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  • Why do I get empty request from the Jakarta Commons HttpClient?

    - by polyurethan
    I have a problem with the Jakarta Commons HttpClient. Before my self-written HttpServer gets the real request there is one request which is completely empty. That's the first problem. The second problem is, sometimes the request data ends after the third or fourth line of the http request: POST / HTTP/1.1 User-Agent: Jakarta Commons-HttpClient/3.1 Host: 127.0.0.1:4232 For debugging I am using the Axis TCPMonitor. There every things is fine but the empty request. How I process the stream: StringBuffer requestBuffer = new StringBuffer(); InputStreamReader is = new InputStreamReader(socket.getInputStream(), "UTF-8"); int byteIn = -1; do { byteIn = is.read(); if (byteIn > 0) { requestBuffer.append((char) byteIn); } } while (byteIn != -1 && is.ready()); String requestData = requestBuffer.toString(); How I send the request: client.getParams().setSoTimeout(30000); method = new PostMethod(url.getPath()); method.getParams().setContentCharset("utf-8"); method.setRequestHeader("Content-Type", "application/xml; charset=utf-8"); method.addRequestHeader("Connection", "close"); method.setFollowRedirects(false); byte[] requestXml = getRequestXml(); method.setRequestEntity(new InputStreamRequestEntity(new ByteArrayInputStream(requestXml))); client.executeMethod(method); int statusCode = method.getStatusCode(); Have anyone of you an idea how to solve these problems? Alex

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  • How do you refactor a large messy codebase?

    - by Ricket
    I have a big mess of code. Admittedly, I wrote it myself - a year ago. It's not well commented but it's not very complicated either, so I can understand it -- just not well enough to know where to start as far as refactoring it. I violated every rule that I have read about over the past year. There are classes with multiple responsibilities, there are indirect accesses (I forget the technical term - something like foo.bar.doSomething()), and like I said it is not well commented. On top of that, it's the beginnings of a game, so the graphics is coupled with the data, or the places where I tried to decouple graphics and data, I made the data public in order for the graphics to be able to access the data it needs... It's a huge mess! Where do I start? How would you start on something like this? My current approach is to take variables and switch them to private and then refactor the pieces that break, but that doesn't seem to be enough. Please suggest other strategies for wading through this mess and turning it into something clean so that I can continue where I left off!

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  • How to make a thread try to reconnect to the Database x times using JDBCTemplate

    - by gillJ
    Hi, I have a single thread trying to connect to a database using JDBCTemplate as follows: JDBCTemplate jdbcTemplate = new JdbcTemplate(dataSource); try{ jdbcTemplate.execute(new CallableStatementCreator() { @Override public CallableStatement createCallableStatement(Connection con) throws SQLException { return con.prepareCall(query); } }, new CallableStatementCallback() { @Override public Object doInCallableStatement(CallableStatement cs) throws SQLException { cs.setString(1, subscriberID); cs.execute(); return null; } }); } catch (DataAccessException dae) { throw new CougarFrameworkException( "Problem removing subscriber from events queue: " + subscriberID, dae); } I want to make sure that if the above code throws DataAccessException or SQLException, the thread waits a few seconds and tries to re-connect, say 5 more times and then gives up. How can I achieve this? Also, if during execution the database goes down and comes up again, how can i ensure that my program recovers from this and continues running instead of throwing an exception and exiting?

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  • How can I make a family of singletons?

    - by Jay
    I want to create a set of classes that share a lot of common behavior. Of course in OOP when you think that you automatically think "abstract class with subclasses". But among the things I want these classes to do is to each have a static list of instances of the class. The list should function as sort of a singleton within the class. I mean each of the sub-classes has a singleton, not that they share one. "Singleton" to that subclass, not a true singleton. But if it's a static, how can I inherit it? Of course code like this won't work: public abstract A { static List<A> myList; public static List getList() { if (myList==null) myList=new ArrayList<A>(10); return myList; } public static A getSomethingFromList() { List listInstance=getList(); ... do stuff with list ... } public int getSomethingFromA() { ... regular code acting against current instance ... } } public class A1 extends A { ... } public class A2 extends A { ... } A1 somethingfromA1List=(A1) A1.getSomethingFromList(); A2 somethingfromA2List=(A2) A2.getSomethingFromList(); The contents of the list for each subclass would be different, but all the code to work on the lists would be the same. The problem with the above code is that I'd only have one list for all the subclasses, and I want one for each. Yes, I could replicate the code to declare the static list in each of the subclasses, but then I'd also have to replicate all the code that adds to the lists and searches the list, etc, which rather defeats the purpose of subclassing. Any ideas on how to do this without replicating code?

