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  • When are references declared in a switch statement?

    - by sandis
    To my surprise this code works fine: int i = 2; switch(i) { case 1: String myString = "foo"; break; case 2: myString = "poo"; System.out.println(myString); } But the String reference should never be declared? Could it be that all variables under every case always are declared no matter what, or how is this resolved?

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  • Is it better to use List or Collection?

    - by Vivin Paliath
    I have an object that stores some data in a list. The implementation could change later, and I don't want to expose the internal implementation to the end user. However, the user must have the ability to modify and access this collection of data. Currently I have something like this: public List<SomeDataType> getData() { return this.data; } public void setData(List<SomeDataType> data) { this.data = data; } Does this mean that I have allowed the internal implementation details to leak out? Should I be doing this instead? public Collection<SomeDataType> getData() { return this.data; } public void setData(Collection<SomeDataType> data) { this.data = new ArrayList<SomeDataType>(data); }

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  • Constructor versus setter injection

    - by Chris
    Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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  • Wicket and Spring Intergation

    - by Vinothbabu
    I have a wicket contact form, and i receive the form object. Now i need to pass this object to Spring Service. package com.mysticcoders.mysticpaste.web.pages; import org.apache.wicket.markup.html.WebPage; import org.apache.wicket.markup.html.form.Form; import org.apache.wicket.markup.html.form.TextField; import org.apache.wicket.markup.html.panel.FeedbackPanel; import com.mysticcoders.mysticpaste.model.Contact; import org.apache.wicket.model.CompoundPropertyModel; import com.mysticcoders.mysticpaste.services.IContact; public class FormPage extends WebPage { private Contact contact; private IContact icontact; public FormPage() { // Add a FeedbackPanel for displaying our messages FeedbackPanel feedbackPanel = new FeedbackPanel("feedback"); add(feedbackPanel); Form<Object> form = new Form<Object>("contactForm", new CompoundPropertyModel<Object>(contact)) { private static final long serialVersionUID = 1L; protected void onSubmit(Contact contact) { icontact.saveContact(contact); } }; form.add(new TextField<Object>("name")); form.add(new TextField<Object>("email")); form.add(new TextField<Object>("country")); form.add(new TextField<Object>("age")); add(form); // add a simple text field that uses Input's 'text' property. Nothing // can go wrong here } } I am pretty much sure that we need to do something with application-context xml where i may need to wire out. My Application-context.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"> <bean id="WicketApplication" class="com.mysticcoders.mysticpaste.web.pages.WicketApplication" /> </beans> My Question is simple. What should i do which can make my onSubmit method call the Spring Service? Could someone let me know what needs to modified in my Application-context.xml so that once the form gets submitted, it contacts the Spring Service class.

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  • Why doesnt R.raw.'songname' not work on android devices?

    - by James Rattray
    I have some media (Audio tracks) on an app... With file path 'R.raw.test' I use some code to get it into a mediaplayer... MediaPlayer.create(Textbox.this, R.raw.fly); And it works PERFECTLY on the Android Emulator... (Plays track on click of button) Can someone explain why, when I put it on my Archos (5 IT) it doesnt work at all? -As soon as the button is clicked, it crashes... Do you have to do something to file paths or what? Please help... Thanks alot... James

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  • Beginner: Restore previously serialized JFrame-object, how?

    - by elementz
    Hi all. I have managed to serialize my very basic GUI-object containing a JTextArea and a few buttons to a file 'test.ser'. Now, I would like to completely restore the previously saved state from 'test.ser', but seem to have a misconception of how to properly deserialize an objects state. The class MyFrame creates the JFrame and serializes it. Now I tried to deserialize like so: public class Deserialize { static Deserialize ds; MyFrame frame; public static void main(String[] args) { try { ds.deserialize(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void deserialize() throws ClassNotFoundException { try { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.ser")); frame = (MyFrame) ois.readObject(); ois.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } Maybe somebody could point me into the direction where my misconception is? Thx in advance!

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  • How do I migrate a ManyToOne to a ManyToMany relationship in Hibernate?

    - by spderosso
    I have a instance field of a class X that is mapped using Hibernate as a Many to One relationship. E.g: public class X{ ... @ManyToOne(optional=false) private Y iField; ... } That is correctly working with a particular schema. I know want to change this instance field iField to a List and a Many to Many relationship. public class X{ ... @ManyToMany(optional=false) private List<Y> iField; ... } What steps should I follow? Do I have to change the schema? in which way? In case you need more info let me know. Thanks!

