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  • Obtain container type from (its) iterator type in C++ (STL)

    - by KRao
    It is easy given a container to get the associated iterators, example: std::vector<double>::iterator i; //An iterator to a std::vector<double> I was wondering if it is possible, given an iterator type, to deduce the type of the "corresponding container" (here I am assuming that for each container there is one and only one (non-const) iterator). More precisely, I would like a template metafunction that works with all STL containers (without having to specialize it manually for each single container) such that, for example: ContainerOf< std::vector<double>::iterator >::type evaluates to std::vector<double> Is it possible? If not, why? Thank you in advance for any help!

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  • STL for games, yea or nay?

    - by munificent
    Every programming language has its standard library of containers, algorithms, and other helpful stuff. With languages like C#, Java, and Python, it's practically inconceivable to use the language without its standard lib. Yet, on many C++ games I've worked on, we either didn't use the STL at all, used a tiny fraction of it, or used our own implementation. It's hard to tell if that was a sound decision for our games, or one simply made out of ignorance of the STL. So... is the STL a good fit or not?

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  • STL for games, yea or nay?

    - by munificent
    Every programming language has its standard library of containers, algorithms, and other helpful stuff. With languages like C#, Java, and Python, it's practically inconceivable to use the language without its standard lib. Yet, on many C++ games I've worked on, we either didn't use the STL at all, used a tiny fraction of it, or used our own implementation. It's hard to tell if that was a sound decision for our games, or one simply made out of ignorance of the STL. So... is the STL a good fit or not?

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  • Models, collections...and then what? Processes?

    - by Dan
    I'm a LAMP-stack dev who's been more on the JavaScript side the last few years and really enjoying the Model + Collection approach to data entities that BackboneJS, etc. uses. It's helped me organize my code in such a way that it is extremely portable, keeping all my properties and methods in the scope (model, collection, etc.) in which they apply. One thing that keeps bugging me though is how to organize the next level up, the 'process layer' as you might call it, that can potentially operate on instances of either models or collections or whatever else. Where should methods like find() (which returns a collection) and create() (which returns a model) reside? I know some people would put a create() in the Collection prototype, but while a collection operates on models I don't think it's exactly right to create them. And while a find() would return a collection I don't think it correct to have that action within the collection prototype itself (it should be a layer up). Can anyone offer some examples of any patterns that employ some kind of OOP-friendly 'process' layer? I'm sorry if this is a fairly well-known discussion but I'm afraid I can't seem to find the terminology to search for.

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  • VS2008 -> VS2010 leads to cryptic STL errors

    - by Jakobud
    The following C++ library was successfully compiled in VS2008 http://sourceforge.net/projects/xmlrpcc4win/files/xmlrpcc4win/XmlRpcC4Win1.0.8.zip/download When I open it in VS2010, it goes through the conversion wizard process without any errors. Now, when I attempt to compile it in VS2010, I get some weird STL errors like these: 1>TimXmlRpc.cpp(1018): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2275: 'XmlRpcValue::BinaryData' : illegal use of this type as an expression 1>TimXmlRpc.cpp(1018): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1018): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1018): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1019): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_insert_iterator' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C2065: 'back_insert_iterator' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2275: 'std::vector<_Ty>' : illegal use of this type as an expression 1> with 1> [ 1> _Ty=char 1> ] 1>TimXmlRpc.cpp(1031): error C2065: 'ins' : undeclared identifier 1>TimXmlRpc.cpp(1031): error C2039: 'back_inserter' : is not a member of 'std' 1>TimXmlRpc.cpp(1031): error C3861: 'back_inserter': identifier not found 1>TimXmlRpc.cpp(1032): error C2065: 'ins' : undeclared identifier I'm not sure what to make of some of these. For instance, back_insert_iterator is in fact a member of std, but VS doesn't seem to think it is. How do I fix errors like these? They just don't seem to make much sense so I'm not sure where to begin. Perhaps its something in my project settings? For example, here is line 1018, which gives the std error: std::back_insert_iterator<BinaryData> ins = std::back_inserter(*(u.asBinary)); If anyone could give me some direction I'd appreciate it. I'm new enough to C++ that I'm having a tough time figuring out this one.

