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  • Best practice when removing entity regarding mappedBy collections?

    - by Daniel Bleisteiner
    I'm still kind of undecided which is the best practice to handle em.remove(entity) with this entity being in several collections mapped using mappedBy in JPA. Consider an entity like a Property that references three other entities: a Descriptor, a BusinessObject and a Level entity. The mapping is defined using @ManyToOne in the Property entity and using @OneToMany(mappedBy...) in the other three objects. That inverse mapping is defined because there are some situations where I need to access those collections. Whenever I remove a Property using em.remove(prop) this element is not automatically removed from managed entities of the other three types. If I don't care about that and the following page load (webapp) doesn't reload those entities the Property is still found and some decisions might be taken that are no longer true. The inverse mappings may become quite large and though I don't want to use something like descriptor.getProperties().remove(prop) because it will load all those properties that might have been lazy loaded until then. So my currently preferred way is to refresh the entity if it is managed: if (em.contains(descriptor)) em.refresh(descriptor) - which unloads a possibly loaded collection and triggers a reload upon the next access. Is there another feasible way to handle all those mappedBy collections of already loaded entites?

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  • jsf custom control strange behaviour

    - by Cristian Boariu
    hi, I have a jsf custom control which contains this: <rich:column> <c:if test="#{not empty columnTitle}"> <f:facet name="header"> <rich:spacer/> </f:facet> </c:if> <s:link view="#{view}" value="#{messages['edit']}" propagation="#{propagation}"> <f:param name="${paramName}" value="${paramValue}"/> </s:link> &#160; <h:commandLink action="#{entityHome.removeMethodName(entity)}" value="#{messages['remove']}"/> </rich:column> You see that command link action. I want it to call an action like this: action="#{documentHome.removeProperty(property)"} Well, in order to do this i call the control like: <up:columnDetails view="/admin/property.xhtml" columnTitle="yes" entity="#{property}" paramValue="#{property.propertyId}" propagation="nest" entityHome="documentHome" removeMethodName="removeProperty"/> So, i hardcode entityHome and removeMethodName. Well an error is firing. Caused by javax.servlet.ServletException with message: "#{entityHome.removeMethodName(entity)}: javax.el.MethodNotFoundException It seems that it cannot interpret "removeMethodName". If i print entityHome or removeMethodName it correctly shows the values i pass. But i think jsf has an error like not beeing able to "believe" that after an object.something, that something can be a parameter... Can anyone guide me...?

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  • ServiceLoader double iterator issues

    - by buge
    Is this a known issue? I had trouble finding any search results. When iterating over a ServiceLoader while an iteration already is in progress, the first iteration will be aborted. For example, assuming there are at least two implementations of Foo, the following code will fail with an AssertionError: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); while (iter2.hasNext()) { iter2.next(); } assert iter1.hasNext(); This only seems to occur, if the second iterator really terminates. The code will succeed in this variation for example: ServiceLoader<Foo> loader = ServiceLoader.load(Foo.class); Iterator<Foo> iter1 = loader.iterator(); iter1.next(); Iterator<Foo> iter2 = loader.iterator(); iter2.next(); assert iter1.hasNext(); Is this a bug or a feature? :p Is there a ticket for this already anywhere?

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  • how to add list to button

    - by priya
    hi... how to add a list to a button.. for example if i have four button like classic, western, jazz,pop.if i click classic button i should get subtitle .or if i click western i should get sub title... so how to creat

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  • Why is the output like this?

    - by javatechi
    class another { public void method(Object o) { System.out.println("This is in method which takes object"); } public void method(String s) { System.out.println("This is method which takes string"); } } public class NewClass { public static void main(String args[]) { another an = new another(); an.method(null); } } When I try to execute this, I get This is method which takes string as the output. Why not "This is in method which takes object"? Object can also be null and string can also be null, why doesn't it invoke first method?

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  • Join data from two Lists into one object

    - by Petr Mensik
    I ran into following situation and I am wondering about best solution. Let's say I have List<Object1> and List<Object2>, these lists are result of two separated queries. Both of them have the same size and there is relationship 1:1 between elements in the lists based on ID. I know that best solution would be fetching data in one DB query but that's possible right now. So my question is, what is the best way to join these lists into let's say List<Object3>?

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  • new Integer vs valueOf

    - by LB
    Hi, I was using Sonar to make my code cleaner, and it pointed that I'm using new Integer(1) instead of Integer.valueOf(1). Because it seems that valueOf does not instantiate a new object so is more memory-friendly. How can valueOf not instantiate a new object ? How does it work ? Is this true for all integers ? thanks.

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  • AJAX Problem - No response text in FireFox, but ok in IE

    - by Taiba
    Hi, I am making a simple AJAX call to an external site. It works ok in IE, but in Firefox, not response text is returned. I think it might have something to do with the response being "chunked", but I'm not sure. Any ideas? Thanks. function loadXMLDoc() { var xmlhttp; var urlString = "http://drc.edeliver.com.au/ratecalc.asp?Pickup_Postcode=6025&Destination_Postcode=6055&Country=AU&Weight=100&Service_Type=STANDARD&Length=100&Width=100&Height=100&Quantity=2"; if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4) { window.alert(xmlhttp.responseText); } } xmlhttp.open("GET", urlString, true); xmlhttp.send(); }

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  • Why the generated key size is not constant?

