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  • Should I create protected constructor for my singleton classes?

    - by Vijay Shanker
    By design, in Singleton pattern the constructor should be marked private and provide a creational method retuning the private static member of the same type instance. I have created my singleton classes like this only. public class SingletonPattern {// singleton class private static SingletonPattern pattern = new SingletonPattern(); private SingletonPattern() { } public static SingletonPattern getInstance() { return pattern; } } Now, I have got to extend a singleton class to add new behaviors. But the private constructor is not letting be define the child class. I was thinking to change the default constructor to protected constructor for the singleton base class. What can be problems, if I define my constructors to be protected? Looking for expert views....

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  • Representing element as boolean with JAXB?

    - by Marcus
    We have this XML: <Summary> <ValueA>xxx</ValueA> <ValueB/> </Summary> <ValueB/> will never have any attributes or inner elements. It's a boolean type element - it exists (true) or it doesn't (false). JAXB generated a Summary class with a String valueA member, which is good. But for ValueB, JAXB generated a ValueB inner class and a corresponding member: @XmlElement(name = "ValueB") protected Summary.ValueB valueB; But what I'd like is a boolean member and no inner class: @XmlElement(name = "ValueB") protected boolean valueB; How can you do this? I'm not looking to regenerate the classes, I'd like to just make the code change manually. Update: In line with the accepted answer, we created a new method returning the boolean value conditional on whether valueB == null. As we are using Hibernate, we annotated valueB with @Transient and annotated the boolean getter with Hibernate's @Column annotation.

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  • AddAllAttributes method spring mvc

    - by Nick Robertson
    I have two lists List<User> list_of_users=new ArrayList<User>(); List<String> list_of_attributes=new ArrayList<String>(); When i try to use the following lines of code: model.addAttribute("takeattributes",list_of_users); model.addAttribute("takeattributes",list_of_attributes); I realise that it keeps only the second list (list_of_attributes) and the first deleted. I was wondering how to keep both of these two lists in the model.Is this possible to be happened?Is the AddAllAttributes method what i need?If yes can anyone explain me how the AddAllAttributes method is working.I look at the spring mvc documentation but i didn't really understand.

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  • Managed bean property value not set to null

    - by Vladimir
    Hi! I'm new to JSF, so this question might be strange. I have an inputText component's value bound to managed bean's property of type Float. I need to set property to null when inputText field is empty, not to 0 value. It's not done by default, so I added converter with the following method implemented: public Object getAsObject(FacesContext arg0, UIComponent arg1, String arg2) throws ConverterException { if (StringUtils.isEmpty(arg2)) { return null; } float result = Float.parseFloat(arg2); if (result == 0) { return null; } return result; } I registered converter, and assigned it to inputText component. I logged arg2 argument, and also logged return value from getAsObject method. By my log I can see that it returns null value. But, I also log setter property on backing bean and argument is 0 value, not null as expected. To be more precise, it is setter property is called twice, once with null argument, second time with 0 value argument. It still sets backing bean value to 0. How can I set value to null? Thanks in advance.

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  • How to Implement Custom List View for the list Items in Android Application

    - by avadhani
    I had a problem with the list view having both parent list and the child list of the list activity(implemented through database query). I wish to show them differing their properties by changing the text style (parent list items are in bold, child list items are in normal style). The following is the code from which all the child and parent list items having the same style(bold): String sql = "SELECT Parentid,Childid,Name from (select com.Parentid, com.Childid, com.Name from table1 mem inner join table2 cd on mem.column1=cd.column1 inner join table3 com on com.childid = mem.childid where Parentid is NULL UNION SELECT com.Parentid, com.Childid,com.Name from table1 mem inner join table3 com on com.childid = mem.childid inner join table2 cd on mem.column1=cd.column1 where Parentid is NOT NULL) a group by Parentid, Childid;"; Cursor cdata = myDbHelper.getView(sql); and the List Adapter is: private static final String fields[] = {"Name"}; int[] names = new int[] {R.id.name}; SimpleCursorAdapter adapter2 = new SimpleCursorAdapter(this,R.layout.clientlist1, cdata, fields,names ); and the clientlist.xml is: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/MainLayout" android:padding="5px"> <TextView android:id="@+id/name" android:layout_alignParentRight="true" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="12sp" android:textColor="#104082" android:textStyle="bold" android:layout_weight="1" /> From this i am getting the list having the complete list having both parent and child list items in a single list view. I wish to differ in their text style(bold, normal) for parent and child items respectively. Please help me with the code/links. Thanks a lot in advance.

