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• java hashmap array to double array

  - by Tweety

  Hi, I declared LinkedHashMap<String, float[]> and now I want to convert float[] values into double[][]. I am using following code. LinkedHashMap<String, float[]> fData; double data[][] = null; Iterator<String> iter = fData.keySet().iterator(); int i = 0; while (iter.hasNext()) { faName = iter.next(); tValue = fData.get(faName); //data = new double[fData.size()][tValue.length]; for (int j = 0; j < tValue.length; j++) { data[i][j] = tValue[j]; } i++; } When I try to print data System.out.println(Arrays.deepToString(data)); it doesn't show the data :( I tried to debug my code and i figured out that I have to initialize data outside the while loop but then I don't know the array dimensions :( How to solve it? Thanks

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• Strange overloading rules in C++

  - by bucels

  I'm trying to compile this code with GCC 4.5.0: #include <algorithm> #include <vector> template <typename T> void sort(T, T) {} int main() { std::vector<int> v; sort(v.begin(), v.end()); } But it doesn't seem to work: $ g++ -c nm.cpp nm.cpp: In function ‘int main()’: nm.cpp:9:28: error: call of overloaded ‘sort(std::vector<int>::iterator, std::vector<int>::iterator)’ is ambiguous nm.cpp:4:28: note: candidates are: void sort(T, T) [with T = __gnu_cxx::__normal_iterator<int*, std::vector<int> >] /usr/lib/gcc/i686-pc-linux-gnu/4.5.0/../../../../include/c++/4.5.0/bits/stl_algo.h:5199:69: note: void std::sort(_RAIter, _RAIter) [with _RAIter = __gnu_cxx::__normal_iterator<int*, std::vector<int> >] Comeau compiles this code without errors. (4.3.10.1 Beta2, strict C++03, no C++0x) Is this valid C++?

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• thrust::unique_by_key eating up last element

  - by Programmer

  Please consider the below simple code: thrust::device_vector<int> positions(6); thrust::sequence(positions.begin(), positions.end()); thrust::pair<thrust::device_vector<int>::iterator, thrust::device_vector<int>::iterator > end; //copyListOfNgramCounteachdoc contains: 0,1,1,1,1,3 end.first = copyListOfNgramCounteachdoc.begin(); end.second = positions.begin(); for(int i =0 ; i < numDocs; i++){ end= thrust::unique_by_key(end.first, end.first + 3,end.second); } int length = end.first - copyListOfNgramCounteachdoc.begin() ; cout<<"the value of end -s is: "<<length; for(int i =0 ; i< length ; i++){ cout<<copyListOfNgramCounteachdoc[i]; } I expected the output to be 0,1,1,3 of this code; however, the output is 0,1,1. Can anyone let me know what I am missing? Note: the contents of copyListOfNgramCounteachdoc is 0,1,1,1,1,3 . Also the type of copyListOfNgramCounteachdoc is thrust::device_vector<int>.

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• Android - update widget text

  - by david

  Hi, i have 2 questions about widgets update I have 2 buttons and i need to change one button text when i press the other one, how can i do this? The first time i open the widget it calls the onUpdate method, but it never calls it again. I need to update the widget every 2 seconds and i have this line in the xml. android:updatePeriodMillis="2000" Do i need a service or should it works just with the updatePeriodMillis tag? onUpdate method RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.newswidget); Intent intent = new Intent(context, DetalleConsulta.class); intent.putExtra(DetalleConsulta.CONSULTA_ID_NAME, "3"); PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0); views.setOnClickPendingIntent(R.id.btNews, pendingIntent); /* Inicializa variables para llamar el controlador */ this.imei = ((TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE)).getDeviceId(); this.controlador = new Controlador(this.imei); try { this.respuestas = this.controlador.recuperarNuevasRespuestas(); if(this.respuestas != null &amp;&amp; this.respuestas.size() &gt; 0){ Iterator&lt;Consulta&gt; iterRespuestas = this.respuestas.iterator(); views.setTextViewText(R.id.btNews, ((Consulta)iterRespuestas.next()).getRespuesta()); } } catch (PersistenciaException e) { //TODO manejar error } appWidgetManager.updateAppWidget(appWidgetIds, views); thx a lot!!!

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• Read all sub directories within a certain folder to display a random image.

  - by Andy

  I have this code i have been using....but i need a conditional where it will read all the sub directories of /bg to select an image as opposed to a specific folder if they were on a subpage. Heres my code so far which works perfectly for all subpages to display specific images: //This would tell us its on the homepage if it helps: $this->level() == 0 //This is the code so far $path = '/home/sites/mydomain.co.uk/public_html/public/images/bg/'.$this->slug; $homepagefile = URL_PUBLIC.'public/images/bg/'.$this->slug.'/main.jpg'; $bgimagearray = array(); $iterator = new DirectoryIterator($path); foreach ($iterator as $fileinfo) { if ($fileinfo->isFile() && !preg_match('\.jpg$/', $fileinfo->getFilename())) { $bgimagearray[] = "'" . $fileinfo->getFilename() . "'"; } } $bgimage = array_rand($bgimagearray); ?> <div id="bg"> <div> <table cellspacing="0" cellpadding="0"> <tr> <td><img src="<?php echo $file.trim($bgimagearray[$bgimage], "'"); ?>" alt=""/></td> </tr> </table> </div> </div> Any help would be appreciated, im sure its not rocket science but ive tried a few ways and cant get my head around it. Thanks in advance.

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• Finding the unique paths through a Neo4j graph

  - by Larry

  I have a Neo4j graph with 12 inputs and 4 outputs, and am trying to write a query with the Java Traverser that will return the 14 unique paths from an input to an output node. All the queries I have tried return only a subset of the 14 paths. For example, the code below returns 4 paths, but the other 10 all stop 1 node short of the output. RelationshipType relType = RelationshipTypes.EDGE; TraversalDescription td = new TraversalDescriptionImpl() .depthFirst() .relationships(relType, Direction.OUTGOING); for (Node node : inputs){ Traverser tv = td.traverse(node); Iterator<Path> iter = tv.iterator(); // ... print path } I've tried uniqueness and depth settings as well, with no effect. The query below returns all 14 paths using the web interface, but when I use the ExecutionEngine class, I only get 13 paths back. START s=node(*) MATCH (s)-[p:EDGE*]->(c) WHERE s.type! = "INPUT" AND c.type! = "OUTPUT" RETURN p How do I get all the unique paths using the Java API?

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• why the exception is not caught?

  - by Álvaro García

  I have the following code: List<MyEntity> lstAllMyRecords = miDbContext.MyEntity.ToList<MyEntity>(); foreach MyEntity iterator in lstMainRecord) { tasks.Add( TaskEx.Run(() => { try { checkData(lstAllMyRecords.Where(n => n.IDReference == iterator.IDReference).ToList<MyEntity>()); } catch CustomRepository ex) { //handle my custom repository } catch (Exception) { throw; } }) ); }//foreach Task.WaitAll(tasks.ToArray()); I get all the records from my data base and in the foreach loop, I group all the records that have the same IDReference. Thenk I check if the data is correct with the method chekData. The checkData method throw a custom exception if something is wrong. I would like to catch this exception to handle it. But the problem is that with this code the exceptions are not caught and all seem to work without errors, but I know that this is not true. I try to check only one group of records that I know that has problems. If I check only one group of registrers, the loop is execute once and then only task is created. In this case the exception is caught, but if I have many groups, then any exception s thrwon. Why when I only have one task the exception is caught and with many groups are not? Thanks.

