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  • Progress Dialog on open activity

    - by GeeXor
    hey guys, i've a problem with progress dialog on opening an activity (called activity 2 in example). The activity 2 has a lot of code to execute in this OnCreate event. final ProgressDialog myProgressDialog = ProgressDialog.show(MyApp.this,getString(R.string.lstAppWait), getString(R.string.lstAppLoading), true); new Thread() { public void run() { runOnUiThread(new Runnable() { @Override public void run() { showApps(); } }); myProgressDialog.dismiss(); } }.start(); The showApps function launch activity 2. if i execute this code on my button click event on activity 1, i see the progress, but she doesn't move and afeter i have a black screen during 2 or 3 seconds the time for android to show the activity. If i execute this code in the OnCreate of Activity2 and if i replace the showApps by the code on OnCreate, Activity1 freeze 2 seconds, i don't see the progress dialog, and freeze again 2 seconds on activity 2 before seeing the result. An idea ?

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  • as3 this.graphics calls do nothing

    - by zzz
    class A: [SWF(width='800',height='600',frameRate='24')] public class A extends MovieClip { private var b:B; public function A(){ super(); b = new B(); addChild(b); addEventListener(Event.ENTER_FRAME, update); } private function update(e:Event):void { b.draw(); } } class B: public class B extends MovieClip { public function draw():void { //! following code works well if put in constructor, but not here this.graphics.beginFill(0xff0000); this.graphics.drawCircle(200,200,50); } } this.graphics calls do nothing in draw method, but work fine inside B`s constructor, what i am doing wrong ?

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  • base pointer to derived class

    - by Jay
    Suppose there are Base class and Derived class. Base *A = new Base; Here A is a pointer point to Base class, and new constructs one that A points to. I also saw Base *B = new Derived; How to explain this? B is a pointer to Base Class, and a Derived class constructed and pointed by B? If there is a function derived from Base class, say, Virtual void f(), and it's been overridden in Derived class, then B->f() will invoke which version of the function? version in Base class, or version that overridden in Derived Class. What if there is a new function void g()in Derived, is B->g() going to invoke this function properly? One more is, is int *a = new double; or int *a = new int; legal?

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  • Struct like objects in Java

    - by cdv
    Is it completely against the Java way to create struct like objects? class SomeData1 { public int x; public int y; } I can see a class with accessors and mutators being more Java like. class SomeData2 { int getX(); void setX(int x); int getY(); void setY(int y); private int x; private int y; } The class from the first example is notationally convenient. // a function in a class public int f(SomeData1 d) { return (3 * d.x) / d.y; } This is not as convenient. // a function in a class public int f(SomeData2 d) { return (3 * d.getX()) / d.getY(); }

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  • Visual C++ CreateThread Parameter Problem

    - by Vanwaril
    I have a class that contains a function that calls create thread, and needs to pass itself (this) as a parameter: DWORD threadId; HANDLE h = CreateThread( NULL, 0, runThread, this, 0, &threadId); My runThread definition is as follows: DWORD WINAPI runThread(LPVOID args) { Obj *t = (Obj*)args; t->funct(); return 0; } Unfortunately, the object t that I get in runThread() gets garbage. My Obj class has a function pointer attribute. Could that be the problem? class Obj{ void(*funct)(); and in the constructor: Obj(void(*f)()) { funct = f; } where is my mistake? The function pointer, the createThread itself, or type-casting? I tried whatever I could think of.

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  • please help me to solve problem

    - by davit-datuashvili
    i have operation on heap fixdown operation below is code public class HEap{ public static void fixdown(int a[],int k,int n){ while(2*k<=n){ int j=2*k; if (j<n && a[j]<a[j+1]) j++; if (!(a[k]<a[j])) break; int t=a[k]; a[k]=a[j]; a[j]=k; k=j; } } public static void main(String[]args){ int a[]=new int[]{12,15,20,29,23,22,17,40,26,35,19,51}; fixdown(a,1,a.length); for (int i=0;i<a.length;i++){ System.out.println(a[i]); } } } //and result is 12 29 20 40 23 22 17 3 26 35 19 51 i am interested why is 3 in the list?in the array is not

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  • Is read-only auto-imlemented property possible?