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  • Why a EDT violation happens?

    - by Roman
    I started to use CheckThreadViolationRepaintManager to detect EDT violations. It complains about: partner = getParameter("partner",generatePartnerSelectionPanel(),Design.partnerSelectionDuration); Because it does not like generatePartnerSelectionPanel() because it does not like JPanel panel = new JPanel(); in this method. But I cannot find out why there should be a problem around that. In more details, generatePartnerSelectionPanel() generates a JPanel (I do it not in the EDT) but then, in the getParameter I add the JPanel to the main JFrame and I do it in the EDT (using invokeLater). So, why there should be a problem?

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  • swing gui improving

    - by radi
    hi all , i am looking for some methods to improve swing gui for example i want to know about new components libraries , new methods to enhance swing performance , new methods to add special effect to swing gui and new plaf for swing . please i want to know how to use this topics and where to find some tutorials about it . thanks.

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  • How to pass data from selected rows using checkboxes from JSP to the server

    - by eddy
    Hi, I'd like to know if there's any way to send data to the server for the selected rows using the checkboxes I've put on those rows? I mean , how can I send only the data (in this case mileage ) of those selected rows (selected with the checkboxes) to the server ? see the image Here's the html code I use: <table> <thead> <tr class="tableheader"> <td width="10%"></td> <td width="30%">Vehicle</td> <td width="40%">Driver</td> <td width="10%">Mileage</td> </tr> </thead> <tbody> <c:forEach items="${list}" var="item"> <tr> <td align="center"> <input type="checkbox" name="selectedItems" value="c:out value="${item.numberPlate}"/>"/> </td> <td align="left"><c:out value="${item.numberPlate}"/></td> <td align="left"><c:out value="${item.driver.fullName}" /></td> <td align="left"><input type="text" name="mileage" value="" /></td> </tr> </c:forEach> </tbody> </table> I really hope you can give some guidance on this. Thanks in beforehand.

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  • Calculated group-by fields in MongoDB

    - by Navin Viswanath
    For this example from the MongoDB documentation, how do I write the query using MongoTemplate? db.sales.aggregate( [ { $group : { _id : { month: { $month: "$date" }, day: { $dayOfMonth: "$date" }, year: { $year: "$date" } }, totalPrice: { $sum: { $multiply: [ "$price", "$quantity" ] } }, averageQuantity: { $avg: "$quantity" }, count: { $sum: 1 } } } ] ) Or in general, how do I group by a calculated field?

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  • JavaApplicationStub with SWT causing problems

    - by mystro
    I created an application in Eclipse that uses SWT for the GUI. I've attempted to deploy the application using the Eclipse deploy, but it seems that when I do that, LSUIElement is not respected, and I can't force the application to disappear from the dock. Nonwhistanding that issue, the application actually deploys ok and is runnable. I attempted to deploy the application using Jar Bundler, but when I try to run the application, I get the following errors: 2010-06-09 21:44:02.564 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x10021f260 of class NSCFString autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.568 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x10010a0a0 of class NSCFNumber autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.569 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x1001127a0 of class NSCFString autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.582 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x7fff70b7af70 of class NSCFString autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.583 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x100123ea0 of class NSCFData autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.587 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x100225b90 of class NSCFDictionary autoreleased with no pool in place - just leaking 2010-06-09 21:44:02.588 JavaApplicationStub[89045:2003] * __NSAutoreleaseNoPool(): Object 0x100225ee0 of class __NSFastEnumerationEnumerator autoreleased with no pool in place - just leaking in a very, very, very, long list. The application launches and appears to hang with the icon constantly bouncing in the dock, and the first GUI menu only partially loaded (it looks like one of the text boxes is semi visible, and the overall rectangle is the right size, but the GUI is not showing properly. It is essentially hung.) I'm hoping someone has had experience with this problem, and may be able to help! Thanks!

