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  • Will this SQL screw up

    - by Joshua
    I'm sure everyone knows the joys of concurrency when it comes to threading. Imagine the following scenario on every page-load on a noobily set up MySQL db: UPDATE stats SET visits = (visits+1) If a thousand users load the page at same time, will the count screw up? is this that table locking/row locking crap? Which one mysql use.

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  • What are the advantages of using J2EE over ASP.net?

    - by m_oLogin
    We are currently planning to launch a couple of internal web projects in the future. Our company's dev teams are mostly experienced in J2EE and have worked with it for years. Today, we have the choice of launching a couple of our projects on .net. I have checked out a couple of sources on the net, and it seems like the "J2EE vs ASP.net" combat brings out as much discord as the overseen "Apple vs Microsoft" or "Free Eclipse vs Visual Studio"... Nevertheless, I have been somewhat quite impressed with ASP.net's abilities to create great things with huge simplicity (for ex. asp.net ajax's demos). No more tons of xmls to play with, no more tons of frameworks to configure (we usually use the famous combo struts/spring/hibernate)... It just seemed to me that ASP.net had some good advantages over J2EE, but then again, I may speak by ignorance. What I want to know is this : What are the real advantages of using J2EE over ASP.net? Is there anything that cannot be done in ASP.net that can be done in J2EE? Once the frameworks are all in place and configured, is it faster to develop apps in J2EE than it is in .net? Are the applications generally easier to maintain in J2EE than in ASP.net? Is it worth it for some developpers to leave their J2EE knowledge on the side and move on to ASP.net if it does exactly the same thing?

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  • What tool/framework to use for technical documentation?

    - by Pangea
    We develop products and frameworks to be used with in our organization. I am looking for programmer friendly documentation tools. I have researched on few options sometime back but couldn't decide which one to use. I am looking for suggestions from the people who already used these tools. docbook: springframework and hibernate use this format and this looks good. but I believe they have customized the default xslt/stylesheet. Can I copy and use their xslt and css (ofcourse with colors and images changed). Can I integrate the doc generation using maven? wiki: this is not friendly to the technical document writers and the documentation doesn't look professional. versioning is also not possible I believe word docs: this is what we use currently but it is hard to link and reuse common documents. DITA?

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  • Are entities cached in jpa by default ?

    - by Nitesh Panchal
    Hello, I add entity to my database and it works fine. But when i retrieve the List, i get the old entity, the new entities i add are not shown until i undeploy the application and redeploy it again. This means are my entities cached by default? But, I haven't made any settings for caching entities in my persistence.xml or any such file. I have even tried calling flush(), refresh() and merge(). But still it shows the old entities only. Am i missing something? Please help me.

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  • What are annotations and how do they actually work for frameworks like Spring?

    - by Rachel
    I am new to Spring and now a days I hear a lot about Spring Framework. I have two sets of very specific questions: Set No. 1: What are annotations in general ? How does annotations works specifically with Spring framework ? Can annotations be used outside Spring Framework or are they Framework specific ? Set No. 2: What module of Spring Framework is widely used in Industry ? I think it is Spring MVC but why it is the most used module, if am correct or correct me on this ? I am newbie to Spring and so feel free to edit this questions to make more sense.

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  • recommendations for firestorm dao replacement

    - by Casey
    I have taken over some code that has been using the Firestorm DAO code generator from CodeFutures. I believe that the license for this is going to be up soon, and was wondering if anyone could recommend any alternatives, open source or not, so that I can get an idea of what's out there to better make a decision.

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  • Connection hangs after time of inactivity

