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  • Is Catching a Null Pointer Exception a Code Smell?

    - by Drew
    Recently a co-worker of mine wrote in some code to catch a null pointer exception around an entire method, and return a single result. I pointed out how there could've been any number of reasons for the null pointer, so we changed it to a defensive check for the one result. However, catching NullPointerException just seemed wrong to me. In my mind, Null pointer exceptions are the result of bad code and not to be an expected exception in the system. Are there any cases where it makes sense to catch a null pointer exception?

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  • Correct handling of return data

    - by Serhiy
    Hello, I have a question related to correct handling of returns of the DAO library I'm writing for one project. This library probably is going to be used by another people and I want to do it correctly. So I would like to know, how I should deal with return statements of the functions of my DAO. Example 1 I have function to getCustomer which should return String. In case query doesn't return any result should I return null, empty string or throw some kind of Exception? Example 2 I have function getCutomerList which return ArrayList. In case query doesn't return any result should I return null, empty ArrayList or throw some Exception? Example 3 Some sql exception was detected, what should I do: throw exception or do try..catch of the block where it can occur? What is the "good" practice or "best" practice to apply in my case? Thanks on advance, Serhiy.

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  • this implementation does not contain a WSDL definition and is not a SOAP 1.1

    - by user1635118
    I am trying to deploy a simple SOAP 1.2 web service to WebSphere v8. My service is @Stateless @WebService(serviceName = "MemberServices", portName = "MemberPort", endpointInterface = "gov.virginia.vita.edmsvc.ws.MemberWS") @BindingType(value=SOAPBinding.SOAP12HTTP_BINDING) @TransactionAttribute(TransactionAttributeType.REQUIRED) public class MemberBean implements MemberWS, MemberBeanLocal { .... } However the server is throwing the following error: "This implementation does not contain a WSDL definition and is not a SOAP 1.1 based binding. Per the JAXWS specification, a WSDL definition cannot be generated for this implementation.error" this same service deploy successfully on Glashfish and JBoss, any ideas ?

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  • Redeclaration of parameters

    - by Scott
    While looking through the Selenium source code I noticed the following in the PageFactory: public static <T> T initElements(WebDriver driver, Class<T> pageClassToProxy) { T page = instantiatePage(driver, pageClassToProxy); initElements(driver, page); return page; } public static void initElements(WebDriver driver, Object page) { final WebDriver driverRef = driver; initElements(new DefaultElementLocatorFactory(driverRef), page); } What is the benefit of having the following line? final WebDriver driverRef = driver; Wouldn't it have made sense to just make the parameter final, and then passing that along to the next method without declaring the new reference?

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  • Format a number as currency in a JTable?

    - by llm
    Given a JTable where one of the columns contains a number, how do I display this number as a currency? I.e. 5 should display as $5.00 etc. Can this be done directly on the JTable after it has been populated with data, or do I have to do this earlier? Thanks.

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  • TransactionRequiredException on OptimisticLockException

    - by João Madureira Pires
    Hi there. I have the following class that generates sequencial Card Numbers. I'm trying to recover from OptimisticLockException, by calling recursively the same method. however, i'm getting TransactionRequiredException. Dows anyone knows how to recover from OptimisticLockException in my case? Thanks a lot in advance @Name("simpleAutoIncrementGenerator") public class SimpleAutoIncrementGenerator extends CardNumberGenerator{ private static final long serialVersionUID = 2869548248468809665L; private int numberOfRetries = 0; @Override public String generateNextNumber(CardInstance cardInstance, EntityManager entityManager) { try{ EntityCard card = (EntityCard)entityManager.find(EntityCard.class, cardInstance.getId()); if(card != null){ String nextNumber = ""; String currentNumber = card.getCurrentCardNumber(); if(currentNumber != null && !currentNumber.isEmpty()){ Long numberToInc = Long.parseLong(currentNumber); numberToInc ++; nextNumber = String.valueOf(numberToInc); card.setCurrentCardNumber(nextNumber); // this is just to cause a OptimisticLock Exception try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } entityManager.persist(card); entityManager.flush(); return nextNumber; } } }catch (OptimisticLockException oLE) { System.out.println("\n\n\n\n OptimisticLockException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (TransactionRequiredException trE) { System.out.println("\n\n\n\n TransactionRequiredException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (StaleObjectStateException e) { System.out.println("\n\n\n\n StaleObjectStateException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } } return null; } }

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  • Hibernate: getting a record but it's being updated in the database?

