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  • question about polynomial multiplication

    - by davit-datuashvili
    i know that horners method for polynomial pultiplication is faster but here i dont know what is happening here is code public class horner{ public static final int n=10; public static final int x=7; public static void main(String[] args){ //non fast version int a[]=new int[]{1,2,3,4,5,6,7,8,9,10}; int xi=1; int y=a[0]; for (int i=1;i<n;i++){ xi=x*xi; y=y+a[i]*xi; } System.out.println(y); //fast method int y1=a[n-1]; for (int i=n-2;i>=0;i--){ y1=x*y+a[i]; } System.out.println(y1); } } result of this two methods are not same result of first method is 462945547 and result of second method is -1054348465 please help

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  • What is a right way to use servlets?

    - by vikp
    Hi, I'm studying EJB3. I have a session bean which provides services to create/update customer accounts. This session bean offers services on the lines of: public void addCustomer(Customer c); public void updateCustomer(Customer c); Ideally I'd like to have a single servlet: CustomerServlet and it would invoke the session beans that I have listed above. Problem is that I have two JSPs: UpdateAccount.jsp and CreateAccount.jsp. Both of these JSPs have a form with a method POST and action "CustomerServlet". How can I distinguish in a customer servlet which operation I should carry out: createAccount or updateAccount? I guess the alternative is to have a separate servlet for each operation... Thank you

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  • Trying to create spring project with maven

    - by Gandalf StormCrow
    Hello everyone I was just going trough http://static.springsource.org/docs/Spring-MVC-step-by-step/part1.html spring tutorial, and I thought its old I'll think something better on my own. For starters how do I start spring project with maven, which archtype should I choose? I wanna create simple spring app, write class which I will deploy to jboss, spring will instansiate it at startup .. that is what have in mind for now .. for now I need to start it first

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  • Efficient representation of Hierarchies in Hibernate.

    - by Alison G
    I'm having some trouble representing an object hierarchy in Hibernate. I've searched around, and haven't managed to find any examples doing this or similar - you have my apologies if this is a common question. I have two types which I'd like to persist using Hibernate: Groups and Items. * Groups are identified uniquely by a combination of their name and their parent. * The groups are arranged in a number of trees, such that every Group has zero or one parent Group. * Each Item can be a member of zero or more Groups. Ideally, I'd like a bi-directional relationship allowing me to get: * all Groups that an Item is a member of * all Items that are a member of a particular Group or its descendants. I also need to be able to traverse the Group tree from the top in order to display it on the UI. The basic object structure would ideally look like this: class Group { ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { ... } /** @return all direct children of this group */ Set<Group> getChildren() { ... } ... } class Item { ... /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { ... } ... } Originally, I had just made a simple bi-directional many-to-many relationship between Items and Groups, such that fetching all items in a group hierarchy required recursion down the tree, and fetching groups for an Item was a simple getter, i.e.: class Group { ... private Set<Item> items; private Set<Group> children; ... /** @return all items in this group and its descendants */ Set<Item> getAllItems() { Set<Item> allItems = new HashSet<Item>(); allItems.addAll(this.items); for(Group child : this.getChildren()) { allItems.addAll(child.getAllItems()); } return allItems; } /** @return all direct children of this group */ Set<Group> getChildren() { return this.children; } ... } class Item { ... private Set<Group> groups; /** @return all groups that this Item is a direct member of */ Set<Group> getGroups() { return this.groups; } ... } However, this resulted in multiple database requests to fetch the Items in a Group with many descendants, or for retrieving the entire Group tree to display in the UI. This seems very inefficient, especially with deeper, larger group trees. Is there a better or standard way of representing this relationship in Hibernate? Am I doing anything obviously wrong or stupid? My only other thought so far was this: Replace the group's id, parent and name fields with a unique "path" String which specifies the whole ancestry of a group, e.g.: /rootGroup /rootGroup/aChild /rootGroup/aChild/aGrandChild The join table between Groups and Items would then contain group_path and item_id. This immediately solves the two issues I was suffering previously: 1. The entire group hierarchy can be fetched from the database in a single query and reconstructed in-memory. 2. To retrieve all Items in a group or its descendants, we can select from group_item where group_path='N' or group_path like 'N/%' However, this seems to defeat the point of using Hibernate. All thoughts welcome!

