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  • Java: dangerous self-returning-recursive function by IOException?

    - by HH
    I had very errorsome Exception handling with if-clauses. An exception occurs if not found path. An exception returns the function again. The function is recursive. Safe? $ javac SubDirs.java $ java SubDirs Give me an path. . HELLO com TOASHEOU google common annotations base collect internal Give me an path. IT WON'T FIND ME, SO IT RETURNS ITSELF due to Exception caught Give me an path. $ cat SubDirs.java import java.io.*; import java.util.*; public class SubDirs { private List<File> getSubdirs(File file) throws IOException { List<File> subdirs = Arrays.asList(file.listFiles(new FileFilter() { public boolean accept(File f) { return f.isDirectory(); } })); subdirs = new ArrayList<File>(subdirs); List<File> deepSubdirs = new ArrayList<File>(); for(File subdir : subdirs) { deepSubdirs.addAll(getSubdirs(subdir)); } subdirs.addAll(deepSubdirs); return subdirs; } public static void search() { try{ BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String s; System.out.println("Give me an path."); while ((s = in.readLine()) != null && s.length() != 0){ SubDirs dirs = new SubDirs(); List<File> subDirs = dirs.getSubdirs(new File(s)); for ( File f : subDirs ) { System.out.println(f.getName()); } System.out.println("Give me an path."); } }catch(Exception e){ // Simple but is it safe? search(); } } public static void main(String[] args) throws IOException { search(); } }

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  • Type-conditional controls in Haskell

    - by estanford
    I'm going through the 99 Haskell problems to build my proficiency with the language. On problem 7 ("Flatten a nested list structure"), I found myself wanting to define a conditional behavior based on the type of argument passed to a function. That is, since *Main> :t 1 1 :: (Num t) => t *Main> :t [1,2] [1,2] :: (Num t) => [t] *Main> :t [[1],[2]] [[1],[2]] :: (Num t) => [[t]] (i.e. lists nested at different levels have different data types) it seems like I should be able to write a function that can read the type of the argument, and then behave accordingly. My first attempt was along these lines: listflatten l = do if (:t l) /= ((Num t) => [t]) then listflatten (foldl (++) [] l) else id l But when I try to do that, Haskell returns a parse error. Is Haskell flexible enough to allow this sort of type manipulation, do I need to find another way?

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  • bitset to dynamic bitset

    - by mr.bio
    Hi.. I have a function where i use bitset.Now i need to convert it to a dynamic bitset.. but i don't know how. Can somebody help me ? set<string> generateCandidates(set<string> ck,unsigned int k){ set<string> nk ; for (set<string>::const_iterator p = ck.begin( );p != ck.end( ); ++p){ for (set<string>::const_iterator q = ck.begin( );q != ck.end( ); ++q){ bitset<4> bs1(*p); bitset<4> bs2(*q); bs1|= bs2 ; if(bs1.count() == k){ nk.insert(bs1.to_string<char,char_traits<char>,allocator<char> >()); } } } return nk; }

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  • Java: startingPath as "public static final" exception

    - by HH
    [Updated] Thanks to polygenelubricants's reply, the real problem is the exception from the method getCanonicalPath() because I cannot include try-catch-loop there. $ cat StartingPath.java import java.util.*; import java.io.*; public class StartingPath { public static final String startingPath = (new File(".")).getCanonicalPath(); public static void main(String[] args){ System.out.println(startingPath); } } $ javac StartingPath.java StartingPath.java:5: unreported exception java.io.IOException; must be caught or declared to be thrown public static final String startingPath = (new File(".")).getCanonicalPath(); ^ 1 error

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  • I'm having trouble with using std::stack to retrieve the values from a recursive function.

    - by Peter Stewart
    Thanks to the help I received in this post: http://stackoverflow.com/questions/2761918/how-do-i-use-this-in-a-member-function I have a nice, concise recursive function to traverse a tree in postfix order: void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } cout<<cargo<<"\n"; return; }; Now I need to evaluate the values and operators as they are returned. My problem is how to retrieve them. I tried the std::stack: #include <stack> stack <char*> s; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } s.push(cargo); return; }; but when I tried to access it in main() while (!s.empty()) { cout<<s.top<<"\n"; s.pop; } I got the error: 'std::stack<_Ty::top': function call missing argument list; use '&std::stack<_Ty::top' to create a pointer to member' I'm stuck. Another question to follow shortly.

