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  • Long running method causing race condition

    - by keeleyt83
    Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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  • How to write a jUnit test for this class?

    - by flash
    Hi, I would like to know what's the best approach to test the method "pushEvent()" in the following class with a jUnit test. My problem is, that the private method "callWebsite()" always requires a connection to the network. How can I avoid this requirement or refactor my class that I can test it without a connection to the network? class MyClass { public String pushEvent (Event event) { //do something here String url = constructURL (event); //construct the website url String response = callWebsite (url); return response; } private String callWebsite (String url) { try { URL requestURL = new URL (url); HttpURLConnection connection = null; connection = (HttpURLConnection) requestURL.openConnection (); String responseMessage = responseParser.getResponseMessage (connection); return responseMessage; } catch (MalformedURLException e) { e.printStackTrace (); return e.getMessage (); } catch (IOException e) { e.printStackTrace (); return e.getMessage (); } } }

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  • How to set a bean property before executing this f:event listener

    - by user
    How to set a bean property from jsf page before executing this f:event listener: <f:event type="preRenderComponent" listener="bean.method}"/> I tried the below code but it does not set the value to the bean property. <f:event type="preRenderComponent" listener="bean.method}"> <f:setPropertyActionListener target="#{bean.howMany}" value="2"/> </f:event> JSF2.1.6 with PF 3.3 EDIT Any issues with this below code? (This works! but I just want to confirm if there are any issues with this!?) <f:event type="preRenderComponent" listener="#{bean.setHowMany(15)}"/> <f:event type="preRenderComponent" listener="#{bean.method}"/>

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  • Hibernate/JPA DB Schema Generation Best Practices

    - by Bytecode Ninja
    I just wanted to hear the opinion of Hibernate experts about DB schema generation best practices for Hibernate/JPA based projects. Especially: What strategy to use when the project has just started? Is it recommended to let Hibernate automatically generate the schema in this phase or is it better to create the database tables manually from earliest phases of the project? Pretending that throughout the project the schema was being generated using Hibernate, is it better to disable automatic schema generation and manually create the database schema just before the system is released into production? And after the system has been released into production, what is the best practice for maintaining the entity classes and the DB schema (e.g. adding/renaming/updating columns, renaming tables, etc.)? Thanks in advance.

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  • Swing Timer in Conjunction with Possible Long-running Background Task

    - by javacavaj
    I need to perform a task repeatedly that affects both GUI-related and non GUI-related objects. One caveat is that no action should performed if the previous task had not completed when the next timer event is fired. My initial thoughts are to use a SwingTimer in conjunction with a javax.swing.SwingWorker object. The general setup would look like this. class { timer = new Timer(speed, this); timer.start(); public void actionPerformed(ActionEvent e) { SwingWorker worker = new SwingWorker() { @Override public ImageIcon[] doInBackground() { // potential long running task } @Override public void done() { // update GUI on event dispatch thread when complete } } } Some potential issues I see with this approach are: 1) Multiple SwingWorkers will be active if a worker has not completed before the next ActionEvent is fired by the timer. 2) A SwingWorker is only designed to be executed once, so holding a reference to the worker and reusing (is not?) a viable option. Is there a better way to achieve this?

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  • removing horizontal scrollbar for textarea

    - by charan
    Hi. im working on javaswings. i had a textarea in a panel. i dont need horizontal scrollbar for that textArea. only vertical scrollbar is needed. i disabled auto scrollbar options, but still the horizantal scrollbar is working. please help me in thz..

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  • How to retrieve the ordered list of best articles having a minimum number of votes by using HSQL ?

    - by fabien7474
    I have a Vote domain class from my grails application containing properties like article_id and note I want to HQL query the Vote domain class in order to retrieve the 5 best rated articles having at least 10 votes. I tried : SELECT v.article_id, avg(v.note), count(*) FROM vote v where count(*) >= 10 group by v.article_id order by avg(v.note) desc limit 5; But unfortunately the insertion of where count(*) >= 10 throws an error. How can I do that in a simple way? Thank you for your help.

