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  • Efficient database access when dealing with multiple abstracted repositories

    - by Nathan Ridley
    I want to know how most people are dealing with the repository pattern when it involves hitting the same database multiple times (sometimes transactionally) and trying to do so efficiently while maintaining database agnosticism and using multiple repositories together. Let's say we have repositories for three different entities; Widget, Thing and Whatsit. Each repository is abstracted via a base interface as per normal decoupling design processes. The base interfaces would then be IWidgetRepository, IThingRepository and IWhatsitRepository. Now we have our business layer or equivalent (whatever you want to call it). In this layer we have classes that access the various repositories. Often the methods in these classes need to do batch/combined operations where multiple repositories are involved. Sometimes one method may make use of another method internally, while that method can still be called independently. What about, in this scenario, when the operation needs to be transactional? Example: class Bob { private IWidgetRepository _widgetRepo; private IThingRepository _thingRepo; private IWhatsitRepository _whatsitRepo; public Bob(IWidgetRepository widgetRepo, IThingRepository thingRepo, IWhatsitRepository whatsitRepo) { _widgetRepo = widgetRepo; _thingRepo= thingRepo; _whatsitRepo= whatsitRepo; } public void DoStuff() { _widgetRepo.StoreSomeStuff(); _thingRepo.ReadSomeStuff(); _whatsitRepo.SaveSomething(); } public void DoOtherThing() { _widgetRepo.UpdateSomething(); DoStuff(); } } How do I keep my access to that database efficient and not have a constant stream of open-close-open-close on connections and inadvertent invocation of MSDTS and whatnot? If my database is something like SQLite, standard mechanisms like creating nested transactions are going to inherently fail, yet the business layer should not have to be concerning itself with such things. How do you handle such issues? Does ADO.Net provide simple mechanisms to handle this or do most people end up wrapping their own custom bits of code around ADO.Net to solve these types of problems?

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  • Getting problem in threading in JAVA