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• Exporting to CSV/Excel in Java

  - by WIOijwww

  I'm trying to export data into a CSV file through Java and I've got some code to do it but it doesn't seem to be outputting the CSV file. Could someone tell me what's wrong? What I would like to do is rather than saving the file somewhere, I would like it to be directly exported to the user. EDIT: Just in case it's not clear, I don't want the file to be saved anywhere but would like it to be outputted automatically to the user i.e. they click export and get the "Run/Save results.csv" window and they open the file. Currently the file is getting saved so I know that the method seems to work, just in the opposite way that I want it to. public static void writeToCSV(List<Map> objectList) { String CSV_SEPARATOR = ","; try { BufferedWriter bw = new BufferedWriter(new OutputStreamWriter( new FileOutputStream("results.csv"), "UTF-8")); for (Map objectDetails : objectList) { StringBuffer oneLine = new StringBuffer(); Iterator it = objectDetails.values().iterator(); while (it.hasNext()) { Object value = it.next(); if(value !=null){ oneLine.append(value.toString()); } if (it.hasNext()) { oneLine.append(CSV_SEPARATOR); } } bw.write(oneLine.toString()); bw.newLine(); } bw.flush(); bw.close(); } catch (UnsupportedEncodingException e) { } catch (FileNotFoundException e) { } catch (IOException e) { } }

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• how to get something to display only once in a while loop

  - by Matt Nathanson

  I've got a mysql query running and it checks to see if an iterator is equal to 1, then display this div title... if ($this->dliterator == 1) {echo "<div class='clientsection' id='downloads'>Downloads</div><br/>";}; The problem is, is that the dl iterator may not necessarily start at 1. (it is directly related to a downloadid from the database). How can I get this to display only for the first time through the loop ONLY? while ($row = mysql_fetch_assoc($result)) { if ($row['download'] != null){ if ($this->dliterator == 1) {echo "<div class='clientsection' id='downloads'>Downloads</div><br/>";}; if ($editDownload == 1) { echo "<div class='clientlink' style='margin-top: 15px;'>"; echo "<input name='downloads[$this->dliterator][name]' type='text' id='download$this->dliterator' value='" . $row['download'] . "'/>"; echo "<input name='downloads[$this->dliterator][title]' type='text' id='downloadtitle$this->dliterator' value='" . $row['downloadtitle'] . "'/>"; echo "<img class='removelink' src='/images/deletelink.png' width='15' />"; echo "<input id='downloadid' name='downloads[$this->dliterator][id]' type='hidden' value='".$row['downloadid']."' style='display: none'/>"; echo "<br/><img id='uploaddownload$uploaditerator' class='uploaddownload' src='../images/upload.png' width='80'/>"; echo "</div>"; }; }; $this->dliterator++; $uploaditerator++; };

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• java: List wrapper where get()/set() is allowed but add/remove is not

  - by Jason S

  I need to wrap a List<T> with some class that allows calls to set/get but does not allow add/remove calls, so that the list remains "stuck" at a fixed length. I think I have a thin wrapper class (below) that will work, but I'm not 100% positive. Did I miss anything obvious? import java.util.Collection; import java.util.Iterator; import java.util.List; import java.util.ListIterator; class RestrictedListWrapper<T> implements List<T> { static <T> T fail() throws UnsupportedOperationException { throw new UnsupportedOperationException(); } static private class IteratorWrapper<T> implements ListIterator<T> { final private ListIterator<T> iter; private IteratorWrapper(ListIterator<T> iter) { this.iter = iter; } static public <T> RestrictedListWrapper.IteratorWrapper<T> wrap(ListIterator<T> target) { return new RestrictedListWrapper.IteratorWrapper<T>(target); } @Override public void add(T e) { fail(); } @Override public boolean hasNext() { return this.iter.hasNext(); } @Override public boolean hasPrevious() { return this.iter.hasPrevious(); } @Override public T next() { return this.iter.next(); } @Override public int nextIndex() { return this.iter.nextIndex(); } @Override public T previous() { return this.iter.previous(); } @Override public int previousIndex() { return this.iter.previousIndex(); } @Override public void remove() { fail(); } @Override public void set(T e) { this.iter.set(e); } } final private List<T> list; private RestrictedListWrapper(List<T> list) { this.list = list; } static public <T> RestrictedListWrapper<T> wrap(List<T> target) { return new RestrictedListWrapper<T>(target); } @Override public boolean add(T arg0) { return fail(); } @Override public void add(int index, T element) { fail(); } @Override public boolean addAll(Collection<? extends T> arg0) { return fail(); } @Override public boolean addAll(int arg0, Collection<? extends T> arg1) { return fail(); } /** * clear() allows setting all members of the list to null */ @Override public void clear() { ListIterator<T> it = this.list.listIterator(); while (it.hasNext()) { it.set(null); it.next(); } } @Override public boolean contains(Object o) { return this.list.contains(o); } @Override public boolean containsAll(Collection<?> c) { return this.list.containsAll(c); } @Override public T get(int index) { return this.list.get(index); } @Override public int indexOf(Object o) { return this.list.indexOf(o); } @Override public boolean isEmpty() { return false; } @Override public Iterator<T> iterator() { return listIterator(); } @Override public int lastIndexOf(Object o) { return this.list.lastIndexOf(o); } @Override public ListIterator<T> listIterator() { return IteratorWrapper.wrap(this.list.listIterator()); } @Override public ListIterator<T> listIterator(int index) { return IteratorWrapper.wrap(this.list.listIterator(index)); } @Override public boolean remove(Object o) { return fail(); } @Override public T remove(int index) { fail(); return fail(); } @Override public boolean removeAll(Collection<?> c) { return fail(); } @Override public boolean retainAll(Collection<?> c) { return fail(); } @Override public T set(int index, T element) { return this.list.set(index, element); } @Override public int size() { return this.list.size(); } @Override public List<T> subList(int fromIndex, int toIndex) { return new RestrictedListWrapper<T>(this.list.subList(fromIndex, toIndex)); } @Override public Object[] toArray() { return this.list.toArray(); } @Override public <T> T[] toArray(T[] a) { return this.list.toArray(a); } }

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• Erasing and modifying elements in Boost MultiIndex Container

  - by Sarah

  I'm trying to use a Boost MultiIndex container in my simulation. My knowledge of C++ syntax is very weak, and I'm concerned I'm not properly removing an element from the container or deleting it from memory. I also need to modify elements, and I was hoping to confirm the syntax and basic philosophy here too. // main.cpp ... #include <boost/multi_index_container.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/mem_fun.hpp> #include <boost/tokenizer.hpp> #include <boost/shared_ptr.hpp> ... #include "Host.h" // class Host, all members private, using get fxns to access using boost::multi_index_container; using namespace boost::multi_index; typedef multi_index_container< boost::shared_ptr< Host >, indexed_by< hashed_unique< const_mem_fun<Host,int,&Host::getID> > // ordered_non_unique< BOOST_MULTI_INDEX_MEM_FUN(Host,int,&Host::getAge) > > // end indexed_by > HostContainer; typedef HostContainer::nth_index<0>::type HostsByID; int main() { ... HostContainer allHosts; Host * newHostPtr; newHostPtr = new Host( t, DOB, idCtr, 0, currentEvents ); allHosts.insert( boost::shared_ptr<Host>(newHostPtr) ); // allHosts gets filled up int randomHostID = 4; int newAge = 50; modifyHost( randomHostID, allHosts, newAge ); killHost( randomHostID, allHosts ); } void killHost( int id, HostContainer & hmap ){ HostsByID::iterator it = hmap.find( id ); cout << "Found host id " << (*it)->getID() << "Attempting to kill. hmap.size() before is " << hmap.size() << " and "; hmap.erase( it ); // Is this really erasing (freeing from mem) the underlying Host object? cout << hmap.size() << " after." << endl; } void modifyHost( int id, HostContainer & hmap, int newAge ){ HostsByID::iterator it = hmap.find( id ); (*it) -> setAge( newAge ); // Not actually the "modify" function for MultiIndex... } My questions are In the MultiIndex container allHosts of shared_ptrs to Host objects, is calling allHosts.erase( it ) on an iterator to the object's shared_ptr enough to delete the object permanently and free it from memory? It appears to be removing the shared_ptr from the container. The allhosts container currently has one functioning index that relies on the host's ID. If I introduce an ordered second index that calls on a member function (Host::getAge()), where the age changes over the course of the simulation, is the index always going to be updated when I refer to it? What is the difference between using the MultiIndex's modify to modify the age of the underlying object versus the approach I show above? I'm vaguely confused about what is assumed/required to be constant in MultiIndex. Thanks in advance. Update Here's my attempt to get the modify syntax working, based on what I see in a related Boost example. struct update_age { update_age():(){} // have no idea what this really does... elicits error void operator() (boost::shared_ptr<Host> ptr) { ptr->incrementAge(); // incrementAge() is a member function of class Host } }; and then in modifyHost, I'd have hmap.modify(it,update_age). Even if by some miracle this turns out to be right, I'd love some kind of explanation of what's going on.

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• Of these 3 methods for reading linked lists from shared memory, why is the 3rd fastest?

