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  • Improving field get and set performance with ASM or Javassist

    - by ng
    I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM and Javasist examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and one with Javassist? Any help would be greatly appreciated.

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  • How do I use Google's Gson API to deserialize JSON properly?

    - by FK82
    Hi, In short, this is a sketch of the JSON object I want to parse in JAVA: { object1: { item1: //[String | Array | Object] , item2: // ... //<> more items object2: { // } //<> more objects } These are the POJO s I created for parsing (I'll leave out the import statements for brevity's sake): (1) The representation of the complete JSON object public class JObjectContainer { private List<JObject> jObjects ; public JObjectContainer() { // } //get & set methods } (2) The representation of the nested objects: public class JObject { private String id ; private List<JNode> jObjects ; public JObject() { // } //get & set methods } (3) The representation of the items: public class JNode { private JsonElement item1 ; private JsonElement item2 ; //<> more item fields public JNode() { // } //get & set methods } Now, creating a Gson instance (FileReader for importing the jsonFile), Gson gson = new Gson() ; JObjectContainer joc = gson(jsonFile,JObjectContainer.class) ; I get a NullPointerException whenever I try to access the parseable object (e.g. through a ListIterator). Gson does however create an object of the class I specified and does not throw any subsequent errors. I know that this has been done before. So, what am I missing? TIA

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  • How to implement an ID field on a POCO representing an Identity field in MS SQL?

    - by Dr. Zim
    If I have a Domain Model that has an ID that maps to a SQL identity column, what does the POCO look like that contains that field? Candidate 1: Allows anyone to set and get the ID. I don't think we want anyone setting the ID except the Repository, from the SQL table. public class Thing { public int ID {get;set;} } Candidate 2: Allows someone to set the ID upon creation, but we won't know the ID until after we create the object (factory creates a blank Thing object where ID = 0 until we persist it). How would we set the ID after persisting? public class Thing { public Thing () : This (ID: 0) {} public Thing (int ID) { this.ID = ID } private int _ID; public int ID { get { return this.ID;}; } Candidate 3: Methods to set ID? Somehow we would need to allow the Repository to set the ID without allowing the consumer to change it. Any ideas? Is this barking up the wrong tree? Do we send the object to the Repository, save it, throw it away, then create a new object from the loaded version and return that as a new object?

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  • error LNK2001: unresolved external symbol

    - by numerical25
    I am receiving this error >GXRenderManager.obj : error LNK2001: unresolved external symbol "private: static class GXRenderer * GXRenderManager::renderDevice" (?renderDevice@GXRenderManager@@0PAVGXRenderer@@A) The following is my code... GXDX.h class GXDX: public GXRenderer { public: void Render(); void StartUp(); }; GXGL.h class GXGL: public GXRenderer { public: void Render(); void StartUp(); }; GXRenderer class GXRenderer { public: virtual void Render() = 0; virtual void StartUp() = 0; }; GXRenderManager.h #ifndef GXRM #define GXRM #include <windows.h> #include "GXRenderer.h" #include "GXDX.h" #include "GXGL.h" enum GXDEVICE { DIRECTX, OPENGL }; class GXRenderManager { public: static int Ignite(GXDEVICE); private: static GXRenderer *renderDevice; }; #endif GXRenderManager.cpp #include "GXRenderManager.h" int GXRenderManager::Ignite(GXDEVICE DeviceType) { switch(DeviceType) { case DIRECTX: GXRenderManager::renderDevice = new GXDX; return 1; break; case OPENGL: GXRenderManager::renderDevice = new GXGL; return 1; break; default: return 0; } } main.cpp #include "GXRenderManager.h" int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { return 0; } I am not trying to get it to do anything. I am just trying to compile with no errors. I am new with all this so if anyone can give me a hand. that will be great. thanks

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  • How to build a sequence in the method calls of a fluent interface