    - by abatishchev
    Hello. I found a topic on MSDN that talks that yes, this is possible. I did a test that seems to break this statement: using System; namespace Test { class Program { static void Main(string[] args) { Foo f = new Foo("1"); Console.WriteLine(f.Bar); // prints 1 f.Test("2"); Console.WriteLine(f.Bar);// successfully prints 2 } } class Foo { public Foo(string b) { this.Bar = b; } public string Bar { get; private set; } public void Test(string b) { // this would be impossible for readonly field! // next error would be occur: CS0191 or CS0191 // A readonly field cannot be assigned to (except in a constructor or a variable initializer) this.Bar = b; } } } Where am I wrong?

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  • Operation Problems in Java Generic

    - by alantheweasel
    I got some problem when i was learning Java Generic : interface calculator<T, R> { public void execute(T t, R r); } class executeAdd<T, R> implements calculator<T, R> { private T first; private R second; public executeAdd(T first, R second) { super(); this.first = first; this.second = second; } @Override public void execute(T t, R r) { // TODO Auto-generated method stub Object o = t + r // ERROR ! What i could do it ? } }

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  • pass by const reference of class

    - by small_potato
    void foo(const ClassName &name) { ... } How can I access the method of class instance name? name.method() didn't work. then I tried: void foo(const ClassName &name) { ClassName temp = name; ... .... } I can use temp.method, but after foo was executed, the original name screwed up, any idea? BTW, the member variable of name didn't screwed up, but it was the member variable of subclass of class screwed up.

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  • What are these c++ statements doing

    - by codingguy3000
    void useproxynum ( ) { bUseProxy = true; return; }; void useacctnum ( ) { bUseProxy = false; return; }; Can anyone give me some insight into what these c++ statements are doing? There are in a header file. bUseProxy is defined above bool bUseProxy; I'm trying to figure out what useproxynum is (method call?) and I'm also trying to figure out how to find the code behind it. This is in Visual Studio 6.

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  • Grid View selected index

    - by user2924573
    I have a grid which contains a edit button . When i click the edit button and debug it does not hit to the selected index change event . There are no build errors code behind the grid public void btnModemDetailsEdit_Click(object sender, EventArgs e) { isEdit = true; } protected void gridModemDetails_SelectedIndexChanged(object sender, EventArgs e) { int id = Convert.ToInt32(GridModemDetails.DataKeys[GridModemDetails.SelectedIndex].Values["gridModemDetails_SelectedIndexChanged"].ToString()); } <asp:GridView ID="GridModemDetails" runat="server" Width="435px" DataKeyNames="ModemId" AllowPaging="True" OnSelectedIndexChanged="gridModemDetails_SelectedIndexChanged" AutoGenerateColumns="False"> <Columns> <asp:TemplateField HeaderText="Edit" Visible="True" > <ItemTemplate> <asp:LinkButton ID="btnModemDetailsEdit" AccessibleHeaderText="Edit" ButtonType="Button" Text="Edit" HeaderText="Edit" runat="server" OnClick="btnModemDetailsEdit_Click" runat="server"/> </ItemTemplate> </asp:TemplateField>

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  • accessing ok.DialogResult inside a function

    - by sayyad
    I am writing function which accepts user input from textbox. Action will take place when ok button is clicked. i made button(DialogResult=OK). code looks like private void canny() { // if (this.DialogResult == DialogResult.OK) { MessageBox.Show("ok"); } //to Do } But I can't see any messagebox. What I am missing. private void ok_Click(object sender, EventArgs e) { // should I add here some thing } Should I add control Form1.Control.Add(Ok)?????????????????? if yes in which part of code. regards,

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  • How can I loop through all the open instances of a particular form?