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  • for loop will not loop

    - by Bjørn Jostein Aurheim
    I have a for loop that I will use to compute time intervals to add to an ArrayList. The problem is that I can not prove that the for loop is being executed. Nothing is printed when using the system.out.println() statement, and nothing is added to the array from inside the loop ... any sugestions? // lager tidspunkter og legger disse inn i en Array kalt tider tid.setTimer(16); tid.setMinutter(0); tid.setSekunder(0); tider.add(tid.asString());// String "16:00" is added as it should System.out.println("tiden er: "+tid.asString());// gives 16:00 printed for(int i=0;i>12;i++){ System.out.println("er i løkken");// gives nothing printed tid.increaseMinutter(30); System.out.println(tid.asString());// gives nothing printed tider.add(tid.asString()); }

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  • ResultSet and aggregation

    - by kachanov
    Ok, I admit my situation is special There is a data system that supports SQL-92 and JDBC interface However the SQL requets are pretty expensive, and in my application I need to retreive the same data multiple times and aggregate it ("group by") on different fields to show different dimensions of the same data. For example on one screen I have three tables that show the same set or records but aggregated by City (1st grid), by Population (2nd grid), by number of babies (3rd grid) This amounts to 3 SQL queries (which is very slow), UNLESS anyone of you can suggest any idea any library from apache commons or from google code, so that I can select all records into ResultSet and get 3 arrays of data group by different fields from this single ResultSet. Am I'm missing some obvious and unexpected solution to this problem?

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  • Maven Ant BuildException with maven-antrun-plugin ... unable to find javac compiler

    - by robsbobs
    Im trying to make Maven call an ANT build for some legacy code. the ant build builds correctly through ant however when i call it using the maven ant plugin it fails with the following error: [ ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (default) on project CoreServices: An Ant BuildException has occured: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:158: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:62: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:33: The following error occurred while executing this line: [ERROR] C:\dev\projects\ods\build.xml:41: Unable to find a javac compiler; [ERROR] com.sun.tools.javac.Main is not on the classpath. [ERROR] Perhaps JAVA_HOME does not point to the JDK. [ERROR] It is currently set to "C:\bea\jdk150_11\jre" My javac exists at C:\bea\jdk150_11\bin and this works for all other things. Im not sure where Maven is getting this version of JAVA_HOME. JAVA_HOME in windows envionrmental variables is set to C:\bea\jdk150_11\ as it should be. The Maven code that im using to call the build.xml is <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <version>1.6</version> <executions> <execution> <phase>install</phase> <configuration> <target> <ant antfile="../build/build.xml" target="deliver" > </ant> </target> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> </plugin> </plugins> </build>

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  • which toString() method can be used performance wise??

    - by Mrityunjay
    hi, I am working on one project for performance enhancement. I had one doubt, while we are during a process, we tend to trace the current state of the DTO and entity used. So, for this we have included toString() method in all POJOs for the same. I have now implemented toString() in three different ways which are following :- public String toString() { return "POJO :" + this.class.getName() + " RollNo :" + this.rollNo + " Name :" + this.name; } public String toString() { StringBuffer buff = new StringBuffer("POJO :").append(this.class.getName()).append(" RollNo :").append(this.rollNo).append(" Name :").append(this.name); return buff.toString(); } public String toString() { StringBuilder builder = new StringBuilder("POJO :").append(this.class.getName()).append(" RollNo :").append(this.rollNo).append(" Name :").append(this.name); return builder .toString(); } can anyone please help me to find out which one is best and should be used for enhancing performance.

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  • Is J2SE a framework?

    - by Alvin
    Hello, I want to know is this legitimate to say J2SE a framework? If J2SE is a framework, then why there is a collection framework? Isn't collection framework inside J2SE? Please help me!

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  • Servlets, long operations

    - by asrijaal
    Hi there, I'm refactoring a big piece of code atm where a long taking operation is executed in a servlet. Now sometimes I don't get a response after the operation has finished. (It has finished because it is printed into the logs) What I wish to achieve would some "fire and forget" behavior by the servlet. I would pass my params to the action and the servlet would immediately return a status (something like: the operation has started, check your logs for further info) Is this possible with servlet 2.5 spec? I think I could get such a behavior with JMS maybe any other solutions out there?

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  • class not found when running

    - by captfrank
    I'm getting "could not find class" error when I run my app. Understand that copulation and execution path different but I followed the recommendations of another question to create a sub dir under my project of lib and put the jar there but still no luck. using Eclipse and it is when I run on a device from eclipse (unable to get the broadcast events I want to trigger this code from simulator, i.e. wifi and blue-tooth). Any way to look at the apk to see what's in it like this jar file? looking around did not see anything.

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  • Use ObjectOutputStream and FileOutputStream with FileWriter

    - by wishi
    Hi! Is there any way to use ObjectOutputStream like this: <tag>output of the ObjectOutputStream</tag> If I try: FileOutputStream fos = new FileOutputStream(filename); ObjectOutputStream oos = new ObjectOutputStream(fos); FileWriter fw = new FileWriter(fos); And for example: fw.write("<tag>"); oos.write(cool_object); fw.wrote("</tag>"); I don't get that result. It seems the ObjectOutputStream overwrites the file completly each and every time.