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  • maps, iterators, and complex structs - STL errors

    - by Austin Hyde
    So, I have two structs: struct coordinate { float x; float y; } struct person { int id; coordinate location; } and a function operating on coordinates: float distance(const coordinate& c1, const coordinate& c2); In my main method, I have the following code: map<int,person> people; // populate people map<int,map<float,int> > distance_map; map<int,person>::iterator it1,it2; for (it1=people.begin(); it1!=people.end(); ++it1) { for (it2=people.begin(); it2!=people.end(); ++it2) { float d = distance(it1->second.location,it2->second.location); distance_map[it1->first][d] = it2->first; } } However, I get the following error upon build: stl_iterator_base_types.h: In instantiation of ‘std::iterator_traits<coordinate>’: stl_iterator_base_types.h:129: error: no type named ‘iterator_category’ in ‘struct coordinate’ stl_iterator_base_types.h:130: error: no type named ‘value_type’ in ‘struct coordinate’ stl_iterator_base_types.h:131: error: no type named ‘difference_type’ in ‘struct coordinate’ stl_iterator_base_types.h:132: error: no type named ‘pointer’ in ‘struct coordinate’ stl_iterator_base_types.h:133: error: no type named ‘reference’ in ‘struct coordinate’ And it blames it on the line: float d = distance(it1->second.location,it2->second.location); Why does the STL complain about my code?

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  • shared memory STL maps

    - by user306963
    Hello, I am writing an Apache module in C++. I need to store the common data that all childs need to read as a portion of shared memory. Structure is kind of map of vectors, so I want to use STL map and vectors for it. I have written a shared allocator and a shared manager for the purpose, they work fine for vectors but not for maps, below is the example: typedef vector<CustomersData, SharedAllocator<CustomersData> > CustomerVector; CustomerVector spData; //this one works fine typedef SharedAllocator< pair< const int, CustomerVector > > PairAllocator; typedef map< int, CustomerVector, less<int>, PairAllocator > SharedMap; SharedMap spIndex; //this one doesn't work I get compile time errors when I try to use the second object (spIndex), which are someting like: ../SpatialIndex.h:97: error: '((SpatialIndex*)this)-SpatialIndex::spIndex' does not have class type It looks like the compiler cannot determine a type for SharedMap template type, which is strange in my opinion, it seems to me that all the template parameters have been specified. Can you help? Thanks Benvenuto

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  • Idiomatic STL: Iterating over a list and inserting elements

    - by mkilling
    I'm writing an algorithm that iterates over a list of points, calculates the distance between them and inserts additional points if the distance is too great. However I seem to be lacking the proper familiarity with STL to come up with an elegant solution. I'm hoping that I can learn something, so I'll just show you my code. You might have some hints for me. for (std::list<PathPoint>::iterator it = ++points_.begin(); it != points_.end(); it++) { Vector curPos = it->getPosition(); Vector prevPos = (--it)->getPosition(); Vector vecFromPrev = curPos - prevPos; float distance = vecFromPrev.abs(); it++; if (distance > MAX_DISTANCE_BETWEEN_POINTS) { int pointsToInsert = (int)(distance / MAX_DISTANCE_BETWEEN_POINTS); Vector curPos = prevPos; for (int i = 0; i < pointsToInsert; i++) { curPos += vecFromPrev / pointsToInsert; it = points_.insert(it, PathPoint(curPos, false)); it++; } } }

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  • How to load/save C++ class instance (using STL containers) to disk

    - by supert
    I have a C++ class representing a hierarchically organised data tree which is very large (~Gb, basically as large as I can get away with in memory). It uses an STL list to store information at each node plus iterators to other nodes. Each node has only one parent, but 0-10 children. Abstracted, it looks something like: struct node { public: node_list_iterator parent; // iterator to a single parent node double node_data_array[X]; map<int,node_list_iterator> children; // iterators to child nodes }; class strategy { private: list<node> tree; // hierarchically linked list of nodes struct some_other_data; public: void build(); // build the tree void save(); // save the tree from disk void load(); // load the tree from disk void use(); // use the tree }; I would like to implement the load() and save() to disk, and it should be fairly fast, however the obvious problems are: I don't know the size in advance; The data contains iterators, which are volatile; My ignorance of C++ is prodigious. Could anyone suggest a pure C++ solution please?

