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  • J2EE/EJB + service locator: is it safe to cache EJB Home lookup result ?

    - by Guillaume
    In a J2EE application, we are using EJB2 in weblogic. To avoid losing time building the initial context and looking up EJB Home interface, I'm considering the Service Locator Pattern. But after a few search on the web I found that event if this pattern is often recommended for the InitialContext caching, there are some negative opinion about the EJB Home caching. Questions: Is it safe to cache EJB Home lookup result ? What will happen if one my cluster node is no more working ? What will happen if I install a new version of the EJB without refreshing the service locator's cache ?

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  • Why wait should always be in synchronized block

    - by diy
    Hi gents, We all know that in order to invoke Object.wait() , this call must be placed in synchronized block,otherwise,IllegalMonitorStateException is thrown.But what's the reason for making this restriction?I know that wait() releases the monitor, but why do we need to explicitly acquire the monitor by making particular block synchronized and then release the monitor by calling wait() ? What is the potential damage if it was possible to invoke wait() outside synch block, retaining it's semantics - suspending the caller thread ? Thanks in advance

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  • What can you do in the ant Task.init() method?

    - by skiphoppy
    I'm developing a few custom ant tasks that all need to initialize the same objects. I wanted to initialize those object's in a common superclass that extends from Task, in the init() method. But I see from the lifecycle of an ant task that init() gets called before the tasks child elements and attributes are set. So all of the data I need for initializing those objects is unavailable during init(), if I am reading right. So, why is init() called at this point? What do you even know that you could use in init()? What could it be used for? (And is there some other method that I can rely on to be called before execute(), but after my data is available?)

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  • Can I write a test without any assert in it ?

    - by stratwine
    Hi, I'd like to know if it is "ok" to write a test without any "assert" in it. So the test would fail only when an exception / error has occured. Eg: like a test which has a simple select query, to ensure that the database configuration is right. So when I change some db-configuration, I re-run this test and check if the configuration is right. ? Thanks!

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  • Android Sqlite - obtaining the correct database row id

    - by Dan_Dan_Man
    I'm working on an app that allows the user to create notes while rehearsing a play. The user can view the notes they have created in a listview, and edit and delete them if they wish. Take for example the user creates 3 notes. In the database, the row_id's will be 1, 2 and 3. So when the user views the notes in the listview, they will also be in the order 1, 2, 3 (intially 0, 1, 2 before I increment the values). So the user can view and delete the correct row from the database. The problem arises when the user decides to delete a note. Say the user deletes the note in position 2. Thus our database will have row_id's 1 and 3. But in the listview, they will be in the position 1 and 2. So if the user clicks on the note in position 2 in the listview it should return the row in the database with row_id 3. However it tries to look for the row_id 2 which doesn't exist, and hence crashes. I need to know how to obtain the corresponding row_id, given the user's selection in the listview. Here is the code below that does this: // When the user selects "Delete" in context menu public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item .getMenuInfo(); switch (item.getItemId()) { case DELETE_ID: deleteNote(info.id + 1); return true; } return super.onContextItemSelected(item); } // This method actually deletes the selected note private void deleteNote(long id) { Log.d(TAG, "Deleting row: " + id); mNDbAdapter.deleteNote(id); mCursor = mNDbAdapter.fetchAllNotes(); startManagingCursor(mCursor); fillData(); // TODO: Update play database if there are no notes left for a line. } // When the user clicks on an item, display the selected note protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); viewNote(id, "", "", true); } // This is where we display the note in a custom alert dialog. I've ommited // the rest of the code in this method because the problem lies in this line: // "mCursor = mNDbAdapter.fetchNote(newId);" // I need to replace "newId" with the row_id in the database. private void viewNote(long id, String defaultTitle, String defaultNote, boolean fresh) { final int lineNumber; String title; String note; id++; final long newId = id; Log.d(TAG, "Returning row: " + newId); mCursor = mNDbAdapter.fetchNote(newId); lineNumber = (mCursor.getInt(mCursor.getColumnIndex("number"))); title = (mCursor.getString(mCursor.getColumnIndex("title"))); note = (mCursor.getString(mCursor.getColumnIndex("note"))); . . . } Let me know if you would like me to show anymore code. It seems like something so simple but I just can't find a solution. Thanks!