  - by Joseph Garvin

  I have a 'server' program that updates many linked lists in shared memory in response to external events. I want client programs to notice an update on any of the lists as quickly as possible (lowest latency). The server marks a linked list's node's state_ as FILLED once its data is filled in and its next pointer has been set to a valid location. Until then, its state_ is NOT_FILLED_YET. I am using memory barriers to make sure that clients don't see the state_ as FILLED before the data within is actually ready (and it seems to work, I never see corrupt data). Also, state_ is volatile to be sure the compiler doesn't lift the client's checking of it out of loops. Keeping the server code exactly the same, I've come up with 3 different methods for the client to scan the linked lists for changes. The question is: Why is the 3rd method fastest? Method 1: Round robin over all the linked lists (called 'channels') continuously, looking to see if any nodes have changed to 'FILLED': void method_one() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { Data* current_item = channel_cursors[i]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[i] = static_cast<Data*>(current_item->next_.get(segment)); } } } Method 1 gave very low latency when then number of channels was small. But when the number of channels grew (250K+) it became very slow because of looping over all the channels. So I tried... Method 2: Give each linked list an ID. Keep a separate 'update list' to the side. Every time one of the linked lists is updated, push its ID on to the update list. Now we just need to monitor the single update list, and check the IDs we get from it. void method_two() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { if(update_cursor->state_ == NOT_FILLED_YET) { continue; } ::uint32_t update_id = update_cursor->list_id_; Data* current_item = channel_cursors[update_id]; if(current_item->state_ == NOT_FILLED_YET) { std::cerr << "This should never print." << std::endl; // it doesn't continue; } log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[update_id] = static_cast<Data*>(current_item->next_.get(segment)); update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } } Method 2 gave TERRIBLE latency. Whereas Method 1 might give under 10us latency, Method 2 would inexplicably often given 8ms latency! Using gettimeofday it appears that the change in update_cursor-state_ was very slow to propogate from the server's view to the client's (I'm on a multicore box, so I assume the delay is due to cache). So I tried a hybrid approach... Method 3: Keep the update list. But loop over all the channels continuously, and within each iteration check if the update list has updated. If it has, go with the number pushed onto it. If it hasn't, check the channel we've currently iterated to. void method_three() { std::vector<Data*> channel_cursors; for(ChannelList::iterator i = channel_list.begin(); i != channel_list.end(); ++i) { Data* current_item = static_cast<Data*>(i->get(segment)->tail_.get(segment)); channel_cursors.push_back(current_item); } UpdateID* update_cursor = static_cast<UpdateID*>(update_channel.tail_.get(segment)); while(true) { for(std::size_t i = 0; i < channel_list.size(); ++i) { std::size_t idx = i; ACQUIRE_MEMORY_BARRIER; if(update_cursor->state_ != NOT_FILLED_YET) { //std::cerr << "Found via update" << std::endl; i--; idx = update_cursor->list_id_; update_cursor = static_cast<UpdateID*>(update_cursor->next_.get(segment)); } Data* current_item = channel_cursors[idx]; ACQUIRE_MEMORY_BARRIER; if(current_item->state_ == NOT_FILLED_YET) { continue; } found_an_update = true; log_latency(current_item->tv_sec_, current_item->tv_usec_); channel_cursors[idx] = static_cast<Data*>(current_item->next_.get(segment)); } } } The latency of this method was as good as Method 1, but scaled to large numbers of channels. The problem is, I have no clue why. Just to throw a wrench in things: if I uncomment the 'found via update' part, it prints between EVERY LATENCY LOG MESSAGE. Which means things are only ever found on the update list! So I don't understand how this method can be faster than method 2. The full, compilable code (requires GCC and boost-1.41) that generates random strings as test data is at: http://pastebin.com/e3HuL0nr

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• Looking for a better way to integrate a static list into a set of classes

  - by EvilTeach

  I'm trying to expand my sons interest from Warcraft 3 programming into C++ to broaden his horizons to a degree. We are planning on porting a little game that he wrote. The context goes something like this. There are Ships and Missiles, for which Ships will use Missiles and interact with them A Container exists which will hold 'a list' of ships. A Container exists which will hold 'a list' of planets. One can apply a function over all elements in the Container (for_each) Ships and Missles can be created/destroyed at any time New objects automatically insert themselves into the proper container. I cobbled a small example together to do that job, so we can talk about topics (list, templates etc) but I am not pleased with the results. #include <iostream> #include <list> using namespace std; /* Base class to hold static list in common with various object groups */ template<class T> class ObjectManager { public : ObjectManager ( void ) { cout << "Construct ObjectManager at " << this << endl; objectList.push_back(this); } virtual ~ObjectManager ( void ) { cout << "Destroy ObjectManager at " << this << endl; } void for_each ( void (*function)(T *) ) { for (objectListIter = objectList.begin(); objectListIter != objectList.end(); ++objectListIter) { (*function)((T *) *objectListIter); } } list<ObjectManager<T> *>::iterator objectListIter; static list<ObjectManager<T> *> objectList; }; /* initializer for static list */ template<class T> list<ObjectManager<T> *> ObjectManager<T>::objectList; /* A simple ship for testing */ class Ship : public ObjectManager<Ship> { public : Ship ( void ) : ObjectManager<Ship>() { cout << "Construct Ship at " << this << endl; } ~Ship ( void ) { cout << "Destroy Ship at " << this << endl; } friend ostream &operator<< ( ostream &out, const Ship &that ) { out << "I am a ship"; return out; } }; /* A simple missile for testing */ class Missile : public ObjectManager<Missile> { public : Missile ( void ) : ObjectManager<Missile>() { cout << "Construct Missile at " << this << endl; } ~Missile ( void ) { cout << "Destroy Missile at " << this << endl; } friend ostream &operator<< ( ostream &out, const Missile &that ) { out << "I am a missile"; return out; } }; /* A function suitable for the for_each function */ template <class T> void show ( T *it ) { cout << "Show: " << *it << " at " << it << endl; } int main ( void ) { /* Create dummy planets for testing */ Missile p1; Missile p2; /* Demonstrate Iterator */ p1.for_each(show); /* Create dummy ships for testing */ Ship s1; Ship s2; Ship s3; /* Demonstrate Iterator */ s1.for_each(show); return 0; } Specifically, The list is effectively embedded in each ship though the inheritance mechanism. One must have a ship, in order to access the list of ships. One must have a missile in order to be able to access the list of missiles. That feels awkward. My question boils down to "Is there a better way to do this?" Automatic object container creation Automatic object insertion Container access without requiring an object in the list to access it. I am looking for better ideas. All helpful entries get an upvote. Thanks Evil.

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• WPD MTP data stream hanging on Release

  - by Jonathan Potter

  I've come across a weird problem when reading data from a MTP-compatible mobile device using the WPD (Windows Portable Devices) API, under Windows 8 (not tried any other Windows versions yet). The symptom is, when calling Release on an IStream interface obtained via the IPortableDeviceResources::GetStream function, occasionally the Release call will hang and not return until the device is disconnected from the PC. After some experimentation I've discovered that this never happens as long as the entire contents of the stream have been read. But if the stream has only been partially read (say, the first 256Kb of the file), it can happen seemingly at random (although quite frequently). This has been reproduced with an iPhone and a Windows Phone 8 mobile, so it does not seem to be device-specific. Has anyone come across this sort of issue before? And more importantly, does anyone know of a way to solve it other than by always reading the entire contents of the stream? Thanks!