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  • C++ STL question related to insert iterators and sets

    - by rshepherd
    #include #include #include #include using namespace std; class MyContainer { public: string value; MyContainer& operator=(const string& s) { this->value = s; return *this; } }; int main() { list<string> strings; strings.push_back("0"); strings.push_back("1"); strings.push_back("2"); set<MyContainer> containers; copy(strings.begin(), strings.end(), inserter(containers, containers.end())); } The preceeding code does not compile. In typical STL style the error output is verbose and difficult to understand. The key part seems to be this... /usr/include/c++/4.4/bits/stl_algobase.h:313: error: no match for ‘operator=’ in ‘__result.std::insert_iterator::operator* [with _Container = std::set, std::allocator ]() = __first.std::_List_iterator::operator* [with _Tp = std::basic_string, std::allocator ]()’ ...which I interpet to mean that the assignment operator needed is not defined. I took a look at the source code for insert_iterator and noted that it has overloaded the assignment operator. The copy algorithm must uses the insert iterators overloaded assignment operator to do its work(?). I guess that because my input iterator is on a container of strings and my output iterator is on a container of MyContainers that the overloaded insert_iterator assignment operator can no longer work. This is my best guess, but I am probably wrong. So, why exactly does this not work and how can I accomplish what I am trying to do?

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  • Book Review &ndash; Developer&rsquo;s Guide To Collections in Microsoft&reg; .NET

    - by Lori Lalonde
    Developer’s Guide To Collections in Microsoft® .NET, by Calvin Janes, discusses the various collections available in the built-in NET libraries, as well as  the advantages and disadvantages of using each type of collection. Other areas are also covered including how collections utilize memory, how to use LINQ with collections, using threading with collections, serializing collections, and how to bind collections to controls in Windows Forms, WPF and Silverlight. For developers looking for a simple reference book on collections, then this book will serve that purpose and serve it well. For those looking for a great read from cover-to-cover, they may be disappointed. This book tends to be repetitive in discussion topics, examples, and code samples in the first two parts of the book. In the first part, the author conducts walk-throughs to develop custom collections. In  the second part, the author conducts walk-throughs on using the built-in .NET collections. For experienced .NET developers, the first two parts will not provide much value. However, it is beneficial for new developers who have not worked with the built-in collections in .NET. They will obtain an understanding of the mechanics of the built-in collections and how memory is utilized when using the various types of collections. So in this aspect, new developers will get more value out of this book. The third and fourth parts delve into advanced topics, including using LINQ, threading, serialization and data binding. I find these two parts of the book are well written and flow better than the first two parts. Both beginner and experienced developers will find value in this half of the book, mainly on the topics of threading and serialization. The eBook format of this book was provided free through O'Reilly's Blogger Review program. This book can be purchased from the O'Reilly book store at: http://shop.oreilly.com/product/0790145317193.do

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  • C++ STL make_heap and pop_heap not working.

    - by Henrique
    I need to use a Heap, so i've searched about the STL one, but it doesn't seem to work, i wrote some code to explain what i mean: #include <stdio.h> #include <stdlib.h> #include <vector> #include <algorithm> struct data { int indice; int tamanho; }; bool comparator2(const data* a, const data* b) { return (a->tamanho < b->tamanho); } int main() { std::vector<data*> mesas; data x1, x2, x3, x4, x5; x1.indice = 1; x1.tamanho = 3; x2.indice = 2; x2.tamanho = 5; x3.indice = 3; x3.tamanho = 2; x4.indice = 4; x4.tamanho = 6; x5.indice = 5; x5.tamanho = 4; mesas.push_back(&x1); mesas.push_back(&x2); mesas.push_back(&x3); mesas.push_back(&x4); mesas.push_back(&x5); make_heap(mesas.begin(), mesas.end(), comparator2); for(int i = 0 ; i < 5 ; i++) { data* mesa = mesas.front(); pop_heap(mesas.begin(),mesas.end()); mesas.pop_back(); printf("%d, %d\n", mesa->indice, mesa->tamanho); } return 0; }; and this is what i get: 4, 6 2, 5 1, 3 3, 2 5, 4 So it's not working as a heap, as the maximum element on the vector is not being returned right. Or am i doing something wrong?