    - by Tom Brito
    The following code prints randomly 634, 635, 636, each time I run it. Why its not constant? public static void main(String[] args) throws Exception { KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA", "BC"); keyPairGen.initialize(1024); RsaKeyPair keyPair = new RsaKeyPair(keyPairGen.generateKeyPair()); System.out.println(keyPair.getPrivate().getEncoded().length); }

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  • Keeping track of threads when creating them recursively

    - by 66replica
    I'm currently working on some code for my Programming Languages course. I can't post the code but I'm permitted to talk about some high level concepts that I'm struggling with and receive input on them. Basically the code is a recursive DFS on a undirected graph that I'm supposed to convert to a concurrent program. My professor already specified that I should create my threads in the recursive DFS method and then join them in another method. Basically, I'm having trouble thinking of how I should keep track of the threads I'm creating so I can join all of them in the other method. I'm thinking an array of Threads but I'm unsure how to add each new thread to the array or even if that's the right direction.

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  • How do I ensure my abstract class's function can only operate on extenders of the same type as the c

    - by incrediman
    For example, let's say this is my abstract class: abstract class A{ int x; int y; void foo(A fooMe); } ...and B and C are two classes which extend A. What I want is for B to only be able to call foo() on other Bs, and for C to only be able to call foo() on other Cs. But I want this to be out of the hands of the programmer who's extending my A class - that is, I want a way to ensure this functionality within As code alone. What can I do? (If possible) I'd like to avoid any hack or generics solution that's too messy - I still want foo to be able to be called like this, for example: B b=new B(); B bb=new B(); bb.foo(b);

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  • Can't access a property with <html:checkbox property="..."> when iterating a list

    - by Bernhard V
    Hi. In my Struts form I've got a list. In a JSP I iterate over it like this: <c:forEach items="${MyForm.auspraegungen}" var="auspraegung"> <tr> <td>${auspraegung.name}</td> <td>${auspraegung.forced}</td> <td>${auspraegung.cbx_uebernehmen}</td> <html:checkbox property="auspraegung.cbx_uebernehmen" /> </tr> </c:forEach> Now the <html:checkbox isn't working. I'm always getting the following error: Caused by: javax.servlet.jsp.JspException: No getter method for property auspraegung.cbx_uebernehmen of bean org.apache.struts.taglib.html.BEAN But actually there is a getter for this property in my form class. It's written like this: public Boolean getCbx_uebernehmen() { return cbx_uebernehmen; } When I remove the checkbox it's also possible to display the property as in the <td>-tag above so I don't know where the problem is. Maybe I'm accessing it in the wrong way?

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  • jaxb: How can I bind nested element

    - by user368532
    There is my xml: <parent> <children> <child>1</child> <child>2</child> </children> </parent> I want to have the following Parent class: @XmlRootElement Parent{ @XmlElement(name="children/child") List<Child> children; } I don't want to have class for element 'children'. How should I map field children ?

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  • LRU LinkedHashMap that limits size based on available memory

    - by sanity
    I want to create a LinkedHashMap which will limit its size based on available memory (ie. when freeMemory + (maxMemory - allocatedMemory) gets below a certain threshold). This will be used as a form of cache, probably using "least recently used" as a caching strategy. My concern though is that allocatedMemory also includes (I assume) un-garbage collected data, and thus will over-estimate the amount of used memory. I'm concerned about the unintended consequences this might have. For example, the LinkedHashMap may keep deleting items because it thinks there isn't enough free memory, but the free memory doesn't increase because these deleted items aren't being garbage collected immediately. Does anyone have any experience with this type of thing? Is my concern warranted? If so, can anyone suggest a good approach? I should add that I also want to be able to "lock" the cache, basically saying "ok, from now on don't delete anything because of memory usage issues".

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  • Automatically Add a Prefix to Column Names for @Embeddable Classes

    - by VeeArr
    I am developing a project in which I am persisting some POJOs by adding Hibernate annotations. One problem I am running into is that code like this fails, as Hibernate tries to map the sub-fields within the Time_T onto the same column (i.e. startTime.sec and stopTime.sec both try to map to the colum sec, causing an error). @Entity public class ExampleClass { @Id long eventId; Time_T startTime; Time_T stopTime; } @Embeddable public class Time_T { int sec; int nsec; } As there will be many occurrences like this throughout the system, it would be nice if there was an option to automatically append a prefix to the column name (e.g. make the columns be startTime_sec, startTime_nsec, stopTime_sec, stopTime_nsec), without having to apply overrides on a per-field basis. Does Hibernate have this capability, or is there any other reasonable work-around?

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  • Mapping restful ajax requests to spring

    - by Diones
    I have this piece of code: @RequestMapping(value = "/test.json", method = RequestMethod.GET) @ResponseStatus(HttpStatus.OK) public @ResponseBody Object[] generateFile(@RequestParam String tipo) { Object[] variaveis = Variavel.getListVariavelByTipo(tipo); return variaveis; } As far as I know it should take a request to test.json?tipo=H and return the JSON representation of Variavel[], however when I make such request I get: HTTP Status 406 - type Status report message descriptionThe resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers () By using the following function I can get the expected json: @RequestMapping(value = "/teste.json") public void testeJson(Model model, @RequestParam String tipo) { model.addAttribute("data", Variavel.getListVariavelByTipo("H")); } What I'm doing wrong?

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