    - by silverfighter
    Hi I would like to build a fluent interface for creating am object some sort of factory or builder. I understand that I have to "return this" in order to make the methods chainable. public class CarBuilder { public CarBuilder() { car = new Car(); } private Car car; public CarBuilder AddEngine(IEngineBuilder engine) { car.Engine = engine.Engine(); return this; } public CarBuilder AddWheels(IWheelsBuilder wheels) { car.Wheels = wheels.Wheels(); return this; } public CarBuilder AddFrame(IFrameBuilder frame) { car.Frame = frame.Frame(); return this; } public Car BuildCar() { return car; } } with this I could build a car like that: Car c = builder.AddFrame(fBuilder).AddWheels(wBuilder).AddEngine(eBuilder).BuildCar(); But what I need is a special sequence or workflow: I can only build the wheels on top of the frame and when the wheels exist then I'll be able to build up the engine. So instead of offering every method of the car builder I want to be able to add only the frame to the builder and then only the wheels to the frame and then the engine on top of that... And how would it be or what would be a good implementation if the EngineBuilder itself has a fluent api like eBuilder.Cylinders(12).WithPistons().... Would it be possible to have something like this Car c = builder.AddFrame(fBuilder).AddWheels(wBuilder).AddEngine(x=>x.WithCylinders(12).WithPistons()).BuildCar(); So in sum how to structure the flow of the fluent interface and how to nest fluent Interfaces?

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  • Passing an arbitrary JSONValue to a JSNI function

    - by Riley Lark
    I have a JSONValue in my Java that may be a JSONArray, a JSONObject, a JSONString, etc. I want to pass it to a JSNI function that can accept any of those types. If I naively write my JSNI as something like: public final native jsni(Object parameter) /*-{ doSomething(parameter); }-*/; public void useFunction(JSONValue value) { jsni(value); //Throws js exception at runtime :( } then I get a javascript exception, because GWT doesn't know how to convert the JSONValue to a JavaScriptObject (or native string / number value). My current workaround is public final native jsniForJSO(Object parameter) /*-{ doSomething(parameter); }-*/; public final native jsniForString(String parameter) /*-{ doSomething(parameter); }-*/; public final native jsniForNumber(double parameter) /*-{ doSomething(parameter); }-*/; public actuallyUseFunction(JSONValue value) { if (value.isObject()) { jsniForJSO(value.isObject().getJavaScriptObject()); } else if (value.isString()) { jsniForString(value.isString().stringValue()); } else { //etc } } This is a big burden for code maintainability, etc... especially if you have more than one parameter. Is there a way to generate these functions automatically, or get around this issue altogether? I've taken to wrapping everything in a JSONObject first, so I can definitely get a JavaScriptObject to pass to my jsni, but that's another clumsy mechanic.

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  • Why doesn't is operator take in consideration if the explicit operator is overriden when checking ty

    - by Galilyou
    Hey Guys, Consider this code sample: public class Human { public string Value { get; set;} } public class Car { public static explicit operator Human (Car c) { Human h = new Human(); h.Value = "Value from Car"; return h; } } public class Program { public static void Mani() { Car c = new Car(); Human h = (Human)c; Console.WriteLine("h.Value = {0}", h.Value); Console.WriteLine(c is Human); } } Up I provide a possibility of an explicit cast from Car to Human, though Car and Human hierarchically are not related! The above code simply means that "Car is convertible to human" However, if you run the snippet you will find the expression c is Human evaluates to false! I used to believe that the is operator is kinda expensive cause it attempts to do an actual cast that might result in an InvalidCastException. If the operator is trying to cast, then the cast should succeed as there's an operator logic that should perform the cast! What does "is" test? Does test a hierarchical "is-a" relationship? Does test whether a variable type is convertible to a type?