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  • Using Session Bean provided data on JSF welcome page

    - by takachgeza
    I use JSF managed beans calling EJB methods that are provide data from database. I want to use some data already on the welcome page of the application. What is the best solution for it? EJBs are injected into JSF managed beans and it looks like the injection is done after executing the constructor. So I am not able to call EJB methods in the constructor. The normal place for EJB call is in the JSF action methods but how to call such a method prior to loding the first page of the application? A possible solution would be to call the EJB method conditionally in a getter that is used on the welcome page, for example: public List getProductList(){ if (this.productList == null) this.productList = myEJB.getProductList(); return this.productList; } Is there any better solution? For example, in some config file?

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  • Delete files from blobstore using file serving URL

    - by Arturo
    In my app (GWT on GAE) we are storing on our database the serving URL that is stored on blobstore. When user selects one of these files and clicks "delete", we need to delete the file from blobstore. This is our code, but it is not deleting the file at all: public void remove(String fileURL) { BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService(); String key = getBlobKeyFromURL(box.getImageURL()); BlobKey blobKey = new BlobKey(key); blobstoreService.delete(blobKey); } Where fileURL looks like this: http://lh6.ggpht.com/d5VC0ywISACeJRiC3zkzaZug-tPsaI_LGt93-e_ATGTCwnGLao4yTWjLVppQ And getBlobKeyFromURL() would return what is after the last "/", in this example: d5VC0ywISACeJRiC3zkzaZug-tPsaI_LGt93-e_ATGTCwnGLao4yTWjLVppQ Could you please advice? Thanks

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  • Accessing the value of a Richfaces calendar during validation.

    - by JBristow
    I am trying to validate a field based on another field's value. <h:form id="item"> <s:validateAll/> <h:selectBooleanCheckbox id="selected" value="#{bean.selected}" validator="selectedValidator"/> <rich:calendar id="startDate" value="#{bean.startDate}"/> </h:form> However, inside my validator. public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException { UIInput startComp = (UIInput) context.getViewRoot().findComponent("item:startDate"); if(value != null && value) { // Check value of startComp and throw exception if null or empty. } } The component startComp resolves, but has no value. Where is the value that appears in the text box of the richfaces calendar component?

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  • JUnitCore.runClasses doesn't print anything....

    - by Grégoire
    I have a test class that I'm trying to run from a main method with the folowing code : Result r = org.junit.runner.JUnitCore.runClasses(TestReader.class); when I examine the Result object I can see that 5 tests have been run but nothing is printed on the screen. Should I do something else to get an output ?

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  • Finding key Solr performance metrics

    - by Mike Malloy
    To improve performance of Solr find your slowest searches, monitor query results, cache hit rate and cache size, document cache and filter cache; find problems with Solr update handlers by tracking index operations and document operations. There is a tool from New Relic which may help. http://www.newrelic.com/solr.html

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  • How can I interrupt a ServerSocket accept() method?

    - by lukeo05
    Hi, In my main thread I have a while(listening) loop which calls accept() on my ServerSocket object, then starts a new client thread and adds it to a Collection when a new client is accepted. I also have an Admin thread which I want to use to issue commands, like 'exit', which will cause all the client threads to be shut down, shut itself down, and shut down the main thread, by turning listening to false. However, the accept() call in the while(listening) loop blocks, and there doesn't seem to be any way to interrupt it, so the while condition cannot be checked again and the program cannot exit! Is there a better way to do this? Or some way to interrupt the blocking method? Thanks!

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  • Creating circular generic references

    - by M. Jessup
    I am writing an application to do some distributed calculations in a peer to peer network. In defining the network I have two class the P2PNetwork and P2PClient. I want these to be generic and so have the definitions of: P2PNetwork<T extends P2PClient<? extends P2PNetwork<T>>> P2PClient<T extends P2PNetwork<? extends T>> with P2PClient defining a method of setNetwork(T network). What I am hoping to describe with this code is: A P2PNetwork is constituted of clients of a certain type A P2PClient may only belong to a network whose clients consist of the same type as this client (the circular-reference) This seems correct to me but if I try to create a non-generic version such as MyP2PClient<MyP2PNetwork<? extends MyP2PClient>> myClient; and other variants I receive numerous errors from the compiler. So my questions are as follows: Is a generic circular reference even possible (I have never seen anything explicitly forbidding it)? Is the above generic definition a correct definition of such a circular relationship? If it is valid, is it the "correct" way to describe such a relationship (i.e. is there another valid definition, which is stylistically preferred)? How would I properly define a non-generic instance of a Client and Server given the proper generic definition?