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  • Android - Can display a single Activity using two layout.xml files?

    - by Avadhani
    I had developed Android app having some screens with common UI format. The format in top-down approach is: Title Header (Two buttons, ImageView) Content Area- It will differ among Activities (contains ListView, Tabs, Buttons, TextView, WebView....) Footer Layout (Relative Layout with three Imagebuttons) I want to reformat the code in such a way that one xml contains Title Header and Footer Layout and other xml contains ListView,Tabs, Buttons.. based on the usage. Can i acheive this? Please help me with sample code/links....

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  • What happens if an exception is thrown in finalize()

    - by Psykocyber
    What would happen if an exception is thrown during the execution of finalize()? Is the stack unwind like normally? Does it continue finalize() and ignore the exception? Does it stop finalize() and continue GC the object? Or something else? I'm not looking for guidelines of using finalize() there are plently of pages explaining that.

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  • Linked List Inserting in sorted format

    - by user2738718
    package practise; public class Node { public int data; public Node next; public Node (int data, Node next) { this.data = data; this.next = next; } public int size (Node list) { int count = 0; while(list != null){ list = list.next; count++; } return count; } public static Node insert(Node head, int value) { Node T; if (head == null || head.data <= value) { T = new Node(value,head); return T; } else { head.next = insert(head.next, value); return head; } } } This work fine for all data values less than the first or the head. anything greater than than doesn't get added to the list.please explain in simple terms thanks.

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  • Is it possible to call the main(String[] args) after catching an exception?

    - by Jason
    I'm working on a Serpinski triangle program that asks the user for the levels of triangles to draw. In the interests of idiot-proofing my program, I put this in: Scanner input= new Scanner(System.in); System.out.println(msg); try { level= input.nextInt(); } catch (Exception e) { System.out.print(warning); //restart main method } Is it possible, if the user punches in a letter or symbol, to restart the main method after the exception has been caught?

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  • Resizing JPanel to prepare for printing without removing it from its original position

    - by Lesman
    In my program I frequently need to print various JComponents (generally JPanels) and I like them to be full-page. The way I do it now is by using the following code: g2d.scale(pf.getImageableWidth()/componentToPrint.getWidth(), pf.getImageableHeight()/componentToPrint.getHeight()); but this often stretches or otherwise deforms whatever I am trying to print, and I would much prefer to do something that re-sized intelligently, perhaps a functional version of: componentToPrint.setSize(pf.ImageableWidth(), pf.ImageableHeight); or say adding the component into a new JFrame and then setting the frame size (problem is components can't exist in two place at once). I wouldn't care if the resizing would make the rest of the GUI look terrible, as long as it is something that can easily be reset. Is there any way to do this?

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  • How can I get an image too big from a server?

    - by Daniel Calderon Mori
    I'm currenty developing for blackberry and just bumped into this problem as i was trying to download an image from a server. The servlet which the device communicates with is working correctly, as I have made a number of tests for it. But it gives me the 413 HTTP error ("Request entity too large"). I figure i will just get the bytes, uhm, portion by portion. How can i accomplish this? This is the code of the servlet (the doGet() method): try { ImageIcon imageIcon = new ImageIcon("c:\\Users\\dcalderon\\prueba.png"); Image image = imageIcon.getImage(); PngEncoder pngEncoder = new PngEncoder(image, true); output.write(pngEncoder.pngEncode()); } finally { output.close(); } Thanks. It's worth mentioning that I am developing both the client-side and the server-side.

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  • Accessing inter-schema tables and relations in hibernate

    - by nitesh
    There is a typical situation being faced where different tables are scattered through different schemas in Oracle database and they are related to each other (encompassing all different types of relations). How can they be represented in Hibernate using annotations as when a sessionfactory handle is created for one schema, tables in that schema can't access other related tables (foreign key relation to tables in other schema)? For a query like following, exception is thrown - "from table1 as model where model.table2Name.table2column = "+foo Exception comes as - org.hibernate.QueryException: could not resolve property: table2column of: com.test.table1 [from com.test.table1 as model where model.table2Name.table2column = 1] Here table1 and table2 are present in different schemas.