    - by Sinuhe
    In my application, Spring manages connection pool for database access. Hibernate uses these connections for its queries. At first glance, I have no problems with the pool: it works correctly with concurrent clients and a pool with only one connection. I can execute a lot of queries, so I think that I (or Spring) don't leave open connections. My problem appears after some time of inactivity (sometimes 30 minutes, sometimes more than 2 hours). Then, when Hibernate does some search, it lasts too much. Setting log4j level to TRACE, I get this logs: ... 18:27:01 DEBUG nsactionSynchronizationManager - Retrieved value [org.springframework.orm.hibernate3.SessionHolder@99abd7] for key [org.hibernate.impl.SessionFactoryImpl@7d2897] bound to thread [http-8080-Processor24] 18:27:01 DEBUG HibernateTransactionManager - Found thread-bound Session [org.hibernate.impl.SessionImpl@8878cd] for Hibernate transaction 18:27:01 DEBUG HibernateTransactionManager - Using transaction object [org.springframework.orm.hibernate3.HibernateTransactionManager$HibernateTransactionObject@1b2ffee] 18:27:01 DEBUG HibernateTransactionManager - Creating new transaction with name [com.acjoventut.service.GenericManager.findByExample]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT 18:27:01 DEBUG HibernateTransactionManager - Preparing JDBC Connection of Hibernate Session [org.hibernate.impl.SessionImpl@8878cd] 18:27:01 TRACE SessionImpl - setting flush mode to: AUTO 18:27:01 DEBUG JDBCTransaction - begin 18:27:01 DEBUG ConnectionManager - opening JDBC connection Here it gets frozen for about 2 - 10 minutes. But then continues: 18:30:11 DEBUG JDBCTransaction - current autocommit status: true 18:30:11 DEBUG JDBCTransaction - disabling autocommit 18:30:11 TRACE JDBCContext - after transaction begin 18:30:11 DEBUG HibernateTransactionManager - Exposing Hibernate transaction as JDBC transaction [jdbc:oracle:thin:@212.31.39.50:30998:orcl, UserName=DEVELOP, Oracle JDBC driver] 18:30:11 DEBUG nsactionSynchronizationManager - Bound value [org.springframework.jdbc.datasource.ConnectionHolder@843a9d] for key [org.apache.commons.dbcp.BasicDataSource@7745fd] to thread [http-8080-Processor24] 18:30:11 DEBUG nsactionSynchronizationManager - Initializing transaction synchronization ... After that, it works with no problems, until another period of inactivity. IMHO, it seems like connection pool returns an invalid/closed connection, and when Hibernate realizes that, ask another connection to the pool. I don't know how can I solve this problem or things I can do for delimiting it. Any help achieving this will be appreciate. Thanks. EDIT: Well, it finally was due a firewall rule. Database detects the connection is lost, but pool (dbcp or c3p0) not. So, it tries to query the database with no success. What is still strange for me is that timeout period is very variable. Maybe the rule is specially strange or firewall doesn't work correctly. Anyway, I have no access to that machine and I can only wait for an explanation. :(

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  • Inheriting the main method

    - by Eric
    I want to define a base class that defines a main method that instantiates the class, and runs a method. There are a couple of problems though. Here is the base class: public abstract class Strategy { abstract void execute(SoccerRobot robot); public static void main(String args) { Strategy s = new /*Not sure what to put here*/(); s.execute(new SoccerRobot()) } } And here is an example derived class: public class UselessStrategy { void execute(SoccerRobot robot) { System.out.println("I'm useless") } } It defines a simple execute method, which should be called in a main method upon usage as a the main application. However, in order to do so, I need to instantiate the derived class from within the base class's main method. Which doesn't seem to be possible. I'd rather not have to repeat the main method for every derived class, as it feels somewhat unnessary. Is there a right way of doing this?

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  • Reverse List<Object>

    - by Mercer
    Hello, i have a List List<DataClient> listDataClient; My class DataCLient: Client client; List<String> phoneNumber; i have a second list List<DataPhoneNumber> listPhoneNumber; My class DataPhoneNumber: String phoneNumber; List<Client> client; In my code i put data in my first list but now i want to reverse my list in the second. In the first list i have a Client wiht x NumberPhone now i want to have NumberPhone for x Client

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  • Why can't I retrieve the entities I've just persisted?