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  • leiningen - how to add dependencies for local jars?

    - by signalseeker
    Hi, I want to use leiningen to build and develop my clojure project. Is there a way to modify project.clj to tell it to pick some jars from local directories? I have some proprietary jars that cannot be uploaded to public repos. Also, can leiningen be used to maintain a "lib" directory for clojure projects? If a bunch of my clojure projects share the same jars, I don't want to maintain a separate copy for each of them. Thanks

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  • calendar.getInstance() or calendar.clone()

    - by Pangea
    I need to make a copy of a given date 100s of times (I cannot pass-by-reference). I am wondering which of the below two are better options newTime=Calendar.getInstance().setTime(originalDate); OR newTime=originalDate.clone(); Performance is of main conern here. thx.

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  • why toString method does not work here??

    - by user329820
    Hi this is my whole class ,I have added number 2 to the doubly linked list and then I want it to be be print in the concole but it will show this "datastructureproject.Node@f62373" thanks! package datastructureproject; public class DoublyLinkedList { private Node head = new Node(0); private Node tail = new Node(0); private int length = 0; public DoublyLinkedList() { head.setPrev(null); head.setNext(tail); tail.setPrev(head); tail.setNext(null); } public void add(int index, int value) throws IndexOutOfBoundsException { Node cursor = get(index); Node temp = new Node(value); temp.setPrev(cursor); temp.setNext(cursor.getNext()); cursor.getNext().setPrev(temp); cursor.setNext(temp); length++; } private Node get(int index) throws IndexOutOfBoundsException { if (index < 0 || index > length) { throw new IndexOutOfBoundsException(); } else { Node cursor = head; for (int i = 0; i < index; i++) { cursor = cursor.getNext(); } return cursor; } } public long size() { return length; } public boolean isEmpty() { return length == 0; } @Override public String toString() { StringBuffer result = new StringBuffer(); result.append("(head) - "); Node temp = head; while (temp.getNext() != tail) { temp = temp.getNext(); result.append(temp.getValue() + " - "); } result.append("(tail)"); return result.toString(); } public static void main(String[] args){ DoublyLinkedList list = new DoublyLinkedList(); list.add(0,2 ); System.out.println(list.get(0).toString()); } }

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  • Creating custom Android project templates in Eclipse?

    - by Rich
    Every app I make starts out with a number of common base classes, interfaces, utility classes and a basic package structure that has been working for me. Is there a way for me to set up a project template in Eclipse that will give me all of the basic Android project stuff PLUS a bunch of custom packages, classes and interfaces? I guess I could just put all of this stuff into one or more libraries as opposed to creating a whole project template, so if you have a preferred approach or information/links/etc on how to do any of the above, please share (I'm relatively inexperienced with Eclipse, so the more detail the better). Thanks.

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  • Spring Form: Submitting extra parameter on submit buttons

    - by theringostarrs
    Hi, I am working on a form with a bunch of selection criteria that will generate a report when the form is submitted. I also have a number of different reports that can be generated form this same criteria, and want the type of report to be selectable by using a tab system where each tab clicked on submits the form and generates the correct report. I was to do this by passing an extra parameter into the form to switch onto the right form type I am new to Spring, and from the guidance of an elder was told to use an input button for each tab with the following approximate syntax: <input type="submit" name="${form.selectionValues.tabSelection}" value="1" /> tabSelection form property of the SelectionValues object is not being set. I wasn't surprised ;) DIdn't think this would work. So I am wondering how can I can submit a post back from a button in Spring containing the form values plus an extra tabSelection parameter and value? How should I mark up this mechanism? Will I have to do anything to the form controller to register this extra parameter? The original markup I was using to build this page, was using HTML anchor tags instead of buttons for the tab links, which would be much better for the CSS, is there any way to trigger a full form submit using an anchor href? I know this will be a GET request instead of a POST, and not associated with the form.. so I dont expect this to work.. just trying to think of solutions! I would prefer to use the priginal markup, as the styles are there. Any help would be appreciated

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  • Type mismatch: cannot convert from ArrayList<Data> to MyCollection

    - by Tommy
    I've read similar questions here but I'm still a little confused. MyCollection extends ArrayList<MyClass> MyClass implements Data yet this gives me the "cannot convert from ArrayList to MyCollection" MyCollection mycollection = somehandler.getCollection(); where getCollection looks like this public ArrayList<Data> getCollection() So my assumptions are obviously wrong. How can I make this work like I would like it to

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