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  • lwjgl 101: How can I write applets?

    - by Vuntic
    I have a working app in lwjgl. It doesn't do much yet; I've just started, but it does compile and run like it's supposed to. I want to make it into an applet. I've followed the guide here, and I have an applet that runs nicely and displays text and such in the applet area and can access the functions of lwjgl (like Sys.alert), but I can't figure out how to get opengl to actually render. I've tried extending an AWTGLCanvas and calling this.add(myAWTGLCanvas), where this is the Applet that I'm using, but... nothing. The initGL() and paintGL() methods never get called. I wonder if I'm supposed to be doing something with Display, but that's not for applets, right? Help? Also: This counts as a "beginner" question, right? Edit: Here's a simplified version of what I have.

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  • SoundPool repeating issue for Samsung Galaxy S3

    - by Alaa Eldin
    I'm trying to play a background sound for my application, I use SoundPool class, my problem is that, sound plays well only when I set the loop parameter with zero value, but it doesn't work for any other value. My code for initialization is: soundpool = new SoundPool(4, AudioManager.STREAM_MUSIC, 0); soundsMap = new HashMap<Integer, Integer>(); soundsMap.put(1, soundpool.load(this, R.raw.soundfile_1, 1)); soundsMap.put(2, soundpool.load(this, R.raw.soundfile_2, 1)); my code for playing is soundpool.play(1, 0.9f, 0.9f, 1, -1, 1f); as I mentioned sound works when I put (0) instead of (-1) for the loop value, anyone has any idea why (-1) or any value other than (0) doesn't work (there is no output sound) ?

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  • How to check if a variable exists in a FreeMarker template?

    - by Don
    Hi, I have a Freemarker template which contains a bunch of placeholders for which values are supplied when the template is processed. I want to conditionally include part of the template if the userName variable is supplied, something like: [#if_exists userName] Hi ${userName}, How are you? [/#if_exists] However, the FreeMarker manual seems to indicate that if_exists is deprecated, but I can't find another way to achieve this. Of course, I could simple providing an additional boolean variable isUserName and use that like this: [#if isUserName] Hi ${userName}, How are you? [/#if] But if there's a way of checking whether userName exists then I can avoid adding this extra variable. Cheers, Don

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  • Can i write to data output stream after reading response from data input stream?

    - by Sirius
    Hi, i want to do a client-server activity like this: 1. first the client sends/writes to output stream 2. the server responses with some data that will be read with input stream 3. after receiving the data, the client sends/writes to output stream again to respond that the data has been received now, do i have to close the output stream and re-open it again before doing step no.3 ? also if someone could provide me with a snippet, it would be really helpful. thanks

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  • JSP request parameter is returning null on a jsp include with Weblogic.

    - by doug
    Hello, I am having trouble with the jsp:include tag. I have code like the following: <jsp:include page="./Address.jsp"> <jsp:param value="30" name="tabIndex"/> <jsp:param value="true" name="showBox"/> <jsp:param value="none" name="display"/> </jsp:include> The page is included fine, but when I try to access the parameters on the Address.jsp page, they are null. I have tried accessing them the following ways (with jstl): <c:out value="${param.tabIndex}" /> <c:out value="${param['tabIndex']} /> <%= request.getParameter("tabIndex") %> <c:out value="${pageScope.param.tabIndex} /> ${param.tabIndex} etc... Here is the kicker, The above works fine in tomcat 5.5. However, when I deploy the application in Weblogic 10, it does not. Also, the code works fine in other areas of my application (on weblogic) just not a particular page. Any Ideas? Thanks!

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  • Remove robot as an editor of a blip

    - by Lee
    I have a Google Wave robot which makes changes to some blip content depending on what a user inputs. When this edit is made, the robot is listed in the blip as one of the people who have edited it (so shows its Avatar and robot name). I was wondering if anyone knew if it was possible (and if so how), to stop the robot being listed as an editor (either by it not happening in the first place, or removing it afterwards).

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