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  • Synchronize write to two collections

    - by glaz666
    I need to put some value to maps if it is not there yet. The key-value (if set) should always be in two collections (that is put should happen in two maps atomically). I have tried to implement this as follows: private final ConcurrentMap<String, Object> map1 = new ConcurrentHashMap<String, Object>(); private final ConcurrentMap<String, Object> map2 = new ConcurrentHashMap<String, Object>(); public Object putIfAbsent(String key) { Object retval = map1.get(key); if (retval == null) { synchronized (map1) { retval = map1.get(key); if (retval == null) { Object value = new Object(); //or get it somewhere synchronized (map2) { map1.put(key, value); map2.put(key, new Object()); } retval = value; } } } return retval; } public void doSomething(String key) { Object obj1 = map1.get(key); Object obj2 = map2.get(key); //do smth } Will that work fine in all cases? Thanks

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  • Adding to existing JList

    - by Máca Danilov
    I need some help about adding items to JList. I work on some "library" kind of project. And I need to add readers to already existing JList. But when I try to add it, JList just resets, removes all the readers and starts adding readers to a new blank JList. But I don't need it to make new list but add it to the already existing one. I know it's something about creating new model after adding, but i don't know where to fix it. panelHorni = new JPanel(); listModel = new DefaultListModel(); listCtenaru = new JList(listModel); FileInputStream fis = new FileInputStream("myjlist.bin"); ObjectInputStream ois = new ObjectInputStream(fis); listCtenaru = (JList)ois.readObject(); listScroll = new JScrollPane(); listScroll.add(listCtenaru); listCtenaru.setPreferredSize(new Dimension(350, 417)); listCtenaru.setBackground(new Color(238,238,238)); panelHorni.add(listCtenaru); listener public void actionPerformed(ActionEvent e) { String jmeno = pole1.getText(); String prijmeni = pole2.getText(); listModel.addElement(jmeno +" "+ prijmeni); listCtenaru.setModel(listModel); pole1.setText(""); pole2.setText(""); pole1.requestFocus();

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  • Set request attributes when a Form is POSTed

    - by ssahmed555
    Is there any way to set request attributes (not parameters) when a form is posted? The problem I am trying to solve is: I have a JSP page displaying some data in a couple of dropdown lists. When the form is posted, my Controller servlet processes this request (based on the parameters set/specified in the form) and redirects to the same JSP page that is supposed to display addition details. I now want to display the same/earlier data in the dropdown lists without having to recompute or recalculate to get that same data. And in the said JSP page, the dropdown lists in the form are populated by data that is specified through request attributes. Right now, after the Form is POSTed and I am redirected to the same JSP page the dropdown lists are empty because the necessary request attributes are not present. I am quite the n00b when it comes to web apps, so an obvious & easy solution to this problem escapes me at the moment! I am open to suggestions on how to restructure the control flow in the Servlet. Some details about this app: standard Servlet + JSP, JSTL, running in Apache Tomcat 6.0. Thanks.

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  • Get first character of each word and its position in a sentence/paragraph

    - by Radhika
    I am trying to create a map by taking the first character of each word and it's position in a sentence/paragraph. I am using regex pattern to achieve this. Regex is a costly operation. Are there are any ways to achieve this? Regex way: public static void getFirstChar(String paragraph) { Pattern pattern = Pattern.compile("(?<=\\b)[a-zA-Z]"); Map newMap = new HashMap(); Matcher fit = pattern.matcher(paragraph); while (fit.find()) { newMap.put((fit.group().toString().charAt(0)), fit.start()); } }

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  • Table per subclass inheritance relationship: How to query against the Parent class without loading a

    - by Arthur Ronald F D Garcia
    Suppose a Table per subclass inheritance relationship which can be described bellow (From wikibooks.org - see here) Notice Parent class is not abstract @Entity @Inheritance(strategy=InheritanceType.JOINED) public class Project { @Id private long id; // Other properties } @Entity @Table(name="LARGEPROJECT") public class LargeProject extends Project { private BigDecimal budget; } @Entity @Table(name="SMALLPROJECT") public class SmallProject extends Project { } I have a scenario where i just need to retrieve the Parent class. Because of performance issues, What should i do to run a HQL query in order to retrieve the Parent class and just the Parent class without loading any subclass ???