    - by jack
    For some reason Hibernate seems to be keeping my session open and updating the object without me explicitely invoking a save/update/saveorupdate. I guess the session is staying open and it's beeing marked as dirty. However this is not the desired behaviour, so what's the cleanest way to fix this? The issue seems to occur because I store a phone number without formatting in the database but the getter of the object returns a formatted telephone number. My flow: go to a jsp = controller = service = dao DAO getter function if(userId != 0) { return (User)dbFactory.get(User.class, userId); } return null; The service just passes it to the controller and the controller puts te User object in the request scope. I display it on my JSP page using EL.

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  • Error in my web.xml

    - by Mercer
    Why i have an error in my web.xml when i want add servlet..? <servlet> <servlet-name>ClientServlet</servlet-name> <servlet-class>org.task.ClientServlet</servlet-class> <servlet-name>FactoryServlet</servlet-name> <servlet-class>org.task.FactoryServlet</servlet-class> <servlet-name>TraderServlet</servlet-name> <servlet-class>org.task.TraderServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ClientServlet</servlet-name> <url-pattern>/ClientServlet</url-pattern> <servlet-name>FactoryServlet</servlet-name> <url-pattern>/FactoryServlet</url-pattern> <servlet-name>TraderServlet</servlet-name> <url-pattern>/TraderServlet</url-pattern> </servlet-mapping>

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  • Please help me with Red5 server

    - by Nitesh Panchal
    hello, I have installed Red5 server successfully and also am able to run the demos fine. Now, I want to create a sample red5 server application. I created a sample project according to the specific directory structure that Red5 requires. But, now when i try to open this project in Netbeans 6.8, i am unable to because both have a different directory structure. So, Netbeans doesn't consider it as a project. I actually want to convert this project to a war file, so i can deploy it to red5/webapps directory and then red5 deployer service can make project out it automatically. How do i convert this project to a war file? because in Netbeans i am unable to open it. Please help. Thanks in advance :)

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  • How to design authentication in a thick client, to be fail safe?

    - by Jay
    Here's a use case: I have a desktop application (built using Eclipse RCP) which on start, pops open a dialog box with 'UserName' and 'Password' fields in it. Once the end user, inputs his UserName and Password, a server is contacted (a spring remote-servlet, with the client side being a spring httpclient: similar to the approaches here.), and authentication is performed on the server side. A few questions related to the above mentioned scenario: If said this authentication service were to go down, what would be the best way to handle further proceedings? Authentication is something that I cannot do away with. Would running the desktop client in a "limited" mode be a good idea? For instance, important features/menus/views will be disabled, rest of the application will be accessible? Should I have a back up authentication service running on a different machine, working as a backup? What are the general best-practices in this scenario? I remember reading about google gears and how it would let you edit and do stuff offline - should something like this be designed? Please let me know your design/architectural comments/suggestions. Appreciate your help.

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  • how to sort JTable by providing column index externally.