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• Convert C++Builder AnsiString to std::string via boost::lexical_cast

  - by David Klein

  For a school assignment I have to implement a project in C++ using Borland C++ Builder. As the VCL uses AnsiString for all GUI Components I have to convert all of my std::strings to AnsiString for the sake of displaying. std::string inp = "Hello world!"; AnsiString outp(inp.c_str()); works of course but is a bit tedious to write and code duplication I want to avoid. As we use Boost in other contexts I decided to provide some helper functions go get boost::lexical_cast to work with AnsiString. Here is my implementation so far: std::istream& operator>>(std::istream& istr, AnsiString& str) { istr.exceptions(std::ios::badbit | std::ios::failbit | std::ios::eofbit); std::string s; std::getline(istr,s); str = AnsiString(s.c_str()); return istr; } In the beginning I got Access Violation after Access Violation but since I added the .exceptions() stuff the picture gets clearer. When the conversion is performed I get the following Exception: ios_base::eofbit set [Runtime Error/std::ios_base::failure] Does anyone have an idea how to fix it and can explain why the error occurs? My C++ experience is very limited. The conversion routine the other way round would be: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); return ostr; } Maybe someone will spot an error here too :) With best regards! Edit: At the moment I'm using the edited version of Jem, it works in the beginning. After a while of using the programm the Borland Codeguard mentions some pointer arithmetic in already freed regions. Any ideas how this could be related? The Codeguard log (I'm using the german version, translations marked with stars): ------------------------------------------ Fehler 00080. 0x104230 (r) (Thread 0x07A4): Zeigerarithmetik in freigegebenem Speicher: 0x0241A238-0x0241A258. **(pointer arithmetic in freed region)** | d:\program files\borland\bds\4.0\include\dinkumware\sstream Zeile 126: | { // not first growth, adjust pointers | _Seekhigh = _Seekhigh - _Mysb::eback() + _Ptr; |> _Mysb::setp(_Mysb::pbase() - _Mysb::eback() + _Ptr, | _Mysb::pptr() - _Mysb::eback() + _Ptr, _Ptr + _Newsize); | if (_Mystate & _Noread) Aufrufhierarchie: **(stack-trace)** 0x00411731(=FOSChampion.exe:0x01:010731) d:\program files\borland\bds\4.0\include\dinkumware\sstream#126 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 0x004080C9(=FOSChampion.exe:0x01:0070C9) D:\Projekte\Schule\foschamp\lib\boost_1_34_1\boost/lexical_cast.hpp#151 Objekt (0x0241A238) [Größe: 32 Byte] war erstellt mit new **(Object was created with new)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 28: | _Ty _FARQ *_Allocate(_SIZT _Count, _Ty _FARQ *) | { // allocate storage for _Count elements of type _Ty |> return ((_Ty _FARQ *)::operator new(_Count * sizeof (_Ty))); | } | Aufrufhierarchie: **(stack-trace)** 0x0040ED90(=FOSChampion.exe:0x01:00DD90) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#28 0x0040E194(=FOSChampion.exe:0x01:00D194) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#143 0x004115CF(=FOSChampion.exe:0x01:0105CF) d:\program files\borland\bds\4.0\include\dinkumware\sstream#105 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 Objekt (0x0241A238) war Gelöscht mit delete **(Object was deleted with delete)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 138: | void deallocate(pointer _Ptr, size_type) | { // deallocate object at _Ptr, ignore size |> ::operator delete(_Ptr); | } | Aufrufhierarchie: **(stack-trace)** 0x004044C6(=FOSChampion.exe:0x01:0034C6) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#138 0x00411628(=FOSChampion.exe:0x01:010628) d:\program files\borland\bds\4.0\include\dinkumware\sstream#111 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 ------------------------------------------ Ansistringkonverter.h is the file with the posted operators and line 31 is: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); **(31)** return ostr; } Thanks for your help :)

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• JNI 'problmatic frame' causes JVM to crash