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  • exceptions with python unicode encode/decode functions (why doesn't errors=ignore actually ignore th

    - by gatoatigrado
    Does anyone know why the string conversion functions throw exceptions when errors="ignore" is passed? How can I convert from regular Python string objects to unicode without errors being thrown? Thanks very much! python -c "import codecs; codecs.open('tmp', 'wb', encoding='utf8', errors='ignore').write('?????')" returns Traceback (most recent call last): File "", line 1, in File "/usr/lib/python2.6/codecs.py", line 686, in write return self.writer.write(data) File "/usr/lib/python2.6/codecs.py", line 351, in write data, consumed = self.encode(object, self.errors) UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)

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  • jQuery: Checking for length of ul and removing an li element?

    - by Legend
    I am trying to remove the last <li> element from a <ul> element only if it exceeds a particular length. For this, I am doing something like this: var selector = "#ulelement" if($(selector).children().length > threshold) { $(selector + " >:last").remove(); } I don't like the fact that I have to use the selector twice. Is there a shorter way to do this? Something like a "remove-if-length-greater-than-threshold" idea. I was thinking that maybe there is a way to do this using the live() function but I have no idea how.

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  • Easiest Java image processing solution

    - by Daniel Fath
    Here is the deal, in my Java project I have to make a composite document that combines both text and images; So I'm looking for a way to manipulate pictures (rotate, change size, that sort of thing). The API I'm looking for should be clear and easy to learn (preferably with some examples), it should cover the basic transformations I made above - rotate,change size, eventually crop.

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  • Java: define terms initialization, declaration and assignment

    - by HH
    I find the defs circular statements, the subjects are defined by their verbs but the verbs are undefined! So how do you define them? The question is central to understand the term final, related. The Circular Definitions itialization: to initilise a variable. It can be can be done at the time of declaration. assignment: to assign value to a variable. It can be done anywhere. declaration: to declare value to a variable.

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  • I'm capturing keys on my WinForm but I'm trying to see if the pressed key is a 'String' - getting an

    - by Sergio Tapia
    Here's my code: void gkh_KeyDown(object sender, KeyEventArgs e) { if (e.KeyCode == neededLetter as Keys) { if (neededLetter == "n") { neededLetter = "o"; } else if (neededLetter == "o") { neededLetter = "t"; } else if (neededLetter == "t") { neededLetter = "e"; } else if (neededLetter == "e") { this.Show(); } } else { neededLetter = "n"; } } I'm getting an error on the first If block: The as operator must be used with a reference type or nullable type

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  • Django and Google App Engine Helper not finding the ipaddr module.

    - by Phil
    I'm trying to get Django running on GAE using this tutorial. When I run python manage.py runserver I get the stacktrace below. I'm new to both django and python so I don't know what my next steps are (This is Ubuntu Jaunty btw). It seems django isn't finding the GAE module ipaddr which comes with SDK 1.3.1. How do I get django to find this module? /home/username/bin/google_appengine/google/appengine/api/datastore_file_stub.py:40: DeprecationWarning: the md5 module is deprecated; use hashlib instead import md5 /home/username/bin/google_appengine/google/appengine/api/memcache/__init__.py:31: DeprecationWarning: the sha module is deprecated; use the hashlib module instead import sha Traceback (most recent call last): File "manage.py", line 18, in <module> InstallAppengineHelperForDjango() File "/home/username/Development/GAE/myapp/appengine_django/__init__.py", line 543, in InstallAppengineHelperForDjango InstallDjangoModuleReplacements() File "/home/username/Development/GAE/myapp/appengine_django/__init__.py", line 260, in InstallDjangoModuleReplacements import django.db File "/home/username/Development/GAE/myapp/django/db/__init__.py", line 57, in <module> 'TIME_ZONE': settings.TIME_ZONE, File "/home/username/Development/GAE/myapp/appengine_django/db/base.py", line 117, in __init__ self._setup_stubs() File "/home/username/Development/GAE/myapp/appengine_django/db/base.py", line 128, in _setup_stubs from google.appengine.tools import dev_appserver_main File "/home/username/bin/google_appengine/google/appengine/tools/dev_appserver_main.py", line 82, in <module> from google.appengine.tools import appcfg File "/home/username/bin/google_appengine/google/appengine/tools/appcfg.py", line 53, in <module> from google.appengine.api import dosinfo File "/home/username/bin/google_appengine/google/appengine/api/dosinfo.py", line 25, in <module> import ipaddr ImportError: No module named ipaddr