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  • how to invoke a webservice from one container in another container in glassfish

    - by vinny
    I have webservices deployed on two containers in two separate servers A and B. A webMethod in 'Server A' needs to invoke a webmethod in 'Server B'. I have created a client stub for Sever B. Im trying to make 'Server A' use this client stub and talk to Server B. I get an exception while trying to instantiate the port object specifically at : service.getABCBeanPort(); (using JAX-WS library) Is my approach correct? Is there any better way of invoking a webservice on a remote server?

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  • Array not showing in Jlist but filled in console

    - by OVERTONE
    Hey there. been a busy debugger today. ill give ths short version. ive made an array list that takes names from a database. then i put the contents of the arraylist into an array of strings. now i want too display the arrays contents in a JList. the weird thing is it was working earlier. and ive two methods. ones just a little practice too make sure i was adding to the Jlist correctly. so heres the key codes. this is the layout of my code. variables constructor methods in my variables i have these 3 defined String[] contactListNames = new String[5]; ArrayList<String> rowNames = new ArrayList<String>(); JList contactList = new JList(contactListNames); simple enough. in my constructor i have them again. contactListNames = new String[5]; contactList = new JList(contactListNames); //i dont have the array list defined though. printSqlDetails(); // the prinSqldetails was too make sure that the connectionw as alright. and its working fine. fillContactList(); // this is the one thats causing me grief. its where all the work happens. // fillContactListTest(); // this was the tester that makes sure its adding to the list alright. heres the code for fillContactListTest() public void fillContactListTest() { for(int i = 0;i<3;i++) { try { String contact; System.out.println(" please fill the list at index "+ i); Scanner in = new Scanner(System.in); contact = in.next(); contactListNames[i] = contact; in.nextLine(); } catch(Exception e) { e.printStackTrace(); } } } heres the main one thats supposed too work. public void fillContactList() { int i =0; createConnection(); ArrayList<String> rowNames = new ArrayList<String>(); try { Statement stmt = conn.createStatement(); ResultSet namesList = stmt.executeQuery("SELECT name FROM Users"); try { while (namesList.next()) { rowNames.add(namesList.getString(1)); contactListNames =(String[])rowNames.toArray(new String[rowNames.size()]); // this used to print out contents of array list // System.out.println("" + rowNames); while(i<contactListNames.length) { System.out.println(" " + contactListNames[i]); i++; } } } catch(SQLException q) { q.printStackTrace(); } conn.commit(); stmt.close(); conn.close(); } catch(SQLException e) { e.printStackTrace(); } } i really need help here. im at my wits end. i just cant see why the first method would add to the JList no problem. but the second one wont. both the contactListNames array and array list can print fine and have the names in them. but i must be transfering them too the jlist wrong. please help p.s im aware this is long. but trust me its the short version.

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  • Inheriting the main method

    - by Eric
    I want to define a base class that defines a main method that instantiates the class, and runs a method. There are a couple of problems though. Here is the base class: public abstract class Strategy { abstract void execute(SoccerRobot robot); public static void main(String args) { Strategy s = new /*Not sure what to put here*/(); s.execute(new SoccerRobot()) } } And here is an example derived class: public class UselessStrategy { void execute(SoccerRobot robot) { System.out.println("I'm useless") } } It defines a simple execute method, which should be called in a main method upon usage as a the main application. However, in order to do so, I need to instantiate the derived class from within the base class's main method. Which doesn't seem to be possible. I'd rather not have to repeat the main method for every derived class, as it feels somewhat unnessary. Is there a right way of doing this?