  - by HJED

  Hi I'm using JNI to access the exiv2 library (written in C++) in Java and I'm getting a weird runtime error in the JNI code. I've tried using various -Xms and -Xmx options, but that seems to have no affect. I've also tried running this code on JDK1.7.0 with the same result. # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x00007ff31807757f, pid=4041, tid=140682078746368 # # JRE version: 6.0_20-b20 # Java VM: OpenJDK 64-Bit Server VM (19.0-b09 mixed mode linux-amd64 ) # Derivative: IcedTea6 1.9.2 # Distribution: Ubuntu 10.10, package 6b20-1.9.2-0ubuntu2 # Problematic frame: # V [libjvm.so+0x42757f] # # If you would like to submit a bug report, please include # instructions how to reproduce the bug and visit: # https://bugs.launchpad.net/ubuntu/+source/openjdk-6/ # --------------- T H R E A D --------------- Current thread (0x000000000190d000): JavaThread "main" [_thread_in_Java, id=4043, stack(0x00007ff319447000,0x00007ff319548000)] siginfo:si_signo=SIGSEGV: si_errno=0, si_code=1 (SEGV_MAPERR), si_addr=0x0000000000000024 Registers: ... Register to memory mapping: RAX=0x0000000000000002 0x0000000000000002 is pointing to unknown location RBX=0x000000000190db90 0x000000000190db90 is pointing to unknown location RCX=0x0000000000000000 0x0000000000000000 is pointing to unknown location RDX=0x00007ff3195463f8 0x00007ff3195463f8 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE RSP=0x00007ff319546270 0x00007ff319546270 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE RBP=0x00007ff319546270 0x00007ff319546270 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE RSI=0x0000000000000024 0x0000000000000024 is pointing to unknown location RDI=0x00007ff3195463e0 0x00007ff3195463e0 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R8 =0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R9 =0x000000000190db88 0x000000000190db88 is pointing to unknown location R10=0x00007ff319546300 0x00007ff319546300 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R11=0x0000000000000002 0x0000000000000002 is pointing to unknown location R12=0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R13=0x00007ff319546560 0x00007ff319546560 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R14=0x00007ff3195463e0 0x00007ff3195463e0 is pointing into the stack for thread: 0x000000000190d000 "main" prio=10 tid=0x000000000190d000 nid=0xfcb runnable [0x0000000000000000] java.lang.Thread.State: RUNNABLE R15=0x0000000000000003 0x0000000000000003 is pointing to unknown location Top of Stack: (sp=0x00007ff319546270) ... Instructions: (pc=0x00007ff31807757f) 0x00007ff31807756f: e2 03 48 03 57 58 31 c9 48 8b 32 48 85 f6 74 03 0x00007ff31807757f: 48 8b 0e 48 89 0a 8b 77 68 83 c0 01 39 f0 7c d1 Stack: [0x00007ff319447000,0x00007ff319548000], sp=0x00007ff319546270, free space=1020k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) V [libjvm.so+0x42757f] V [libjvm.so+0x42866b] V [libjvm.so+0x4275c8] V [libjvm.so+0x4331bd] V [libjvm.so+0x44e5c7] C [libExiff2-binding.so+0x1f16] _ZN7JNIEnv_15CallVoidMethodAEP8_jobjectP10_jmethodIDPK6jvalue+0x40 C [libExiff2-binding.so+0x1b96] _Z8loadIPTCSt8auto_ptrIN5Exiv25ImageEEPKcP7JNIEnv_P8_jobject+0x2ba C [libExiff2-binding.so+0x1d3f] _Z7getVarsPKcP7JNIEnv_P8_jobject+0x176 C [libExiff2-binding.so+0x1de7] Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv+0x4b j photo.exiv2.Exiv2MetaDataStore.impl_loadFromExiv(Ljava/lang/String;Lphoto/exiv2/Exiv2MetaDataStore;)V+0 j photo.exiv2.Exiv2MetaDataStore.loadFromExiv2()V+9 j photo.exiv2.Exiv2MetaDataStore.loadData()V+1 j photo.exiv2.Exiv2MetaDataStore.<init>(Lphoto/ImageFile;)V+10 j test.Main.main([Ljava/lang/String;)V+76 v ~StubRoutines::call_stub V [libjvm.so+0x428698] V [libjvm.so+0x4275c8] V [libjvm.so+0x432943] V [libjvm.so+0x447f91] C [java+0x3495] JavaMain+0xd75 --------------- P R O C E S S --------------- Java Threads: ( => current thread ) 0x00007ff2c4027800 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=4060, stack(0x00007ff2c9052000,0x00007ff2c9153000)] 0x00007ff2c4025000 JavaThread "CompilerThread1" daemon [_thread_blocked, id=4059, stack(0x00007ff2c9153000,0x00007ff2c9254000)] 0x00007ff2c4022000 JavaThread "CompilerThread0" daemon [_thread_blocked, id=4058, stack(0x00007ff2c9254000,0x00007ff2c9355000)] 0x00007ff2c401f800 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=4057, stack(0x00007ff2c9355000,0x00007ff2c9456000)] 0x00007ff2c4001000 JavaThread "Finalizer" daemon [_thread_blocked, id=4056, stack(0x00007ff2c994d000,0x00007ff2c9a4e000)] 0x0000000001984000 JavaThread "Reference Handler" daemon [_thread_blocked, id=4055, stack(0x00007ff2c9a4e000,0x00007ff2c9b4f000)] =>0x000000000190d000 JavaThread "main" [_thread_in_Java, id=4043, stack(0x00007ff319447000,0x00007ff319548000)] Other Threads: 0x000000000197d800 VMThread [stack: 0x00007ff2c9b4f000,0x00007ff2c9c50000] [id=4054] 0x00007ff2c4032000 WatcherThread [stack: 0x00007ff2c8f51000,0x00007ff2c9052000] [id=4061] VM state:not at safepoint (normal execution) VM Mutex/Monitor currently owned by a thread: None Heap PSYoungGen total 18432K, used 316K [0x00007ff2fed30000, 0x00007ff3001c0000, 0x00007ff313730000) eden space 15808K, 2% used [0x00007ff2fed30000,0x00007ff2fed7f0b8,0x00007ff2ffca0000) from space 2624K, 0% used [0x00007ff2fff30000,0x00007ff2fff30000,0x00007ff3001c0000) to space 2624K, 0% used [0x00007ff2ffca0000,0x00007ff2ffca0000,0x00007ff2fff30000) PSOldGen total 42240K, used 0K [0x00007ff2d5930000, 0x00007ff2d8270000, 0x00007ff2fed30000) object space 42240K, 0% used [0x00007ff2d5930000,0x00007ff2d5930000,0x00007ff2d8270000) PSPermGen total 21248K, used 2827K [0x00007ff2cb330000, 0x00007ff2cc7f0000, 0x00007ff2d5930000) object space 21248K, 13% used [0x00007ff2cb330000,0x00007ff2cb5f2f60,0x00007ff2cc7f0000) Dynamic libraries: 00400000-00409000 r-xp 00000000 08:03 141899 /usr/lib/jvm/java-6-openjdk/jre/bin/java 00608000-00609000 r--p 00008000 08:03 141899 /usr/lib/jvm/java-6-openjdk/jre/bin/java 00609000-0060a000 rw-p 00009000 08:03 141899 /usr/lib/jvm/java-6-openjdk/jre/bin/java 01904000-019ad000 rw-p 00000000 00:00 0 [heap] ... 7ff2c820c000-7ff2c8232000 r-xp 00000000 08:03 917704 /lib/libexpat.so.1.5.2 7ff2c8232000-7ff2c8432000 ---p 00026000 08:03 917704 /lib/libexpat.so.1.5.2 7ff2c8432000-7ff2c8434000 r--p 00026000 08:03 917704 /lib/libexpat.so.1.5.2 7ff2c8434000-7ff2c8435000 rw-p 00028000 08:03 917704 /lib/libexpat.so.1.5.2 7ff2c8435000-7ff2c844a000 r-xp 00000000 08:03 917708 /lib/libgcc_s.so.1 7ff2c844a000-7ff2c8649000 ---p 00015000 08:03 917708 /lib/libgcc_s.so.1 7ff2c8649000-7ff2c864a000 r--p 00014000 08:03 917708 /lib/libgcc_s.so.1 7ff2c864a000-7ff2c864b000 rw-p 00015000 08:03 917708 /lib/libgcc_s.so.1 7ff2c864b000-7ff2c8733000 r-xp 00000000 08:03 134995 /usr/lib/libstdc++.so.6.0.14 7ff2c8733000-7ff2c8932000 ---p 000e8000 08:03 134995 /usr/lib/libstdc++.so.6.0.14 7ff2c8932000-7ff2c893a000 r--p 000e7000 08:03 134995 /usr/lib/libstdc++.so.6.0.14 7ff2c893a000-7ff2c893c000 rw-p 000ef000 08:03 134995 /usr/lib/libstdc++.so.6.0.14 7ff2c893c000-7ff2c8951000 rw-p 00000000 00:00 0 7ff2c8951000-7ff2c8af3000 r-xp 00000000 08:03 134599 /usr/lib/libexiv2.so.6.0.0 7ff2c8af3000-7ff2c8cf2000 ---p 001a2000 08:03 134599 /usr/lib/libexiv2.so.6.0.0 7ff2c8cf2000-7ff2c8d0f000 r--p 001a1000 08:03 134599 /usr/lib/libexiv2.so.6.0.0 7ff2c8d0f000-7ff2c8d10000 rw-p 001be000 08:03 134599 /usr/lib/libexiv2.so.6.0.0 7ff2c8d10000-7ff2c8d23000 rw-p 00000000 00:00 0 7ff2c8d42000-7ff2c8d45000 r-xp 00000000 08:03 800718 /home/hjed/libExiff2-binding.so 7ff2c8d45000-7ff2c8f44000 ---p 00003000 08:03 800718 /home/hjed/libExiff2-binding.so 7ff2c8f44000-7ff2c8f45000 r--p 00002000 08:03 800718 /home/hjed/libExiff2-binding.so 7ff2c8f45000-7ff2c8f46000 rw-p 00003000 08:03 800718 /home/hjed/libExiff2-binding.so 7ff2c8f46000-7ff2c8f49000 r--s 0000f000 08:03 141333 /usr/lib/jvm/java-6-openjdk/jre/lib/ext/pulse-java.jar 7ff2c8f49000-7ff2c8f51000 r--s 00066000 08:03 408472 /usr/share/java/gnome-java-bridge.jar ... 7ff2ca559000-7ff2ca55b000 r--s 0001d000 08:03 141354 /usr/lib/jvm/java-6-openjdk/jre/lib/plugin.jar 7ff2ca55b000-7ff2ca560000 r--s 00044000 08:03 141353 /usr/lib/jvm/java-6-openjdk/jre/lib/netx.jar 7ff2ca560000-7ff2ca592000 rw-p 00000000 00:00 0 7ff2ca592000-7ff2ca720000 r--s 038af000 08:03 141833 /usr/lib/jvm/java-6-openjdk/jre/lib/rt.jar ... 7ff31673b000-7ff316742000 r-xp 00000000 08:03 141867 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libzip.so 7ff316742000-7ff316941000 ---p 00007000 08:03 141867 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libzip.so 7ff316941000-7ff316942000 r--p 00006000 08:03 141867 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libzip.so 7ff316942000-7ff316943000 rw-p 00007000 08:03 141867 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libzip.so 7ff316943000-7ff31694f000 r-xp 00000000 08:03 921396 /lib/libnss_files-2.12.1.so 7ff31694f000-7ff316b4e000 ---p 0000c000 08:03 921396 /lib/libnss_files-2.12.1.so 7ff316b4e000-7ff316b4f000 r--p 0000b000 08:03 921396 /lib/libnss_files-2.12.1.so 7ff316b4f000-7ff316b50000 rw-p 0000c000 08:03 921396 /lib/libnss_files-2.12.1.so 7ff316b50000-7ff316b5a000 r-xp 00000000 08:03 921398 /lib/libnss_nis-2.12.1.so 7ff316b5a000-7ff316d59000 ---p 0000a000 08:03 921398 /lib/libnss_nis-2.12.1.so 7ff316d59000-7ff316d5a000 r--p 00009000 08:03 921398 /lib/libnss_nis-2.12.1.so 7ff316d5a000-7ff316d5b000 rw-p 0000a000 08:03 921398 /lib/libnss_nis-2.12.1.so 7ff316d5b000-7ff316d63000 r-xp 00000000 08:03 921393 /lib/libnss_compat-2.12.1.so 7ff316d63000-7ff316f62000 ---p 00008000 08:03 921393 /lib/libnss_compat-2.12.1.so 7ff316f62000-7ff316f63000 r--p 00007000 08:03 921393 /lib/libnss_compat-2.12.1.so 7ff316f63000-7ff316f64000 rw-p 00008000 08:03 921393 /lib/libnss_compat-2.12.1.so 7ff316f64000-7ff316f6c000 r-xp 00000000 08:03 141869 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/native_threads/libhpi.so 7ff316f6c000-7ff31716b000 ---p 00008000 08:03 141869 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/native_threads/libhpi.so 7ff31716b000-7ff31716c000 r--p 00007000 08:03 141869 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/native_threads/libhpi.so 7ff31716c000-7ff31716d000 rw-p 00008000 08:03 141869 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/native_threads/libhpi.so 7ff31716d000-7ff317184000 r-xp 00000000 08:03 921392 /lib/libnsl-2.12.1.so 7ff317184000-7ff317383000 ---p 00017000 08:03 921392 /lib/libnsl-2.12.1.so 7ff317383000-7ff317384000 r--p 00016000 08:03 921392 /lib/libnsl-2.12.1.so 7ff317384000-7ff317385000 rw-p 00017000 08:03 921392 /lib/libnsl-2.12.1.so 7ff317385000-7ff317387000 rw-p 00000000 00:00 0 7ff317387000-7ff3173b2000 r-xp 00000000 08:03 141850 