    - by raz3r
    I need to update a ListBox of a Form2 created dinamically. Let's say that in the event where I have to update this ListBox (in Form1 of course) I don't have a reference of this Form2 so I can't call the UpdateList method (and no, I can't make it static). I don't even know if there is a Form2 opened, it could be or not. What do you suggest? Is there a way to loop through all the open istances of Form2? Code Sample: //Form1 public void event() { //UPDATE FORM2 LISTBOX } //SOMEWHERE IN FORM1 Form2 runTime = new Form2(); //Form2 public void UpdateList() { //UPDATE LISTBOX }

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  • Passing a generic class to a java function?

    - by rodo
    Is it possible to use Generics when passing a class to a java function? I was hoping to do something like this: public static class DoStuff { public <T extends Class<List>> void doStuffToList(T className) { System.out.println(className); } public void test() { doStuffToList(List.class); // compiles doStuffToList(ArrayList.class); // compiler error (undesired behaviour) doStuffToList(Integer.class); // compiler error (desired behaviour) } } Ideally the List.class and ArrayList.class lines would work fine, but the Integer.class line would cause a compile error. I could use Class as my type instead of T extends Class<List> but then I won't catch the Integer.class case above.

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  • Need help with map (c++, STL)

    - by Mike Dooley
    Hi folks! Actually I'm new to C++. I tried something out (actually the map container) but it doesn't work the way I assumed it will... Before posting my code, I will explain it shortly. I created 3 classes: ClassA ClassDerivedA ClassAnotherDerivedA The two last ones are derived from "ClassA". Further I created a map: map<string,ClassA> test_map; I put some objects (from Type ClassDerivedA and ClassAnotherDerivedA) into the map. Keep in mind: the mapped value is from type "ClassA". This will only work because of Polymorphism. Finally I created an iterator which runs over my map and compares the user input with my keys in the map. If they match, it will call a specific method called "printOutput". And there is the Problem: Although i declared "printOutput" as "virtual" the only method called is the one from my base class, but why? and here is the code: #include <iostream> #include <map> using namespace std; class ClassA { public: virtual void printOutput() { cout << "ClassA" << endl; } }; class ClassDerivedA : public ClassA { public: void printOutput() { cout << "ClassDerivedA" << endl; } }; class ClassAnotherDerivedA: public ClassA { public: void printOutput() { cout << "ClassAnotherDerivedA" << endl; } }; int main() { ClassDerivedA class_derived_a; ClassAnotherDerivedA class_another_a; map<string,ClassA> test_map; test_map.insert(pair<string,ClassA>("deriveda", class_derived_a)); test_map.insert(pair<string,ClassA>("anothera", class_another_a)); string s; while( cin >> s ) { if( s != "quit" ) { map<string,ClassA>::iterator it = test_map.find(s); if(it != test_map.end()) it->second.printOutput(); } else break; } } Blockquote

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  • Load HTML NSString into a UIWebView

    - by ehenrik
    Im doing a project where I connect to a webpage using the NSURLConnection to be able to monitor the status codes that are returned (200 OK / 404 ERROR). I would like to send the user to the top url www.domain.com if I recieve 404 as status code and if i recieve as 200 status code I would like to load the page in to a webview. I have seen several implementations of this problem by creating a new request but I feel that it is unnecessary since you already received the html in the first request so i would just like to load that HTML in to the webView. So i try to use the [webView loadHTMLFromString: baseURL:] but it doesn't always work, I have noticed that when i print the NSString with html in the connectionDidFinnishLoading it sometimes is null and when I monitor these cases by printing the html in didReceiveData a random number of the last packets is NULL (differs between 2-10). It is always the same webpages that doesn't get loaded. If I load them to my webView using [webView loadRequest:myRequest] it always works. My implementation looks like this perhaps someone of you can see what Im doing wrong. I create my first request with a button click. -(IBAction)buttonClick:(id)sender { NSURL *url = [NSURL URLWithString:@"http://www.domain.com/page2/apa.html"]; NSURLRequest *theRequest = [NSURLRequest requestWithURL:url] NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; if( theConnection ) { webData = [[NSMutableData data] retain]; } else { } } Then I monitor the response code in the didReceiveResponse method by casting the request to a NSHTTPURLResponse to be able to access the status codes and then setting a Bool depending on the status code. -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { NSHTTPURLResponse *ne = (NSHTTPURLResponse *)response; if ([ne statusCode] == 200){ ok = TRUE; } [webData setLength: 0]; } I then check the bools value in connectionDidFinnishLoading. If I log the html NSString I get the source of the webpage so i know that it isn't an empty string. -(void)connectionDidFinishLoading:(NSURLConnection *)connection { NSString *html = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]; NSURL *url = [NSURL URLWithString:@"http://www.domain.com/"]; if (ok){ [webView loadHTMLString:html baseURL:url]; ok = FALSE; } else{ //Create a new request to www.domain.com } } webData is an instance variable and I load it in didReceiveData like this. -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [webData appendData:data]; }