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  • Strange GWT serialization exception when overiding method of serialized object

    - by Flueras Bogdan
    Hi there! I have a GWT serializable class, lets call it Foo. Foo implements IsSerializable, has primitive and serializable members as well as other transient members and a no-arg constructor. class Foo implements IsSerializable { // transient members // primitive members public Foo() {} public void bar() {} } Also a Service which handles RPC comunication. // server code public interface MyServiceImpl { public void doStuff(Foo foo); } public interface MyServiceAsync { void doStuff(Foo foo, AsyncCallback<Void> async); } How i use this: private MyServiceAsync myService = GWT.create(MyService.class); Foo foo = new Foo(); ... AsyncCallback callback = new new AsyncCallback {...}; myService.doStuff(foo, callback); In the above case the code is running, and the onSuccess() method of callback instance gets executed. But when I override the bar() method on foo instance like this: Foo foo = new Foo() { public void bar() { //do smthng different } } AsyncCallback callback = new new AsyncCallback {...}; myService.doStuff(foo, callback); I get the GWT SerializationException. Please enlighten me, because I really don't understand why.

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  • How to easily substitute a Base class

    - by JTom
    Hi, I have the following hierarchy of classes class classOne { virtual void abstractMethod() = 0; }; class classTwo : public classOne { }; class classThree : public classTwo { }; All classOne, classTwo and classThree are abstract classes, and I have another class that is defining the pure virtual methods class classNonAbstract : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; And right now I need it differently...I need it like class classNonAbstractOne : public classOne { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; class classNonAbstractTwo : public classTwo { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; and class classNonAbstractThree : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; But all the nonAbstract classes have the same new methods, with the same code...and I would like to avoid copying all the methods and it's code to every nonAbstract class. How could I accomplish that? Hopefully it's understandable...

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  • Is it bad practice to have state in a static class?

    - by Matthew
    I would like to do something like this: public class Foo { // Probably really a Guid, but I'm using a string here for simplicity's sake. string Id { get; set; } int Data { get; set; } public Foo (int data) { ... } ... } public static class FooManager { Dictionary<string, Foo> foos = new Dictionary<string, Foo> (); public static Foo Get (string id) { return foos [id]; } public static Foo Add (int data) { Foo foo = new Foo (data); foos.Add (foo.Id, foo); return foo; } public static bool Remove (string id) { return foos.Remove (id); } ... // Other members, perhaps events for when Foos are added or removed, etc. } This would allow me to manage the global collection of Foos from anywhere. However, I've been told that static classes should always be stateless--you shouldn't use them to store global data. Global data in general seems to be frowned upon. If I shouldn't use a static class, what is the right way to approach this problem? Note: I did find a similar question, but the answer given doesn't really apply in my case.

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  • An Interactive Console I/O Wrapper/Interceptor in C# - What is the issue?

    - by amazedsaint
    I was trying to put together an interactive Console interceptor/wrapper in C# over the weekend, by re-mixing few code samples I've found in SO and other sites. With what I've as of now, I'm unable to read back from the console reliably. Any quick pointers? public class ConsoleInterceptor { Process _interProc; public event Action<string> OutputReceivedEvent; public ConsoleInterceptor() { _interProc = new Process(); _interProc.StartInfo = new ProcessStartInfo("cmd"); InitializeInterpreter(); } public ConsoleInterceptor(string command) { _interProc = new Process(); _interProc.StartInfo = new ProcessStartInfo(command); InitializeInterpreter(); } public Process InterProc { get { return _interProc; } } private void InitializeInterpreter() { InterProc.StartInfo.RedirectStandardInput = true; InterProc.StartInfo.RedirectStandardOutput = true; InterProc.StartInfo.RedirectStandardError = true; InterProc.StartInfo.CreateNoWindow = true; InterProc.StartInfo.UseShellExecute = false; InterProc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; bool started = InterProc.Start(); Redirect(InterProc.StandardOutput); Redirect(InterProc.StandardError); } private void Redirect(StreamReader input) { new Thread((a) => { var buffer = new char[1]; while (true) { if (input.Read(buffer, 0, 1) > 0) OutputReceived(new string(buffer)); }; }).Start(); } private void OutputReceived(string text) { if (OutputReceivedEvent != null) OutputReceivedEvent(text); } public void Input(string input) { InterProc.StandardInput.WriteLine(input); InterProc.StandardInput.Flush(); } }

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  • Java assignment issues - Is this atomic?

