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  • In which layer should I join 2 entities together?

    - by William
    I use Spring MVC and a regular JDBC. I've just learned that I should separate business process into layers which are presentation layer, controller layer, service layer, and repository/DAO layer. Now suppose that I have an Entity called Person that can have multiple Jobs. Job itself is another entity which have its own properties. From what I gathered, the repository layer only manages one entity. Now I have one entity that contains another entity. Where do I "join" them? The service layer? Suppose I want to get a person whose job isn't known yet (lazy loading). But the system might ask what the job of that particular person is later on. What is the role of each layer in this case? Please let me know if I need to add any detail into this question.

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  • Getting a JFrame's actual current location

    - by Ian Fellows
    Hello community, I am trying to create a (child) JFrame which slides out from underneath one side of a second (parent) JFrame. The goal is to then have the child follow the parent around when it is moved, and respond to resizing events. This is somewhat related to this question. I have tried using a ComponentListener, but with this method the child only moves once the parent has come to a stop, whereas I would like the child to move as the parent is dragged around the screen. Another option I attempted was to start a new refresher thread that continually updated the child's location using getLocation() or getLocationOnScreen(), but the lag was the same as with ComponentListener. Is there a way to get the true actual location of a JFrame even in the midst of a drag? or if not, is there a way to get the effect of a sheet sliding out from underneath and following the Frame around?

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  • Why does every thread in my application use a different hibernate session?

    - by Ittai
    Hi, I have a web-application which uses hibernate and for some reason every thread (httprequest or other threads related to queueing) uses a different session. I've implemented a HibernateSessionFactory class which looks like this: public class HibernateSessionFactory { private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>(); private static Configuration configuration = new AnnotationConfiguration(); private static org.hibernate.SessionFactory sessionFactory; static { try { configuration.configure(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) {} } private HibernateSessionFactory() {} public static Session getSession() throws HibernateException { Session session = (Session) threadLocal.get(); if (session == null || !session.isOpen()) { if (sessionFactory == null) { rebuildSessionFactory();//This method basically does what the static init block does } session = (sessionFactory != null) ? sessionFactory.openSession(): null; threadLocal.set(session); } return session; } //More non relevant methods here. Now from my testing it seems that the threadLocal member is indeed initialized only once when the class is first loaded by the JVM but for some reason when different threads access the getSession() method they use different sessions. When a thread first accesses this class (Session) threadLocal.get(); will return null but as expected all other access requests will yeild the same session. I'm not sure how this can be happening as the threadLocal variable is final and the method threadLocal.set(session) is only used in the above context (which I'm 99.9% sure has to yeild a non null session as I would have encountered a NullPointerException at a different part of my app). I'm not sure this is relevant but these are the main parts of my hibernate.cfg.xml file: <hibernate-configuration> <session-factory> <property name="connection.url">someURL</property> <property name="connection.driver_class"> com.microsoft.sqlserver.jdbc.SQLServerDriver</property> <property name="dialect">org.hibernate.dialect.SQLServerDialect</property> <property name="hibernate.connection.isolation">1</property> <property name="hibernate.connection.username">User</property> <property name="hibernate.connection.password">Password</property> <property name="hibernate.connection.pool_size">10</property> <property name="show_sql">false</property> <property name="current_session_context_class">thread</property> <property name="hibernate.hbm2ddl.auto">update</property> <property name="hibernate.cache.use_second_level_cache">false</property> <property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <!-- Mapping files --> I'd appreciate any help granted and of course if anyone has any questions I'd be happy to clarify. Ittai

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  • Is Catching a Null Pointer Exception a Code Smell?

    - by Drew
    Recently a co-worker of mine wrote in some code to catch a null pointer exception around an entire method, and return a single result. I pointed out how there could've been any number of reasons for the null pointer, so we changed it to a defensive check for the one result. However, catching NullPointerException just seemed wrong to me. In my mind, Null pointer exceptions are the result of bad code and not to be an expected exception in the system. Are there any cases where it makes sense to catch a null pointer exception?

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  • ANDROID : how to get value stored in ArrayList<HashMap<key,value>>?

    - by Roshni Kyada
    I have ArrayList. At another activity i want to access all values stored in ArrayList. I tried following code. ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>(); for(Hashmap<String, String> map: mylist) { for(Entry<String, String> mapEntry: map) { String key = mapEntry.getKey(); String value = mapEntry.getValue(); } } but it shows an error at for(Entry mapEntry: map) that it only interate over Array.