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libjava.so 7ff3173b2000-7ff3175b1000 ---p 0002b000 08:03 141850 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libjava.so 7ff3175b1000-7ff3175b2000 r--p 0002a000 08:03 141850 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libjava.so 7ff3175b2000-7ff3175b5000 rw-p 0002b000 08:03 141850 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libjava.so 7ff3175b5000-7ff3175c3000 r-xp 00000000 08:03 141866 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libverify.so 7ff3175c3000-7ff3177c2000 ---p 0000e000 08:03 141866 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libverify.so 7ff3177c2000-7ff3177c4000 r--p 0000d000 08:03 141866 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libverify.so 7ff3177c4000-7ff3177c5000 rw-p 0000f000 08:03 141866 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/libverify.so 7ff3177c5000-7ff3177cc000 r-xp 00000000 08:03 921405 /lib/librt-2.12.1.so 7ff3177cc000-7ff3179cb000 ---p 00007000 08:03 921405 /lib/librt-2.12.1.so 7ff3179cb000-7ff3179cc000 r--p 00006000 08:03 921405 /lib/librt-2.12.1.so 7ff3179cc000-7ff3179cd000 rw-p 00007000 08:03 921405 /lib/librt-2.12.1.so 7ff3179cd000-7ff317a4f000 r-xp 00000000 08:03 921390 /lib/libm-2.12.1.so 7ff317a4f000-7ff317c4e000 ---p 00082000 08:03 921390 /lib/libm-2.12.1.so 7ff317c4e000-7ff317c4f000 r--p 00081000 08:03 921390 /lib/libm-2.12.1.so 7ff317c4f000-7ff317c50000 rw-p 00082000 08:03 921390 /lib/libm-2.12.1.so 7ff317c50000-7ff3184c4000 r-xp 00000000 08:03 141871 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server/libjvm.so 7ff3184c4000-7ff3186c3000 ---p 00874000 08:03 141871 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server/libjvm.so 7ff3186c3000-7ff318739000 r--p 00873000 08:03 141871 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server/libjvm.so 7ff318739000-7ff318754000 rw-p 008e9000 08:03 141871 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server/libjvm.so 7ff318754000-7ff31878d000 rw-p 00000000 00:00 0 7ff31878d000-7ff318907000 r-xp 00000000 08:03 921385 /lib/libc-2.12.1.so 7ff318907000-7ff318b06000 ---p 0017a000 08:03 921385 /lib/libc-2.12.1.so 7ff318b06000-7ff318b0a000 r--p 00179000 08:03 921385 /lib/libc-2.12.1.so 7ff318b0a000-7ff318b0b000 rw-p 0017d000 08:03 921385 /lib/libc-2.12.1.so 7ff318b0b000-7ff318b10000 rw-p 00000000 00:00 0 7ff318b10000-7ff318b12000 r-xp 00000000 08:03 921388 /lib/libdl-2.12.1.so 7ff318b12000-7ff318d12000 ---p 00002000 08:03 921388 /lib/libdl-2.12.1.so 7ff318d12000-7ff318d13000 r--p 00002000 08:03 921388 /lib/libdl-2.12.1.so 7ff318d13000-7ff318d14000 rw-p 00003000 08:03 921388 /lib/libdl-2.12.1.so 7ff318d14000-7ff318d18000 r-xp 00000000 08:03 141838 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/jli/libjli.so 7ff318d18000-7ff318f17000 ---p 00004000 08:03 141838 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/jli/libjli.so 7ff318f17000-7ff318f18000 r--p 00003000 08:03 141838 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/jli/libjli.so 7ff318f18000-7ff318f19000 rw-p 00004000 08:03 141838 /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/jli/libjli.so 7ff318f19000-7ff318f31000 r-xp 00000000 08:03 921401 /lib/libpthread-2.12.1.so 7ff318f31000-7ff319130000 ---p 00018000 08:03 921401 /lib/libpthread-2.12.1.so 7ff319130000-7ff319131000 r--p 00017000 08:03 921401 /lib/libpthread-2.12.1.so 7ff319131000-7ff319132000 rw-p 00018000 08:03 921401 /lib/libpthread-2.12.1.so 7ff319132000-7ff319136000 rw-p 00000000 00:00 0 7ff319136000-7ff31914c000 r-xp 00000000 08:03 917772 /lib/libz.so.1.2.3.4 7ff31914c000-7ff31934c000 ---p 00016000 08:03 917772 /lib/libz.so.1.2.3.4 7ff31934c000-7ff31934d000 r--p 00016000 08:03 917772 /lib/libz.so.1.2.3.4 7ff31934d000-7ff31934e000 rw-p 00017000 08:03 917772 /lib/libz.so.1.2.3.4 7ff31934e000-7ff31936e000 r-xp 00000000 08:03 921379 /lib/ld-2.12.1.so 7ff319387000-7ff319391000 rw-p 00000000 00:00 0 7ff319391000-7ff319447000 rw-p 00000000 00:00 0 7ff319447000-7ff31944a000 ---p 00000000 00:00 0 7ff31944a000-7ff31954d000 rw-p 00000000 00:00 0 7ff319562000-7ff31956a000 rw-s 00000000 08:03 1966453 /tmp/hsperfdata_hjed/4041 7ff31956a000-7ff31956b000 rw-p 00000000 00:00 0 7ff31956b000-7ff31956c000 r--p 00000000 00:00 0 7ff31956c000-7ff31956e000 rw-p 00000000 00:00 0 7ff31956e000-7ff31956f000 r--p 00020000 08:03 921379 /lib/ld-2.12.1.so 7ff31956f000-7ff319570000 rw-p 00021000 08:03 921379 /lib/ld-2.12.1.so 7ff319570000-7ff319571000 rw-p 00000000 00:00 0 7fff0fb03000-7fff0fb24000 rw-p 00000000 00:00 0 [stack] 7fff0fbff000-7fff0fc00000 r-xp 00000000 00:00 0 [vdso] ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall] VM Arguments: jvm_args: -Dfile.encoding=UTF-8 java_command: test.Main Launcher Type: SUN_STANDARD Environment Variables: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games USERNAME=hjed LD_LIBRARY_PATH=/usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server:/usr/lib/jvm/java-6-openjdk/jre/lib/amd64:/usr/lib/jvm/java-6-openjdk/jre/../lib/amd64 SHELL=/bin/bash DISPLAY=:0.0 Signal Handlers: SIGSEGV: [libjvm.so+0x712700], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGBUS: [libjvm.so+0x712700], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGFPE: [libjvm.so+0x5d4020], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGPIPE: [libjvm.so+0x5d4020], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGXFSZ: [libjvm.so+0x5d4020], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGILL: [libjvm.so+0x5d4020], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGUSR1: SIG_DFL, sa_mask[0]=0x00000000, sa_flags=0x00000000 SIGUSR2: [libjvm.so+0x5d3730], sa_mask[0]=0x00000004, sa_flags=0x10000004 SIGHUP: [libjvm.so+0x5d61a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGINT: SIG_IGN, sa_mask[0]=0x00000000, sa_flags=0x00000000 SIGTERM: [libjvm.so+0x5d61a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 SIGQUIT: [libjvm.so+0x5d61a0], sa_mask[0]=0x7ffbfeff, sa_flags=0x10000004 --------------- S Y S T E M --------------- OS:Ubuntu 10.10 (maverick) uname:Linux 2.6.35-24-generic #42-Ubuntu SMP Thu Dec 2 02:41:37 UTC 2010 x86_64 libc:glibc 2.12.1 NPTL 2.12.1 rlimit: STACK 8192k, CORE 0k, NPROC infinity, NOFILE 1024, AS infinity load average:0.25 0.16 0.21 /proc/meminfo: MemTotal: 4048200 kB MemFree: 1230476 kB Buffers: 589572 kB Cached: 911132 kB SwapCached: 0 kB Active: 1321712 kB Inactive: 1202272 kB Active(anon): 1023852 kB Inactive(anon): 7168 kB Active(file): 297860 kB Inactive(file): 1195104 kB Unevictable: 64 kB Mlocked: 64 kB SwapTotal: 7065596 kB SwapFree: 7065596 kB Dirty: 632 kB Writeback: 0 kB AnonPages: 1023368 kB Mapped: 145832 kB Shmem: 7728 kB Slab: 111136 kB SReclaimable: 66316 kB SUnreclaim: 44820 kB KernelStack: 3824 kB PageTables: 27736 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 9089696 kB Committed_AS: 2378396 kB VmallocTotal: 34359738367 kB VmallocUsed: 332928 kB VmallocChunk: 34359397884 kB HardwareCorrupted: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 67136 kB DirectMap2M: 4118528 kB CPU:total 8 (4 cores per cpu, 2 threads per core) family 6 model 26 stepping 5, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1, sse4.2, popcnt, ht Memory: 4k page, physical 4048200k(1230476k free), swap 7065596k(7065596k free) vm_info: OpenJDK 64-Bit Server VM (19.0-b09) for linux-amd64 JRE (1.6.0_20-b20), built on Dec 10 2010 19:45:55 by "buildd" with gcc 4.4.5 time: Sat Jan 1 14:12:27 2011 elapsed time: 0 seconds The java code is: ... public class Main { public static void main(String[] args) { ... ImageFile img = new ImageFile(System.getProperty("user.home") + "/PC100001.JPG"); Exiv2MetaDataStore e = new Exiv2MetaDataStore(img); Iterator<Entry<String, String>> i = e.entrySet().iterator(); while (i.hasNext()) { Entry<String, String> entry = i.next(); System.out.println(entry.getKey() + ":" + entry.getValue()); } //if you switch this print statment with the while loop you get the same error. // System.out.print(e.toString()); } } and /** NB: MetaDataStore is an abstract class that extends HashMap<String,String> */ public class Exiv2MetaDataStore extends MetaDataStore{ ... private final ImageFile F; /** * Creates an meta data store from an ImageFile using Exiv2 * this calls loadData(); * @param f */ public Exiv2MetaDataStore(ImageFile f) { F = f; loadData(); } ... @Override protected void loadData() { loadFromExiv2(); } ... private void loadFromExiv2() { impl_loadFromExiv(F.getAbsolutePath(), this); } private native void impl_loadFromExiv(String path, Exiv2MetaDataStore str); //this method called by the C++ code public void exiv2_reciveElement(String key, String value) { super.put(key,value); } static { Runtime.getRuntime().load("/home/hjed/libExiff2-binding.so"); } } C++ code: #include <exif.hpp> #include <image.hpp> #include <iptc.hpp> #include <exiv2/exiv2.hpp> #include <exiv2/error.hpp> #include <iostream> #include <iomanip> #include <cassert> void loadIPTC(Exiv2::Image::AutoPtr image, const char * path, JNIEnv * env, jobject obj) { Exiv2::IptcData &iptcData = image->iptcData(); //load method jclass cls = env->GetObjectClass(obj); jmethodID mid = env->GetMethodID(cls, "exiv2_reciveElement", "(Ljava/lang/String;Ljava/lang/String;)V"); //is there any IPTC data AND check that method exists if (iptcData.empty() | (mid == NULL)) { std::string error(path); error += ": failed loading IPTC data, there may not be any data"; } else { Exiv2::IptcData::iterator end = iptcData.end(); for (Exiv2::IptcData::iterator md = iptcData.begin(); md != end; ++md) { jvalue values[2]; const char* key = md->key().c_str(); values[0].l = env->NewStringUTF(key); md->value().toString().c_str(); const char* value = md->typeName(); values[2].l = env->NewStringUTF(value); //If I replace the code for values[2] with the commented out code I get the same error. //const char* type = md->typeName(); //values[2].l = env->NewStringUTF(type); env->CallVoidMethodA(obj, mid, values); } } } void getVars(const char* path, JNIEnv * env, jobject obj) { //Load image Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open(path); assert(image.get() != 0); image->readMetadata(); //Load IPTC data loadIPTC(image, path, env, obj); } JNIEXPORT void JNICALL Java_photo_exiv2_Exiv2MetaDataStore_impl_1loadFromExiv(JNIEnv * env, jobject obj, jstring path, jobject obj2) { const char* path2 = env->GetStringUTFChars(path, NULL); getVars(path2, env, obj); env->ReleaseStringUTFChars(path, path2); } I've searched for a fix for this, but I can't find one. I don't have much experience using C++ so if I've made an obvious mistake in the C code I apologies. Thanks for any help, HJED P.S. This is my first post on this site and I wasn't sure how much of the code I needed to show. Sorry if I've put to much up.