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  • jaxb entity print out as xml

    - by Cristian Boariu
    Hi, I have a class, let's say User adnotated with @XmlRootElement, with some properties (name, surname etc). I use this class for REST operations, as application/xml. The client will POST User class so i want to keep the values in the log. Is there any method in jax-ws to prints out this object as xml? For instance: log.info("Customers sent a USER"+user.whichMethod()); Customer sent a User <user> <name>cristi</name> <surname>kevin</surname> </user> Thanks.

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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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  • How do we achieve "substring-match" under O(n) time?

    - by Pacerier
    I have an assignment that requires reading a huge file of random inputs, for example: Adana Izmir Adnan Menderes Apt Addis Ababa Aden ADIYAMAN ALDAN Amman Marka Intl Airport Adak Island Adelaide Airport ANURADHAPURA Kodiak Apt DALLAS/ADDISON Ardabil ANDREWS AFB etc.. If I specify a search term, the program is supposed to find the lines whereby a substring occurs. For example, if the search term is "uradha", the program is supposed to show ANURADHAPURA. If the search term is "airport", the program is supposed to show Amman Marka Intl Airport, Adelaide Airport A quote from the assignment specs: "You are to program this application taking efficiency into account as though large amounts of data and processing is involved.." I could easily achieve this functionality using a loop but the performance would be O(n). I was thinking of using a trie but it seems to only work if the substring starts from index 0. I was wondering what solutions are there which gives a performance better than O(n)?

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  • How to deferentiate between Programmer and JVM Exceptions

    - by Haxed
    As the title suggests, how can I tell a JVM thrown exception from a Programmatically(does this mean, thrown by a programmer or the program) thrown exception ? JVM Exceptions 1) ArrayIndexOutOfBoundsException 2) ClassCastException 3) NullPointerException Programmatically thrown 1) NumberFormatException 2) AssertionError Many Thanks

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  • Unique task queue task names only for active duration

    - by antony.trupe
    I want to guarantee that a task is not in a task queue more then once, so I generate a unique name based on it's payload. But, that task name is reserved for up to 7 days, which is not what I want; I only want it reserved for the duration the task is queued; it could be immediately re-queued. Once a Task with name N is written, any subsequent attempts to insert a Task named N will fail. Eventually (at least seven days after the task successfully executes), the task will be deleted and the name N can be reused. Is there a way to check if the named task is already in the queue then add it if it's not? Or a totally different approach?

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  • What can cause my code to run slower when the server JIT is activated?

    - by durandai
    I am doing some optimizations on an MPEG decoder. To ensure my optimizations aren't breaking anything I have a test suite that benchmarks the entire codebase (both optimized and original) as well as verifying that they both produce identical results (basically just feeding a couple of different streams through the decoder and crc32 the outputs). When using the "-server" option with the Sun 1.6.0_18, the test suite runs about 12% slower on the optimized version after warmup (in comparison to the default "-client" setting), while the original codebase gains a good boost running about twice as fast as in client mode. While at first this seemed to be simply a warmup issue to me, I added a loop to repeat the entire test suite multiple times. Then execution times become constant for each pass starting at the 3rd iteration of the test, still the optimized version stays 12% slower than in the client mode. I am also pretty sure its not a garbage collection issue, since the code involves absolutely no object allocations after startup. The code consists mainly of some bit manipulation operations (stream decoding) and lots of basic floating math (generating PCM audio). The only JDK classes involved are ByteArrayInputStream (feeds the stream to the test and excluding disk IO from the tests) and CRC32 (to verify the result). I also observed the same behaviour with Sun JDK 1.7.0_b98 (only that ist 15% instead of 12% there). Oh, and the tests were all done on the same machine (single core) with no other applications running (WinXP). While there is some inevitable variation on the measured execution times (using System.nanoTime btw), the variation between different test runs with the same settings never exceeded 2%, usually less than 1% (after warmup), so I conclude the effect is real and not purely induced by the measuring mechanism/machine. Are there any known coding patterns that perform worse on the server JIT? Failing that, what options are available to "peek" under the hood and observe what the JIT is doing there?