    - by Bob
    Hi, I've got some questions about Java's assigment. Strings I've got a class: public class Test { private String s; public synchronized void setS(String str){ s = s + " - " + str; } public String getS(){ return s; } } I'm using "synchronized" in my setter, and avoiding it in my getter, because in my app, there are a tons of data gettings, and very few settings. Settings must be synchronized to avoid inconsistency. My question is: is getting and setting a variable atomic? I mean, in a multithreaded environment, Thread1 is about to set variable s, while Thread2 is about to get "s". Is there any way the getter method could get something different than the s's old value or the s's new value (suppose we've got only two threads)? In my app it is not a problem to get the new value, and it is not a problem to get the old one. But could I get something else? What about HashMap's getting and putting? considering this: public class Test { private Map<Integer, String> map = Collections.synchronizedMap(new HashMap<Integer, String>()); public synchronized void setMapElement(Integer key, String value){ map.put(key, value); } public String getValue(Integer key){ return map.get(key); } } Is putting and getting atomic? How does HashMap handle putting an element into it? Does it first remove the old value and put the now one? Could I get other than the old value or the new value? Thanks in advance!

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  • How to make a thread that runs at x:00 x:15 x:30 and x:45 do something different at 2:00.

    - by rmarimon
    I have a timer thread that needs to run at a particular moments of the day to do an incremental replication with a database. Right now it runs at the hour, 15 minutes past the hour, 30 minutes past the hour and 45 minutes past the hour. This is the code I have which is working ok: public class TimerRunner implements Runnable { private static final Semaphore lock = new Semaphore(1); private static final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); public static void initialize() { long delay = getDelay(); executor.schedule(new TimerRunner(), delay, TimeUnit.SECONDS); } public static void destroy() { executor.shutdownNow(); } private static long getDelay() { Calendar now = Calendar.getInstance(); long p = 15 * 60; // run at 00, 15, 30 and 45 minutes past the hour long second = now.get(Calendar.MINUTE) * 60 + now.get(Calendar.SECOND); return p - (second % p); } public static void replicate() { if (lock.tryAcquire()) { try { Thread t = new Thread(new Runnable() { public void run() { try { // here is where the magic happens } finally { lock.release(); } } }); t.start(); } catch (Exception e) { lock.release(); } } else { throw new IllegalStateException("already running a replicator"); } } public void run() { try { TimerRunner.replicate(); } finally { long delay = getDelay(); executor.schedule(new TimerRunner(), delay, TimeUnit.SECONDS); } } } This process is started by calling TimerRunner.initialize() when a server starts and calling TimerRunner.destroy(). I have created a full replication process (as opposed to incremental) that I would like to run at a certain moment of the day, say 2:00am. How would change the above code to do this? I think that it should be very simple something like if it is now around 2:00am and it's been a long time since I did the full replication then do it now, but I can't get the if right. Beware that sometimes the replicate process takes way longer to complete. Sometimes beyond the 15 minutes, posing a problem in running at around 2:00am.

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  • ResourceFilterFactory and non-Path annotated Resources

    - by tousdan
    (I'm using Jersey 1.7) I am attempting to add a ResourceFilterFactory in my project to select which filters are used per method using annotations. The ResourceFilterFactory seems to be able to filters on Resources which are annotated with the Path annotation but it would seem that it does not attempt to generate filters for the methods of the SubResourceLocator of the resources that are called. @Path("a") public class A { //sub resource locator? @Path("b") public B getB() { return new B(); } @GET public void doGet() {} } public class B { @GET public void doOtherGet() { } @Path("c") public void doInner() { } } When ran, the Filter factory will only be called for the following: AbstractResourceMethod(A#doGet) AbstractSubResourceLocator(A#getB) When I expected it to be called for every method of the sub resource. I'm currently using the following options in my web.xml; <init-param> <param-name>com.sun.jersey.spi.container.ResourceFilters</param-name> <param-value>com.my.MyResourceFilterFactory</param-value> </init-param> <init-param> <param-name>com.sun.jersey.config.property.packages</param-name> <param-value>com.my.resources</param-value> </init-param> Is my understanding of the filter factory flawed?