    - by chetans
    In this program i want to stop GenerateImage & MovingImage Thread both... And i want to start those threads from begining. Can u send me the solution? Here is the code........ package Game; import java.applet.Applet; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Image; import java.awt.MediaTracker; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.net.MalformedURLException; import java.net.URL; public class ThreadInApplet extends Applet implements KeyListener { private static final long serialVersionUID = 1L; Image[] asteroidImage; Image spaceshipImage; String levelstr="Easy Level"; int[] XPos,YPos; int number=0,XPosOfSpaceship,YPosOfSpaceship,NoOfObstacles=5,speed=1,level=1,spaceBtnPressdCntr=0; boolean gameStart=false,pauseGame=false,collideUp=false,collideDown=false,collideLeft=false,collideRight=false; private Image offScreenImage; private Dimension offScreenSize; private Graphics offScreenGraphics; Thread GenerateImages,MoveImages; public void init() { try { GenerateImages=new Thread () //thread to create obstacles { synchronized public void run () { for(int g=0;g<NoOfObstacles;g++) { try { sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } number++; // Temporary counter to count the no of obstacles created } } } ; MoveImages=new Thread () //thread to move obstacles { @SuppressWarnings("deprecation") synchronized public void run () { while(YPos[NoOfObstacles-1]!=600) { pauseGame=false; if(collide()==true) { GenerateImages.suspend(); repaint(); } else GenerateImages.resume(); for(int l=0;l<number;l++) { if(collide()==false) YPos[l]++; else GenerateImages.suspend(); } repaint(); try { sleep(speed); } catch (InterruptedException e) { e.printStackTrace(); } } if(YPos[NoOfObstacles-1]>=600) //level complete state { level++; try { levelUpdation(level); System.out.println("aahe"); } catch (MalformedURLException e) { e.printStackTrace(); } repaint(); } } }; initialPos(); spaceshipImage=getImage(new URL(getCodeBase(),"images/space.png")); for(int i=0;i<NoOfObstacles;i++) { asteroidImage[i]=getImage(new URL(getCodeBase(),"images/asteroid.png")); XPos[i]=(int) (Math.random()*700); YPos[i]=0; } MediaTracker tracker = new MediaTracker (this); for(int i=0;i<NoOfObstacles;i++) { tracker.addImage (asteroidImage[i], 0); } } catch (MalformedURLException e) { e.printStackTrace(); } setBackground(Color.black); addKeyListener(this); } //Sets initial positions of spaceship & obstacle images------------------------------------------------------ public void initialPos() throws MalformedURLException { asteroidImage=new Image[NoOfObstacles]; XPos=new int[NoOfObstacles]; YPos=new int[NoOfObstacles]; XPosOfSpaceship=getWidth()/2-35; YPosOfSpaceship=getHeight()-100; collideUp = false; collideDown=false; collideLeft=false; collideRight=false; } //level finished updations------------------------------------------------------------------------------ @SuppressWarnings("deprecation") public void levelUpdation(int level) throws MalformedURLException { NoOfObstacles=NoOfObstacles+20; speed=speed-3; System.out.println(NoOfObstacles+" "+speed); pauseGame=true; initialPos(); repaint(); } //paint method of graphics to print the messages--------------------------------------------------------- public void paint(Graphics g) { g.setColor(Color.white); if(gameStart==false) { g.drawString("SPACE to start", (getWidth()/2)-15, getHeight()/2); g.drawString(levelstr, (getWidth()/2), getHeight()/2+20); } if(level>1) { if(level==2) levelstr="Medium Level"; else levelstr="High Level"; g.drawString("Level Complete ", (getWidth()/2)-15, getHeight()/2); g.drawString(levelstr, (getWidth()/2), getHeight()/2+20); //g.drawString("SPACE to start", (getWidth()/2)-15, getHeight()/2+40); } for(int n=0;n<number;n++) { if(n>0) g.drawImage(asteroidImage[n],XPos[n],YPos[n],this); } g.drawImage(spaceshipImage,XPosOfSpaceship,YPosOfSpaceship,this); } //update method of graphics to print the messages--------------------------------------------------------- @SuppressWarnings("deprecation") public void update(Graphics g) { Dimension d = size(); if((offScreenImage == null) || (d.width != offScreenSize.width) || (d.height != offScreenSize.height)) { offScreenImage = createImage(d.width, d.height); offScreenSize = d; offScreenGraphics = offScreenImage.getGraphics(); } offScreenGraphics.clearRect(0, 0, d.width, d.height); paint(offScreenGraphics); g.drawImage(offScreenImage, 0, 0, null); } public void keyReleased(KeyEvent arg0){} public void keyTyped(KeyEvent arg0) {} //---------------------Key pressed event to start game & to move the spaceship-------------------------------------- public void keyPressed(KeyEvent e) { if(e.getKeyCode()==32) { spaceBtnPressdCntr++; if(spaceBtnPressdCntr==1) { gameStart=true; GenerateImages.start(); MoveImages.start(); } } if(gameStart==true) { if(e.getKeyCode()==37) { new Thread () { @SuppressWarnings("deprecation") synchronized public void run () { for(int cnt1=1;cnt1<=10;cnt1++) { if(collide()==true && collideLeft == true) { GenerateImages.suspend(); } else { if(XPosOfSpaceship>0) XPosOfSpaceship--; } } repaint(); } }.start(); } if(e.getKeyCode()==38) { new Thread () { @SuppressWarnings("deprecation") synchronized public void run () { for(int cnt1=1;cnt1<=10;cnt1++) { if(collide()==true && collideUp == true) { GenerateImages.suspend(); } else { if(YPosOfSpaceship>10) YPosOfSpaceship--; } } repaint(); } }.start(); } if(e.getKeyCode()==39) { new Thread () { @SuppressWarnings("deprecation") synchronized public void run () { for(int cnt1=1;cnt1<=10;cnt1++) { if(collide()==true && collideRight == true) { GenerateImages.suspend(); } else { if(XPosOfSpaceship<750) XPosOfSpaceship++; } } repaint(); } }.start(); } if(e.getKeyCode()==40) { new Thread () { @SuppressWarnings("deprecation") synchronized public void run () { for(int cnt1=1;cnt1<=10;cnt1++) { if(collide()==true && collideDown == true) { GenerateImages.suspend(); } else { if(YPosOfSpaceship<550) YPosOfSpaceship++; } } repaint(); } }.start(); } } } //------------------------------Collision checking between Spaceship & obstacles------------------------------ public boolean collide() { int x1,y1,x2,y2,x3,y3,x4,y4; //coordinates of obstacles int a1,b1,a2,b2,a3,b3,a4,b4; //coordinates of spaceship a1 =XPosOfSpaceship; b1=YPosOfSpaceship; a2=a1+spaceshipImage.getWidth(this); b2=b1; a3=a1; b3=b1+spaceshipImage.getHeight(this); a4=a2; b4=b3; for(int a=0;a<number;a++) { x1 =XPos[a]; y1=YPos[a]; x2=x1+asteroidImage[a].getWidth(this); y2=y1; x3=x1; y3=y1+asteroidImage[a].getHeight(this); x4=x2; y4=y3; /********checking asteroid touch spaceship from up direction********/ if(y3==b1 && x4>=a1 && x4<=a2) { collideUp = true; collideDown=false; collideLeft=false; collideRight=false; return(true); } if(y3==b1 && x3>=a1 && x3<=a2) { collideUp = true; collideDown=false; collideLeft=false; collideRight=false; return(true); } /********checking asteroid touch spaceship from left direction******/ if(x2==a1 && y4>=b1 && y4<=b3) { collideLeft=true; collideUp = false; collideDown=false; collideRight=false; return(true); } if(x2==a1 && y2>=b1 && y2<=b3) { collideLeft=true; collideUp = false; collideDown=false; collideRight=false; return(true); } /********checking asteroid touch spaceship from right direction*****/ if(x1==a2 && y3>=b2 && y3<=b4) { collideRight=true; collideLeft=false; collideUp = false; collideDown=false; return(true); } if(x1==a2 && y1>=b2 && y1<=b4) { collideRight=true; collideLeft=false; collideUp = false; collideDown=false; return(true); } /********checking asteroid touch spaceship from down direction*****/ if(y1==b3 && x2>=a3 && x2<=a4) { collideDown=true; collideRight=false; collideLeft=false; collideUp = false; return(true); } if(y1==b3 && x1>=a3 && x1<=a4) { collideDown=true; collideRight=false; collideLeft=false; collideUp = false; return(true); } } return(false); } }