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  • Trying to manually recreate a simple generate/scaffolding script

    - by montooner
    I'm trying to understand Rails from the ground up. I want to learn how to manually create basic show-all/show-single/CRUD functionality in the framework. I currently am working on the display-all functionality, but am stopped by an error when I try to request all items in the Products db Here are the steps I've taken so far: script/generate controller Products script/generate model Products rake db:migrate modified products_controller.rb to add: def index() { @products = Product.all} (error: uninitialized constant ProductsController::Product) ideally, dump all orders in the view What's the fix?

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  • ActionScript 3.0: placing code on stage/MC timelines a la AS2 instead of in classes

    - by BoltClock
    I'm aware that ActionScript 3.0 is designed from the ground up to be a largely object-oriented language and using it means less or even no timeline code in Flash documents. I'm quite experienced with OOP and am comfortable writing classes. However, since I mostly use Flash for animations, I hardly ever need to write ActionScript code other than for preloaders, subtitles, quality controls, website links and so on. In fact, I still set my Flash movies to use AS2 to this day because I'm used to gotoAndPlay()/gotoAndStop(), AS2 preloaders, subtitles, quality controls and even getURL(). Of course, I really want to move on now that practically everyone's on Flash Player 9 or 10 and now that I've dabbled with other OO languages like Java, C# and Objective-C too. I'm a complete newcomer to AS3 and am not very learned with AS2 either. Considering my current use of ActionScript, are there any cases where it's still OK to use very simple AS3 code in the timeline instead of moving code to a class, especially since moving to a class might mean unnecessarily increasing the number of LOC from 4 to 40? (Heck, is the latter case ('instead of ...') even a valid concern at all?)

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  • Changing classes on multiple divs when selecting specific radio buttons

    - by Rob
    Hey everyone I got a javascript problem I can't seem to find a specific solution for on the web. What I want to be able to do is select one of the radio buttons and have that change the class of #home-right to either .rackmount or .shipping and add the class of .displaynone to the type of dimensions I don't want shown. <div id="home-right" class="rackmount"> <h4 class="helvneuebcn">Case Finder</h4> <div class="cta-options"> <input type="radio" value="Shipping and Storage" name="" checked> Shipping and Storage<br/> <input type="radio" value="Rackmount Enclosures" name=""> Rackmount Enclosures<br/> </div> <div class="shipping-dimensions displaynone"> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">H x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">W x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">L</span></div> </div> <div class="rackmount-dimensions"> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">U Height x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">Rack Depth</span></div> </div> <div class="clear"></div> <input type="button" value="Submit" class="findcase"> </div>

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  • Microsoft C Compiler: Inline variable declaration?

    - by Rosarch
    I'm writing C in Visual Studio 2010. The compiler doesn't seem to want to let me use inline variable declarations. The following code produces an error: unsigned int fibonacci_iterative(unsigned int n) { if (n == 0) { return 0; } if (n == 1) { return 1; } unsigned int prev_prev = 0; // error unsigned int prev = 1; // error unsigned int next = 0; // error for (int term_number = 0; term_number < n; term_number++) { unsigned int temp = prev_prev + prev; prev = next; prev_prev = prev; next = temp; } return next; } Error: error C2143: syntax error : missing ';' before 'type' error C2143: syntax error : missing ';' before 'type' error C2143: syntax error : missing ';' before 'type' Why is this happening? Is there a setting to make the compiler not so strict?

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  • How can ported code be detected?

    - by NiallJG
    If you port code over from one language to another, how can this be detected? Say you were porting code from c++ to Java, how could you tell? What would be the difference between a program designed and implemented in Java, and a near identical program ported over to Java?