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• Storing UTF-8 XML using Word's CustomXMLPart or any other supported way

  - by wpfwannabe

  I am writing a Word add-in which is supposed to store some own XML data per document using Word object model and its CustomXMLPart. The problem I am now facing is the lack of IStream-like functionality for reading/writing XML to/from a CustomXMLPart. It only provides BSTR interface and I am puzzled how to handle UTF-8 XMLs with BSTRs. To my understanding an UTF-8 XML file should really never have to undergo this sort of Unicode conversion. I am not sure what to expect as a result here. Is there another way of using Word automation interfaces to store arbitrary custom information inside a DOCX file?

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• Writing my own iostream utility class: Is this a good idea?

  - by Alex

  I have an application that wants to read word by word, delimited by whitespace, from a file. I am using code along these lines: std::istream in; string word; while (in.good()) { in>>word; // Processing, etc. ... } My issue is that the processing on the words themselves is actually rather light. The major time consumer is a set of mySQL queries I run. What I was thinking is writing a buffered class that reads something like a kilobyte from the file, initializes a stringstream as a buffer, and performs extraction from that transparently to avoid a great many IO operations. Thoughts and advice?

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• Problem of using cin twice.

  - by gc

  Here is the code: string str; cinstr; cout<<"first input:"<<str<<endl; getline(cin, str); cout<<"line input:"<<str<<endl; The result is that getline never pauses for user input, therefore the second output is always empty. After spending some time on it, I realized after the first call "cinstr", it seems '\n' is still stored in cin (using cin.peek() to check), which ends getline immediately. The solution will be adding one more line between the first usage and the second one: cin.ignore(numeric_limits::max(), '\n'); However, I still don't understand, why is '\n' left there after the first call? What does istream& operator really do?

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• redirect inputStream to JTextField

  - by gt_ebuddy

  I want to redirect the Standard System input to JTextField, So that a user must type his/her input in JTextField (instead of console.) I found System.setIn(InputStream istream) for redirecting System.in. Here is my scratch code where i confused on reading from JTextField - inputJTextField. System.setIn(new InputStream() { @Override public int read() throws IOException { //how to read content? return Integer.parseInt(inputJTextField.getText()); } }); My Question is how to read content from GUI Component ( like JTextField and Cast it to String and other types after redirecting the input stream?

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• How to compile a C++ source code written for Linux/Unix on Windows Vista (code given)

