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  • Is it a good idea to close and open hibernate sessions frequently?

    - by Gaurav
    Hi, I'm developing an application which requires that state of entities be read from a database at frequent intervals or triggers. However, once hibernate reads the state, it doesn't re-read it unless I explicitly close the session and read the entity in a new session. Is it a good idea to open a session everytime I want to read the entity and then close it afterwards? How much of an overhead does this put on the application and the database (we use a c3p0 connection pool also)? Will it be enough to simply evict the entity from the session before reading it again?

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  • JButtons re-enable themselves after being disabled

    - by Anarchist
    I have an array of JButtons which form a keypad interface. After six numbers are entered I want to disable the keypad so that no further numbers can be entered by the user. I have written the code and the buttons do disable until the mouse hovers above any of them, then the buttons seem to re-enable themselves and run actionEvents added to them. The full code is available here. Possible things that I think are wrong. There is some sort of MouseListener which is ignoring when I set button.setEnabled(false); I haven't separated attributes from the buildGUI(); correctly, I only did this anyway so that the inner class could access them. Possibly something to do with the gridLayout as disabling the buttons seems to work for my services JPanel buttons.

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  • when get pagecontent from URL the connect alway return nopermistion ?

    - by tiendv
    I have a methor to return pagecontent of link but when it run, alway return "Do not perrmisson ", plesea check it here is code to return string pagecontent public static String getPageContent(String targetURL) throws Exception { Hashtable contentHash = new Hashtable(); URL url; URLConnection conn; // The data streams used to read from and write to the URL connection. DataOutputStream out; DataInputStream in; // String returned as the result . String returnString = ""; // Create the URL object and make a connection to it. url = new URL(targetURL); conn = url.openConnection(); // check out permission of acess URL if (conn.getPermission() != null) { returnString = "Do not Permission access URL "; } else { // Set connection parameters. We need to perform input and output, // so set both as true. conn.setDoInput(true); conn.setDoOutput(true); // Disable use of caches. conn.setUseCaches(false); // Set the content type we are POSTing. We impersonate it as // encoded form data conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // get the output stream . out = new DataOutputStream(conn.getOutputStream()); String content = ""; // Create a single String value pairs for all the keys // in the Hashtable passed to us. Enumeration e = contentHash.keys(); boolean first = true; while (e.hasMoreElements()) { // For each key and value pair in the hashtable Object key = e.nextElement(); Object value = contentHash.get(key); // If this is not the first key-value pair in the hashtable, // concantenate an "&" sign to the constructed String if (!first) content += "&"; // append to a single string. Encode the value portion content += (String) key + "=" + URLEncoder.encode((String) value); first = false; } // Write out the bytes of the content string to the stream. out.writeBytes(content); out.flush(); out.close(); // check if can't read from URL // Read input from the input stream. in = new DataInputStream(conn.getInputStream()); String str; while (null != ((str = in.readLine()))) { returnString += str + "\n"; } in.close(); } // return the string that was read. return returnString; }

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  • pattern to transfer search model to dao

    - by zeroed
    We have a dao as a project (jar file). Clients use its interfaces and factories to operate with database. Using standard CRUD operations, dao allows you to search an entity by some search criteria. What is the best way to represent this criteria? Is transfer object appropriate pattern in this situation? How should client create SearchModel instance? Please, share. Regards.

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  • Best practice for passing configuration to each GUI object

    - by Laimoncijus
    Hi, I am writing an application, where I do have few different windows implemented, where each window is a separate class. Now I need somehow to pass a single configuration object to all of them. My GUI is designed in way, where I have one main window, which may create some child windows of its own, and these child windows can have their own childs (so there is no possibility to create all windows in initialization part and feed the config object to all of them from the very beginning)... What would be best practice for sharing this configuration object between them? Always passing via constructor or maybe making it somewhere as final public static and let each window object to access it when needed? Thanks

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  • Hibernate is performing unwanted SELECTs on call to saveOrUpdate

    - by digiarnie
    Let's say I have a House entity which maps to many Person entities. I then load an existing House which has 20 occupants. beginTransaction(); House house = houseDao.find(1L); commitTransaction(); Later in the code, I can then add a new Person to the House: ... List<Person> people = house.getPeople(); people.add(new Person("Dilbert")); .... When I make the call: session.saveOrUpdate(house); Hibernate performs 21 queries: 1 to SELECT the House and 20 to SELECT each existing Person in the House. I'm sure it's a small issue on my part, however, what should I do so that I can add a new Person to the house without having such a heavy hit on the database in this situation? This is all done within the same session.

