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  • simple process rollback question

    - by OckhamsRazor
    hi folks! while revising for an exam, i came across this simple question asking about rollbacks in processes. i understand how rollbacks occur, but i need some validation on my answer. The question: my confusion results from the fact that there is interprocess communication between the processes. does that change anything in terms of where to rollback? my answer would be R13, R23, R32 and R43. any help is greatly appreciated! thanks!

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  • Does Hibernate always need a setter when there is a getter?

    - by Marcus
    We have some Hibernate getter methods annotated with both @Column and @Basic. We get an exception if we don't have the corresponding setter. Why is this? In our case we are deriving the value returned from the getter (to get stored in the DB) and the setter has no functional purpose. So we just have an empty method to get around the error condition..

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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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  • Can I connect to SQL from JavaScript MVC?

    - by user54197
    I am populating a list of names that will be added to my Sql Database. In this simple case, how do I send the information to SQL server without my page being refreshed? <script type="text/javascript"> function addNewRow() { $('#displayPropertyTable tr:last').after('<tr><td style="font-size:smaller;" class="name"></td><td style="font-size:smaller;" class="address"></td></tr>'); var $tr = $('#displayPropertyTable tr:last'); var propertyCondition = $('#txtPropAddress').val(); if (propertyCondition != "") { $tr.find('.name').text($('#txtPropName').val()); $tr.find('.address').text($('#txtPropAddress').val()); } } </script> ... <table id="displayPropertyTable" width= "100%"> <tr> <td style="font-size:smaller;" class="name"></td> <td style="font-size:smaller;" class="address"></td> </tr> </table> ... <table> <tr> <td><b>Name</b></td> <td colspan="2"><input id="txtPropName" type="text" /></td> </tr> <tr> <td><b>Address</b></td> <td colspan="2"><input id="txtPropAddress" type="text" /></td> </tr> </table> ... <button onclick="addNewRow();">Add</button>

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  • Inheritance or identifier

    - by Lina
    Hi! Does anyone here have opinions about when to user inheritance and when to use an identifier instead? Inheritance example: class Animal { public int Name { get; set; } } class Dog : Animal {} class Cat : Animal {} Identifier example: class Animal { public int Name { get; set; } public AnimalType { get; set; } } In what situations should i prefer which solution and what are the pros and cons for them? /Lina

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  • How to access a variable in other class?

    - by Christine
    Hi! I've problem regarding GUI with one Menu and one Order Class. I've created a variable to store how many items have been selected in the Menu Class. private int totalSelected; The var totalSelected is live updated. It can be changed anytime depending on actionPerformed() function.(Exp: totalSelected will add up all the selected items) In the Order Class, how can I access to the live update variable totalSelected in order to retrieve the live update value? When I invoke getTotalSelected() function inside the Menu Class, I will only obtain a 0 value. Thanks for your help ^^! Please allow me to specify my question clearer. public class MenuTab extends JPanel { private JLabel display; private int totalSelected; public MenuTab() { .... } } public getTotalSelected(){ return totalSelected; } private class SelectedListener implements ActionListener { public void actionPerformed() { ....... //Assume that totalSelected has been updated! display = new JLabel("Total: " + totalSelected); // OK to display totalSelected live value here. } } // A new class is the confirmation of order public class OrderConfirmedTab extends JPanel{ private JLabel displayTotal; private MenuTab order = new MenuTab(); public OrderConfirmedTab() { ...... int totalSelected = order.getTotalSelected(); displayTotal = new JLabel("Total: " + totalSelected); // Problem to display totalSelected live value here. // Will obtain 0; // How can I obtain the live updated value from class MenuTab? Thanks! } }

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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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  • JSF: Showing/Calling a dialog programatically