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  • Java: design problem with final-value and empty constructor

    - by HH
    $ javac InitInt.java InitInt.java:7: variable right might not have been initialized InitInt(){} ^ 1 error $ cat InitInt.java import java.util.*; import java.io.*; public class InitInt { private final int right; // Design Problem? // I feel the initialization problem is just due to bad style. InitInt(){} InitInt{ // Still the error, "may not be initialized" // How to initialise it? if(snippetBuilder.length()>(charwisePos+25)){ right=charwisePos+25; }else{ right=snippetBuilder.length()-1; } } public static void main(String[] args) { InitInt test = new InitInt(); System.out.println(test.getRight()); } public int getRight(){return right;} } Partial Solutions and Suggestions use "this" to access methods in the class, instead of creating empty constructor change final to non-final with final field value: initialize all final values in every constructor remove the empty constructor, keep your code simple and clean

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  • Haskell simple compilation bug

    - by fmsf
    I'm trying to run this code: let coins = [50, 25, 10, 5, 2,1] let candidate = 11 calculate :: [Int] calculate = [ calculate (x+candidate) | x <- coins, x > candidate] I've read some tutorials, and it worked out ok. I'm trying to solve some small problems to give-me a feel of the language. But I'm stuck at this. test.hs:3:0: parse error (possibly incorrect indentation) Can anyone tell me why? I've started with haskell today so please go easy on the explanations. I've tried to run it like: runghc test.hs ghc test.hs but with: ghci < test.hs it gives this one: <interactive>:1:10: parse error on input `=' Thanks

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  • Add New Gist using the Github API

    - by Ben Shelock
    I'm making a small app in Adobe Air which I need to interact with the Github Gist API. However I'm kind of stuck. If you're not familiar with Adobe Air you can still help, the XMLHttpRequest javascript object can do cross domain requests, as there is no domain as such. So theres nothing Adobe Air specific here. Where I'm stuck is I think I need to authenticate myself then make the POST. I just don't understand it

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  • Should I learn VB.NET or C#?

    - by Ravi
    Background I have decided to do my graduation project (yet to start) in .NET. Regarding it, I am bit confused about: what language should I learn: VB.NET or C#? What I have learnt from those who know it that both VB.NET and C# have: The same concepts VB.NET is simpler as it is more like English statements but also C# is simple too if you already know C (Which I do know) Question So considering some factors, e.g. career point of view, newness, challenging and beneficial, etc., what language should I choose? Please help me out. And clearly do justify your answer (whatever reason you have.) References (Extra) A little information about what project I am doing: It is a database file system. Technologies I'll be using are SQL Server, WPF, etc. I just love the concept of Database file system.So those who want to know more about Database file system, here are the links DBFS (This one is really good.Serves as primary reference for me) Towards A Single Folder Filesystem stackoverflow-What is a database file system? UPDATE1 : After some really good explained answers (actually all are good at their place), I have finally decided to go with C# for myself. Thank you all. Still, you are requested to put your opinion (Once it is reopened,of course) UPDATE2 : Question reopened and made community wiki.Thank you all.

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  • Unreachable statement when using return in finally?

    - by abson
    this compiles class ex1 { public int show() { try { int a=10/10; return 10; } catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally"); } System.out.println("hello"); return 20; } } on the other hand this doesn't class ex15 { public int show() { try { int a=10/0; return 10; } catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally"); return 40; } System.out.println("hello"); return 20; } } and gives unreachable statement System.out.println("hello"); error. why is it so?

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  • Connect to Mongodb in python

    - by SpawnCxy
    I'm a little confused by the document when I tried to connect to the Mongodb.And I find it's different from mysql.I want to create a new database named "mydb" and insert some posts into it.The follows is what I'm trying. from pymongo.connection import Connection import datetime host = 'localhost' port = 27017 user = 'ucenter' passwd = '123' connection = Connection(host,port) db = connection['mydb'] post = {'author':'mike', 'text':'my first blog post!', 'tags':['mongodb','python','pymongo'], 'date':datetime.datetime.utcnow()} posts = db.posts posts.insert(post) #print str(db.collection_names()) And I got an error as pymongo.errors.OperationFailure: database error: unauthorized.How can I do the authorizing part?Thanks.

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