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  • SQLiteOpenHelper.getWriteableDatabase() null pointer exception on Android

    - by Drew Dara-Abrams
    I've had fine luck using SQLite with straight, direct SQL in Android, but this is the first time I'm wrapping a DB in a ContentProvider. I keep getting a null pointer exception when calling getWritableDatabase() or getReadableDatabase(). Is this just a stupid mistake I've made with initializations in my code or is there a bigger issue? public class DatabaseProvider extends ContentProvider { ... private DatabaseHelper databaseHelper; private SQLiteDatabase db; ... @Override public boolean onCreate() { databaseHelper = new DatabaseProvider.DatabaseHelper(getContext()); return (databaseHelper == null) ? false : true; } ... @Override public Uri insert(Uri uri, ContentValues values) { db = databaseHelper.getWritableDatabase(); // NULL POINTER EXCEPTION HERE ... } private static class DatabaseHelper extends SQLiteOpenHelper { public static final String DATABASE_NAME = "cogsurv.db"; public static final int DATABASE_VERSION = 1; public static final String[] TABLES = { "people", "travel_logs", "travel_fixes", "landmarks", "landmark_visits", "direction_distance_estimates" }; // people._id does not AUTOINCREMENT, because it's set based on server's people.id public static final String[] CREATE_TABLE_SQL = { "CREATE TABLE people (_id INTEGER PRIMARY KEY," + "server_id INTEGER," + "name VARCHAR(255)," + "email_address VARCHAR(255))", "CREATE TABLE travel_logs (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "start DATE," + "stop DATE," + "type VARCHAR(15)," + "uploaded VARCHAR(1))", "CREATE TABLE travel_fixes (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "datetime DATE, " + "latitude DOUBLE, " + "longitude DOUBLE, " + "altitude DOUBLE," + "speed DOUBLE," + "accuracy DOUBLE," + "travel_mode VARCHAR(50), " + "person_local_id INTEGER," + "person_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE landmarks (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "name VARCHAR(150)," + "latitude DOUBLE," + "longitude DOUBLE," + "person_local_id INTEGER," + "person_server_id INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE landmark_visits (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "landmark_local_id INTEGER," + "landmark_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "datetime DATE," + "number_of_questions_asked INTEGER," + "uploaded VARCHAR(1))", "CREATE TABLE direction_distance_estimates (_id INTEGER PRIMARY KEY AUTOINCREMENT," + "server_id INTEGER," + "person_local_id INTEGER," + "person_server_id INTEGER," + "travel_log_local_id INTEGER," + "travel_log_server_id INTEGER," + "landmark_visit_local_id INTEGER," + "landmark_visit_server_id INTEGER," + "start_landmark_local_id INTEGER," + "start_landmark_server_id INTEGER," + "target_landmark_local_id INTEGER," + "target_landmark_server_id INTEGER," + "datetime DATE," + "direction_estimate DOUBLE," + "distance_estimate DOUBLE," + "uploaded VARCHAR(1))" }; public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); Log.v(Constants.TAG, "DatabaseHelper()"); } @Override public void onCreate(SQLiteDatabase db) { Log.v(Constants.TAG, "DatabaseHelper.onCreate() starting"); // create the tables int length = CREATE_TABLE_SQL.length; for (int i = 0; i < length; i++) { db.execSQL(CREATE_TABLE_SQL[i]); } Log.v(Constants.TAG, "DatabaseHelper.onCreate() finished"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { for (String tableName : TABLES) { db.execSQL("DROP TABLE IF EXISTS" + tableName); } onCreate(db); } } } As always, thanks for the assistance! -- Not sure if this detail helps, but here's LogCat showing the exception:

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  • Pointer to NSWindow Xib after loading it?

    - by Brock Woolf
    In my code below, CustomWindow is a subclass of NSWindow. CustomWindow *window = [[CustomWindow alloc] init]; if (![NSBundle loadNibNamed:@"NibName" owner:window]) [window center]; // doesn't work How do you get a pointer to control your XIB after you load it so you can do things such as centering the XIB? What am i doing wrong here?

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  • "this" pointer changes in GDB backtrace

    - by Hans
    I am examining a core dump, and noticed that in one frame the 'this' pointer is different than in the next frame (in the same thread). Not just a little different, it went from 0x8167428 to 0x200. I am not that well-versed in using GDB, but this does not seem right to me. Is this problematic, and if so, what could be the cause?

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  • passing argument 1 from incompatible pointer type

    - by Andrew
    Why does this code...: NSDictionary *testDictionary = [NSDictionary dictionaryWithObjectsAndKeys:kABOtherLabel, @"other", kABWorkLabel, @"work", nil]; throw this warning: warning: passing argument 1 of 'dictionaryWithObjectsAndKeys' from incompatible pointer type Incidentally, the code works as expected, but I don't like leaving warnings un-delt-with. I assume it doesn't like that I'm storing a constant in a dictionary. Well, where can I store it then? Should I just place (void *) before every constant?