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  • What OpenGL functions are not GPU accelerated?

    - by Xavier Ho
    I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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  • Lightweight HTTP application/server for static content

    - by PartlyCloudy
    Hi, I am in need of a scalable and performant HTTP application/server that will be used for static file serving/uploading. So I only need support for GET and PUT operations. However, there are a few extra features that I need: Custom authentication: I need to check credentials against a database for each request. Thus I must be able to integrate propietary database interaction. Support for signed access keys: The access to resources via PUT should be signed using a key like http://uri/?key=foo The key then contains information about the request like md5(user + path + secret) which allows me to block unwanted requests. The application/server should allow me to check for this. Performance: I'd like to avoid piping content as much as possible. Otherwise the whole application could be implemented in Perl/etc. in a few lines as CGI. Perlbal (in webserver mode) looks nice, however the single-threaded model does not fit with my database lookup and it does also not support query strings. Lighttp/Nginx/… have some modules for these tasks, however it is not feasible putting everything together without ending up writing own extensions/modules. So how would you solve this? Are there other leightweight webservers available for this? Should I implement an application inside of a webserver (i.e. CGI). How can I avoid/speed up piping content between the webserver and my application. Thanks in advance!

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  • StoreFilterField input doesn't react

    - by user1289877
    I'm trying to build grid with build in column filtering (using sencha gxt), here is my code: public Grid<Stock> createGrid() { // Columns definition ColumnConfig<Stock, String> nameCol = new ColumnConfig<Stock, String>(props.name(), 100, "Company"); // Column model definition and creation List<ColumnConfig<Stock, ?>> cl = new ArrayList<ColumnConfig<Stock, ?>>(); cl.add(nameCol); ColumnModel<Stock> cm = new ColumnModel<Stock>(cl); // Data populating ListStore<Stock> store = new ListStore<Stock>(props.key()); store.addAll(TestData.getStocks()); // Grid creation with data final Grid<Stock> grid = new Grid<Stock>(store, cm); grid.getView().setAutoExpandColumn(nameCol); grid.setBorders(false); grid.getView().setStripeRows(true); grid.getView().setColumnLines(true); // Filters definition StoreFilterField<Stock> filter = new StoreFilterField<Stock>() { @Override protected boolean doSelect(Store<Stock> store, Stock parent, Stock item, String filter) { // Window.alert(String.valueOf("a")); String name = item.getName(); name = name.toLowerCase(); if (name.startsWith(filter.toLowerCase())) { return true; } return false; } }; filter.bind(store); cm.addHeaderGroup(0, 0, new HeaderGroupConfig(filter, 1, 1)); filter.focus(); return grid; } My problem is: after I run this code, I cannot write anything to filter input, I'm using test data and classes (Stock.java and StockProperties.java) from this example: http://sencha.com/examples-dev/#ExamplePlace:filtergrid I try to put allert in doSelect method to check if this function was called, but it wasn't. Any idea will be welcome. Thanks.