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  • Help need for openfast implementation

    - by ganuke
    Our stock exchange going to implement FAST messaging in their system in order to reduced the bandwidth usage. We have already implement the FIX based application to trade with Stock exchange. In future we need implement FIX FAST in our application to communicate with them. I found that OPEN FAST is FAST based library. But I do not have any idea how to start with it. I went through OpenFast web site but could not find much support on how to use templates and dictionaries. Can some one guide me or provide some resources to start with? Thanks in advance.

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  • get value from jtable

    - by jouzef19
    hi I have a jtable and I want the user to fill its cells then i get what he wrote! the problem is when i try getValueAt(row index,col index ) the programe give me null , and i am sure that the cell i choose has a value .

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  • any way to use ajax with jstl customtags without duplicating tags in javascript?

    - by CodeMonkeyB
    I am working on a page where part of the content is loaded normally and the pages are rendered using jsps. The product images and links generated on that page are by custom jstl tags. When the user scrolls more products are requested from the server in a JSON response and then using UnderscoreJS templates they are rendered and added to the bottom of the page. Is there any way I can use the JSTL tags in Javascript without recreating them using a javascript function (it won't be possible to re-create all of them in javascript). What is the best way to handle this scenario? I guess I could return a rendered html response for the ajax call, but that would mean I have some ajax requests which use json and some that use rendered html...

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  • Singletons vs. Application Context in Android?

    - by mschonaker
    Recalling this post enumerating several problems of using singletons and having seen several examples of Android applications using singleton pattern, I wonder if it's a good idea to use Singletons instead of single instances shared through global application state (subclassing android.os.Application and obtaining it through context.getApplication()). What advantages/drawbacks would have both mechanisms? To be honest, I expect the same answer in this post http://stackoverflow.com/questions/2709071/singleton-pattern-with-web-application-not-a-good-idea but applied to Android. Am I correct? What's different in DalvikVM otherwise? EDIT: I would like to have opinions on several aspects involved: Synchronization Reusability Testing Thanks in advance.

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  • No operations allowed after statement closed issue

    - by Washu
    I have the next methods in my singleton to execute the JDBC connections public void openDB() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException { Class.forName("com.mysql.jdbc.Driver").newInstance(); String url = "jdbc:mysql://localhost/mbpe_peru";//mydb conn = DriverManager.getConnection(url, "root", "admin"); st = conn.createStatement(); } public void sendQuery(String query) throws SQLException { st.executeUpdate(query); } public void closeDB() throws SQLException { st.close(); conn.close(); } And I'm having a problem in a void where i have to call this twice. private void jButton1ActionPerformed(ActionEvent evt) { Main.getInstance().openDB(); Main.getInstance().sendQuery("call insertEntry('"+EntryID()+"','"+SupplierID()+"');"); Main.getInstance().closeDB(); Main.getInstance().openDB(); for(int i=0;i<dataBox.length;i++){ Main.getInstance().sendQuery("call insertCount('"+EntryID()+"','"+SupplierID()+"','"+BoxID()+"'); Main.getInstance().closeDB(); } } I have already tried to keep the connection open and send the 2 querys and after that closed and it didnt work... The only way it worked was to not use the methods, declare the commands for the connection and use different variables for the connection and the statement. I thought that if i close the Connecion and the Statement I could use the variable once again since is a method but I'm not able to. Is there any way to solve this using my methods for the JDBC connection?

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  • Write to text file using ArrayList