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  • ASP.NET MVC Conditional validation

    - by Peter Stegnar
    How to use data annotations to do a conditional validation on model? For example, lets say we have the following model (Person and Senior): public class Person { [Required(ErrorMessage = "*")] public string Name { get; set; } public bool IsSenior { get; set; } public Senior Senior { get; set; } } public class Senior { [Required(ErrorMessage = "*")]//this should be conditional validation, based on the "IsSenior" value public string Description { get; set; } } And the following view: <%= Html.EditorFor(m => m.Name)%> <%= Html.ValidationMessageFor(m => m.Name)%> <%= Html.CheckBoxFor(m => m.IsSenior)%> <%= Html.ValidationMessageFor(m => m.IsSenior)%> <%= Html.CheckBoxFor(m => m.Senior.Description)%> <%= Html.ValidationMessageFor(m => m.Senior.Description)%> I would like to be the "Senior.Description" property conditional required field based on the selection of the "IsSenior" propery (true - required). How to implement conditional validation in ASP.NET MVC 2 with data annotations? UPDATE Found nice solution. Look below.

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  • User entered value validation and level of error catching

    - by Terry
    May I ask should the error catching code be placed at the lowest level or at the top as I am not sure what is the best practice? I prefer placing at the bottom, example a, as Example a public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { if (month < 1 || month > 12) { throw new Exception(""); } } public static void DoDate(int date) { if (date < 1 || date > 31) { throw new Exception(""); } } or example b public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date" && (date < 1 || date > 12)) { throw new Exception(""); } else if (operation == "month" && (month < 1 || month > 31)) { throw new Exception(""); } if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { } public static void DoDate(int date) { }

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  • Which view will be resolved, code from spring's docs

    - by Blankman
    So when you go to /appointments the get() action is called, so then would the view be get.jsp (assuming you are using .jsp, and assuming you are mapping action names to views)? And what about the getnewform? It seems to be returning an object? Is that basically passed into the view? @Controller @RequestMapping("/appointments") public class AppointmentsController { private final AppointmentBook appointmentBook; @Autowired public AppointmentsController(AppointmentBook appointmentBook) { this.appointmentBook = appointmentBook; } @RequestMapping(method = RequestMethod.GET) public Map<String, Appointment> get() { return appointmentBook.getAppointmentsForToday(); } @RequestMapping(value="/{day}", method = RequestMethod.GET) public Map<String, Appointment> getForDay(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date day, Model model) { return appointmentBook.getAppointmentsForDay(day); } @RequestMapping(value="/new", method = RequestMethod.GET) public AppointmentForm getNewForm() { return new AppointmentForm(); } @RequestMapping(method = RequestMethod.POST) public String add(@Valid AppointmentForm appointment, BindingResult result) { if (result.hasErrors()) { return "appointments/new"; } appointmentBook.addAppointment(appointment); return "redirect:/appointments"; } } In the example, the @RequestMapping is used in a number of places. The first usage is on the type (class) level, which indicates that all handling methods on this controller are relative to the /appointments path. The get() method has a further @RequestMapping refinement: it only accepts GET requests, meaning that an HTTP GET for /appointments invokes this method. The post() has a similar refinement, and the getNewForm() combines the definition of HTTP method and path into one, so that GET requests for appointments/new are handled by that method.

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  • How to Elegantly convert switch+enum with polymorphism