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  • Handle BACK key event in child view

    - by Mick Byrne
    In my app, users can tap on image thumbnails to see a full size version. When the thumbnail is tapped a bunch of new views are created in code (i.e. no XML), appended at the end of the view hierarchy and some scaling and rotating transitions happen, then the full size, high res version of the image is displayed. Tapping on the full size image reverses the transitions and removes the new views from the view hierarchy. I want users to also be able to press the BACK key to reverse the image transitions. However, I can't seem to catch the KeyEvent. This is what I'm trying at the moment: // Set a click listener on the image to reverse everything frameView.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { zoomOut(); // This works fine } }); // Set the focus onto the frame and then set a key listener to catch the back buttons frameView.setFocusable(true); frameView.setFocusableInTouchMode(true); frameView.requestFocus(); frameView.setOnKeyListener(new OnKeyListener() { @Override public boolean onKey(View v, int keyCode, KeyEvent event) { // The code never even gets here !!! if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { zoomOut(); return true; } return false; } });

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  • Project Euler, Problem 10 java solution now working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • Is this a correct way to stop Execution Task

    - by Yan Cheng CHEOK
    I came across code to stop execution's task. private final ExecutorService executor = Executors.newSingleThreadExecutor(); public void stop() { executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (!Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; } I realize that, it is possible for Runnable to be in forever loop, as Unknown fun may Thread.sleep, clear the interrupt flag and ignore the InterruptedException Unknown fun may Thread.interrupted, clear the interrupt flag. I was wondering, is the following way correct way to fix the code? private final ExecutorService executor = Executors.newSingleThreadExecutor(); private volatile boolean flag = true; public void stop() { flag = false; executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (flag && !Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; }

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  • Java/Hibernate using interfaces over the entities.

    - by Dennetik
    I am using annoted Hibernate, and I'm wondering whether the following is possible. I have to set up a series of interfaces representing the objects that can be persisted, and an interface for the main database class containing several operations for persisting these objects (... an API for the database). Below that, I have to implement these interfaces, and persist them with Hibernate. So I'll have, for example: public interface Data { public String getSomeString(); public void setSomeString(String someString); } @Entity public class HbnData implements Data, Serializable { @Column(name = "some_string") private String someString; public String getSomeString() { return this.someString; } public void setSomeString(String someString) { this.someString = someString; } } Now, this works fine, sort of. The trouble comes when I want nested entities. The interface of what I'd want is easy enough: public interface HasData { public Data getSomeData(); public void setSomeData(Data someData); } But when I implement the class, I can follow the interface, as below, and get an error from Hibernate saying it doesn't know the class "Data". @Entity public class HbnHasData implements HasData, Serializable { @OneToOne(cascade = CascadeType.ALL) private Data someData; public Data getSomeData() { return this.someData; } public void setSomeData(Data someData) { this.someData = someData; } } The simple change would be to change the type from "Data" to "HbnData", but that would obviously break the interface implementation, and thus make the abstraction impossible. Can anyone explain to me how to implement this in a way that it will work with Hibernate?

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  • Can Haskell's monads be thought of as using and returning a hidden state parameter?

    - by AJM
    I don't understand the exact algebra and theory behind Haskell's monads. However, when I think about functional programming in general I get the impression that state would be modelled by taking an initial state and generating a copy of it to represent the next state. This is like when one list is appended to another; neither list gets modified, but a third list is created and returned. Is it therefore valid to think of monadic operations as implicitly taking an initial state object as a parameter and implicitly returning a final state object? These state objects would be hidden so that the programmer doesn't have to worry about them and to control how they gets accessed. So, the programmer would not try to copy the object representing the IO stream as it was ten minutes ago. In other words, if we have this code: main = do putStrLn "Enter your name:" name <- getLine putStrLn ( "Hello " ++ name ) ...is it OK to think of the IO monad and the "do" syntax as representing this style of code? putStrLn :: IOState -> String -> IOState getLine :: IOState -> (IOState, String) main :: IOState -> IOState -- main returns an IOState we can call "state3" main state0 = putStrLn state2 ("Hello " ++ name) where (state2, name) = getLine state1 state1 = putStrLn state0 "Enter your name:"

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  • Forming triangles from points and relations