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  • Is it a good idea to create an STL iterator which is noncopyable?

    - by BillyONeal
    Most of the time, STL iterators are CopyConstructable, because several STL algorithms require this to improve performance, such as std::sort. However, I've been working on a pet project to wrap the FindXFile API (previously asked about), but the problem is it's impossible to implement a copyable iterator around this API. A find handle cannot be duplicated by any means -- DuplicateHandle specifically forbids passing handles to it. And if you just maintain a reference count to the find handle, then a single increment by any copy results in an increment of all copies -- clearly that is not what a copy constructed iterator is supposed to do. Since I can't satisfy the traditional copy constructible requirement for iterators here, is it even worth trying to create an "STL style" iterator? On one hand, creating some other enumeration method is going to not fall into normal STL conventions, but on the other, following STL conventions are going to confuse users of this iterator if they try to CopyConstruct it later. Which is the lesser of two evils?

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  • What is the right approach when using STL container for median calculation?

    - by sharkin
    Let's say I need to retrieve the median from a sequence of 1000000 random numeric values. If using anything but STL::list, I have no (built-in) way to sort sequence for median calculation. If using STL::list, I can't randomly access values to retrieve middle (median) of sorted sequence. Is it better to implement sorting myself and go with e.g. STL::vector, or is it better to use STL::list and use STL::list::iterator to for-loop-walk to the median value? The latter seems less overheadish, but also feels more ugly.. Or are there more and better alternatives for me?

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  • Bewildering SegFault involving STL sort algorithm.

    - by just_wes
    Hello everybody, I am completely perplexed at a seg fault that I seem to be creating. I have: vector<unsigned int> words; and global variable string input; I define my custom compare function: bool wordncompare(unsigned int f, unsigned int s) { int n = k; while (((f < input.size()) && (s < input.size())) && (input[f] == input[s])) { if ((input[f] == ' ') && (--n == 0)) { return false; } f++; s++; } return true; } When I run the code: sort(words.begin(), words.end()); The program exits smoothly. However, when I run the code: sort(words.begin(), words.end(), wordncompare); I generate a SegFault deep within the STL. The GDB back-trace code looks like this: #0 0x00007ffff7b79893 in std::string::size() const () from /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/libstdc++.so.6 #1 0x0000000000400f3f in wordncompare (f=90, s=0) at text_gen2.cpp:40 #2 0x000000000040188d in std::__unguarded_linear_insert<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, unsigned int, bool (*)(unsigned int, unsigned int)> (__last=..., __val=90, __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1735 #3 0x00000000004018df in std::__unguarded_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1812 #4 0x0000000000402562 in std::__final_insertion_sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:1845 #5 0x0000000000402c20 in std::sort<__gnu_cxx::__normal_iterator<unsigned int*, std::vector<unsigned int, std::allocator<unsigned int> > >, bool (*)(unsigned int, unsigned int)> (__first=..., __last=..., __comp=0x400edc <wordncompare(unsigned int, unsigned int)>) at /usr/lib/gcc/x86_64-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:4822 #6 0x00000000004012d2 in main (argc=1, args=0x7fffffffe0b8) at text_gen2.cpp:70 I have similar code in another program, but in that program I am using a vector instead of vector. For the life of me I can't figure out what I'm doing wrong. Thanks!