    - by user345940
    I would like to implement sorting on JTable by providing column index externally in program. Here is my sample code in which i have initialize JTable, Add one Column and 30 rows to JTable. After rows has been added i am sorting JTable by providing column index 0 but i could not get sorted data. how can i get my first column in sorted order? what's wrong with my code. **Why sortCTableonColumnIndex() method could not sort data for specify column index? ` public class Test { private JTable oCTable; private DefaultTableModel oDefaultTableModel; private JScrollPane oPane; private JTableHeader oTableHeader; private TableRowSorter sorter; public void adddata() { for (int i = 0; i < 30; i++) { Object[] row = new Object[1]; String sValueA = "A"; String sValueB = "A"; row[0] = ""; if (i % 2 == 0) { if (i < 15) { sValueA = sValueA + sValueA; row[1] = sValueA; } else { if (i == 16) { sValueB = "D"; row[1] = sValueA; } else { sValueB = sValueB + sValueB; row[1] = sValueA; } } } else { if (i < 15) { sValueB = sValueB + sValueB; row[1] = sValueB; } else { if (i == 17) { sValueB = "C"; row[1] = sValueB; } else { sValueB = sValueB + sValueB; row[1] = sValueB; } } } } } public void createTable() { oCTable = new JTable(); oDefaultTableModel = new DefaultTableModel(); oCTable.setModel(oDefaultTableModel); oTableHeader = oCTable.getTableHeader(); oCTable.setAutoResizeMode(oCTable.AUTO_RESIZE_OFF); oCTable.setFillsViewportHeight(true); JTable oTable = new LineNumberTable(oCTable); oPane = new JScrollPane(oCTable); oPane.setRowHeaderView(oTable); JPanel oJPanel = new JPanel(); oJPanel.setLayout(new BorderLayout()); oJPanel.add(oPane, BorderLayout.CENTER); JDialog oDialog = new JDialog(); oDialog.add(oJPanel); oDialog.setPreferredSize(new Dimension(500, 300)); oDialog.pack(); oDialog.setVisible(true); } public void insert() { oDefaultTableModel.addColumn("Name"); int iColumnPlace = ((DefaultTableModel) oCTable.getModel()).findColumn("Name"); CellRendererForRowHeader oCellRendererForRowHeader = new CellRendererForRowHeader(); TableColumn Column = oCTable.getColumn(oTableHeader.getColumnModel().getColumn(iColumnPlace).getHeaderValue()); Column.setPreferredWidth(300); Column.setMaxWidth(300); Column.setMinWidth(250); Column.setCellRenderer(oCellRendererForRowHeader); for (int i = 0; i < 30; i++) { Object[] row = new Object[1]; String sValueA = "A"; if (i % 2 == 0) { if (i < 15) { sValueA = sValueA + "a"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { if (i == 16) { sValueA = sValueA + "b"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { sValueA = sValueA + "c"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } } } else { if (i < 15) { sValueA = sValueA + "d"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { if (i == 17) { sValueA = sValueA + "e"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { sValueA = sValueA + "f"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } } } } } public void showTable() { createTable(); insert(); sortCTableonColumnIndex(0, true); } public void sortCTableonColumnIndex(int iColumnIndex, boolean bIsAsc) { sorter = new TableRowSorter(oDefaultTableModel); List<RowSorter.SortKey> sortKeys = new ArrayList<RowSorter.SortKey>(); if (bIsAsc) { sortKeys.add(new RowSorter.SortKey(iColumnIndex, SortOrder.ASCENDING)); } else { sortKeys.add(new RowSorter.SortKey(iColumnIndex, SortOrder.DESCENDING)); } sorter.setSortKeys(sortKeys); oDefaultTableModel.fireTableStructureChanged(); oCTable.updateUI(); } public static void main(String[] argu) { Test oTest = new Test(); oTest.showTable(); } class CellRendererForRowHeader extends DefaultTableCellRenderer { public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) { JLabel label = null; try { label = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column); if (column == 0) { label.setBackground(new JLabel().getBackground()); label.setForeground(Color.BLACK); } } catch (RuntimeException ex) { } return label; } } class LineNumberTable extends JTable { private JTable mainTable; public LineNumberTable(JTable table) { super(); mainTable = table; setAutoCreateColumnsFromModel(false); setModel(mainTable.getModel()); setAutoscrolls(false); addColumn(new TableColumn()); getColumnModel().getColumn(0).setCellRenderer(mainTable.getTableHeader().getDefaultRenderer()); getColumnModel().getColumn(0).setPreferredWidth(40); setPreferredScrollableViewportSize(getPreferredSize()); } @Override public boolean isCellEditable(int row, int column) { return false; } @Override public Object getValueAt(int row, int column) { return Integer.valueOf(row + 1); } @Override public int getRowHeight(int row) { return mainTable.getRowHeight(); } } } `

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  • Is ArrayList.size() method cached?

    - by Peterdk
    I was wondering, is the size() method that you can call on a existing ArrayList<T> cached? Or is it preferable in performance critical code that I just store the size() in a local int? I would expect that it is indeed cached, when you don't add/remove items between calls to size(). Am I right?

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  • Getting N random numbers that the sum is M

    - by marionmaiden
    Hello I want to get N random numbers that the sum of them is a value. For example, let's suppose I want 5 random numbers that their sum is 1 Then, a valid possibility is: 0.2 0.2 0.2 0.2 0.2 Other possibility is: 0.8 0.1 0.03 0.03 0.04 And so on. I need this for the creation of the matrix of belongings of the Fuzzy C-means.

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  • Multi-Threaded Application - Help with some pseudo code!!

    - by HonorGod
    I am working on a multi-threaded application and need help with some pseudo-code. To make it simpler for implementation I will try to explain that in simple terms / test case. Here is the scenario - I have an array list of strings (say 100 strings) I have a Reader Class that reads the strings and passes them to a Writer Class that prints the strings to the console. Right now this runs in a Single Thread Model. I wanted to make this multi-threaded but with the following features - Ability to set MAX_READERS Ability to set MAX_WRITERS Ability to set BATCH_SIZE So basically the code should instantiate those many Readers and Writers and do the work in parallel. Any pseudo code will really be helpful to keep me going!