    - by SiN
    Hello, I want to generate triangles from points and optional relations between them. Not all points form triangles, but many of them do. In the initial structure, I've got a database with the following tables: Nodes(id, value) Relations(id, nodeA, nodeB, value) Triangles(id, relation1_id, relation2_id, relation3_id) In order to generate triangles from both nodes and relations table, I've used the following query: INSERT INTO Triangles SELECT t1.id, t2.id , t3.id, FROM Relations t1, Relations t2, Relations t3 WHERE t1.id < t2.id AND t3.id > t1.id AND ( t1.nodeA = t2.nodeA AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeB OR t3.nodeA = t2.nodeB AND t3.nodeB = t1.nodeB) OR t1.nodeA = t2.nodeB AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeA OR t3.nodeA = t2.nodeA AND t3.nodeB = t1.nodeB) ) It's working perfectly on small sized data. (~< 50 points) In some cases however, I've got around 100 points all related to each other which leads to thousands of relations. So when the expected number of triangles is in the hundreds of thousands, or even in the millions, the query might take several hours. My main problem is not in the select query, while I see it execute in Management Studio, the returned results slow. I received around 2000 rows per minute, which is not acceptable for my case. As a matter of fact, the size of operations is being added up exponentionally and that is terribly affecting the performance. I've tried doing it as a LINQ to object from my code, but the performance was even worse. I've also tried using SqlBulkCopy on a reader from C# on the result, also with no luck. So the question is... Any ideas or workarounds?

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  • Refactor link to show/hide a table row

    - by abatishchev
    I have a table with row which cab be hidden by user. It's implemented this way: Markup: <table> <tr> <td> <table style="margin-left: auto; text-align: right;"> <tr> <td class="stats-hide"> <a href="#" onclick="hideStats();">Hide</a> </td> <td class="stats-show" style="display: none;"> <a href="#" onclick="showStats();">Show</a> </td> </tr> </table> </td> </tr> <tr class="stats-hide"> <td> <!-- data --> </td> </tr> </table> And jQuery code: <script type="text/javascript" language="javascript"> function hideStats() { hideControls(true, $('.stats-hide')); hideControls(false, $('.stats-show')); } function showStats() { hideControls(false, $('.stats-hide')); hideControls(true, $('.stats-show')); } function hideControls(value, arr) { $(arr).each(function () { if (value) { $(this).hide(); } else { $(this).show(); } }); } </script> How to implement the same behavior with one, single link and one, probably, CSS class? My idea - store somewhere a boolean variable and toggle controls visibility relatively to this variable. Are there more?

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  • How to write a "thread safe" function in C ?

    - by Andrei Ciobanu
    Hello I am writing some data structures in C, and I've realized that their associated functions aren't thread safe. The i am writing code uses only standard C, and I want to achieve some sort of 'synchronization'. I was thinking to do something like this: enum sync_e { TRUE, FALSE }; typedef enum sync_e sync; struct list_s { //Other stuff struct list_node_s *head; struct list_node_s *tail; enum sync_e locked; }; typedef struct list_s list; , to include a "boolean" field in the list structure that indicates the structures state: locked, unlocked. For example an insertion function will be rewritten this way: int list_insert_next(list* l, list_node *e, int x){ while(l->locked == TRUE){ /* Wait */ } l->locked = TRUE; /* Insert element */ /* -------------- */ l->locked = FALSE; return (0); } While operating on the list the 'locked' field will be set to TRUE, not allowing any other alterations. After operation completes the 'locked' field will be again set to 'TRUE'. Is this approach good ? Do you know other approaches (using only standard C).

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  • Recursive Enumeration in Java

    - by Harm De Weirdt
    Hello everyone. I still have a question about Enumerations. Here's a quick sketch of the situation. I have a class Backpack that has a Hashmap content with as keys a variable of type long, and as value an ArrayList with Items. I have to write an Enumeration that iterates over the content of a Backpack. But here's the catch: in a Backpack, there can also be another Backpack. And the Enumeration should also be able to iterate over the content of a backpack that is in the backpack. (I hope you can follow, I'm not really good at explaining..) Here is the code I have: public Enumeration<Object> getEnumeration() { return new Enumeration<Object>() { private int itemsDone = 0; //I make a new array with all the values of the HashMap, so I can use //them in nextElement() Collection<Long> keysCollection = getContent().keySet(); Long [] keys = keysCollection.toArray(new Long[keysCollection.size()]); public boolean hasMoreElements() { if(itemsDone < getContent().size()) { return true; }else { return false; } } public Object nextElement() { ArrayList<Item> temporaryList= getContent().get(keys[itemsDone]); for(int i = 0; i < temporaryList.size(); i++) { if(temporaryList.get(i) instanceof Backpack) { return temporaryList.get(i).getEnumeration(); }else { return getContent().get(keys[itemsDone++]); } } } }; Will this code work decently? It's just the "return temporaryList.get(i).getEnumeration();" I'm worried about. Will the users still be able to use just the hasMoreElemens() and nextElement() like he would normally do? Any help is appreciated, Harm De Weirdt

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  • Java string to double conversion.