    - by Sway
    has anybody an idea to show/call a dialog programatically and add this to stage(actual browser window) ?! I am running in circles and cannot find a solution :/ More background what I want to do: I want to trigger a database update every 2 hours. This I have done with a TimerTask... This works fine for me, the Timertask gets all the data I want from the database... Before this TimerTask is triggered I want to "lock" the screen for some seconds that no user(session scoped) can access the database(this I also know how this will work) ... My problem is that I don't know/ cannot find a way/ i am to stupid to call a dialog programatically ... Any tips, hints would be very cool :) Thanks a lot ! UPDATE: I want to set this primefaces dialog: Dialog dialog = new Dialog(); dialog.setAppendToBody(true); dialog.setModal(true); dialog.setVisible(true); dialog.setWidgetVar("generatedDialog"); dialog.setId("fancyDialog"); dialog.setClosable(false); dialog.setHeader("Getting latest information from the database"); dialog.setDynamic(true); dialog.setResizable(false); dialog.setDraggable(false); How can I do that ? :/ How do I display it to my browser ? :o Regards

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  • How do I iterate over a collection that is in an object passed as parameter in a jasper report?

    - by spderosso
    Hi, I have an object A that has as an instance variable a collection of object Bs. Example: public class A{ String name; List<B> myList; ... public List<B> getMyList(){ return myList; } ... } I want this object to be the only source of information the jasper report gets, since all the information the report need is in A. I am currently doing something like: A myObjectA = new A(...); InputStream reportFile = MyPage.this.getClass().getResourceAsStream("test.jrxml"); HashMap<String, Object> parameters = new HashMap<String, Object>(); parameters.put("objectA", myObjectA); ... JasperReport report = JasperCompileManager.compileReport(reportFile); JasperPrint print = JasperFillManager.fillReport(report, parameters, new JRBeanCollectionDataSource(myObjectA.getMyList())); return JasperExportManager.exportReportToPdf(print); thereby passing "two" parameters, the objectA as a concrete parameter and the collection of object Bs that is in A as a bean data source. How do I iterate over the Bs in A by passing only A? Thanks!

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  • Questions about serving static files from a servlet

    - by Geo
    I'm very new to servlets. I'd like to serve some static files, some css and some javascript. Here's what I got so far: in web.xml: <servlet> <description></description> <display-name>StaticServlet</display-name> <servlet-name>StaticServlet</servlet-name> <servlet-class>StaticServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>StaticServlet</servlet-name> <url-pattern>/static/*</url-pattern> </servlet-mapping> I'm assuming in the StaticServlet I'd have to work with request.getPathInfo to see what was requested, get a mime type, read the file & write it to the client. If this is not the way to go, or is not a viable way of doing things, please suggest a better way. I'm not really sure where to place the static directory, because if I try to print new File(".") it gives me the directory of my Eclipse installation. Is there a way to find out the project's directory?

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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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  • How to use LocalValueBean in jsp page.

    - by Himanshu
    I have set certain bean label and bean value in one of my dao class.. I have created a list of LocalValueBean objects and passed it as a list to jsp.. now here at jsp i need to print the label seperately and on hover to the label i need to show the value.. i need to exttract or to say get those values in jsp directly... i have also imported the org.apache.struts.util.LabelValueBean in my jsp but still its not working.. please let me know if you any ideas...

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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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  • Parsing a String into date with pattern:"dd/MM/yyyy"

    - by kawtousse
    Hi, I want to insert a date having this format MM/dd/YYYY for example:04/29/2010 to 29/04/2010 to be inserted into mysql database in a field typed Date. So i have this code: String dateimput=request.getParameter("datepicker"); DateFormat df = new SimpleDateFormat("dd/MM/yyyy"); Date dt = null; try { dt = df.parse(dateimput); System.out.println("date imput is:" +dt); } catch (ParseException e) { e.printStackTrace(); } but it gives me those error: 1-date imput is:Fri May 04 00:00:00 CEST 2012 (it is not the correct value that have been entered). 2-dismatching with mysql date type. I can not detect the error exactly. Please help.