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  • SCCM 2007 Collections per OU

    - by VirtualizeIT
    Recently I wanted to create our SCCM collections setup as our Active Directory structure. I finally figured out how to create collections per OU of the domain. I decided to create a simple tutorial that may help other IT professionals the steps to complete this task.   1. Open the ConfigMgr and navigation to the collections. To navigate to the collections go to Site Database>Computer Management>Collections. 2. In the ‘Collections’ right-click and select New Collections. Then it will pop up a Wizards so you can enter the name of the collection and any notes that you may want to add that is associated with the collection.                       3. Next, select the database icon. In the ‘Name’ textbox enter the name of the query. I named mine ‘Query’ just for simplicity sake. After you enter the name select ‘Edit Query Statement…’ 4. Select the ‘Criteria’ tab 5. Select the icon that looks like a sun. 6. At this point you should see a dialog box like this…                     7. Next, click the ‘select’ button. 8. Under the ‘Attribute class’ scroll through until you see ’System Resource’ and for the ‘Attribute"’ scroll through you see ‘System OU Name’. It should look something like this…                 9. After that select OK. 10. In the ‘Value’ textbox enter the string that is associated with the OU in your domain. NOTE: If you don’t know your string name for your OU you can simply go to “Active Directory Users and Computers” and right-click on the OU and select properties. In the ‘object’ tab you should see the string under the ‘Canonical name of object”. That is the string that you put in the ‘Value’ text box. 11. After you enter the OU string name press OK>OK>OK>NEXT>NEXT>FINISH.   That’s it!   I hope this tutorial has help you understand how to create a collection through your OU structure.

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  • c++ stl priority queue insert bad_alloc exception

    - by bsg
    Hi, I am working on a query processor that reads in long lists of document id's from memory and looks for matching id's. When it finds one, it creates a DOC struct containing the docid (an int) and the document's rank (a double) and pushes it on to a priority queue. My problem is that when the word(s) searched for has a long list, when I try to push the DOC on to the queue, I get the following exception: Unhandled exception at 0x7c812afb in QueryProcessor.exe: Microsoft C++ exception: std::bad_alloc at memory location 0x0012ee88.. When the word has a short list, it works fine. I tried pushing DOC's onto the queue in several places in my code, and they all work until a certain line; after that, I get the above error. I am completely at a loss as to what is wrong because the longest list read in is less than 1 MB and I free all memory that I allocate. Why should there suddenly be a bad_alloc exception when I try to push a DOC onto a queue that has a capacity to hold it (I used a vector with enough space reserved as the underlying data structure for the priority queue)? I know that questions like this are almost impossible to answer without seeing all the code, but it's too long to post here. I'm putting as much as I can and am anxiously hoping that someone can give me an answer, because I am at my wits' end. The NextGEQ function is too long to put here, but it reads a list of compressed blocks of docids block by block. That is, if it sees that the lastdocid in the block (in a separate list) is larger than the docid passed in, it decompresses the block and searches until it finds the right one. If it sees that it was already decompressed, it just searches. Below, when I call the function the first time, it decompresses a block and finds the docid; the push onto the queue after that works. The second time, it doesn't even need to decompress; that is, no new memory is allocated, but after that time, pushing on to the queue gives a bad_alloc error. struct DOC{ long int docid; long double rank; public: DOC() { docid = 0; rank = 0.0; } DOC(int num, double ranking) { docid = num; rank = ranking; } bool operator>( const DOC & d ) const { return rank > d.rank; } bool operator<( const DOC & d ) const { return rank < d.rank; } }; struct listnode{ int* metapointer; int* blockpointer; int docposition; int frequency; int numberdocs; int* iquery; listnode* nextnode; }; void QUERYMANAGER::SubmitQuery(char *query){ vector<DOC> docvec; docvec.reserve(20); DOC doct; //create a priority queue to use as a min-heap to store the documents and rankings; //although the priority queue uses the heap as its underlying data structure, //I found it easier to use the STL priority queue implementation priority_queue<DOC, vector<DOC>,std::greater<DOC>> q(docvec.begin(), docvec.end()); q.push(doct); //do some processing here; startlist is a pointer to a listnode struct that starts the //linked list cout << "Opening lists:" << endl; //point the linked list start pointer to the node returned by the OpenList method startlist = &OpenList(value); listnode* minpointer; q.push(doct); //more processing here; else{ //start by finding the first docid in the shortest list int i = 0; q.push(doct); num = NextGEQ(0, *startlist); q.push(doct); while(num != -1) cout << "finding nextGEQ from shortest list" << endl; q.push(doct); //the is where the problem starts - every previous q.push(doct) works; the one after //NextGEQ(num +1, *startlist) gives the bad_alloc error num = NextGEQ(num + 1, *startlist); q.push(doct); //if you didn't break out of the loop; i.e., all lists contain a matching docid, //calculate the document's rank; if it's one of the top 20, create a struct //containing the docid and the rank and add it to the priority queue if(!loop) { cout << "found match" << endl; if(num < 0) { cout << "reached end of list" << endl; //reached the end of the shortest list; close the list CloseList(startlist); break; } rank = calculateRanking(table, num); try{ //if the heap is not full, create a DOC struct with the docid and //rank and add it to the heap if(q.size() < 20) { doc.docid = num; doc.rank = rank; q.push(doct); q.push(doc); } } catch (exception& e) { cout << e.what() << endl; } } } Thank you very much, bsg.