  - by HTMZ

  I have a c++ source code that was written in linux/unix environment by some other author. It gives me errors when i compile it in windows vista environment. I am using Bloodshed Dev C++ v 4.9. please help. #include <iostream.h> #include <map> #include <vector> #include <string> #include <string.h> #include <strstream> #include <unistd.h> #include <stdlib.h> using namespace std; template <class T> class PrefixSpan { private: vector < vector <T> > transaction; vector < pair <T, unsigned int> > pattern; unsigned int minsup; unsigned int minpat; unsigned int maxpat; bool all; bool where; string delimiter; bool verbose; ostream *os; void report (vector <pair <unsigned int, int> > &projected) { if (minpat > pattern.size()) return; // print where & pattern if (where) { *os << "<pattern>" << endl; // what: if (all) { *os << "<freq>" << pattern[pattern.size()-1].second << "</freq>" << endl; *os << "<what>"; for (unsigned int i = 0; i < pattern.size(); i++) *os << (i ? " " : "") << pattern[i].first; } else { *os << "<what>"; for (unsigned int i = 0; i < pattern.size(); i++) *os << (i ? " " : "") << pattern[i].first << delimiter << pattern[i].second; } *os << "</what>" << endl; // where *os << "<where>"; for (unsigned int i = 0; i < projected.size(); i++) *os << (i ? " " : "") << projected[i].first; *os << "</where>" << endl; *os << "</pattern>" << endl; } else { // print found pattern only if (all) { *os << pattern[pattern.size()-1].second; for (unsigned int i = 0; i < pattern.size(); i++) *os << " " << pattern[i].first; } else { for (unsigned int i = 0; i < pattern.size(); i++) *os << (i ? " " : "") << pattern[i].first << delimiter << pattern[i].second; } *os << endl; } } void project (vector <pair <unsigned int, int> > &projected) { if (all) report(projected); map <T, vector <pair <unsigned int, int> > > counter; for (unsigned int i = 0; i < projected.size(); i++) { int pos = projected[i].second; unsigned int id = projected[i].first; unsigned int size = transaction[id].size(); map <T, int> tmp; for (unsigned int j = pos + 1; j < size; j++) { T item = transaction[id][j]; if (tmp.find (item) == tmp.end()) tmp[item] = j ; } for (map <T, int>::iterator k = tmp.begin(); k != tmp.end(); ++k) counter[k->first].push_back (make_pair <unsigned int, int> (id, k->second)); } for (map <T, vector <pair <unsigned int, int> > >::iterator l = counter.begin (); l != counter.end (); ) { if (l->second.size() < minsup) { map <T, vector <pair <unsigned int, int> > >::iterator tmp = l; tmp = l; ++tmp; counter.erase (l); l = tmp; } else { ++l; } } if (! all && counter.size () == 0) { report (projected); return; } for (map <T, vector <pair <unsigned int, int> > >::iterator l = counter.begin (); l != counter.end(); ++l) { if (pattern.size () < maxpat) { pattern.push_back (make_pair <T, unsigned int> (l->first, l->second.size())); project (l->second); pattern.erase (pattern.end()); } } } public: PrefixSpan (unsigned int _minsup = 1, unsigned int _minpat = 1, unsigned int _maxpat = 0xffffffff, bool _all = false, bool _where = false, string _delimiter = "/", bool _verbose = false): minsup(_minsup), minpat (_minpat), maxpat (_maxpat), all(_all), where(_where), delimiter (_delimiter), verbose (_verbose) {}; ~PrefixSpan () {}; istream& read (istream &is) { string line; vector <T> tmp; T item; while (getline (is, line)) { tmp.clear (); istrstream istrs ((char *)line.c_str()); while (istrs >> item) tmp.push_back (item); transaction.push_back (tmp); } return is; } ostream& run (ostream &_os) { os = &_os; if (verbose) *os << transaction.size() << endl; vector <pair <unsigned int, int> > root; for (unsigned int i = 0; i < transaction.size(); i++) root.push_back (make_pair (i, -1)); project (root); return *os; } void clear () { transaction.clear (); pattern.clear (); } }; int main (int argc, char **argv) { extern char *optarg; unsigned int minsup = 1; unsigned int minpat = 1; unsigned int maxpat = 0xffffffff; bool all = false; bool where = false; string delimiter = "/"; bool verbose = false; string type = "string"; int opt; while ((opt = getopt(argc, argv, "awvt:M:m:L:d:")) != -1) { switch(opt) { case 'a': all = true; break; case 'w': where = true; break; case 'v': verbose = true; break; case 'm': minsup = atoi (optarg); break; case 'M': minpat = atoi (optarg); break; case 'L': maxpat = atoi (optarg); break; case 't': type = string (optarg); break; case 'd': delimiter = string (optarg); break; default: cout << "Usage: " << argv[0] << " [-m minsup] [-M minpat] [-L maxpat] [-a] [-w] [-v] [-t type] [-d delimiter] < data .." << endl; return -1; } } if (type == "int") { PrefixSpan<unsigned int> prefixspan (minsup, minpat, maxpat, all, where, delimiter, verbose); prefixspan.read (cin); prefixspan.run (cout); }else if (type == "short") { PrefixSpan<unsigned short> prefixspan (minsup, minpat, maxpat, all, where, delimiter, verbose); prefixspan.read (cin); prefixspan.run (cout); } else if (type == "char") { PrefixSpan<unsigned char> prefixspan (minsup, minpat, maxpat, all, where, delimiter, verbose); prefixspan.read (cin); prefixspan.run (cout); } else if (type == "string") { PrefixSpan<string> prefixspan (minsup, minpat, maxpat, all, where, delimiter, verbose); prefixspan.read (cin); prefixspan.run (cout); } else { cerr << "Unknown Item Type: " << type << " : choose from [string|int|short|char]" << endl; return -1; } return 0; }

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• How to switch iostream from binary to text mode and vice versa?

  - by Mad Fish

  I want to read both formatted text and binary data from the same iostream. How can I do that? Why? Imagine this situation: You have different resources, and resource loaders for them, that take a std::istream as a parameter. And there are a "resource source" that provides these streams. Resources can be both text and binary and I need to handle both cases with resource loaders. Or other situation: Image that you have an archive with resources of mixed types. How can I get a text stream from inside the binary archive stream?

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• Modify input stream data on the fly

  - by Frizi

  I would like to implement a std::stream modifier/parser, that is doing data manipulation on the fly. Is it possible to create it in form of stream manipulator? For example, i want to strip all the line comments (from any // to the end of line) out of the stdin and pass it to stdout. string str; istream strippingCin = cin >> stripcomments; while(strippingCin.good()) { strippingCin >> str; cout << str; } There may be also a large file input instead of cin, so i don't want to load full stream data into memory at once. Is it possible without writing my own stream class? Maybe is there another route i should take instead?

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• C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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• Getting selected row in inputListOfValues returnPopupListener

  - by Frank Nimphius

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Model driven list-of-values in Oracle ADF are configured on the ADF Business component attribute which should be updated with the user value selection. The value lookup can be configured to be displayed as a select list, combo box, input list of values or combo box with list of values. Displaying the list in an af:inputListOfValues component shows the attribute value in an input text field and with an icon attached to it for the user to launch the list-of-values dialog. The list-of-values dialog allows users to use a search form to filter the lookup data list and to select an entry, which return value then is added as the value of the af:inputListOfValues component. Note: The model driven LOV can be configured in ADF Business Components to update multiple attributes with the user selection, though the most common use case is to update the value of a single attribute. A question on OTN was how to access the row of the selected return value on the ADF Faces front end. For this, you need to know that there is a Model property defined on the af:inputListOfValues that references the ListOfValuesModel implementation in the model. It is the value of this Model property that you need to get access to. The af:inputListOfValues has a ReturnPopupListener property that you can use to configure a managed bean method to receive notification when the user closes the LOV popup dialog by selecting the Ok button. This listener is not triggered when the cancel button is pressed. The managed bean signature can be created declaratively in Oracle JDeveloper 11g using the Edit option in the context menu next to the ReturnPopupListener field in the PropertyInspector. The empty method signature looks as shown below public void returnListener(ReturnPopupEvent returnPopupEvent) { } The ReturnPopupEvent object gives you access the RichInputListOfValues component instance, which represents the af:inputListOfValues component at runtime. From here you access the Model property of the component to then get a handle to the CollectionModel. The CollectionModel returns an instance of JUCtrlHierBinding in its getWrappedData method. Though there is no tree binding definition for the list of values dialog defined in the PageDef, it exists. Once you have access to this, you can read the row the user selected in the list of values dialog. See the following code: public void returnListener(ReturnPopupEvent returnPopupEvent) {   //access UI component instance from return event RichInputListOfValues lovField =        (RichInputListOfValues)returnPopupEvent.getSource();   //The LOVModel gives us access to the Collection Model and //ADF tree binding used to populate the lookup table ListOfValuesModel lovModel =  lovField.getModel(); CollectionModel collectionModel =          lovModel.getTableModel().getCollectionModel();     //The collection model wraps an instance of the ADF //FacesCtrlHierBinding, which is casted to JUCtrlHierBinding   JUCtrlHierBinding treeBinding =          (JUCtrlHierBinding) collectionModel.getWrappedData();     //the selected rows are defined in a RowKeySet.As the LOV table only   //supports single selections, there is only one entry in the rks RowKeySet rks = (RowKeySet) returnPopupEvent.getReturnValue();     //the ADF Faces table row key is a list. The list contains the //oracle.jbo.Key List tableRowKey = (List) rks.iterator().next();   //get the iterator binding for the LOV lookup table binding   DCIteratorBinding dciter = treeBinding.getDCIteratorBinding();   //get the selected row by its JBO key   Key key = (Key) tableRowKey.get(0); Row rw =  dciter.findRowByKeyString(key.toStringFormat(true)); //work with the row // ... }

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