    - by Ugochukwutubelum Chiemenam
    The program is basically about reading from a text file, storing the current data into an ArrayList, then writing data (from user input) into the same text file. Kindly let me know where I am going wrong in this sub-part? The data inside the text file is as follows: abc t1 1900 xyz t2 1700 The compiler is showing an error at the line output.format("%s%s%s%n", public class justTesting { private Scanner input; private Formatter output; private ArrayList<Student> tk = new ArrayList<Student>(); public static void main(String[] args) { justTesting app = new justTesting(); app.create(); app.writeToFile(); } public void create() { Text entry = new Text(); Scanner input = new Scanner(System.in); System.out.printf("%s\n", "Please enter your name, ID, and year: "); while (input.hasNext()) { try { entry.setName(input.next()); entry.setTelNumber(input.next()); entry.setDOB(input.next()); for (int i = 0; i < tk.size(); i++) { output.format("%s%s%s%n", tk.get(i).getName(), tk.get(i) .getTelNumber(), tk.get(i).getDOB()); } } catch (FormatterClosedException fce) { System.err.println("Error writing to file."); return; } catch (NoSuchElementException nsee) { System.err.println("Invalid input. Try again: "); input.nextLine(); } System.out.printf("%s\n", "Please enter your name, ID, and year: "); } } public void writeToFile() { try { output = new Formatter("testing.txt"); } catch (SecurityException se) { System.err .println("You do not have write access permission to this file."); System.exit(1); } catch (FileNotFoundException fnfe) { System.err.println("Error opening or creating file."); System.exit(1); } } }

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  • Have something loaded only when JList item is visibile

    - by elvencode
    Hello, i'm implementing a Jlist populated with a lot of elements. Each element corresponds to a image so i'd like to show a resized preview of them inside each row of the list. I've implemented a custom ImageCellRenderer extending the Jlabel and on getListCellRendererComponent i create the thumbnail if there'snt any for that element. Each row corresponds to a Page class where i store the path of the image and the icon applied to the JLabel. Each Page object is put inside a DefaultListModel to populate the JList. The render code is something like this: public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) { Page page = (Page) value; if (page.getImgIcon() == null) { System.out.println(String.format("Creating thumbnail of %s", page.getImgFilename())); ImageIcon icon = new ImageIcon(page.getImgFilename()); int thumb_width = icon.getIconWidth() > icon.getIconHeight() ? 128 : ((icon.getIconWidth() * 128) / icon.getIconHeight()); int thumb_height = icon.getIconHeight() > icon.getIconWidth() ? 128 : ((icon.getIconHeight() * 128) / icon.getIconWidth()); icon.setImage(getScaledImage(icon.getImage(), thumb_width, thumb_height)); page.setImgIcon(icon); } setIcon(page.getImgIcon()); } I was thinking that only a certain item is visibile in the List the cell renderer is called but i'm seeing that all the thumnails are created when i add the Page object to the list model. I've tried to load the items and after set the model in the JList or set the model first and after starting appending the items but the results are the same. Is there any way to load the data only when necessary or do i need to create a custom control like a JScrollPanel with stacked items inside where i check myself the visibility of each elements? Thanks

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  • Why isn't the @Deprecated annotation triggering a compiler warning about a method?

    - by Scooter
    I am trying to use the @Deprecated annotation. The @Deprecated documentation says that: "Compilers warn when a deprecated program element is used or overridden in non-deprecated code". I would think this should trigger it, but it did not. javac version 1.7.0_09 and compiled using and not using -Xlint and -deprecation. public class test_annotations { public static void main(String[] args) { test_annotations theApp = new test_annotations(); theApp.this_is_deprecated(); } @Deprecated public void this_is_deprecated() { System.out.println("doing it the old way"); } }

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  • How can I add a .jar to my build path in Eclipse?

    - by Roman
    I try to do it the following way: Right click on the name of the project. Click on Build Path in the drop dawn menu. Click on "Configure Build Path" And then I do not know what to do. Should I select "Source", "Projects", "Libraries", "Order and Export"? In "Libraries" I have "Add JARs..." and "Add External JARs...". What should I select? (I have already a .jar file in the lib folder of my project.) ADDED: If I click on "Add JARs" in the "Libraries" tab, I see the "lib" sub-folder but if I go there I do not see my .jar file there (and I know that it is there).

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  • converting result set to list

    - by akshay
    how can i conver result set to list? i am using following code but its not working properly private List<User> convertToList(ResultSet rs) { List<User> userList = new ArrayList(); User user = new User(); try { while (rs.next()) { user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); user.setFname(rs.getString("fname")); user.setLname(rs.getString("lname")); user.setUsertype(rs.getInt("usertype")); user.setPasswd(rs.getString("passwd")); user.setEmail(rs.getString("email")); userList.add(user); } } catch (SQLException ex) { Logger.getLogger(UserDAO.class.getName()).log(Level.SEVERE, null, ex); } finally { closeConnection(); } return userList; }

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