    - by Kyle
    I'm trying to replace simple enums with type classes.. that is, one class derived from a base for each type. So for example instead of: enum E_BASE { EB_ALPHA, EB_BRAVO }; E_BASE message = someMessage(); switch (message) { case EB_ALPHA: applyAlpha(); case EB_BRAVO: applyBravo(); } I want to do this: Base* message = someMessage(); message->apply(this); // use polymorphism to determine what function to call. I have seen many ways to do this which all seem less elegant even then the basic switch statement. Using dyanimc_pointer_cast, inheriting from a messageHandler class that needs to be updated every time a new message is added, using a container of function pointers, all seem to defeat the purpose of making code easier to maintain by replacing switches with polymorphism. This is as close as I can get: (I use templates to avoid inheriting from an all-knowing handler interface) class Base { public: template<typename T> virtual void apply(T* sandbox) = 0; }; class Alpha : public Base { public: template<typename T> virtual void apply(T* sandbox) { sandbox->applyAlpha(); } }; class Bravo : public Base { public: template<typename T> virtual void apply(T* sandbox) { sandbox->applyBravo(); } }; class Sandbox { public: void run() { Base* alpha = new Alpha; Base* bravo = new Bravo; alpha->apply(this); bravo->apply(this); delete alpha; delete bravo; } void applyAlpha() { // cout << "Applying alpha\n"; } void applyBravo() { // cout << "Applying bravo\n"; } }; Obviously, this doesn't compile but I'm hoping it gets my problem accross.

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  • ArrayList.Sort should be a stable sort with an IComparer but is not?

    - by Kaleb Pederson
    A stable sort is a sort that maintains the relative ordering of elements with the same value. The docs on ArrayList.Sort say that when an IComparer is provided the sort is stable: If comparer is set to null, this method performs a comparison sort (also called an unstable sort); that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal. To perform a stable sort, you must implement a custom IComparer interface. Unless I'm missing something, the following testcase shows that ArrayList.Sort is not using a stable sort: internal class DisplayOrdered { public int ID { get; set; } public int DisplayOrder { get; set; } public override string ToString() { return string.Format("ID: {0}, DisplayOrder: {1}", ID, DisplayOrder); } } internal class DisplayOrderedComparer : IComparer { public int Compare(object x, object y) { return ((DisplayOrdered)x).DisplayOrder - ((DisplayOrdered)y).DisplayOrder; } } [TestFixture] public class ArrayListStableSortTest { [Test] public void TestWeblinkCallArrayListIsSortedUsingStableSort() { var call1 = new DisplayOrdered {ID = 1, DisplayOrder = 0}; var call2 = new DisplayOrdered {ID = 2, DisplayOrder = 0}; var call3 = new DisplayOrdered {ID = 3, DisplayOrder = 2}; var list = new ArrayList {call1, call2, call3}; list.Sort(new DisplayOrderedComparer()); // expected order (by ID): 1, 2, 3 (because the DisplayOrder // is equal for ID's 1 and 2, their ordering should be // maintained for a stable sort.) Assert.AreEqual(call1, list[0]); // Actual: ID=2 ** FAILS Assert.AreEqual(call2, list[1]); // Actual: ID=1 Assert.AreEqual(call3, list[2]); // Actual: ID=3 } } Am I missing something? If not, would this be a documentation bug or a library bug? Apparently using an OrderBy in Linq gives a stable sort.

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  • Hibernate: deletes not cascading for self-referencing entities

    - by jwaddell
    I have the following (simplified) Hibernate entities: @Entity @Table(name = "package") public abstract class Package { protected Content content; @ManyToOne(cascade = {javax.persistence.CascadeType.ALL}) @JoinColumn(name = "content_id") @Fetch(value = FetchMode.JOIN) public Content getContent() { return content; } public void setContent(Content content) { this.content = content; } } @Entity @Table(name = "content") public class Content { private Set<Content> subContents = new HashSet<Content>(); @ManyToMany(fetch = FetchType.EAGER) @JoinTable(name = "subcontents", joinColumns = {@JoinColumn(name = "content_id")}, inverseJoinColumns = {@JoinColumn(name = "elt")}) @Cascade(value = {org.hibernate.annotations.CascadeType.DELETE, org.hibernate.annotations.CascadeType.REPLICATE}) @Fetch(value = FetchMode.SUBSELECT) public Set<Content> getSubContents() { return subContents; } public void setSubContents(Set<Content> subContents) { this.subContents = subContents; } } So a Package has a Content, and a Content is self-referencing in that it has many sub-Contents (which may contain sub-Contents of their own etc). The relationships are required to be ManyToOne (Package to Content) and ManyToMany (Content to sub-Contents) but for the case I am currently testing each sub-Content only relates to one Package or Content. The problem is that when I delete a Package and flush the session, I get a Hibernate error stating that I'm violating a foreign key constraint on table subcontents, with a particular content_id still referenced from table subcontents. I've tried specifically (recursively) deleting the Contents before deleting the Package but I get the same error. Is there a reason why this entity tree is not being deleted properly?