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  • Using a type parameter and a pointer to the same type parameter in a function template

    - by Darel
    Hello, I've written a template function to determine the median of any vector or array of any type that can be sorted with sort. The function and a small test program are below: #include <algorithm> #include <vector> #include <iostream> using namespace::std; template <class T, class X> void median(T vec, size_t size, X& ret) { sort(vec, vec + size); size_t mid = size/2; ret = size % 2 == 0 ? (vec[mid] + vec[mid-1]) / 2 : vec[mid]; } int main() { vector<double> v; v.push_back(2); v.push_back(8); v.push_back(7); v.push_back(4); v.push_back(9); double a[5] = {2, 8, 7, 4, 9}; double r; median(v.begin(), v.size(), r); cout << r << endl; median(a, 5, r); cout << r << endl; return 0; } As you can see, the median function takes a pointer as an argument, T vec. Also in the argument list is a reference variable X ret, which is modified by the function to store the computed median value. However I don't find this a very elegant solution. T vec will always be a pointer to the same type as X ret. My initial attempts to write median had a header like this: template<class T> T median(T *vec, size_t size) { sort(vec, vec + size); size_t mid = size/2; return size % 2 == 0 ? (vec[mid] + vec[mid-1]) / 2 : vec[mid]; } I also tried: template<class T, class X> X median(T vec, size_t size) { sort(vec, vec + size); size_t mid = size/2; return size % 2 == 0 ? (vec[mid] + vec[mid-1]) / 2 : vec[mid]; } I couldn't get either of these to work. My question is, can anyone show me a working implementation of either of my alternatives? Thanks for looking!

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  • Pointer-Safe Objects?

    - by cam
    Would it be smart to have a vector in an object with a list of pointers that point to it? This way when the object is deleted, it could delete all the pointers pointing to it to prevent a null-pointer exception?

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  • Smart pointer class predeclaration

    - by tommyk
    I have a header file: class A { public: DeviceProxyPtr GetDeviceProxy(); }; DeviceProxyPtr is defined in a different header file like this: typedef SmartPtrC<DeviceProxyC> DeviceProxyPtr; I don't want to include DeviceProxyPtr definition header. If a return type was DeviceProxy* I could simply use predeclaration class DeviceProxy. Is there any way to do the same with my smart pointer class?

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  • global static boolean pointer causes segmentation fault using pthread

    - by asksw0rder
    New to pthread programming, and stuck on this error when working on a C++&C mixed code. What I have done is to call the c code in the thread created by the c++ code. There is a static boolean pointer used in the thread and should got free when the thread finishes. However I noticed that every time when the program processed into the c function, the value of the boolean pointer would be changed and the segmentation fault then happened due to the free(). Detail code is as follows: static bool *is_center; // omit other codes in between ... void streamCluster( PStream* stream) { // some code here ... while(1){ // some code here ... is_center = (bool*)calloc(points.num,sizeof(bool)); // start the parallel thread here. // the c code is invoked in this function. localSearch(&points,kmin, kmax,&kfinal); // parallel free(is_center); } And the function using parallel is as follows (my c code is invoked in each thread): void localSearch( Points* points, long kmin, long kmax, long* kfinal ) { pthread_barrier_t barrier; pthread_t* threads = new pthread_t[nproc]; pkmedian_arg_t* arg = new pkmedian_arg_t[nproc]; pthread_barrier_init(&barrier,NULL,nproc); for( int i = 0; i < nproc; i++ ) { arg[i].points = points; arg[i].kmin = kmin; arg[i].kmax = kmax; arg[i].pid = i; arg[i].kfinal = kfinal; arg[i].barrier = &barrier; pthread_create(threads+i,NULL,localSearchSub,(void*)&arg[i]); } for ( int i = 0; i < nproc; i++) { pthread_join(threads[i],NULL); } delete[] threads; delete[] arg; pthread_barrier_destroy(&barrier); } Finally the function calling my c code: void* localSearchSub(void* arg_) { // omit some initialize code... // my code begin_papi_thread(&eventSet); // Processing k-means, omit codes. // is_center value will be updated correctly // my code end_papi_thread(&eventSet); // when jumping into this, error happens return NULL; } And from gdb, what I have got for the is_center is: Breakpoint 2, localSearchSub (arg_=0x600000000000bc40) at streamcluster.cpp:1711 1711 end_papi_thread(&eventSet); (gdb) s Hardware watchpoint 1: is_center Old value = (bool *) 0x600000000000bba0 New value = (bool *) 0xa93f3 0x400000000000d8d1 in localSearchSub (arg_=0x600000000000bc40) at streamcluster.cpp:1711 1711 end_papi_thread(&eventSet); Any suggestions? Thanks in advance!