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  • Servlet request getparameter's performance

    - by Bob
    Hi, I noticed that my app is very slow sometimes, so I've done some tests. It's a very simple web app. One servlet gets some parameters than stores them. Everything's fine except one thing. It takes too long to get a parameter for the first time. It doesn't matter which parameter I try to get, but for the first time it is very slow. The strange thing is this doesn't happen always. Sometimes getting a parameter for the first time is not slow. My code looks like this request.getParameter("paramName"); request.getParameter("paramName2"); request.getParameter("paramName3"); Getting "paramName" is slow. Getting the others is very fast. By slow I mean : 200-800 millisec By very fast I mean: ~0 millisec (in the code snippet, I didn't write the performance test, but I'm using System.currentTimeMillis())

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  • how to use JComboBox using Enum in Dialog Box

    - by Edan
    Hi, I define enums: enum itemType {First, Second, Third}; public class Item { private itemType enmItemType; ... } How do I use it inside Dialog box using JComboBox? Means, inside the dialog box, the user will have combo box with (First, Second, Third). Also, is it better to use some sort of ID to each numerator? (Integer) thanks.

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  • Configurable Values in Enum

    - by Omer Akhter
    I often use this design in my code to maintain configurable values. Consider this code: public enum Options { REGEX_STRING("Some Regex"), REGEX_PATTERN(Pattern.compile(REGEX_STRING.getString()), false), THREAD_COUNT(2), OPTIONS_PATH("options.config", false), DEBUG(true), ALWAYS_SAVE_OPTIONS(true), THREAD_WAIT_MILLIS(1000); Object value; boolean saveValue = true; private Options(Object value) { this.value = value; } private Options(Object value, boolean saveValue) { this.value = value; this.saveValue = saveValue; } public void setValue(Object value) { this.value = value; } public Object getValue() { return value; } public String getString() { return value.toString(); } public boolean getBoolean() { Boolean booleanValue = (value instanceof Boolean) ? (Boolean) value : null; if (value == null) { try { booleanValue = Boolean.valueOf(value.toString()); } catch (Throwable t) { } } // We want a NullPointerException here return booleanValue.booleanValue(); } public int getInteger() { Integer integerValue = (value instanceof Number) ? ((Number) value).intValue() : null; if (integerValue == null) { try { integerValue = Integer.valueOf(value.toString()); } catch (Throwable t) { } } return integerValue.intValue(); } public float getFloat() { Float floatValue = (value instanceof Number) ? ((Number) value).floatValue() : null; if (floatValue == null) { try { floatValue = Float.valueOf(value.toString()); } catch (Throwable t) { } } return floatValue.floatValue(); } public static void saveToFile(String path) throws IOException { FileWriter fw = new FileWriter(path); Properties properties = new Properties(); for (Options option : Options.values()) { if (option.saveValue) { properties.setProperty(option.name(), option.getString()); } } if (DEBUG.getBoolean()) { properties.list(System.out); } properties.store(fw, null); } public static void loadFromFile(String path) throws IOException { FileReader fr = new FileReader(path); Properties properties = new Properties(); properties.load(fr); if (DEBUG.getBoolean()) { properties.list(System.out); } Object value = null; for (Options option : Options.values()) { if (option.saveValue) { Class<?> clazz = option.value.getClass(); try { if (String.class.equals(clazz)) { value = properties.getProperty(option.name()); } else { value = clazz.getConstructor(String.class).newInstance(properties.getProperty(option.name())); } } catch (NoSuchMethodException ex) { Debug.log(ex); } catch (InstantiationException ex) { Debug.log(ex); } catch (IllegalAccessException ex) { Debug.log(ex); } catch (IllegalArgumentException ex) { Debug.log(ex); } catch (InvocationTargetException ex) { Debug.log(ex); } if (value != null) { option.setValue(value); } } } } } This way, I can save and retrieve values from files easily. The problem is that I don't want to repeat this code everywhere. Like as we know, enums can't be extended; so wherever I use this, I have to put all these methods there. I want only to declare the values and that if they should be persisted. No method definitions each time; any ideas?

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  • Generate Javadoc for interfaces only?