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  • Call HashMap from jsp EL ?

    - by Parhs
    Here is my Entity Class public enum UnitType { HOSPITAL, HEALTHCENTER } public static LinkedHashMap<UnitType, String> unitType = new LinkedHashMap<UnitType, String>() { { put(UnitType.HEALTHCENTER, "???t?? ??e?a?"); put(UnitType.HOSPITAL, "??s???µe??"); } }; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String name; private String address; @Column(columnDefinition = "TEXT") private String info; @Enumerated(EnumType.STRING) private UnitType type; At my jsp <c:forEach var="unit" items="${requestScope.units}"> <tr> <td>${unit.id}</td> <td>${unit.name}</td> <td>${unit.address}</td> <td>??!?</td> <td><a href="#">?e??ss?te?a</a></td> </tr> </c:forEach> How can i place the text value of the enum at ??!? .. Any idea? Tried some ways but nothing worked..

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  • How do i set the Transaction Isolation in EJB?

    - by Nitesh Panchal
    Hello, I am not able to find a way to set TransactionIsolation in ejb. Can anybody tell me how do i set it? I am using persistence. I have looked the following classes : EntityManager , EntityManagerFactory, UserTransaction. None of them seems to have any method like setTransactionIsolation or such. Do we need to change persistence.xml? I just read a book named Mastering EJB 3.0 4th edition. They gave a full 10 page theory about Isolation level that this problems occur and that occurs and such things but at the end they gave this paragraph :- "As we now know, the EJB standard does not deal with isolation levels directly, and rightly so. EJB is a component specification. It defines the behavior and contracts of a business component with clients and middleware infrastructure (containers) such that the component can be rendered as various middleware services properly. EJBs therefore are transactional components that interact with resource managers, such as the JDBC resource manager or JMS resource manager, via JTS, as part of a transaction. They are not, hence, resource components in themselves. Since isolation levels are very specific to the behavior and capabilities of the underlying resources, they should therefore be specified at the resource API levels. " What exactly does it mean? What is meant by resource level APIs? Please help me. If persistence has no way to set Isolation Level then why do they give such huge theory in an EJB book and make it heavy in weight unnecessarily :(

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  • What's the good of IDE's auto generated @override annotation ?

    - by Tony
    I am using eclipse , when I use shortcut to generate override implementations , there is an override annotation up there , I am using JDK 6 , this is all right , but under JDK 5 this annotation will cause an error, so I want to ask , if this annotation is completely useless ? Will compiler do some kind of optimization using this annotation ?

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  • how to write own serializer/deserializer?

    - by joseph
    Hello, I need to save objects - instances of classes - in my app like some filetype. How I can write own serializer/deserializer for it? Or exist some easier way how to save objects to some filetype? Using of io.serialization was commented as not so good solution for "real" app. Why?

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  • lwjgl 101: How can I use VBOs?

    - by Vuntic
    How can I draw anything in lwjgl using VBOs? When I follow the tutorial, it just breaks. I've also tried running this example (with the byteorder fix) but it just displays a blank window. SO hasn't been helpful to me yet, but this is the last place I can think of that might have an answer...

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  • How do you set a double value to a "non-value"

    - by Ankur
    I have two double data elements in an object. Sometimes they are set with a proper value and sometimes not. When the form field from which they values are received is not filled I want to set them to some value that tells me, during the rest of the code that the form fields were left empty. I can't set the values to null as that gives an error, is there some way I can make them 'Undefined'. PS. Not only am I not sure that this is possible, it might not also make sense. But if there is some best practice for such a situation I would be keen to hear it.

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  • JAXWS serves only 100 requests, how to configure JAXWS to change it to unlimited?

    - by cbz
    Hello, I'm using JAXWS for generating webservices and serving using EndPoint.publish() as well as deploying war file, but as soon as it has served 100 requests it wouldn't return 101st response. How to configure JAXWS to change this count to unlimited? EDIT: solution found, first of all it was not related to JAXWS and I'm sorry for posting it here, in my first impression I thought problem is with JAXWS but after deep exploring and debugging I found problem with my persistence layer (Hibernate) where max number of sessions allowed are 100 by default. Sorry again for making you guys to think which actually does not make sense.

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