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  • Graphing the pitch (frequency) of a sound

    - by Coronatus
    I want to plot the pitch of a sound into a graph. Currently I can plot the amplitude. The graph below is created by the data returned by getUnscaledAmplitude(): AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(new BufferedInputStream(new FileInputStream(file))); byte[] bytes = new byte[(int) (audioInputStream.getFrameLength()) * (audioInputStream.getFormat().getFrameSize())]; audioInputStream.read(bytes); // Get amplitude values for each audio channel in an array. graphData = type.getUnscaledAmplitude(bytes, this); public int[][] getUnscaledAmplitude(byte[] eightBitByteArray, AudioInfo audioInfo) { int[][] toReturn = new int[audioInfo.getNumberOfChannels()][eightBitByteArray.length / (2 * audioInfo. getNumberOfChannels())]; int index = 0; for (int audioByte = 0; audioByte < eightBitByteArray.length;) { for (int channel = 0; channel < audioInfo.getNumberOfChannels(); channel++) { // Do the byte to sample conversion. int low = (int) eightBitByteArray[audioByte]; audioByte++; int high = (int) eightBitByteArray[audioByte]; audioByte++; int sample = (high << 8) + (low & 0x00ff); if (sample < audioInfo.sampleMin) { audioInfo.sampleMin = sample; } else if (sample > audioInfo.sampleMax) { audioInfo.sampleMax = sample; } toReturn[channel][index] = sample; } index++; } return toReturn; } But I need to show the audio's pitch, not amplitude. Fast Fourier transform appears to get the pitch, but it needs to know more variables than the raw bytes I have, and is very complex and mathematical. Is there a way I can do this?

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  • Dynamic context menu items

    - by Willem
    I am using Eclipse RCP to build desktop app. When the user invokes a popup menu I'd like to add some items to the menu. Something like a list of "suggested actions" to take for a problem. The pop-up is is on a table and it already has commands on it. What is the right way to implement this?

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  • Delete element from array

    - by Julio Diaz
    Is there a way I can get rid of some elements in an array. for instance, if i have this array int testArray[] = {0,2,0,3,0,4,5,6} Is there a "fast" way to get rid of the elements that equal 0 int resultArray[] = {2,3,4,5,6} I tried this function but I got lost using Lists public int[] getRidOfZero(int []s){ List<> result=new ArrayList<>(); for(int i=0; i<s.length; i++){ if(s[i]<0){ int temp = s[i]; result.add(temp); } } return result.toArray(new int[]); }

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  • How to figure out which key was pressed on a BlackBerry

    - by Skrud
    What I want: To know when the user has pressed the button that has the number '2' on it, for example. I don't care whether "Alt" or "Shift" has been pressed. The user has pressed a button, and I want to evaluate whether this button has '2' printed on it. Naturally, if I switch devices this key will change. On a Bold 9700/9500 this is the 'E' key. On a Pearl, this is the 'T'/'Y' key. I've managed to get this working in what appears to be a roundabout way, by looking up the keycode of the '2' character with the ALT button enabled and using Keypad.key() to get the actual button: // figure out which key the '2' is on: final int BUTTON_2_KEY = Keypad.key(KeypadUtil.getKeyCode('2', KeypadListener.STATUS_ALT, KeypadUtil.MODE_EN_LOCALE)); protected boolean keyDown(int keycode, int time) { int key = Keypad.key(keycode); if ( key == BUTTON_2_KEY ) { // do something return true; } return super.keyDown(keycode,time); } I can't help but wonder if there is a better way to do this. I've looked at the constants defined in KeypadListener and Keypad but I can't find any constants mapped to the actual buttons on the device. Would any more experienced BlackBerry devs care to lend a helping hand? Thanks!

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  • Can we view objects in the JVM memory?

    - by Sebastien Lorber
    Hey, At work we found that on some instances (particulary the slow ones) we have a different behaviour, acquired at the reboot. We guess a cache is not initialized correctly, or maybe a concurrency problem... Anyway it's not reproductible in any other env than production. We actually don't have loggers to activate... it's an old component... Thus i'd like to know if there are tools that can help us to see the different objets present in the JVM memory in order to check the content of the cache... Thank you!

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