    - by ipkiss
    Hi, I am finding a way to write a script that I can generate javadoc for my program's Interfaces only (not for public classes). I have tried Eclipse built-in tool and even JAutodoc tool but have not been successful yet. Does anyone have some ideas, please? Thanks.

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  • select and jstl query

    - by sarah
    Hi All, I am displaying data in combo box using ${role} the requirement is on clcik of edit i want to show the preselected value in the drop down ,suppose i have cat,rat and i selected rat and i saved it in database ,now when i want to edit the details i want to show rat first in drop down as pre selected and then cat,how to od this ?

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  • How to Canonicalize a Stax XML object.

    - by Enrique San Martín
    Hello, i want to Canonicalize a Stax object, the program it's doing it with DOM, but dom can't manage big XML documents (like 1GB), so STAX it's the solution. The Code that i have it's: File file=new File("big-1gb.xml"); org.apache.xml.security.Init.init(); DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance(); DocumentBuilder documentBuilder = dfactory.newDocumentBuilder(); Document doc = documentBuilder.parse(file); Canonicalizer c14n = Canonicalizer.getInstance("http://www.w3.org/TR/2001/REC-xml-c14n-20010315"); outputBytes = c14n.canonicalizeSubtree(doc.getElementsByTagName("SomeTag").item(0)); The idea it's do the code below with Stax... Thx :)

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  • Overriding or overloading?

    - by atch
    Guys I know this question is silly but just to make sure: Having in my class method: boolean equal(Document d) { //do something } I'm overloading this method nor overriding right? I know that this or similiar question will be on upcoming egzam and would be stupid to not get points for such a simple mistake;

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  • How to use pom.xml/Maven to initialize a local thoughtsite (App Engine sample) project in Eclipse?

    - by ovr
    This sample app ("thoughtsite") for App Engine contains a pom.xml in its trunk: http://code.google.com/p/thoughtsite/source/browse/#svn/trunk But I don't know what command to run in Maven to set up the project locally. (The README doesn't mention anything about Maven.) I tried to just import the project code directly into Eclipse but it doesn't look like it's in an appropriate format for a direct import. So I assume I need to do something with Maven to get it set up correctly. I haven't really used Maven before so I'm not sure what command I would need to run to set everything up. The pom.xml seems like it downloads a bunch of dependencies for the project like the Spring jar files which I don't see anywhere else in the svn repository.

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  • Lost with hibernate - OneToMany resulting in the one being pulled back many times..

    - by Andy
    I have this DB design: CREATE TABLE report ( ID MEDIUMINT PRIMARY KEY NOT NULL AUTO_INCREMENT, user MEDIUMINT NOT NULL, created TIMESTAMP NOT NULL, state INT NOT NULL, FOREIGN KEY (user) REFERENCES user(ID) ON UPDATE CASCADE ON DELETE CASCADE ); CREATE TABLE reportProperties ( ID MEDIUMINT NOT NULL, k VARCHAR(128) NOT NULL, v TEXT NOT NULL, PRIMARY KEY( ID, k ), FOREIGN KEY (ID) REFERENCES report(ID) ON UPDATE CASCADE ON DELETE CASCADE ); and this Hibernate Markup: @Table(name="report") @Entity(name="ReportEntity") public class ReportEntity extends Report{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name="ID") private Integer ID; @Column(name="user") private Integer user; @Column(name="created") private Timestamp created; @Column(name="state") private Integer state = ReportState.RUNNING.getLevel(); @OneToMany(mappedBy="pk.ID", fetch=FetchType.EAGER) @JoinColumns( @JoinColumn(name="ID", referencedColumnName="ID") ) @MapKey(name="pk.key") private Map<String, ReportPropertyEntity> reportProperties = new HashMap<String, ReportPropertyEntity>(); } and @Table(name="reportProperties") @Entity(name="ReportPropertyEntity") public class ReportPropertyEntity extends ReportProperty{ @Embeddable public static class ReportPropertyEntityPk implements Serializable{ /** * long#serialVersionUID */ private static final long serialVersionUID = 2545373078182672152L; @Column(name="ID") protected int ID; @Column(name="k") protected String key; } @EmbeddedId protected ReportPropertyEntityPk pk = new ReportPropertyEntityPk(); @Column(name="v") protected String value; } And i have inserted on Report and 4 Properties for that report. Now when i execute this: this.findByCriteria( Order.asc("created"), Restrictions.eq("user", user.getObject(UserField.ID)) ) ); I get back the report 4 times, instead of just the once with a Map with the 4 properties in. I'm not great at Hibernate to be honest, prefer straight SQL but I must learn, but i can't see what it is that is wrong.....? Any suggestions?