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  • C# background worker while loop

    - by Mike
    What i'm trying to create is a background worker that executes a few processes every 30seconds. But I want this while loop to execute for as long as the program is launched. here is what I am using: private void watcherprocess1() { backgroundWorker1.RunWorkerAsync(); } private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) { while( Thread.Sleep(30000); specficView2(); makeFormlist2(); populateListview2(); } My main issue is ai can think of a good while loop to keep this running

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  • C++ array of classes

    - by nickik
    I working on a game but I have a problem with the initialization of the level. (feld is just field in german) class level{ private: feld spielfeld[10][10]; public: /* other staff */ void init_feld(); }; void level::init_feld() { for(int i=0;i!=10;i++){ for(int n=0;n!=10;n++){ spielfeld[i][n] = new feld(land, i, n); } } } The Error: Error: no match for »operator=« in »((level*)this)-level::spielfeld[i][n] = (operator new(24u), (, ((feld*))))« /home/nick/stratego/feld.h:18:11: Remark: candidate is: feld& feld::operator=(const feld&) Process terminated with status 1 (0 minutes, 0 seconds) 2 errors, 0 warnings

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  • Best way to handle storing (possibly NULL) char * in a std::string

    - by John
    class MyClass { public: void setVar(const char *str); private: std::string mStr; int maxLength; //we only store string up to this length }; What's the best approach to implement setVar when the external code is quite likely to pass in NULL for an empty string (and cannot be changed)? I currently do something a bit like: void MyClass::setVar(const char *str) { mStr.assign(str ? str : "",maxLength); } But it seems kind of messy. ideas?

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  • Java application return codes

    - by doele
    I have a Java program that processes one file at a time. This Java program is called from a wrapper script which logs the return code from the Java program. There are 2 types of errors. Expected errors and unexpected errors. In both cases I just need to log them. My wrapper knows about 3 different states. 0-OK, 1-PROCESSING_FAILED, 2- ERROR. Is this a valid approach? Here is my approach: enum ReturnCodes {OK,PROCESSING_FAILED,ERROR}; public static void main(String[] args) { ... proc.processMyFile(); ... System.exit(ReturnCodes.OK.ordinal()); } catch (Throwable t) { ... System.exit(ReturnCodes.ERROR.ordinal()); } private void processMyFile() { try { ... }catch( ExpectedException e) { ... System.exit(ReturnCodes.PROCESSING_FAILED.ordinal()); } }

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  • question about random select

    - by davit-datuashvili
    here is code print number in decreasing order import java.util.*; public class select { public static void Select(int m,int n){ Random r=new Random(); if (m>0) if (r.nextInt(0x3fff8001) % n <m ){ System.out.println(n-1); Select(m-1,n-1); } else{ Select(m,n-1); } } public static void main(String[]args){ int m=35; int n=200; Select(m,n); } } and question is how to changes code such that print number in increasing order? please help