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  • When using Clipboard, Toolkit and Transferable, I get an error objecting to image width and height

    - by Mike King
    When I run the following code it triggers an error message. The error message is shown below the code. What code changes, or changes to the image file, are needed to fix this error? Help will be appreciated. import java.awt.*; import java.awt.datatransfer.*; public class LoadToClipboard { public static void main( String [] args ) { Toolkit tolkit = Toolkit.getDefaultToolkit(); Clipboard clip = tolkit.getSystemClipboard(); clip.setContents( new ImageSelection( tolkit.getImage("StackOverflowLogo.png")) , null ); } } class ImageSelection implements Transferable { private Image image; public ImageSelection(Image image) { this.image = image; } // Returns supported flavors public DataFlavor[] getTransferDataFlavors() { return new DataFlavor[]{DataFlavor.imageFlavor}; } // Returns true if flavor is supported public boolean isDataFlavorSupported(DataFlavor flavor) { return DataFlavor.imageFlavor.equals(flavor); } // Returns image public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException { if (!DataFlavor.imageFlavor.equals(flavor)) { throw new UnsupportedFlavorException(flavor); } return image; } } Exception in thread "main" java.lang.IllegalArgumentException: Width (-1) and height (-1) cannot be <= 0 at java.awt.image.DirectColorModel.createCompatibleWritableRaster(DirectColorModel.java:999) at sun.awt.datatransfer.DataTransferer.imageToStandardBytes(DataTransferer.java:1994) at sun.awt.windows.WDataTransferer.imageToPlatformBytes(WDataTransferer.java:267) at sun.awt.datatransfer.DataTransferer.translateTransferable(DataTransferer.java:1123) at sun.awt.windows.WDataTransferer.translateTransferable(WDataTransferer.java:163) at sun.awt.windows.WClipboard.setContentsNative(WClipboard.java:73) at sun.awt.datatransfer.SunClipboard.setContents(SunClipboard.java:93) at automateSignature.LoadToClipboard.main(LoadToClipboard.java:8) I have tried to find a place in the code where width and height can be specified, but have not succeeded. I also examined the properties of the jpg file and the w and h are specified.enter code here

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  • unable to compile a servlet in ubuntu

    - by codeomnitrix
    I am newbie to j2ee. I have download and installed j2eesdk-1_4_03-linux.bin in my ubuntu 10.04 distribution. and then i tried to code my first servlet in it as: import java.io.*; import javax.servelet.*; import javax.servelet.http.*; public class HowdyServelet extends HttpServelet{ public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ PrintWriter out = response.getWriter(); response.setContentType("text/html"); out.println("<html>"); out.println("<head><title>howdy</title></head>"); out.println("<body>"); out.println("<center><h1>Howdy</h1></center>"); out.println("</body>"); out.println("</html>"); } } and here are the environment variables i set after installation: 1. J2EE_HOME=/home/vinit/SUNWappserver 2. JAVA_HOME=/home/vinit/SUNWappserver/jdk 3. CLASSPATH=/home/vinit/SUNWappserver/lib and now i tried to compile the servlet using javac HowdyServelet.java But i got following errors: HowdyServelet.java:2: package javax.servelet does not exist import javax.servelet.*; ^ HowdyServelet.java:3: package javax.servelet.http does not exist import javax.servelet.http.*; ^ HowdyServelet.java:5: cannot find symbol symbol: class HttpServelet public class HowdyServelet extends HttpServelet{ ^ HowdyServelet.java:6: cannot find symbol symbol : class HttpServeletRequest location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ HowdyServelet.java:6: cannot find symbol symbol : class HttpServeletResponse location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ HowdyServelet.java:6: cannot find symbol symbol : class ServeletException location: class HowdyServelet public void doGet(HttpServeletRequest request, HttpServeletResponse response) throws IOException, ServeletException{ ^ 6 errors So how to compile this servlet. Thanks in advance.