    - by wretrOvian
    Hi, I've been reading up on the net about the issues with handling float and double types in java. Unfortunately, the image is still not clear. Hence, i'm asking here direct. :( My MySQL table has various DECIMAL(m,d) columns. The m may range from 5 to 30. d stays a constant at 2. Question 1. What equivalent data-type should i be using in Java to work (i.e store, retrieve, and process) with the size of the values in my table? (I've settled with double - hence this post). Question 2. While trying to parse a double from a string, i'm getting errors Double dpu = new Double(dpuField.getText()); for example - "1" -> java.lang.NumberFormatException: empty String "10" -> 1.0 "101" -> 10.0 "101." -> 101.0 "101.1" -> 101.0 "101.19" -> 101.1 What am i doing wrong? What is the correct way to convert a string to a double value? And what measures should i take to perform operations on such values?

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  • Very simple python functions takes spends long time in function and not subfunctions

    - by John Salvatier
    I have spent many hours trying to figure what is going on here. The function 'grad_logp' in the code below is called many times in my program, and cProfile and runsnakerun the visualize the results reveals that the function grad_logp spends about .00004s 'locally' every call not in any functions it calls and the function 'n' spends about .00006s locally every call. Together these two times make up about 30% of program time that I care about. It doesn't seem like this is function overhead as other python functions spend far less time 'locally' and merging 'grad_logp' and 'n' does not make my program faster, but the operations that these two functions do seem rather trivial. Does anyone have any suggestions on what might be happening? Have I done something obviously inefficient? Am I misunderstanding how cProfile works? def grad_logp(self, variable, calculation_set ): p = params(self.p,self.parents) return self.n(variable, self.p) def n (self, variable, p ): gradient = self.gg(variable, p) return np.reshape(gradient, np.shape(variable.value)) def gg(self, variable, p): if variable is self: gradient = self._grad_logps['x']( x = self.value, **p) else: gradient = __builtin__.sum([self._pgradient(variable, parameter, value, p) for parameter, value in self.parents.iteritems()]) return gradient

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  • Problems with Database Search Code (asp.net vb)

    - by Phil
    Here is a sample of my database search code: Dim sql As String = "Select * From Table Where " Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Dim andor As Boolean = AndOr1.SelectedValue 'selection can be AND or OR (0 / 1) 'Code for when the user selects AND If NameSearch.Text.ToString IsNot String.Empty And andor = 0 Then sql += "Surname LIKE '%" & name & "%' AND " End If If EmailSearch.Text.ToString IsNot String.Empty And andor = 0 Then sql += "Email LIKE '%" & email & "%' AND " End If If CitySearchBox.Text.ToString IsNot String.Empty And andor = 0 Then sql += "City LIKE '%" & city & "%' AND " End If 'Code for when the user selects OR If NameSearch.Text.ToString IsNot String.Empty And andor = 1 Then sql += "(Surname LIKE '%" & name & "%' OR " End If If EmailSearch.Text.ToString IsNot String.Empty And andor = 1 Then sql += "Email LIKE '%" & email & "%') OR " End If If CitySearchBox.Text.ToString IsNot String.Empty And andor = 1 Then sql += "(City LIKE '%" & city & "%' OR " End If sql = CleanString(sql) End Sub When the user selects AND (as andor.selectedvalue(0)) then the sql is produced fine like this; Select * From Table Where Surname LIKE '%test%' AND Email LIKE '%test%' AND City LIKE '%test%' But if the user selects OR (as andor.selectedvalue(1)), nothing is outputted except; Select * From Table Where Im sure the controls have values so are not string.empty and when the user selects OR the correct value 1 is being assigned to andor.

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  • Designing a chain of states

    - by devoured elysium
    I want to model a kind of FSM(Finite State Machine). I have a sequence of states (let's say, from StateA to StateZ). This sequence is called a Chain and is implemented internally as a List. I will add states by the order I want them to run. My purpose is to be able to make a sequence of actions in my computer (for example, mouse clicks). (I know this has been done a zillion times). So a state is defined as a: boolean Precondition() <- Checks to see if for this state, some condition is true. For example, if I want to click in the Record button of a program, in this method I would check if the program's process is running or not. If it is, go to the next state in the chain list, otherwise, go to what was defined as the fail state (generally is the first state of them all). IState GetNextState() <- Returns the next state to evaluate. If Precondition() was sucessful, it should yield the next state in the chain otherwise it should yield the fail state. Run() Simply checks the Precondition() and sets the internal data so GetNextState() works as expected. So, a naive approach to this would be something like this: Chain chain = new Chain(); //chain.AddState(new State(Precondition, FailState, NextState) <- Method structure chain.AddState(new State(new WinampIsOpenCondition(), null, new <problem here, I want to referr to a state that still wasn't defined!>); The big problem is that I want to make a reference to a State that at this point still wasn't defined. I could circumvent the problem by using strings when refrering to states and using an internal hashtable, but isn't there a clearer alternative? I could just pass only the pre-condition and failure states in the constructor, having the chain just before execution put in each state the correct next state in a public property but that seems kind of awkward.