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  • logging problems for swing applications

    - by mengmenger
    what kind of logging frame work or API to use for swing applications which is used by multiple users in Unix. Is it possible to log all verbose/exception in one file per day or event one user one file per day? Since the user can open the same application with multiple instance. I also have another solution is to save the exceptions into database. But if I miss the excetpions, those will not be saved in DB. anybody has better solutions? Thank you very much!

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  • Android library to get pitch from WAV file

    - by Sakura
    I have a list of sampled data from the WAV file. I would like to pass in these values into a library and get the frequency of the music played in the WAV file. For now, I will have 1 frequency in the WAV file and I would like to find a library that is compatible with Android. I understand that I need to use FFT to get the frequency domain. Is there any good libraries for that? I found that [KissFFT][1] is quite popular but I am not very sure how compatible it is on Android. Is there an easier and good library that can perform the task I want? EDIT: I tried to use JTransforms to get the FFT of the WAV file but always failed at getting the correct frequency of the file. Currently, the WAV file contains sine curve of 440Hz, music note A4. However, I got the result as 441. Then I tried to get the frequency of G4, I got the result as 882Hz which is incorrect. The frequency of G4 is supposed to be 783Hz. Could it be due to not enough samples? If yes, how much samples should I take? //DFT DoubleFFT_1D fft = new DoubleFFT_1D(numOfFrames); double max_fftval = -1; int max_i = -1; double[] fftData = new double[numOfFrames * 2]; for (int i = 0; i < numOfFrames; i++) { // copying audio data to the fft data buffer, imaginary part is 0 fftData[2 * i] = buffer[i]; fftData[2 * i + 1] = 0; } fft.complexForward(fftData); for (int i = 0; i < fftData.length; i += 2) { // complex numbers -> vectors, so we compute the length of the vector, which is sqrt(realpart^2+imaginarypart^2) double vlen = Math.sqrt((fftData[i] * fftData[i]) + (fftData[i + 1] * fftData[i + 1])); //fd.append(Double.toString(vlen)); // fd.append(","); if (max_fftval < vlen) { // if this length is bigger than our stored biggest length max_fftval = vlen; max_i = i; } } //double dominantFreq = ((double)max_i / fftData.length) * sampleRate; double dominantFreq = (max_i/2.0) * sampleRate / numOfFrames; fd.append(Double.toString(dominantFreq)); Can someone help me out? EDIT2: I manage to fix the problem mentioned above by increasing the number of samples to 100000, however, sometimes I am getting the overtones as the frequency. Any idea how to fix it? Should I use Harmonic Product Frequency or Autocorrelation algorithms?

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  • Regex to match CSV file nested quotes

    - by user361970
    Hi, I know this has been discussed a million times. I tried searching through the forums and have seen some close regex expressions and tried to modify them but to no avail. Say there is a line in a csv file like this: "123", 456, "701 "B" Street", 910 Is there an easy regex to detect "B" (since its a non-escaped set of quotes within the normal CSV quotes) and replace it with something like \"B\" ? The final string would end up looking like this: "123", 456, "701 \"B\" Street", 910 Help would be greatly appreciated!