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  • Collections removeAll method

    - by srinannapa
    I would like to know if something like below is possible , list<**MyObject**>.**removeAll**(list<**String**>) I hope the context is understandable. The list<MyObject : is a ArrayList<MyObject The list<String : is a ArrayList<String I know this can be achieved by overriding equals method in MyObject class. I would like to know if any other choice is prsent. Thanks,Srinivas N

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  • Why in the following code the output is different when I compile or run it more than once

    - by Sanjeev
    class Name implements Runnable { public void run() { for (int x = 1; x <= 3; x++) { System.out.println("Run by " + Thread.currentThread().getName() + ", x is " + x); } } } public class Threadtest { public static void main(String [] args) { // Make one Runnable Name nr = new Name(); Thread one = new Thread(nr); Thread two = new Thread(nr); Thread three = new Thread(nr); one.setName("A"); two.setName("B"); three.setName("C"); one.start(); two.start(); three.start(); } } The answer is different while compiling and running more then one time I don't know why? any idea.

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  • Generics List Interface...newb question

    - by newToProgramming
    The List interface is the following: public interface List<E>{ public boolean add(Object e); public boolean remove(Object e); public boolean contains(Object e); ...etc Why aren't the add, remove and contains methods written like the following? public boolean add(E e) public boolean remove(E e) public boolean contains(E e)

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  • Multivalue Mysql Inserts using HibernateTemplate

    - by Langali
    I am using Spring HibernateTemplate and need to insert hundreds of records into a mysql database every second. Not sure what is the most performant way of doing it, but I am trying to see how the multi value mysql inserts do using hibernate. String query = "insert into user(age, name, birth_date) values(24, 'Joe', '2010-05-19 14:33:14'), (25, 'Joe1', '2010-05-19 14:33:14')" getHibernateTemplate().execute(new HibernateCallback(){ public Object doInHibernate(Session session) throws HibernateException, SQLException { return session.createSQLQuery(query).executeUpdate(); } }); But I get this error: 'could not execute native bulk manipulation query.' Please check your query ..... Any idea of I can use a multi value mysql insert using Hibernate? or is my query incorrect? Any other ways that I can improve the performance? I did try the saveOrUpdateAll() method, and that wasn't good enough!

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  • I have to make a simple app that connects devices in a network, but I have no idea of how to this

    - by Gabriel Casado
    I want to write an App for android that has only one ListView. The App will constantly search for anything (mobile devices, desktops, etc.) that is connected in the wifi network. The problem is, I have no idea how to do this. What do I need to study? I comprehend I'd need to use a Thread or a Runnable to constantly search for those devices. Also I know very little about TCP, UDP or any internet protocols. So, can someone give me a basis of what I need to learn to develop this App?

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  • How do I calculate a good hash code for a list of strings?

    - by Ian Ringrose
    Background: I have a short list of strings. The number of strings is not always the same, but are nearly always of the order of a “handful” In our database will store these strings in a 2nd normalised table These strings are never changed once they are written to the database. We wish to be able to match on these strings quickly in a query without the performance hit of doing lots of joins. So I am thinking of storing a hash code of all these strings in the main table and including it in our index, so the joins are only processed by the database when the hash code matches. So how do I get a good hashcode? I could: Xor the hash codes of all the string together Xor with multiply the result after each string (say by 31) Cat all the string together then get the hashcode Some other way So what do people think? (If you care we are using .NET and SqlServer)

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  • How to construct query to update nested array document in mongo?