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  • MongoDB - proper use of collections?

    - by zmg
    In Mongo my understanding is that you can have databases and collections. I'm working on a social-type app that will have blogs and comments (among other things) and had previously be using MySQL and pretty heavy partitioning in an attempt to limit possible concurrency issues. With MySQL I've stuffed all my user data into a _user database with several tables to further partition the data (blogs, pages, etc). My immediate reaction with Mongo would be to create a 'users' database with one collection per user. In this way user 'zach' blog entries would go into the 'zach' collection with associated comments and such becoming sub-objects in the same collection. Basically like dynamically creating one table per user in MySQL, but apparently without the complexity and limitations that might impose. Of course since I haven't really used Mongo before I'm having trouble gauging the (ahem..) quality of this idea and the potential problems it might cause down the road. I'd like user data to be treated a lot like a users directory in a *nix environment where user created/non-shared (mostly) gets put into one place (currently with MySQL that would be the appname_users as mentioned above). Most of the users data will be specific to the users page(s). Some of the user data which is queried across all site users (searchable user profiles) is currently kept in a separate database/table and I expect things like this could be put into a appname_system database and be broken up into collections and/or application specific databases (appname_profiles). Anyway, since the available documentation on this is currently a little thin and my experience is extremely limited I thought I might find a little guidance from someone with a better working understanding of the system. On the plus side I'd really already been attempting to treat MySQL as a schema-less document-store and doing this with Mongo seems much more intuitive/sane/rational so I'm really looking forward to getting started. Thanks, Zach

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  • Google collections GWT jar

    - by Sudhir Jonathan
    Has anyone had any luck rolling a custom GWT jar for Google Collections / Guava? I've tried uncommenting the relevant ant tasks and running them, but I just get empty folders in the JAR. Can't seem to get the include rules right :-/

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  • Java Collections Sort not accepting comparator constructor with arg

    - by harmzl
    I'm getting a compiler error for this line: Collections.sort(terms, new QuerySorter_TFmaxIDF(myInteger)); My customized Comparator is pretty basic; here's the signature and constructor: public class QuerySorter_TFmaxIDF implements Comparator<Term>{ private int numberOfDocs; QuerySorter_TFmaxIDF(int n){ super(); numberOfDocs = n; } } Is there an error because I'm passing an argument into the Comparator? I need to pass an argument...

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  • To instantiate BiMap Of google-collections in Java

    - by Masi
    How can you instantiate a Bimap of Google-collections? I know the thread. A sample of my code import com.google.common.collect.BiMap; public class UserSettings { private Map<String, Integer> wordToWordID; UserSettings() { this.wordToWordID = new BiMap<String. Integer>(); I get cannot instantiate the type BiMap<String, Integer>.

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  • Java - Collections.sort() performance

    - by msr
    Hello, Im using Collections.sort() to sort a LinkedList whose elements implements Comparable interface, so they are sorted in a natural order. In the javadoc documentation its said this method uses mergesort algorithm wich has n*log(n) performance. My question is if there is a more efficient algorithm to sort my LinkedList? The size of that list could be very high and sort will be also very frequent. Thanks!

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