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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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  • 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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  • 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 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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  • Common Utility for Exception Searching

    - by Andrew
    I wrote this little helper method to search the exception chain for a particular exception (either equals or super class). However, this seems like a solution to a common problem, so was thinking it must already exist somewhere, possibly in a library I have already imported. So, any ideas on if/where this might exist? boolean exceptionSearch(Exception base, Class<?> search) { Throwable e = base; do { if (search.isAssignableFrom(e.getClass())) { return true; } } while ((e = e.getCause()) != null); return false; }

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • BeanUtils getPropertyOfMapBean

    - by dx-cp
    Hi, Im wondering if it is possible to get data from property which is map cotaining pairs Key-StringArray (Map) in BeanUtils library. I just simply need to access one of array elements by calling propertyName=string[0]. Current version (1.8.3) does not support indexed properties. If you look into their code you will find in class PropertyUtilsBean in method getPropertyOfMapBean: if (resolver.isIndexed(propertyName) || resolver.isMapped(propertyName)) { throw new IllegalArgumentException( "Indexed or mapped properties are not supported on" + " objects of type Map: " + propertyName); } way too bad:-( Have any of you any tip how to do it somehow differently?

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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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  • 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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  • Can Spring access-denied-handler refer to popup?

    - by Rens Groenveld
    I am working with Spring Security 3.1.x and have implemented method annotation securities. As I want, when I perform a certain action while being logged in as a used that doesn't have the rights, I get a 403 acces is denied in my console! Perfect! Now I would like to catch this 403, and give the user a popup with a custom message. I don't want to redirect users to a page saying that they have no rights. Is there any way the access-denied-handler of Spring can take care of a popup? Or can it only redirect to another page? Maybe there are other options for me? Thanks in advance!

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  • Delete all previous records and insert new ones

    - by carlos
    When updating an employee with id = 1 for example, what is the best way to delete all previous records in the table certificate for this employee_id and insert the new ones?. create table EMPLOYEE ( id INT NOT NULL auto_increment, first_name VARCHAR(20) default NULL, last_name VARCHAR(20) default NULL, salary INT default NULL, PRIMARY KEY (id) ); create table CERTIFICATE ( id INT NOT NULL auto_increment, certificate_name VARCHAR(30) default NULL, employee_id INT default NULL, PRIMARY KEY (id) ); Hibernate mapping <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="Employee" table="EMPLOYEE"> <id name="id" type="int" column="id"> <generator class="sequence"> <param name="sequence">employee_seq</param> </generator> </id> <set name="certificates" lazy="false" cascade="all"> <key column="employee_id" not-null="true"/> <one-to-many class="Certificate"/> </set> <property name="firstName" column="first_name"/> <property name="lastName" column="last_name"/> <property name="salary" column="salary"/> </class> <class name="Certificate" table="CERTIFICATE"> <id name="id" type="int" column="id"> <param name="sequence">certificate_seq</param> </id> <property name="employee_id" column="employee_id" insert="false" update="false"/> <property name="name" column="certificate_name"/> </class> </hibernate-mapping>

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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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  • 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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  • 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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  • 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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  • package private static member class vs. package private class

    - by Helper Method
    I was writing two implementations of a linked list for an assignment, a doubly linked list and a circular doubly linked list. Now as the class representing a Link within the linked list is the same in both implementations, I want to use it in both. Now I wonder which approach would be better: Implement the Link class as a package private static member class in the first implementation and then use this class in the second implementation or make the Link class a package private class.

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  • Parsing data from txt file in J2ME

    - by CSFYPMAIL
    Basically I'm creating an indoor navigation system in J2ME. I've put the location details in a .txt file i.e. Locations names and their coordinates. Edges with respective start node and end node as well as the weight (length of the node). I put both details in the same file so users dont have to download multiple files to get their map working (it could become time consuming and seem complex). So what i did is to seperate the deferent details by typing out location Names and coordinates first, After that I seperated that section from the next section which is the edges by drawing a line with multiple underscores. Now the problem I'm having is parsing the different details into seperate arrays by setting up a command (while manually tokenizing the input stream) to check wether the the next token is an underscore. If it is, (in pseudocode terms), move to the next line in the stream, create a new array and fill it up with the next set of details. I found a some explanation/code HERE that does something similar but still parses into one array, although it manually tokenizes the input. Any ideas on what to do? Thanks Text File Explanation The text has the following format... <--1stSection--  /**   * Section one has the following format   * xCoordinate;yCoordinate;LocationName   */ 12;13;New York City 40;12;Washington D.C. ...e.t.c _________________________ <--(underscore divider) <--2ndSection--  /**   * Its actually an adjacency list but indirectly provides "edge" details.   * Its in this form   * StartNode/MainReferencePoint;Endnode1;distance2endNode1;Endnode2;distance2endNode2;...e.t.c   */ philadelphia;Washington D.C.;7;New York City;2 New York City;Florida;24;Illinois;71 ...e.t.c

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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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  • 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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