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  • File mkdirs() method not working in android/java

    - by Leif Andersen
    I've been pulling out my hair on this for a while now. The following method is supposed to download a file, and save it to the location specified on the hard drive. private static void saveImage(Context context, boolean backgroundUpdate, URL url, File file) { if (!Tools.checkNetworkState(context, backgroundUpdate)) return; // Get the image try { // Make the file file.getParentFile().mkdirs(); // Set up the connection URLConnection uCon = url.openConnection(); InputStream is = uCon.getInputStream(); BufferedInputStream bis = new BufferedInputStream(is); // Download the data ByteArrayBuffer baf = new ByteArrayBuffer(50); int current = 0; while ((current = bis.read()) != -1) { baf.append((byte) current); } // Write the bits to the file OutputStream os = new FileOutputStream(file); os.write(baf.toByteArray()); os.close(); } catch (Exception e) { // Any exception is probably a newtork faiilure, bail return; } } Also, if the file doesn't exist, it is supposed to make the directory for the file. (And if there is another file already in that spot, it should just not do anything). However, for some reason, the mkdirs() method never makes the directory. I've tried everything from explicit parentheses, to explicitly making the parent file class, and nothing seems to work. I'm fairly certain that the drive is writable, as it's only called after that has already been determined, also that is true after running through it while debugging. So the method fails because the parent directories aren't made. Can anyone tell me if there is anything wrong with the way I'm calling it? Also, if it helps, here is the source for the file I'm calling it in: https://github.com/LeifAndersen/NetCatch/blob/master/src/net/leifandersen/mobile/android/netcatch/services/RSSService.java Thank you

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  • How do I set streetView in my mapview

    - by John
    I an working on an android project whereby i need to set my map to zoom in and show a more detailed view of my map, like the streets of where i want my coordinates to triangulate. The problem is in Mapview class, setStreetView is deprecated, wat is the alternative? This is how setStreetView looks when i use it. package com.HelloMapView; import java.util.List; import com.google.android.maps.GeoPoint; import com.google.android.maps.MapActivity; import com.google.android.maps.MapController; import com.google.android.maps.MapView; import com.google.android.maps.Overlay; import com.google.android.maps.OverlayItem; import android.app.Activity; import android.graphics.drawable.Drawable; import android.os.Bundle; import android.widget.LinearLayout; public class HelloMapView extends MapActivity { MapView mapview; LinearLayout linearlayout; List<Overlay> mapOverlay; Drawable drawable; HelloItemizedOverlay itemizedOverlay; @SuppressWarnings("deprecation") @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mapview=(MapView)findViewById(R.id.mapview); mapview.setBuiltInZoomControls(true); mapview.setStreetView(true); mapOverlay=mapview.getOverlays(); drawable=this.getResources().getDrawable(R.drawable.androidmarker); itemizedOverlay=new HelloItemizedOverlay(drawable); GeoPoint geoPoint=new GeoPoint(19240000,-99120000); OverlayItem overlayitem=new OverlayItem(geoPoint,"",""); itemizedOverlay.addoverlay(overlayitem); mapOverlay.add(itemizedOverlay); } @Override protected boolean isRouteDisplayed() { // TODO Auto-generated method stub return false; } } this does not work it only shows square boxes with no map at all

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  • How can several different datatypes be saved in one table

    - by poseidon
    This is my situation: I am constructing an ad-like application in Django and Mysql. I am using a flexible-ad approach where we have: a table with ad categories (several categories such as home, furniture, cars, etc.) id_category name a table with details for the ad categories (home: area, squared meters. car: seats, color.) id_detail id_category (the categ the detail describes) name type (boolean, char, int, long, etc.) the ad table (i am selling a house. i am selling a car.) id_ad id_category text date a table where i plan to consolidate the details of the ads (home: A-area, 500 sq-meters. car: 5 seats, red.) id_detail_ad id_ad id_detail value Is this possible? Can I have a table of details for all the ads, even if details include numbers, texts, booleans, etc? Or would I have to save them all as text and then interpret them via code accordingly? Please express your opinions. Thank you.