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  • mig layout - span and grow/push problem

    - by pstanton
    i want 3 components laid out on 2 lines, so that the bottom component and the top-right component use all available horizontal space. JFrame frame = new JFrame(); frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); frame.setLayout(new MigLayout("debug, fill")); Container cp = frame.getContentPane(); cp.add(new JTextField("component 1"), ""); cp.add(new JTextField("component 2"), "growx,push,wrap"); cp.add(new JTextField("component 3"), "span,growx,push"); frame.pack(); frame.setVisible(true); considering the above, how do i stop the space between "component 1" and "component 2" from appearing when resizing the frame? thanks.

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  • dynamic button in jsp

    - by kawtousse
    hi everyone, in my jsp i have a table constructed dynamically like the following: retour.append("<tr>"); try { s= HibernateUtil.currentSession(); tx=s.beginTransaction(); Query query = s.createQuery(HQL_QUERY); for(Iterator it=query.iterate();it.hasNext();) { if(it.hasNext()){ Dailytimesheet object=(Dailytimesheet)it.next(); retour.append("<td>" +object.getActivity() +"</td>"); retour.append("<td>" +object.getProjectCode() + "</td>"); retour.append("<td>" +object.getWAName() + "</td>"); retour.append("<td>" +object.getTaskCode() +"</td>"); retour.append("<td>" +object.getTimeFrom() +"</td>"); retour.append("<td>" +object.getTimeSpent() + "</td>"); retour.append("<td>" +object.getPercentTaskComplete() + "</td>"); if (droitdaccess) { retour.append(""); retour.append(""); retour.append(""); retour.append("<td bordercolor=#FFFFFF>"); retour.append("<input type=\"hidden\" id=\"id_"+nomTab+"_"+compteur+"\" value=\""+object.getIdDailyTimeSheet()+"\"/>"); retour.append("<img src=\"icon_delete.gif\" onClick=\"deletearowById('id_"+nomTab+"_"+compteur+"')\" style=\"cursor:pointer\" name=\"action\" value=\"deleting\" />"); retour.append("</td>"); } } compteur++; retour.append("</tr>"); } //terminer la table. retour.append ("</table>"); next to the table i want to display a button named send in order to send the table content. I do not really want to dispaly this button where the table is empty. So at least if the table is populated by nly one record i want that button being displayed. How should i deal in this case. Thanks.

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  • Recursion Question : Revision

    - by stan
    My slides say that: A recursive call should always be on a smaller data structure than the current one There must be a non recursive option if the data structure is too small You need a wrapper method to make the recursive method accessible Just reading this from the slides makes no sense, especially seeing as it was a topic from before christmas! Could anyone try and clear up what it means please? Thank you

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  • Spring Dispatcher Servlet Not Found Problem

    - by hamam
    I'm trying to build a simple spring web application but I get the following error when I run it on Apache Tomcat 6.0 Class Not Found Exception org.springframework.web.servlet.DispatcherServlet I'm using maven to handle libraries. At first I thought it was maven's fault but it adds spring and other libraries succesfully. I tried to import "org.springframework.web.servlet.DispatcherServlet" in a source file and my project has the right package and classes. My development environment : Ubuntu 10.4 Eclipse IDE Tomcat 6.0 I'd appreciate any help

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  • Access JBOSS Tomcat Web Application from Remote Computer

    - by Rod
    Hi, I just deployed a web application on JBOSS 4.2. It can be accessed locally only (http://localhost:8080/myApp). I cant access it from remote computer by typing its domain: (www.hostname.com:8080/myApp). I added Port 8080 as Exception in Windows Firewall. Note that the host (www.hostname.com) is reachable from remote computers via IIS on port 80. Thanks, Rod

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  • Why acegi (Spring Security) converts password to uppercase before comparing ?