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  • Antlr MismatchedSetException During Interpretation

    - by user1646481
    I am new to Antlr and I have defined a basic grammar using Antlr 3. The grammar compiles and ANTLRWorks generates the Parser and Lexer code without any problems. The grammar can be seen below: grammar i; @header { package i; } module : 'Module1'| 'Module2'; object : 'I'; objectType : 'Name'; filters : EMPTY | 'WHERE' module; table : module object objectType; STRING : ('a'..'z'|'A'..'Z')+; EMPTY : ' '; The problem is that when I interpret the table Parser I get a MismatchedSetException. This is due to having the EMPTY. As soon as I remove EMPTY from the grammar, the interpretation works. I have looked on the Antlr website and some other examples and the Empty space is ' '. I am not sure what to do. I need this EMPTY. As soon as I change the EMPTY to be the following: EMPTY : ''; instead of: EMPTY : ' '; It actually interprets it. However, I am getting the following Exception: Interpreting... [10:57:23] problem matching token at 1:4 NoViableAltException(' '@[1:1: Tokens : ( T__4 | T__5 | T__6 | T__7 | T__8 | T__9 | T__10 | T__11 | T__12 | T__13 | T__14 | T__15 | T__16 );]) [10:57:23] problem matching token at 1:9 NoViableAltException(' '@[1:1: Tokens : ( T__4 | T__5 | T__6 | T__7 | T__8 | T__9 | T__10 | T__11 | T__12 | T__13 | T__14 | T__15 | T__16 );]) When I take out the EMPTY, there are no problems at all. I hope you can help.

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  • writing large excel spreadsheets

    - by pstanton
    has anybody found a library that works well with large spreadsheets? I've tried apache's POI but it fails miserably working with large files - both reading and writing. It uses massive amounts of memory leaving you needing a supercomputer to parse or create a 20+mb spreadsheet. Surely there is a more memory efficient way and someone has written it?!

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  • Workaround for richfaces combobox hotkey bug

    - by John
    Hi, Does anyone know a workaround for the bug https://jira.jboss.org/jira/browse/RF-8076 ? Just to clarify things, we have a form with multiple inputs, one of them being a combobox with auto complete features. We've setup a hotkey via <rich:hotKey key="return" ... /> It works great everywhere except in the combobox, and I would really like to get it working on the combobox as well. The behaviour I want when the ENTER key is pressed inside the combobox is: If the combobox context was modified by auto complete then do nothing Else action the event on ENTER key pressed We're running on seam/richfaces. I'm open to any workaround, but simplicity is much sought for. Thanks!

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  • How to perform a non-polymorphic HQL query in Hibernate?

    - by Eli Acherkan
    Hi all, I'm using Hibernate 3.1.1, and in particular, I'm using HQL queries. According to the documentation, Hibernate's queries are polymorphic: A query like: from Cat as cat returns instances not only of Cat, but also of subclasses like DomesticCat. How can I query for instances of Cat, but not of any of its subclasses? I'd like to be able to do it without having to explicitly mention each subclass. I'm aware of the following options, and don't find them satisfactory: Manually filtering the instances after the query, OR: Manually adding a WHERE clause on the discriminator column. It would make sense for Hibernate to allow the user to decide whether a query should be polymorphic or not, but I can't find such an option. Thanks in advance!

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  • Is it possible to use flashvars with JBoss?

    - by Aikanaro
    Hi, I'm part of a team developing a product using JSF 2.0 and I was asked to investigate the possibility of including FusionCharts free in the app. I have tried different ways of inserting a simple chart in a JSF page but with no luck. On of the methods involves using the elements OBJECT and EMBED but hhen I try to use them I get a "null source" error from JBoss. From what I could find online (through Google), I am under the impression that 'flashvars' isn't quite compatible with JBoss. Is anyone here able to confirm this? If this is the case, what workaround would you suggest me? Other ways I also found online didn't show the chart not even an error message. Thanks in advance.

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  • Android ListActivity with Bitmaps and Garbage Collection issue