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  • Files written with FileWriter are either 32 KB, 24 KB, 16 KB, ... big or empty

    - by Bernhard V
    Hi, I read a file into a string, change the first line and then write this string into a new file. I do this through the following code (a little bit shortened): while(jspIterator.hasNext()){ String line = (String) jspIterator.next(); if (i == 0) { if (line.startsWith("bla bla") && line.endsWith("yada")) { line = line.replaceFirst("this", "that"); } } jspAsString += line; i++; } FileWriter newJspWriter = new FileWriter(newJspFile); newJspWriter.write(jspAsString); Now the files written this way are either 32, 24, 16, 8 KByte big or completely empty. When debugging I see that the String is assembled correctly. When I print the variable jspAsString to the console it also appears correct. Do you know why FileWriter behaves this way?

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  • Build specific module in multi-module project

    - by Roman
    Hi I have a multi-module project. I thought I can compile only a single module from that multi module project by that line : mvn -amd -pl "module-name" Seems not to work , this command builds only the specific module. Its dependencies are not compiled yet so it fails. Any ideas how to solve that ? Thanks

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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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  • 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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  • Entities equals(), hashCode() and toString(). How to correctly implement them?

    - by spike07
    I'm implementing equals(), hashCode() and toString() of my entities using all the available fields in the bean. I'm getting some Lazy init Exception on the frontend when I try to compare the equality or when I print the obj state. That's because some list in the entity can be lazy initialized. I'm wondering what's the correct way to for implementing equals() and toString() on an entity object.

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  • How to add a jar build by a project to the project in eclipse?

    - by Xetius
    I have a project which as part of the build process creates an XMLBeans jar file (stbSchemas.jar) which I want to include and reference in this project. Is this the best way to go about this (Single project) or should I have a child project which is built from the parent project? I am building this using Maven2 inside Eclipse. Is there a better way to do this so that I can maintain the integrity of the projects and stability of the builds.

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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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  • Why does a sub-class class of a class have to be static in order to initialize the sub-class in the

    - by Alex
    So, the question is more or less as I wrote. I understand that it's probably not clear at all so I'll give an example. I have class Tree and in it there is the class Node, and the empty constructor of Tree is written: public class RBTree { private RBNode head; public RBTree(RBNode head,RBTree leftT,RBTree rightT){ this.head=head; this.head.leftT.head.father = head; this.head.rightT.head.father = head; } public RBTree(RBNode head){ this(head,new RBTree(),new RBTree()); } public RBTree(){ this(new RBNode(),null,null); } public class RBNode{ private int value; private boolean isBlack; private RBNode father; private RBTree leftT; private RBTree rightT; } } Eclipse gives me the error: "No enclosing instance of type RBTree is available due to some intermediate constructor invocation" for the "new RBTree()" in the empty constructor. However, if I change the RBNode to be a static class, there is no problem. So why is it working when the class is static. BTW, I found an easy solution for the cunstructor: public RBTree(){ this.head = new RBNode(); } So, I have no idea what is the problem in the first piece of code.

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  • Collision of dot and line in 2D space

    - by Anderiel
    So i'm trying to make my first game on android. The thing is i have a small moving ball and i want it to bounce from a line that i drew. For that i need to find if the x,y of the ball are also coordinates of one dot from the line. I tried to implement these equations about lines x=a1 + t*u1 y=a2 + t*u2 = (x-a1)/u1=(y-a2)/u2 (t=t which has to be if the point is on the line) where x and y are the coordinates im testing, dot[a1,a2] is a dot that is on the line and u(u1,u2) is the vector of the line. heres the code: public boolean Collided() { float u1 =Math.abs(Math.round(begin_X)-Math.round(end_X)); float u2 =Math.abs(Math.round(begin_Y)-Math.round(end_Y)); float t_x =Math.round((elect_X - begin_X)/u1); float t_y =Math.round((elect_Y - begin_Y)/u2); if(t_x==t_y) { return true; } else { return false; } } points [begin_X,end_X] and [begin_Y,end_Y] are the two points from the line and [elect_X,elect_Y] are the coordinates of the ball theoreticaly it should work, but in the reality the ball most of the time just goes straigth through the line or bounces somewhere else where it shouldnt

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