of code is inside a method of my panel-derived class: this.Cursor = Cursors.WaitCursor; I can set a break point there, and see that this line is being hit when I expect it to. I've also created an override for the OnCursorChanged method, and set a breakpoint in there just to see if it's being triggered. I can verify that both breakpoints are being hit when I expect them to. However, the cursor just never changes. There must be something that I'm missing. Does anyone have any ideas? P.S. I also did try setting Current.Cursor as well, however that did not help.

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  • Windows: Does something temporarily grab the com ports on startup?

    - by Tim
    I have a WPF/C# app that is launched as part of the "Startup" group on a Windows Embedded Standard machine. One of the first things the app does (in its static App() method) is create a new SerialPort object for COM1. COM1 is a hardwired serial port, not a USB virtual port or anything like that. My problem is that every so often (maybe 1 out of 12) on startup, I get an exception: System.UnauthorizedAccessException: Access to the port 'COM1' is denied. There are no other applications using this port. Also, when I relaunch the app following this error, it grabs the port just fine. It's as if the com port isn't ready/set up for my app sometimes. I'm clueless on this one! Any insight is appreciated! UPDATE: I added a call to SerialPort.GetPortNames() and printout all available ports before attempting to open the port. In the failure case COM1 is indeed THERE! So, it's not that the port isn't ready. It looks like something in Windows is actually grabbing the port temporarily and blocking me.

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  • Implementing a Version check between an Abstract class and it's implementation

    - by Michael Stum
    I have this abstract class and concrete implementation (they are in different assemblies): public abstract class MyAbstractClass { private static readonly int MyAbstractClassVersion = 1; public abstract int ImplementedVersion { get; } protected MyAbstractClass() { CheckVersion(); } private void CheckVersion() { var message = string.Format( "MyAbstractClass implements Version {0}, concrete is Version {1}", RepositoryVersion, ImplementedVersion); if (!MyAbstractClassVersion.Equals(ImplementedVersion)) throw new InvalidOperationException(message); } } public class ConcreteClass : MyAbstractClass { public ConcreteClass() : base() { // ConcreteClass is guaranteed to have // a constructor that calls the base constructor // I just simplified the example } public override int ImplementedVersion { get { return 2; } } } As you see, I call CheckVersion() from the abstract constructor, to get rid of the "virtual member call in base constructor" message, but I am not sure if that's really the way to do it. Sure, it works, but that doesn't mean it will always work, will it? Also, I wonder if I can get the name of the Concrete Type from the CheckVersion() function? I know that adding new abstract members will force an error anyway (System.TypeLoadException) and I'm not sure if I want this type of strict Versioning, but I'm just curious how it would be done properly given only the abstract class and an implementation (I know I could do it by using interfaces and/or a Factory pattern).

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  • Function returning pointer to struct

    - by GammaGuy
    I am having some issues with code that is returning a pointer to a struct declared inside a class. Here is my code so far: SortedList.h #ifndef SORTEDLIST_H #define SORTEDLIST_H class SortedList{ public: SortedList(); ... private: struct Listnode { Student *student; Listnode *next; }; static Listnode *copyList (Listnode *L); }; #endif SortedList.cpp #include "SortedList.h" ... // Here is where the problem lies Listnode SortedList::*copyList(Listnode *L) { return 0; // for NULL } Apparently, the copy list method wont compile. I am using Microsoft Visual Studio and the compiler tells me that "Listnode" is unidentified. When I try to compile, here is whhat I get: 1>------ Build started: Project: Program3, Configuration: Debug Win32 ------ 1> SortedList.cpp 1>c:\users\owner\documents\college\fall 2012\cs 368 - learn c++\program3\program3\sortedlist.cpp(159): error C2657: 'SortedList::*' found at the start of a statement (did you forget to specify a type?) 1>c:\users\owner\documents\college\fall 2012\cs 368 - learn c++\program3\program3\sortedlist.cpp(159): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\users\owner\documents\college\fall 2012\cs 368 - learn c++\program3\program3\sortedlist.cpp(159): error C2065: 'L' : undeclared identifier 1>c:\users\owner\documents\college\fall 2012\cs 368 - learn c++\program3\program3\sortedlist.cpp(159): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 1>c:\users\owner\documents\college\fall 2012\cs 368 - learn c++\program3\program3\sortedlist.cpp(159): fatal error C1903: unable to recover from previous error(s); stopping compilation ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Help would be greatly appreciated...ASAP

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  • WPF: issue updating UI from background thread

    - by Ted Shaffer
    My code launches a background thread. The background thread makes changes and wants the UI in the main thread to update. The code that launches the thread then waits looks something like: Thread fThread = new Thread(new ThreadStart(PerformSync)); fThread.IsBackground = true; fThread.Start(); fThread.Join(); MessageBox.Show("Synchronization complete"); When the background wants to update the UI, it sets a StatusMessage and calls the code below: static StatusMessage _statusMessage; public delegate void AddStatusDelegate(); private void AddStatus() { AddStatusDelegate methodForUIThread = delegate { _statusMessageList.Add(_statusMessage); }; this.Dispatcher.BeginInvoke(methodForUIThread, System.Windows.Threading.DispatcherPriority.Send); } _statusMessageList is an ObservableCollection that is the source for a ListBox. The AddStatus method is called but the code on the main thread never executes - that is, _statusMessage is not added to _statusMessageList while the thread is executing. However, once it is complete (fThread.Join() returns), all the stacked up calls on the main thread are executed. But, if I display a message box between the calls to fThread.Start() and fThread.Join(), then the status messages are updated properly. What do I need to change so that the code in the main thread executes (UI updates) while waiting for the thread to terminate? Thanks.

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  • c# Wrapper to native c++ code, wrapping a parameter which is a pointer to an array

    - by mb300dturbo
    Hi, I have the following simple DLL in c++ un-managed code; extern "C" __declspec(dllexport) void ArrayMultiplier(float (*pointerArray)[3], int scalar, int length); void ArrayMultiplier(float (*pointerArray)[3], int scalar, int length) { for (int i = 0 ; i < length ; length++) { for (int j = 0; j < 3; j++) { pointerArray[i][j] = pointerArray[i][j] * scalar; } } } I have tried writing the following wrapper function for the above in c#: [DllImport("sample.dll")] public static extern void ArrayMultiplier(ref float elements, int scalar, int length); where elements is a 2 dimentional 3x3 array: public float[][] elements = { new float[] {2,5,3}, new float [] {4,8,6}, new float [] {5,28,3} }; The code given above compiles, but the program crashes when the wrapper function is called: Wrapper.ArrayMultiplier(ref elements, scalar, length); Please help me here, and tell me whats wrong with the code above, or how a wrapper can be written for a simple c++ function: void SimpleFunction(float (*pointerToArray)[3]); Thank you all in advance

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