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  • Inheritance issue

    - by VenkateshGudipati
    hi Friends i am facing a issue in Inheritance i have a interface called Irewhizz interface irewhzz { void object save(object obj); void object getdata(object obj); } i write definition in different class like public user:irewhzz { public object save(object obj); { ....... } public object getdata(object obj); { ....... } } this is antoher class public client:irewhzz { public object save(object obj); { ....... } public object getdata(object obj); { ....... } } now i have different classes like public partial class RwUser { #region variables IRewhizzDataHelper irewhizz; IRewhizzRelationDataHelper irewhizzrelation; private string _firstName; private string _lastName; private string _middleName; private string _email; private string _website; private int _addressId; private string _city; private string _zipcode; private string _phone; private string _fax; //private string _location; private string _aboutMe; private string _username; private string _password; private string _securityQuestion; private string _securityQAnswer; private Guid _user_Id; private long _rwuserid; private byte[] _image; private bool _changepassword; private string _mobilephone; private int _role; #endregion //IRewhizz is the interface and its functions are implimented by UserDataHelper class //RwUser Class is inheriting the UserDataHelper Properties and functions. //Here UserDataHelper functions are called with Irewhizz Interface Object but not with the //UserDataHelper class Object It will resolves the unit testing conflict. #region Constructors public RwUser() : this(new UserDataHelper(), new RewhizzRelationalDataHelper()) { } public RwUser(IRewhizzDataHelper repositary, IRewhizzRelationDataHelper relationrepositary) { irewhizz = repositary; irewhizzrelation = relationrepositary; } #endregion #region Properties public int Role { get { return _role; } set { _role = value; } } public string MobilePhone { get { return _mobilephone; } set { _mobilephone = value; } } public bool ChangePassword { get { return _changepassword; } set { _changepassword = value; } } public byte[] Image { get { return _image; } set { _image = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string MiddleName { get { return _middleName; } set { _middleName = value; } } public string Email { get { return _email; } set { _email = value; } } public string Website { get { return _website; } set { _website = value; } } public int AddressId { get { return _addressId; } set { _addressId = value; } } public string City { get { return _city; } set { _city = value; } } public string Zipcode { get { return _zipcode; } set { _zipcode = value; } } public string Phone { get { return _phone; } set { _phone = value; } } public string Fax { get { return _fax; } set { _fax = value; } } //public string Location //{ // get // { // return _location; // } // set // { // _location = value; // } //} public string AboutMe { get { return _aboutMe; } set { _aboutMe = value; } } public string username { get { return _username; } set { _username = value; } } public string password { get { return _password; } set { _password = value; } } public string SecurityQuestion { get { return _securityQuestion; } set { _securityQuestion = value; } } public string SecurityQAnswer { get { return _securityQAnswer; } set { _securityQAnswer = value; } } public Guid UserID { get { return _user_Id; } set { _user_Id = value; } } public long RwUserID { get { return _rwuserid; } set { _rwuserid = value; } } #endregion #region MemberFunctions // DataHelperDataContext db = new DataHelperDataContext(); // RewhizzDataHelper rwdh=new RewhizzDataHelper(); //It saves user information entered by user and returns the id of that user public object saveUserInfo(RwUser userObj) { userObj.UserID = irewhizzrelation.GetUserId(username); var res = irewhizz.saveData(userObj); return res; } //It returns the security questions for user registration } public class Agent : RwUser { IRewhizzDataHelper irewhizz; IRewhizzRelationDataHelper irewhizzrelation; private int _roleid; private int _speclisationid; private int[] _language; private string _brokaragecompany; private int _loctionType_lk; private string _rolename; private int[] _specialization; private string _agentID; private string _expDate; private string _regstates; private string _selLangs; private string _selSpels; private string _locations; public string Locations { get { return _locations; } set { _locations = value; } } public string SelectedLanguages { get { return _selLangs; } set { _selLangs = value; } } public string SelectedSpecialization { get { return _selSpels; } set { _selSpels = value; } } public string RegisteredStates { get { return _regstates; } set { _regstates = value; } } //private string _registeredStates; public string AgentID { get { return _agentID; } set { _agentID = value; } } public string ExpDate { get { return _expDate; } set { _expDate = value; } } private int[] _registeredStates; public SelectList RegisterStates { set; get; } public SelectList Languages { set; get; } public SelectList Specializations { set; get; } public int[] RegisterdStates { get { return _registeredStates; } set { _registeredStates = value; } } //public string RegisterdStates //{ // get // { // return _registeredStates; // } // set // { // _registeredStates = value; // } //} public int RoleId { get { return _roleid; } set { _roleid = value; } } public int SpeclisationId { get { return _speclisationid; } set { _speclisationid = value; } } public int[] Language { get { return _language; } set { _language = value; } } public int LocationTypeId { get { return _loctionType_lk; } set { _loctionType_lk = value; } } public string BrokarageCompany { get { return _brokaragecompany; } set { _brokaragecompany = value; } } public string Rolename { get { return _rolename; } set { _rolename = value; } } public int[] Specialization { get { return _specialization; } set { _specialization = value; } } public Agent() : this(new AgentDataHelper(), new RewhizzRelationalDataHelper()) { } public Agent(IRewhizzDataHelper repositary, IRewhizzRelationDataHelper relationrepositary) { irewhizz = repositary; irewhizzrelation = relationrepositary; } public void inviteclient() { //Code related to mailing } //DataHelperDataContext dataObj = new DataHelperDataContext(); //#region IRewhizzFactory Members //public List<object> getAgentInfo(string username) //{ // var res=dataObj.GetCompleteUserDetails(username); // return res.ToList(); // throw new NotImplementedException(); //} //public List<object> GetRegisterAgentData(string username) //{ // var res= dataObj.RegisteredUserdetails(username); // return res.ToList(); //} //public void saveAgentInfo(string username, string password, string firstname, string lastname, string middlename, string securityquestion, string securityQanswer) //{ // User userobj=new User(); // var result = dataObj.rw_Users_InsertUserInfo(firstname, middlename, lastname, dataObj.GetUserId(username), securityquestion, securityquestionanswer); // throw new NotImplementedException(); //} //#endregion public Agent updateData(Agent objectId) { objectId.UserID = irewhizzrelation.GetUserId(objectId.username); objectId = (Agent)irewhizz.updateData(objectId); return objectId; } public Agent GetAgentData(Agent agentodj) { agentodj.UserID = irewhizzrelation.GetUserId(agentodj.username); agentodj = (Agent)irewhizz.getData(agentodj); if (agentodj.RoleId != 0) agentodj.Rolename = (string)(string)irewhizzrelation.getValue(agentodj.RoleId); if (agentodj.RegisterdStates.Count() != 0) { List<SelectListItem> list = new List<SelectListItem>(); string regstates = ""; foreach (int i in agentodj.RegisterdStates) { SelectListItem listitem = new SelectListItem(); listitem.Value = i.ToString(); listitem.Text = (string)irewhizzrelation.getValue(i); list.Add(listitem); regstates += (string)irewhizzrelation.getValue(i) + ","; } SelectList selectlist = new SelectList(list, "Value", "Text"); agentodj.RegisterStates = selectlist; if(regstates!=null) agentodj.RegisteredStates = regstates.Remove(regstates.Length - 1); } if (agentodj.Language.Count() != 0) { List<SelectListItem> list = new List<SelectListItem>(); string selectedlang = ""; foreach (int i in agentodj.Language) { SelectListItem listitem = new SelectListItem(); listitem.Value = i.ToString(); listitem.Text = (string)irewhizzrelation.getValue(i); list.Add(listitem); selectedlang += (string)irewhizzrelation.getValue(i) + ","; } SelectList selectlist = new SelectList(list, "Value", "Text"); agentodj.Languages = selectlist; // agentodj.SelectedLanguages = selectedlang; } if (agentodj.Specialization.Count() != 0) { List<SelectListItem> list = new List<SelectListItem>(); string selectedspel = ""; foreach (int i in agentodj.Specialization) { SelectListItem listitem = new SelectListItem(); listitem.Value = i.ToString(); listitem.Text = (string)irewhizzrelation.getValue(i); list.Add(listitem); selectedspel += (string)irewhizzrelation.getValue(i) + ","; } SelectList selectlist = new SelectList(list, "Value", "Text"); agentodj.Specializations = selectlist; //agentodj.SelectedSpecialization = selectedspel; } return agentodj; } public void SaveImage(byte[] pic, String username) { irewhizzrelation.SaveImage(pic, username); } } now the issue is when ever i am calling agent class it is given error like null reference exception for rwuser class can any body give the solution thanks in advance