    - by felipecao
    I've got this web service that basically queries the database and returns all persisted entities. For testing purposes, I've created a TestDataManager that persists 2 example entities after Spring context is loaded (BTW, I'm using JAX-WS, Spring, Hibernate and HSQLDB). My TestDataManager looks like this: @Component public class TestDataManager { @Resource private SessionFactory sf; @PostConstruct @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW) public void insertTestData(){ sf.openSession(); sf.openSession().beginTransaction(); sf.openSession().persist(new Site("site one")); sf.openSession().persist(new Site("site two")); sf.openSession().flush(); } } My JAX-WS endpoint looks like this: @WebService public class SmartBrickEndpoint { @Resource private WebServiceContext context; public Set<Site> getSitesForUser(String user){ return getSiteService().findByUser(new User(user)); } private ISiteService getSiteService(){ ServletContext servletContext = (ServletContext) context.getMessageContext().get("javax.xml.ws.servlet.context"); return (ISiteService) BeanRetriever.getBean(servletContext, ISiteService.class); } } This my Service class: @Component @Transactional(readOnly = true) public class SiteService implements ISiteService { @Resource private ISiteDao siteDao; @Override public Set<Site> findByUser(User user) { return siteDao.findByUser(user); } } This is my DAO: @Component @Transactional(readOnly = true) public class SiteDao implements ISiteDao { @Resource private SessionFactory sessionFactory; @Override public Set<Site> findByUser(User user) { Set<Site> sites = new LinkedHashSet<Site>(sessionFactory.getCurrentSession().createCriteria(Site.class).list()); return sites; } } This is my applicationContext.xml: <context:annotation-config /> <context:component-scan base-package="br.unirio.wsimxp.dao"/> <context:component-scan base-package="br.unirio.wsimxp.service"/> <context:component-scan base-package="br.unirio.wsimxp.spring"/> <bean id="applicationDS" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="org.hsqldb.jdbcDriver"/> <property name="url" value="jdbc:hsqldb:file:sites"/> </bean> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="dataSource" ref="applicationDS" /> <property name="configLocation"> <value>classpath:hibernate.cfg.xml</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.connection.release_mode">on_close</prop> <!--<prop key="hibernate.current_session_context_class">thread</prop>--> <prop key="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</prop> <prop key="hibernate.hbm2ddl.auto">create-drop</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> <tx:annotation-driven transaction-manager="transactionManager" /> This is what's going on now: when the app is deployed, TestDataManager#insertTestData kicks-in (due to @PostConstruct) and persist does not raise any exception. I should have 2 entities in the DB by now. Afterwards, I invoke the endpoint by a SOAP client, and the request goes all the way up to the DAO. The Hibernate invocation does not raise any exception, but the returned list is empty. The odd thing is, in TestDataManager, if I switch from sf.openSession() to sf.getCurrentSession(), I get an error message: "No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here". What I am doing wrong here? Why is the query "not seeing" the persisted entities? Why do I need to invoke sf.openSession() on TestDataManager although it's annotated with @Transactional? I have done some tests with hibernate.current_session_context_class=thread in application.xml, but then I just switch problems in each class. I'd like not needing to manually invoke sf.openSession() and leave that for Hibernate to take care. Thanks a lot for any help!

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  • Apache Chainsaw successor ?

    - by elec
    It looks like the development on Chainsaw has stopped 4 years ago (last development build dated 2006-03-02)... Anyone knows of a replacement tool providing the same functionality, but with more up to date releases ?

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  • Jetty offline documentation

    - by Victor Sorokin
    Is there any more-or-less comprehensive documentation for Jetty (e.g., similar to Tomcat or, really, in any form)? Theirs online wikis seems to be quite informative, but servers seem to be slow. Maybe, there some way to build docs from Jetty source distribution? I tried mvn site to no avail.

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  • creational pattern for instances depending on multiple subclass instances

    - by markusw
    I have a problem, for that I was not able to identify a suitable design pattern. I want to create instances depending on a given type that has been passed to a factory method. What I am doing until now is the following: T create(SuperType x) { if (x instanceof SubType1) { // do some stuff and return a new SubType extends T } else if (x instanceof SubType2) { // do some stuff and return a new SubType extends T } else if ... } else { throw new UnSupportedOperationException("nothing defined for " + x); } } It seems not to be best pratice for me. Has anybody an idea how to solve this in a better way?

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  • How could I evaluate this in code?

    - by WM
    There is a medieval puzzle about an old woman and a basket of eggs. On her way to market, a horseman knocks down the old woman and all the eggs are broken. The horseman will pay for the eggs, but the woman does not remember the exact number she had, only that when she took the eggs in pair, there was one left over; similarly, there was one left over when she took them three or five at a time. When she took them seven at a time, however, none were left. Write an application that can determine the smallest number of eggs the woman could have had. It might be a multiple of seven because there are no eggs left when it's seven at a time. But I have a problem. 49 eggs -1=2*24 49 eggs -1=3*16 49 eggs-4=5*9 49 eggs-0=7*7

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  • Android ListActivity with Bitmaps and Garbage Collection issue