    - by GowtGM
    I am having following document in mongo, { "_id" : ObjectId("506e9e54a4e8f51423679428"), "description" : "ffffffffffffffff", "menus" : [ { "_id" : ObjectId("506e9e5aa4e8f51423679429"), "description" : "ffffffffffffffffffff", "items" : [ { "name" : "xcvxc", "description" : "vxvxcvxc", "text" : "vxcvxcvx", "menuKey" : "0", "onSelect" : "1", "_id" : ObjectId("506e9f07a4e8f5142367942f") } , { "name" : "abcd", "description" : "qqq", "text" : "qqq", "menuKey" : "0", "onSelect" : "3", "_id" : ObjectId("507e9f07a4e8f5142367942f") } ] }, { "_id" : ObjectId("506e9e5aa4e8f51423679429"), "description" : "rrrrr", "items" : [ { "name" : "xcc", "description" : "vx", "text" : "vxc", "menuKey" : "0", "onSelect" : "2", "_id" : ObjectId("506e9f07a4e8f5142367942f") } ] } ] } Now , i want to update the following document : { "name" : "abcd", "description" : "qqq", "text" : "qqq", "menuKey" : "0", "onSelect" : "3", "_id" : ObjectId("507e9f07a4e8f5142367942f") } I am having main documnet id: "_id" : ObjectId("506e9e54a4e8f51423679428") and menus id "_id" : ObjectId("506e9e54a4e8f51423679428") as well as items id "_id" : ObjectId("507e9f07a4e8f5142367942f") which is to be updated. I have tried using the following query: db.collection.update({ "_id" : { "$oid" : "506e9e54a4e8f51423679428"} , "menus._id" : { "$oid" : "506e9e5aa4e8f51423679429"}},{ "$set" : { "menus.$.items" : { "_id" : { "$oid" : "506e9f07a4e8f5142367942f"}} , "menus.$.items.$.name" : "xcvxc66666", ...}},false,false); but its not working...

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  • Using methods from the "outer" class in inner classes

    - by devoured elysium
    When defining nested classes, is it possible to access the "outer" class' methods? I know it's possible to access its attributes, but I can't seem to find a way to use its methods. addMouseListener(new MouseAdapter() { @Override public void mouseClicked(MouseEvent e) { if (e.getClickCount() == 2 && //<-- Here I'd like to } // reference a method }); //from the class where //addMouseListener() is defined! Thanks

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  • Customising log4j logging for sensitive data

    - by Xetius
    I have a class which contains sensitive information (Credit card info, phone numbers etc). I want to be able to pass this class to log4j, but have it obscure certain information. If I have a class UserInformation which has getPhoneNumber, getCreditCardNumber methods, how would I customise log4j or this class so that it will obscure the numbers correctly. I want the credit card number to be output as xxxx-xxxx-xxxx-1234 and the phone number to be output as xxxx-xxx-xxx given that these would be 1234-1234-1234-1234 and 1234-567-890 Thanks

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  • Guice expert question

    - by Roman
    Hi All I am wondering if someone would be such an expert in guice that he even would know how to implement that : I have an injection annotation (@ConfParam)with some parameters , like that : class TestClass { private final int intValue; @Inject public TestClass(@ConfParam(section = "test1", key = "1") int intValue{ this.intValue = intValue; } public int getIntValue() { return intValue; } } The ConfParam is my custom annotation. Now , when the injection value is requested , I would like guice to create a dynamic binding, to resolve the value. For that binding I will need the parameters inside the annotation. Some example could be , I will have to look in the database in some table where the section is ? and the key is ?. All the trouble is that the data is not available when the injector is created and could be also be added at runtime. Ps. I static solution is easy. ( just have a look at the Names class)

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  • Is this a correct way to stop Execution Task

    - by Yan Cheng CHEOK
    I came across code to stop execution's task. private final ExecutorService executor = Executors.newSingleThreadExecutor(); public void stop() { executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (!Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; } I realize that, it is possible for Runnable to be in forever loop, as Unknown fun may Thread.sleep, clear the interrupt flag and ignore the InterruptedException Unknown fun may Thread.interrupted, clear the interrupt flag. I was wondering, is the following way correct way to fix the code? private final ExecutorService executor = Executors.newSingleThreadExecutor(); private volatile boolean flag = true; public void stop() { flag = false; executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (flag && !Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; }

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  • Problem processing large data using Applet-Servlet communication

    - by Marquinio
    Hi everyone. I have an Applet that makes a request to a Servlet. On the servlet it's using the PrintWriter to write the response back to Applet: out.println("Field1|Field2|Field3|Field4|Field5......|Field10"); There are about 15000 records, so the out.println() gets executed about 15000 times. Problem is that when the Applet gets the response from Servlet it takes about 15 minutes to process the records. I placed System.out.println's and processing is paused at around 5000, then after 15 minutes it continues processing and then its done. Has anyone faced a similar problem? The servlet takes about 2 seconds to execute. So seems that the browser/Applet is too slow to process the records. Any ideas appreciated. Thanks.

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  • Why is it not saying I won?