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  • MessageBroker.getMessageBroker(null) getting null pointer Exception

    - by Shital
    I am creating Dynamic Destinations MessageBroker broker = MessageBroker.getMessageBroker(null); MessageService service = (MessageService) broker.getService("message-service"); MessageDestination destination = (MessageDestination) service.createDestination("Group1"); if (service.isStarted()) { destination.start(); } But I am getting Null Pointer Exception MessageBroker broker = MessageBroker.getMessageBroker(null); Can Anyone Help Me

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  • Another warning question: "Incompatible intiger to pointer conversion assigning to 'int *' from 'int'"

    - by Preston
    I have yet another pesky warning I would like gone. Basically, I have an int declared like this: @property (nonatomic, assign) int *myInt; and set like this: myInt = 0;. It is also synthesized in the implementation file. I am getting a warning on the line where I set the int's value and it says "Incompatible intiger to pointer conversion assigning to 'int *' from 'int'." What should I do to fix this?

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  • Dangling pointer

    - by viswanathan
    How can the below code result in a dangling pointer. { char *cPointer = malloc ( some constant number ); /* some code */ free ( cPointer ); cPointer = NULL; /* some code */ }

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  • How can I declare a pointer structure?

    - by Y_Y
    This probably is one of the easiest questions ever in C programming language... I have the following code: typedef struct node { int data; struct node * after; struct node * before; }node; struct node head = {10,&head,&head}; Is there a way I can make head to be *head [make it a pointer] and still have the availability to use '{ }' [{10,&head,&head}] to declare an instance of head?

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  • Why is dereferencing a pointer called dereferencing?

    - by optician
    Why is dereferencing called dereferencing? I'm just learning pointers properly, and I'd like to know why dereferencing is called that. It confused me as it sounds like you are removing a reference, rather than going via the pointer to the destination. Can anyone explain why it is called this? To me something like destination or pointed_to_value would make more sense.

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  • C++ using this pointer in constructors

    - by gilbertc
    In c++, during a class constructor, I started a new thread with 'this' pointer as a parameter which will be used in the thread extensively (say, calling member functions). Is that a bad thing to do? Why and what are the consequences? Thanks, Gil.

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  • Advice on "Invalid Pointer Operation" when using complex records

    - by Xaz
    Env: Delphi 2007 <JustificationI tend to use complex records quite frequently as they offer almost all of the advantages of classes but with much simpler handling.</Justification Anyhoo, one particularly complex record I have just implemented is trashing memory (later leading to an "Invalid Pointer Operation" error). This is an example of the memory trashing code: sSignature := gProfiles.Profile[_stPrimary].Signature.Formatted(True); On the second time i call it i get "Invalid Pointer Operation" It works OK if i call it like this: AProfile := gProfiles.Profile[_stPrimary]; ASignature := AProfile.Signature; sSignature := ASignature.Formatted(True); Background Code: gProfiles: TProfiles; TProfiles = Record private FPrimaryProfileID: Integer; FCachedProfile: TProfile; ... public < much code removed > property Profile[ProfileType: TProfileType]: TProfile Read GetProfile; end; function TProfiles.GetProfile(ProfileType: TProfileType): TProfile; begin case ProfileType of _stPrimary : Result := ProfileByID(FPrimaryProfileID); ... end; end; function TProfiles.ProfileByID(iID: Integer): TProfile; begin <snip> if LoadProfileOfID(iID, FCachedProfile) then begin Result := FCachedProfile; end else ... end; TProfile = Record private ... public ... Signature: TSignature; ... end; TSignature = Record private public PlainTextFormat : string; HTMLFormat : string; // The text to insert into a message when using this profile function Formatted(bHTML: boolean): string; end; function TSignature.Formatted(bHTML: boolean): string; begin if bHTML then result := HTMLFormat else result := PlainTextFormat; < SNIP MUCH CODE > end; OK, so I have a record within a record within a record, which is approaching Inception level confusion and I'm the first to admit is not really a good model. Clearly i am going to have to restructure it. What I would like from you gurus is a better understanding of why it is trashing the memory (something to do with the string object that is created then freed...) so that i can avoid making these kinds of errors in future. Thanks

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  • Passing a pointer to a function in objective-c

    - by Chiodo
    Hi, i've a stupid questiona about passing pointer. I've this: @interface MyClass : NSObject myobj* foo; -(void)doSomething:(myobj*)aObj; @end @implementation MyClass -(void)doSomething:(myobj*)aObj { cFuncCall(&aObj); //alloc memory and init the object } -(id)init { //init stuff... [self doSomething:foo]; // foo retun 0x0!!! } @end why foo return nil??? It should be initialized by cFuncCall!

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