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  • Compact data structure for storing a large set of integral values

    - by Odrade
    I'm working on an application that needs to pass around large sets of Int32 values. The sets are expected to contain ~1,000,000-50,000,000 items, where each item is a database key in the range 0-50,000,000. I expect distribution of ids in any given set to be effectively random over this range. The operations I need on the set are dirt simple: Add a new value Iterate over all of the values. There is a serious concern about the memory usage of these sets, so I'm looking for a data structure that can store the ids more efficiently than a simple List<int>or HashSet<int>. I've looked at BitArray, but that can be wasteful depending on how sparse the ids are. I've also considered a bitwise trie, but I'm unsure how to calculate the space efficiency of that solution for the expected data. A Bloom Filter would be great, if only I could tolerate the false negatives. I would appreciate any suggestions of data structures suitable for this purpose. I'm interested in both out-of-the-box and custom solutions. EDIT: To answer your questions: No, the items don't need to be sorted By "pass around" I mean both pass between methods and serialize and send over the wire. I clearly should have mentioned this. There could be a decent number of these sets in memory at once (~100).

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  • TreeView update bug in the VB.NET

    - by CFP
    Consider the following code: Dim Working As Boolean = False Private Sub TreeView1_AfterCheck(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterCheck If Working Then Exit Sub Working = True e.Node.Checked = Not e.Node.Checked Working = False End Sub Private Sub TreeView1_MouseClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TreeView1.MouseClick If e.Button = Windows.Forms.MouseButtons.Right Then MsgBox("Checked = " & TreeView1.SelectedNode.Checked) End Sub Where TreeView1 is a TreeView added to the form, with CheckBoxes set to true and one node added. The code basically cancel any node checking occuring on the form. Single-clicking the top node to check it works well : your click is immediately canceled. Yet if you double-click the checkbox, it will display a tick. But verifying the check state through a right click will yield a Checked = False dialog. How come? Is it a bug (I'm using the latest .Net Framework 4.0, and he same occurs in 2.0), or am I doing something wrong here? Is there a work around? Thanks! EDIT: Additionally, the MouseDoubleClick event is not raised before you click once again. EDIT 2: Posted a bug report at Microsoft Connect

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  • Do I have to implement Add/Delete methods in my NHibernate entities ?

    - by Lisa
    This is a sample from the Fluent NHibernate website: Compared to the Entitiy Framework I have ADD methods in my POCO in this code sample using NHibernate. With the EF I did context.Add or context.AddObject etc... the context had the methods to put one entity into the others entity collection! Do I really have to implement Add/Delete/Update methods (I do not mean the real database CRUD operations!) in a NHibernate entity ? public class Store { public virtual int Id { get; private set; } public virtual string Name { get; set; } public virtual IList<Product> Products { get; set; } public virtual IList<Employee> Staff { get; set; } public Store() { Products = new List<Product>(); Staff = new List<Employee>(); } public virtual void AddProduct(Product product) { product.StoresStockedIn.Add(this); Products.Add(product); } public virtual void AddEmployee(Employee employee) { employee.Store = this; Staff.Add(employee); } }

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  • SQL Server 2008 - Full Text Query

    - by user208662
    Hello, I have two tables in a SQL Server 2008 database in my company. The first table represents the products that my company sells. The second table contains the product manufacturer’s details. These tables are defined as follows: Product ------- ID Name ManufacturerID Description Manufacturer ------------ ID Name As you can imagine, I want to make this as easy as possible for our customers to query this data. However, I’m having problems writing a forgiving, yet powerful search query. For instance, I’m anticipating people to search based on phonetical spellings. Because of this, the data may not match the exact data in my database. In addition, I think some individuals will search by manufacturer’s name first, but I want the matching product names to appear first. Based on these requirements, I’m currently working on the following query: select p.Name as 'ProductName', m.Name as 'Manufacturer', r.Rank as 'Rank' from Product p inner join Manufacturer m on p.ManufacturerID=m.ID inner join CONTAINSTABLE(Product, Name, @searchQuery) as r Oddly, this query is throwing an error. However, I have no idea why. Squiggles appear to the right of the last parenthesis in management studio. The tool tip says "An expression of non-boolean type specified in a context where a condition is expected". I understand what this statement means. However, I guess I do not know how COntainsTable works. What am I doing wrong? Thank you

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