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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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  • 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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  • 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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  • how to share a variable between two threads

    - by prmatta
    I just inherited some code, two threads within this code need to perform a system task. One thread should do the system task before the other thread. They should not be performing the system task together. The two threads do not have references to each other. Now, I know I can use some sort of a semaphore to achieve this. But my question is what is the right way to get both threads to access this semaphore. I could create a static variable/method a new class : public class SharedSemaphore { private static Semaphore s = new Semaphore (1, true); public static void performSystemTask () { s.acquire(); } public static void donePerformingSystemTask() { s.release(); } } This would work (right?) but this doesn't seem like the right thing to do. Because, the threads now have access to a semaphore, without ever having a reference to it. This sort of thing doesn't seem like a good programming practice. Am I wrong?

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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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  • 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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  • inserted in multiple tables of database at a time

    - by rajkumari
    can we work with multiple tables of database with same connection object of database at same time . suppose i have inserted value in table 1 and at same time also inserted value in table 2 of data base with same object of data base connection. I am using sqlite database in code and getting database locked exception while commit() .

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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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  • html:checkbox query

    - by sarah
    Hi All, i have the following code . and in Form is have property called isActive of type char ,how would i get the checked value of it ,i am getting some symbols like 'o' if checked. I am using userform.getIsActive() ,where i am going wrong .I want 'y' or 'n' values

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  • Exception durin processing XSLT transformation!

    - by Artic
    I'm usin such code to generate contents file. try { StreamResult result = new StreamResult(); TransformerFactory tf = TransformerFactory.newInstance(); for (String item: groups){ item = item.replaceAll(" ", "-").toLowerCase(); result.setOutputStream(new FileOutputStream(path+item+".html")); Templates templ = tf.newTemplates(xsltSource); Transformer transf = templ.newTransformer(); transf.clearParameters(); transf.setParameter("group", item); transf.transform(xmlSource, result); } } catch (TransformerConfigurationException e) { throw new SinkException(e.getMessage()); } catch (TransformerException e) { throw new SinkException(e.getMessage()); } But on second iteration I have an exception ERROR: javax.xml.transform.TransformerException: com.sun.org.apache.xml.internal.utils.WrappedRuntimeException: Read error Cann't understand what is the reason?

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  • JAXB Annotated class - setting of a variable which is not an element

    - by sswdeveloper
    I have a JAXB annotated class say @XmlRootElement(namespace = "http://www.abc.com/customer") Class Customer{ @XmlElement(namespace = "http://www.abc.com/customer") private String Name; @XmlElement(namespace = "http://www.abc.com/customer") private String Address; @XmlTransient private HashSet set = new HashSet(); public String getName(){ return Name; } public void setName(String name){ this.Name = name; set.add("Name"); } public String getAddress(){ return Address; } public void setAddress(String address){ this.Address = address; set.add("Address"); } public void getSet(){ return set; } I have a XML of the form <?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Customer xmlns="http://www.abc.com/customer" > <Name>Ralph</Name> <Address>Newton Street</Address> </Customer> I use JAXB unmarshalling to get the object representation of the XML input. The values for Name and Address are set correctly. However the value of set gets lost(since it is @XMLTransient it gets ignored) Is there any way of ensuring that it is still set in the object which has been unmarshalled? Some other annotation which I can use?

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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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  • What if I made an explicit reference to 'this' for use inside an inner class?

    - by badp
    So far, I've used this approach to access this from the scope of an inner class: class FooManagementWindow extends JFrame { JButton rejectFoo; //... void getFooAcceptingPanel(){ //... final FooManagementWindow referenceToThis = this; rejectFoo = new JButton("Reject"); rejectFoo.addEventListener(new EventListener() { @Override public void actionPerformed(ActionEvent arg) { referenceToThis.setEnabled(false); //this requires a network call //... referenceToThis.setEnabled(true); //the user may resume his work } }); //... } } However, I just learned that instead of declaring referenceToThis, a direct reference is kept for me as: FooManagementWindow.this I have no reason to think my less standard approach may lead to errors or weird corner cases. Or are there?

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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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  • 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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  • 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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  • Enum exeeding the 65535 bytes limit of static initializer... what's best to do?

    - by Daniel Bleisteiner
    I've started a rather large Enum of so called Descriptors that I've wanted to use as a reference list in my model. But now I've come across a compiler/VM limit the first time and so I'm looking for the best solution to handle this. Here is my error : The code for the static initializer is exceeding the 65535 bytes limit It is clear where this comes from - my Enum simply has far to much elements. But I need those elements - there is no way to reduce that set. Initialy I've planed to use a single Enum because I want to make sure that all elements within the Enum are unique. It is used in a Hibernate persistence context where the reference to the Enum is stored as String value in the database. So this must be unique! The content of my Enum can be devided into several groups of elements belonging together. But splitting the Enum would remove the unique safety I get during compile time. Or can this be achieved with multiple Enums in some way? My only current idea is to define some Interface called Descriptor and code several Enums implementing it. This way I hope to be able to use the Hibernate Enum mapping as if it were a single Enum. But I'm not even sure if this will work. And I loose unique safety. Any ideas how to handle that case?

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  • Ready to use TSP library

    - by Max
    Hi, I'm currently doing a project that requires some fast TSP solving (about 50-100 nodes in 2 seconds). There are a lots of approximation algorithms out there, but I don't have time nor will to analyze them and code them myself. Are there any free libraries that can solve TSP problem (approximation will do too)? Something like sortedNodes = solveTspPrettyPlease(nodes, 2sec) would be just great. Thanks in advance.

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  • Is it possible to include JButton in a JTable?

    - by Benjamin Confino
    I have a JTable that stores the results of a database query, so far so good. What I want is for the last column in each table to have a clickible JButton that will open the edit screen for the object represented in that row, and that means the button will need to know the details of the first column in the table from its own row (the ID from the database). Any advice? I already tried just adding JButtons but they turned into Text when I tried to run it.

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  • Performance implications of finalizers on JVM

    - by Alexey Romanov
    According to this post, in .Net, Finalizers are actually even worse than that. Besides that they run late (which is indeed a serious problem for many kinds of resources), they are also less powerful because they can only perform a subset of the operations allowed in a destructor (e.g., a finalizer cannot reliably use other objects, whereas a destructor can), and even when writing in that subset finalizers are extremely difficult to write correctly. And collecting finalizable objects is expensive: Each finalizable object, and the potentially huge graph of objects reachable from it, is promoted to the next GC generation, which makes it more expensive to collect by some large multiple. Does this also apply to JVMs in general and to HotSpot in particular?

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  • Ref to map vs. map to refs vs. multiple refs

    - by mikera
    I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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