    - by Tony
    One of my colleague in QA team reported a bug to me, the bug said that can't change password to lowercase, otherwise login is rejected,using number or uppercase is all fine. The login system was implemented using acegi 1.0 (now called Spring Security). This was a very strange bug,changing password is done by encrypting the user input string into MD5 string, I implemented this without using anything related acegi, I don't if the is the origin cause of the problem. When the login is rejected, through debugging, I find that, the user input is converted into uppercase by acegi when passing to the acegi comparing logic. At first, I didn't believe this, when I checkout the acegi source and debugging with it, I find it does convert both username and password to uppercase (source code line 121), Can you tell me why it does this? This can cause password encoding mismatch!

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  • How can i edit OSGi bundles manifest file in Netbeans 6.9?

    - by Deniz Acay
    I'm using Netbeans 6.9 RC2 and Maven OSGi Bundle project template. Actually i dont want to test my bundles in Netbeans environment so i copy the jar file to the OSGi container directory and install it from command line. But when i want to see its headers from OSGi console, i see a lot of Netbeans related unnecessary stuff. Is it possible to edit the contents of the manifest file in Netbeans?

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  • Refreshing WEB-INF/lib in Google App Engine (with Eclipse)

    - by Adrian Petrescu
    Hi, I've created a new Google App Engine project within Eclipse. I copied several JARs that I need for my application into the WEB-INF/lib directory, and add them to the build path. I make some random calls to these JARs from within the handler, deploy, and everything works fine. However, if I then change one of the JARs outside the project, and copy the new version to WEB-INF/lib (with the same name) and re-deploy, it doesn't seem to be sending the new JAR; everything is still linking to the old one even though it's not even in my WEB-INF/lib anymore. I'm guessing it's being cached by the server or Eclipse is not even realizing something has changed in order to upload the new version. If I just create a new project with the new JAR, everything is fine again (until I have to make another change...) but of course I don't want to have to create a new project for every change to a dependency I make. My question is, how can I make GAE re-upload all the JARs I have from within Eclipse? Thanks in advance, guys :) -Adrian

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  • Is it possible to prevent out-of-order execution by using single volatile

    - by Yan Cheng CHEOK
    By referring article, it is using a pair of volatile to prevent out-of-order execution. I was wondering, is it possible to prevent it using single volatile? void fun_by_thread_1() { this.isNuclearFactory = true; this.factory = new NuclearFactory(); } void fun_by_thread_2() { Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } // If out-of-order execution happens, _factory might // be NuclearFactory instance. _factory.operate(); } Factory factory = new FoodFactory(); volatile boolean isNuclearFactory = false; The reason I ask, is because I have a single guard flag (similar to isNuclearFactory flag), to guard against multiple variables (similar to many Factory). I do not wish to mark all the Factory as volatile. Or, shall I fall into the following solution? void fun_by_thread_1() { try { writer.lock(); this.isNuclearFactory = true; this.factory = new NuclearFactory(); } finally { writer.unlock(); } } void fun_by_thread_2() { try { reader.lock(); Factory _factory = this.factory; if (this.isNuclearFactory) { // Do not operate nuclear factory!!! return; } } finally { reader.unlock(); } _factory.operate(); } Factory factory = new FoodFactory(); boolean isNuclearFactory = false; P/S: I know instanceof. Factory is just an example to demonstrate of out-of-order problem.

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  • richfaces keepAlive not working

    - by Jurgen H
    I have a mediaOutput tag which, in its createContent attribute, requires the backing bean to be in a certain state. A list of values, which is filled in an init method, must be available. I therefore added a keepAlive tag for the whole backing bean. I now indeed see the backingBean in stead of some (richfaces) proxy bean, but the filled list is null again. How to make this possible? I checked that the init method was called and that the list is filled in in the init method. <a4j:keepAlive beanName="myBean" /> <a4j:mediaOutput createContent="#{myBean.writeChart}" ... /> The backing bean public class MyBean implements Serializable { public List list; public void init(ActionEvent event) { // call some resource to fill the list list = service.getItems(); } public void writeChart(final OutputStream out, final Object data) throws IOException { // list is null } // getters & setters }

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