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  • Qt : crash due to delete (trying to handle exceptions...)

    - by Seub
    I am writing a program with Qt, and I would like it to show a dialog box with a Exit | Restart choice whenever an error is thrown somewhere in the code. What I did causes a crash and I really can't figure out why it happens, I was hoping you could help me understanding what's going on. Here's my main.cpp: #include "my_application.hpp" int main(int argc, char *argv[]) { std::cout << std::endl; My_Application app(argc, argv); return app.exec(); } And here's my_application:hpp: #ifndef MY_APPLICATION_HPP #define MY_APPLICATION_HPP #include <QApplication> class Window; class My_Application : public QApplication { public: My_Application(int& argc, char ** argv); virtual ~My_Application(); virtual bool notify(QObject * receiver, QEvent * event); private: Window *window_; void exit(); void restart(); }; #endif // MY_APPLICATION_HPP Finally, here's my_application.cpp: #include "my_application.hpp" #include "window.hpp" #include <QMessageBox> My_Application::My_Application(int& argc, char ** argv) : QApplication(argc, argv) { window_ = new Window; window_->setAttribute(Qt::WA_DeleteOnClose, false); window_->show(); } My_Application::~My_Application() { delete window_; } bool My_Application::notify(QObject * receiver, QEvent * event) { try { return QApplication::notify(receiver, event); } catch(QString error_message) { window_->setEnabled(false); QMessageBox message_box; message_box.setWindowTitle("Error"); message_box.setIcon(QMessageBox::Critical); message_box.setText("The program caught an unexpected error:"); message_box.setInformativeText("What do you want to do? <br>"); QPushButton *restart_button = message_box.addButton(tr("Restart"), QMessageBox::RejectRole); QPushButton *exit_button = message_box.addButton(tr("Exit"), QMessageBox::RejectRole); message_box.setDefaultButton(restart_button); message_box.exec(); if ((QPushButton *) message_box.clickedButton() == exit_button) { exit(); } else if ((QPushButton *) message_box.clickedButton() == restart_button) { restart(); } } return false; } void My_Application::exit() { window_->close(); //delete window_; return; } void My_Application::restart() { window_->close(); //delete window_; window_ = new Window; window_->show(); return; } Note that the line window_->setAttribute(Qt::WA_DeleteOnClose, false); means that window_ (my main window) won't be deleted when it is closed. The code I've written above works, but as far as I understand, there's a memory leak: I should uncomment the line //delete window_; in My_Application::exit() and My_Application::restart(). But when I do that, the program crashes when I click restart (or exit but who cares). (I'm not sure this is useful, in fact it might be misleading, but here's what my debugger tells me: a segmentation fault occurs in QWidgetPrivate::PaintOnScreen() const which is called by a function called by a function... called by My_Application::notify()) When I do some std::couts, I notice that the program runs through the entire restart() function and in fact through the entire notify() function before it crashes. I have no idea why it crashes. Thanks in advance for your insights! Update: I've noticed that My_Application::notify() is called very often. For example, it is called a bunch of times while the error dialog box is open, also during the execution of the restart function. The crash actually occurs in the subfunction QApplication::notify(receiver, event). This is not too surprising in light of the previous remark (the receiver has probably been deleted) But even if I forbid the function My_Application::notify() to do anything while restart() is executed, it still crashes (after having called My_Application::notify() a bunch of times, like 15 times, isn't that weird)? How should I proceed? Maybe I should say (to make the question slightly more relevant) that my class My_Application also has a "restore" function, which I've not copied here to try to keep things short. If I just had that restart feature I wouldn't bother too much, but I do want to have that restore feature. I should also say that if I keep the code with the "delete window_" commented, the problem is not only a memory leak, it still crashes sometimes apparently. There must surely be a way to fix this! But I'm clueless, I'd really appreciate some help! Thanks in advance.

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