    - by chis54
    I have a ListActivity and in it I set my list items with a class that extends SimpleCursorAdapter. I'm overriding bindView to set my Views. I have some TextViews and ImageViews. This is how I set my list items in my cursor adapter: String variableName = "drawable/q" + num + "_200px"; int imageResource = context.getResources().getIdentifier(variableName, "drawable", context.getPackageName()); if (imageResource != 0 ) { // The drawable exists Bitmap b = BitmapFactory.decodeResource(context.getResources(), imageResource); width = b.getWidth(); height = b.getHeight(); imageView.getLayoutParams().width = (int) (width); imageView.getLayoutParams().height = (int) (height); imageView.setImageResource(imageResource); } else { imageView.setImageResource(R.drawable.25trans_200px); } The problem I'm having is whenever I update my list with setListAdapter I get a large amount of garbage collection: D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 125K, 51% free 2710K/5447K, external 2022K/2137K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 30K, 51% free 2701K/5447K, external 2669K/2972K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 51% free 2713K/5447K, external 3479K/3579K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 22K, 51% free 2706K/5447K, external 3303K/3352K, paused 64ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 21K, 51% free 2722K/5447K, external 3569K/3685K, paused 102ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2755K/5447K, external 3499K/3605K, paused 65ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 23K, 50% free 2771K/5447K, external 4213K/4488K, paused 53ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 18K, 49% free 2796K/5447K, external 5057K/5343K, paused 75ms D/dalvikvm(18637): GC_EXTERNAL_ALLOC freed 28K, 49% free 2803K/5447K, external 5944K/5976K, paused 53ms D/dalvikvm( 435): GC_EXPLICIT freed 6K, 54% free 2544K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 165): GC_EXPLICIT freed 85K, 52% free 2946K/6087K, external 4838K/5980K, paused 111ms D/dalvikvm( 448): GC_EXPLICIT freed 1K, 54% free 2540K/5511K, external 1625K/2137K, paused 50ms D/dalvikvm( 294): GC_EXPLICIT freed 8K, 55% free 2598K/5703K, external 1625K/2137K, paused 64ms What can I do to avoid this? It's causing my UI to be sluggish and when I scroll, too.

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  • Invalid ADTS sampling_frequency_index and channel_configuration why?

    - by Moto
    Hello all, I hope someone can direct me on the right path before I put a lot of time and effort on this. I'm currently trying to parse an AAC+ frame to get information such as number of channels and sample frequency. So it seems that we can simply get this information from the ADTS header but most of the time this information is inaccurate. So the question is: -Why is this data inaccurate? What is the meaning of the ADTS header channel and sample freq? Should I rely on it? -Should I parse further down the frame to get this information? FYI, the AAC+ raw data is coming from streaming servers... Thanks for the help! -Moto

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  • Cannot access implict object from within method in custom JSP tag file

    - by David Hamilton
    I'm attempting to create a custom jsp tag. Everything is working fine, except for the fact that I the request seems to be out-of-scope for my custom function. Here is the relevant bit from the .tag file: <%! private String process(String age, BigDecimal amount) { //Attempting to access request here results in an compile time error trying to: String url=request.getURL; } %> I'm very new to JSP so I'm sure I'm missing something obvious..but I can't seem to figure out what. Any help is appreciated.

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  • how to remove ConcurrentModificationException

    - by maverick
    what is this exception and how to remove this in my problem i am creating an arraylist of objects, and after checking some condition,i want to remove some objects. but the program is giving this exception ConcurrentModificationException. how to remove this thanks in advance

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  • NullPointerException when thying to add an object to a PriorityQueue

    - by meagan
    i keep getting a null pointer exception when trying to add an object to a priority queue i initialize the queue: private PriorityQueue<NodeObject> nodes; and here i try to add to it: NodeObject childNode = new NodeObject(child, 1); nodes.add(childNode); why doesn't this work? i know my NodeObject is not null because i create it right before i add it.

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  • How do I stop Safari from caching my Servlet response?

    - by Cliff
    I'm having trouble testing a web app with Safari. My app returns wave audio data. The problem happens when I change the application and hit it again from Safari. Safari caches the original response so no matter how many times I hit refresh it seems like I've not updated anything. I can almost get around this using force refresh with Firefox but because I'm having trouble generating the wave headers using the javax.sound API Firefox only plays the first second of audio returned. A few weeks ago I tried setting the HTTP header in my servlet to prevent caching but I don't think I was setting it correctly. (What is the header for browser cache control?) This is becoming a real pain and I'm looking for any ideas, comments, or alternative approaches. I'm getting ready to try again but I figured I'd ask here in the interim to see if someone can provide help.

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