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  • Testing Broadcasting and receiving messages

    - by Avik
    Guys am having some difficulty figuring this out: I am trying to test whether the code(in c#) to broadcast a message and receiving the message works: The code to send the datagram(in this case its the hostname) is: public partial class Form1 : Form { String hostName; byte[] hostBuffer = new byte[1024]; public Form1() { InitializeComponent(); StartNotification(); } public void StartNotification() { IPEndPoint notifyIP = new IPEndPoint(IPAddress.Broadcast, 6000); hostName = Dns.GetHostName(); hostBuffer = Encoding.ASCII.GetBytes(hostName); UdpClient newUdpClient = new UdpClient(); newUdpClient.Send(hostBuffer, hostBuffer.Length, notifyIP); } } And the code to receive the datagram is: public partial class Form1 : Form { byte[] receivedNotification = new byte[1024]; String notificationReceived; StringBuilder listBox; UdpClient udpServer; IPEndPoint remoteEndPoint; public Form1() { InitializeComponent(); udpServer = new UdpClient(new IPEndPoint(IPAddress.Any, 1234)); remoteEndPoint=null; startUdpListener1(); } public void startUdpListener1() { receivedNotification = udpServer.Receive(ref remoteEndPoint); notificationReceived = Encoding.ASCII.GetString(receivedNotification); listBox = new StringBuilder(this.listBox1.Text); listBox.AppendLine(notificationReceived); this.listBox1.Items.Add(listBox.ToString()); } } For the reception of the code I have a form that has only a listbox(listBox1). The problem here is that when i execute the code to receive, the program runs but the form isnt visible. However when I comment the function call( startUdpListener1() ), the purpose isnt served but the form is visible. Whats going wrong?

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  • Why isn't componentHidden called for my JPopupMenu?

    - by heycam
    I want to be notified when my JPopupMenu is hidden — whether because an item was selected, the menu was dismissed, or setVisible(false) was called on it. Here is my test code: import javax.swing.*; import java.awt.*; import java.awt.event.*; public class A extends ComponentAdapter implements Runnable, ActionListener { private JButton b; public static void main(String[] args) { EventQueue.invokeLater(new A()); } public void run() { JFrame f = new JFrame("Test"); b = new JButton("Click me"); b.addActionListener(this); f.add(b); f.pack(); f.setVisible(true); } public void actionPerformed(ActionEvent e) { JPopupMenu pm = new JPopupMenu(); pm.addComponentListener(this); pm.add("Popup..."); pm.add("...menu!"); pm.show(b, 10, 10); } public void componentShown(ComponentEvent e) { System.out.println("componentShown"); } public void componentHidden(ComponentEvent e) { System.out.println("componentHidden"); } } Regardless of how I interact with the menu, neither of the two ComponentListener methods are being called. Why is that? Is there different/better/correct way of finding out when my JPopupMenu is hidden? Thanks, Cameron

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  • how to read in a list of custom configuration objects

    - by Johnny
    hi, I want to implement Craig Andera's custom XML configuration handler in a slightly different scenario. What I want to be able to do is to read in a list of arbitrary length of custom objects defined as: public class TextFileInfo { public string Name { get; set; } public string TextFilePath { get; set; } public string XmlFilePath { get; set; } } I managed to replicate Craig's solution for one custom object but what if I want several? Craig's deserialization code is: public class XmlSerializerSectionHandler : IConfigurationSectionHandler { public object Create(object parent, object configContext, XmlNode section) { XPathNavigator nav = section.CreateNavigator(); string typename = (string)nav.Evaluate("string(@type)"); Type t = Type.GetType(typename); XmlSerializer ser = new XmlSerializer(t); return ser.Deserialize(new XmlNodeReader(section)); } } I think I could do this if I could get Type t = Type.GetType("System.Collections.Generic.List<TextFileInfo>") to work but it throws Could not load type 'System.Collections.Generic.List<Test1.TextFileInfo>' from assembly 'Test1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

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