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  • What is the correct approach to using GWT with persistent objects?

    - by dankilman
    Hi, I am currently working on a simple web application through Google App engine using GWT. It should be noted that this is my first attempt at such a task. I have run into to following problem/dilema: I have a simple Class (getters/setters and nothing more. For the sake of clarity I will refer to this Class as DataHolder) and I want to make it persistent. To do so I have used JDO which required me to add some annotations and more specifically add a Key field to be used as the primary key. The problem is that using the Key class requires me to import com.google.appengine.api.datastore.Key which is ok on the server side, but then I can't use DataHolder on the client side, because GWT doesn't allow it (as far as I know). So I have created a sister Class ClientDataHolder which is almost identical, though it doesn't have all the JDO annotations nor the Key field. Now this actually works but It feels like I'm doing something wrong. Using this approach would require maintaining to separate classes for each entity I wish to have. So my question is: Is there a better way of doing this? Thank you.

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  • runtime/compile time polymorphism

    - by dmadhavaraj
    Hi , In the below code , why b1.subtract() fails . Please explain me the reason ie., what happens in JVM while invoking that method . class Base { public void add() { System.out.println("Base ADD"); } } class Child extends Base { public void add(){ System.out.println("Child ADD"); } public void subtract() { System.out.println("Child Subtract"); } } class MainClass { public static void main(String args[]) { Base b1 = new Base(); Base b2 = new Child(); Child b3 = new Child(); b1.add(); b1.subtract(); // ?????????** b2.add(); b3.subtract(); } }

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  • multi-module maven project

    - by Gandalf StormCrow
    If I have 6 modules in my project is it possible to build only one out of six ? without commenting out others ? EDIT Submodule will not work itselft because or parent tags. I need to install the parent first to make it build. how can I do it without installing parent

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  • Hibernate Annotation (Pyramid Structure - same table)

    - by fatnjazzy
    Hi, I have a person table that contains the following fields: id, name, parent_id. the parent_id is actually a FK for column id. the data should look like this (Like a pyramid): "id" "name" "parent_id" "1" "I am the Top Father" "1" "2" "My Father Is 1" "1" "3" "My Father Is 2" "2" "4" "My Father Is 2" "2" How is my bean suppose to look like? Thanks

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  • Queries with developing a Voice to Text Based Software

    - by harigm
    I am looking for any software which converts the voice to the text. I can get some software which can easily convert the english launguage voice to English text. But my intention is be it any language, whatever the system gets voice that should give the output in the text format in English. Is it possible to get this kind of software? If yes any open source available to help me to use this? If not, Is this feasible to develop this kind of software, Can any one guide how to and where to begin with? I am looking for windows based software

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  • Creating parameterized type object using annonymous class

    - by Andrei Fierbinteanu
    This might be a stupid question, but I just saw a question asking how to create a Type variable for a generic type. The consensus seemed to be that you should have a dummy method returning that type, and then use reflection to get it (in this case he wanted Map<String, String>). Something like this : public Map<String, String> dummy() { throw new Error(); } Type mapStringString = Class.forName("ThisClass").getMethod("dummy").getGenericReturnType(); My question is, not having used reflection that much, couldn't you just do something like: Type mapStringString = new ParameterizedType() { public Type getRawType() { return Map.class; } public Type getOwnerType() { return null; } public Type[] getActualTypeArguments() { return new Type[] { String.class, String.class }; } }; Would this work? If not, why not? And what are some of the dangers/problems if it does (besides being able to return some Type like Integer<String> which is obviously not possible.

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