    - by Itachi
    This is my if statement... The buttons show up like this: This is my if statement if((buttons[3].getName()=="x" && buttons[6].getName()=="x" && buttons[9].getText()=="x")||(buttons[2].getName()=="x" && buttons[5].getName()=="x" && buttons[8].getName()=="x")|| ((buttons[1].getName()=="x") && (buttons[4].getName()=="x") && (buttons[7].getName()=="x"))){ JOptionPane.showMessageDialog(null,"X Wins"); } So if I select the 1st, 4th and 7th buttons (the left most 3 buttons) why does it not say "X Wins"? As a sidenote, yes the buttons should have the name "x"

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  • Use HTTP PUT to create new cache (ehCache) running on the same Tomcat?

    - by socal_javaguy
    I am trying to send a HTTP PUT (in order to create a new cache and populate it with my generated JSON) to ehCache using my webservice which is on the same local tomcat instance. Am new to RESTful Web Services and am using JDK 1.6, Tomcat 7, ehCache, and JSON. I have my POJOs defined like this: Person POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class Person { private String firstName; private String lastName; private List<House> houses; // Getters & Setters } House POJO: import javax.xml.bind.annotation.XmlRootElement; @XmlRootElement public class House { private String address; private String city; private String state; // Getters & Setters } Using a PersonUtil class, I hardcoded the POJOs as follows: public class PersonUtil { public static Person getPerson() { Person person = new Person(); person.setFirstName("John"); person.setLastName("Doe"); List<House> houses = new ArrayList<House>(); House house = new House(); house.setAddress("1234 Elm Street"); house.setCity("Anytown"); house.setState("Maine"); houses.add(house); person.setHouses(houses); return person; } } Am able to create a JSON response per a GET request: @Path("") public class MyWebService{ @GET @Produces(MediaType.APPLICATION_JSON) public Person getPerson() { return PersonUtil.getPerson(); } } When deploying the war to tomcat and pointing the browser to http://localhost:8080/personservice/ Generated JSON: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So far, so good, however, I have a different app which is running on the same tomcat instance (and has support for REST): http://localhost:8080/ehcache/rest/ While tomcat is running, I can issue a PUT like this: echo "Hello World" | curl -S -T - http://localhost:8080/ehcache/rest/hello/1 When I "GET" it like this: curl http://localhost:8080/ehcache/rest/hello/1 Will yield: Hello World What I need to do is create a POST which will put my entire Person generated JSON and create a new cache: http://localhost:8080/ehcache/rest/person And when I do a "GET" on this previous URL, it should look like this: { "firstName" : "John", "lastName" : "Doe", "houses": [ { "address" : "1234 Elmstreet", "city" : "Anytown", "state" : "Maine" } ] } So, far, this is what my PUT looks like: @PUT @Path("/ehcache/rest/person") @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public Response createCache() { ResponseBuilder response = Response.ok(PersonUtil.getPerson(), MediaType.APPLICATION_JSON); return response.build(); } Question(s): (1) Is this the correct way to write the PUT? (2) What should I write inside the createCache() method to have it PUT my generated JSON into: http://localhost:8080/ehcache/rest/person (3) What would the command line CURL comment look like to use the PUT? Thanks for taking the time to read this...

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  • Why does the android emulator camera stop unexpectedly?

    - by user490074
    I am using Android 2.2 (API Level 8). The camera is enabled in the manifest. When I try the camera icon provided by the emulator model, it runs for a few seconds showing a gray box moving around a black and white checkerboard, then dies with the error message: Sorry! The application Camera (process com.android.camera) has stopped unexpectedly. Please try again. Trying again, of course, doesn't help. I am using the provided emulator camera to compare behavior with a camera application I am working on. Why does the android emulator camera stop unexpectedly?

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  • Cast Object to JTable?

    - by Chris
    I am trying to implement a ListSelectionListener for some of my JTables. Simply (at the moment) the ListSelectionListener is supposed to simply return the text of the cell that was selected. My program design has several JTables and I would like to have one ListSelectionListener work for them all. In the valueChanged event of the ListSelectionListener I thought it was possible to do something like: private class SelectionHandler implements ListSelectionListener { public void valueChanged(ListSelectionEvent e) { JTable table = (JTable)e.getSource(); String data = (String) table.getValueAt(table.getSelectedRow(), 0); // Print data } } But when I do this I a ClassCastException error. Is there a way to do something like this? One solution I thought of was to compare the source of the event (e.getSource()) to all my JTables to see if they were equivalent (big if block) and then just calling .getValueAt inside that block but that would making the code in the future difficult if tables were to be added or removed.

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