    - by chis54
    I have a ListActivity and in it I set my list items with a class that extends SimpleCursorAdapter. I'm overriding bindView to set my Views. I have some TextViews and ImageViews. This is how I set my list items in my cursor adapter: String variableName = "drawable/q" + num + "_200px"; int imageResource = context.getResources().getIdentifier(variableName, "drawable", context.getPackageName()); if (imageResource != 0 ) { // The drawable exists Bitmap b = BitmapFactory.decodeResource(context.getResources(), imageResource); width = b.getWidth(); height = b.getHeight(); imageView.getLayoutParams().width = (int) (width); imageView.getLayoutParams().height = (int) (height); imageView.setImageResource(imageResource); } else { imageView.setImageResource(R.drawable.25trans_200px); } The problem I'm having is whenever I update my list with setListAdapter I get a large amount of garbage collection: D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 125K, 51% free 2710K/5447K, external 2022K/2137K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 30K, 51% free 2701K/5447K, external 2669K/2972K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 51% free 2713K/5447K, external 3479K/3579K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 22K, 51% free 2706K/5447K, external 3303K/3352K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 21K, 51% free 2722K/5447K, external 3569K/3685K, paused 102ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2755K/5447K, external 3499K/3605K, paused 65ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2771K/5447K, external 4213K/4488K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 18K, 49% free 2796K/5447K, external 5057K/5343K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 28K, 49% free 2803K/5447K, external 5944K/5976K, paused 53ms D/dalvikvm( 435): GC_EXPLICIT freed 6K, 54% free 2544K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 165): GC_EXPLICIT freed 85K, 52% free 2946K/6087K, external 4838K/5980K, paused 111ms D/dalvikvm( 448): GC_EXPLICIT freed 1K, 54% free 2540K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 294): GC_EXPLICIT freed 8K, 55% free 2598K/5703K, external 1625K/2137K, paused 64ms What can I do to avoid this? It's causing my UI to be sluggish and when I scroll, too.

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  • Using Apache Velocity with StringBuilders/CharSequences

    - by mindas
    We are using Apache Velocity for dynamic templates. At the moment Velocity has following methods for evaluation/replacing: public static boolean evaluate(Context context, Writer writer, String logTag, Reader reader) public static boolean evaluate(Context context, Writer out, String logTag, String instring) We use these methods by providing StringWriter to write evaluation results. Our incoming data is coming in StringBuilder format so we use StringBuilder.toString and feed it as instring. The problem is that our templates are fairly large (can be megabytes, tens of Ms on rare cases), replacements occur very frequently and each replacement operation triples the amount of required memory (incoming data + StringBuilder.toString() which creates a new copy + outgoing data). I was wondering if there is a way to improve this. E.g. if I could find a way to provide a Reader and Writer on top of same StringBuilder instance that only uses extra memory for in/out differences, would that be a good approach? Has anybody done anything similar and could share any source for such a class? Or maybe there any better solutions to given problem?

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  • Is it bad to have multiple return statements?

    - by scot
    Hi, I have a code somethg like below: int method(string a ,int b , int c){ if(cond1) return -1; if(cond2 || cond3) return 3; if(cond1 && cond2) return 0; else return -999; } Does it perform badly when compared to having multiple if else and have single return?

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  • Compute weighted averages for large numbers

    - by Travis
    I'm trying to get the weighted average of a few numbers. Basically I have: Price - 134.42 Quantity - 15236545 There can be as few as one or two or as many as fifty or sixty pairs of prices and quantities. I need to figure out the weighted average of the price. Basically, the weighted average should give very little weight to pairs like Price - 100000000.00 Quantity - 3 and more to the pair above. The formula I currently have is: ((price)(quantity) + (price)(quantity) + ...)/totalQuantity So far I have this done: double optimalPrice = 0; int totalQuantity = 0; double rolling = 0; System.out.println(rolling); Iterator it = orders.entrySet().iterator(); while(it.hasNext()) { System.out.println("inside"); Map.Entry order = (Map.Entry)it.next(); double price = (Double)order.getKey(); int quantity = (Integer)order.getValue(); System.out.println(price + " " + quantity); rolling += price * quantity; totalQuantity += quantity; System.out.println(rolling); } System.out.println(rolling); return totalQuantity / rolling; The problem is I very quickly max out the "rolling" variable. How can I actually get my weighted average? Thanks!

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  • Why does this expression not work? JSF

    - by Nitesh Panchal
    Hello, I have a simple problem on .xhtml page. This expression is not working :- <a href="Photos.jsf?albumId=#{item.albumId}&blogId=#{PhotoAlbumsCommonBean.blogId}"> photos </a> I get this error :- Error Parsing /Common/PhotoAlbums.xhtml: Error Traced[line: 20] The reference to entity "blogId" must end with the ';' delimiter. & is causing some kind of error. Thanks in advance :)

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