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  • Generic type in generic collection

    - by Brian Triplett
    I have generic type that looks like: public class GenericClass<T, U> where T : IComparable<T> { // Class definition here } I then have a collection of these instances. What is the cleanest way to pass through the type constraints? public class GenericCollection<V> where V : GenericClass<T, U> // This won't compile { private GenericClass<T, U>[] entries; public V this[index] { get{ return this.entries[index]; } } } Is there perhaps a better way to design this? I think that specifying GenericCollection<T, U, V> where V : GenericClass<T, U> seems awkward. Might be my only option though....

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  • What is a custom collection?

    - by Win Coder
    A Group of objects. However i am having confusion in the following case. A sample class Class A { public string; } Class A_list { public A[] list; public A_list(A[] _list) { list = new A[_list.length]; for (int i = 0; i < _list.Length; i++) { list[i] = _list[i]; } } } static void Main(String[] args) { A[] names = new A[3] { new A("some"), new A("another"), new A("one"), }; A_list just_an_object = new A_list(names); } Which of the above is a custom collection the array or the object that holds array as a field or are both custom collections.

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  • Using xsl:key to store result of boolean expression

    - by hielsnoppe
    In my transformation there is an expression some elements are repeatedly tested against. To reduce redundancy I'd like to encapsulate this in an xsl:key like this (not working): <xsl:key name="td-is-empty" match="td" use="not(./node()[normalize-space(.) or ./node()])" /> The expected behaviour is the key to yield a boolean value of true in case the expression is evaluated successfully and otherwise false. Then I'd like to use it as follows: <xsl:template match="td[not(key('td-is-empty', .))]" /> Is this possible and in case yes, how?

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  • How to query a date in HQL (Hibernate) with Joda Time?

    - by fabien7474
    I am sure that someone familiar with HQL (I am myself a newbie) can easily answer this question. In my Grails application, I have the following domain class. class Book { org.joda.time.DateTime releaseDate //I use the PersistentDateTime for persisting via Hibernate (that use a DATETIME type for MySQL DB) } In my HQL query, I want to retrieve books whose release date is included in range date1..date2 For instance I tried: DateTime date1, date2 ... def queryStr = "select * from Book as b where b.releaseDate > $date1 and b.releaseDate < $date2" def res = Book.executeQuery(queryStr) But I got the exception ...caused by: org.springframework.orm.hibernate3.HibernateQueryException: unexpected token: The error token points to date format (for instance 2009-11-27T21:57:18.010+01:00 or Fri Nov 27 22:01:20 CET 2009) I have also tried to convert date1 into a Date class without success So what is the correct HQL code ? Should I convert to a specific format (which one?) using the patternForStyle method or is there another -cleaner- way to do it? Thanks, Fabien.

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  • How to convert an existing callback interface to use boost signals & slots

    - by the_mandrill
    I've currently got a class that can notify a number of other objects via callbacks: class Callback { virtual NodulesChanged() =0; virtual TurkiesTwisted() =0; }; class Notifier { std::vector<Callback*> m_Callbacks; void AddCallback(Callback* cb) {m_Callbacks.push(cb); } ... void ChangeNodules() { for (iterator it=m_Callbacks.begin(); it!=m_Callbacks.end(); it++) { (*it)->NodulesChanged(); } } }; I'm considering changing this to use boost's signals and slots as it would be beneficial to reduce the likelihood of dangling pointers when the callee gets deleted, among other things. However, as it stands boost's signals seems more oriented towards dealing with function objects. What would be the best way of adapting my code to still use the callback interface but use signals and slots to deal with the connection and notification aspects?

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  • NSArray safeguards

    - by Spider-Paddy
    If there is a chance that an NSArray is empty, is it better to check it and set equal to nil if it's empty when it is assigned or to rather do the check when it is used? e.g. NSArray *myArray; if ([anotherArray count] > 0) <-- Check when assigned myArray = [anotherArray copy]; else myArray = nil; something = [myArray objectAtIndex:x]; or NSArray *myArray; myArray = [anotherArray copy]; if ([myArray count] > 0) <-- Check when used something = [myArray objectAtIndex:x]; Which is better?

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  • Custom tool error: Command.proto:11:18: "Message2" is not defined.

    - by cornerback84
    I am using the latest version of protobuf-net with VS2008 integration. I have created 2 messages (Message1 and Message2), 1 message in 1 proto file. When I try to reference Message2 in Message1 the code generator tool gives me error "Message2" is not defined and won't generate the code file. The package for both messages is same. It look like that because of the integration of the tool with VS2008 it expects all the messages in same .proto file to compile. Currently I have to paste an empty message with same name in Message1.proto file, like this: message Message1 { optional Message2 message2 = 1; } message Message2 { } And then later on remove the declaration of class Message2 from Message1.cs. Are there any settings that I need to do so to avoid this error, or is providing an empty declaration the only way?

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  • Why does this IF statement fail?

    - by ChosenOne
    If variable path is empty, and editor.Text is not empty, the SaveFileDialog should be displayed. Now, why on earth is this damn thing failing??? I have tried this with many different variations of code with the same result: FAIL: if(path.Length >= 1) // path contains a path. Save changes instead of creating NEW file. { File.WriteAllText(path, content); } else { // no path defined. Create new file and write to it. using(SaveFileDialog saver = new SaveFileDialog()) { if(saver.ShowDialog() == DialogButtons.OK) { File.WriteAllText(saver.Filename, content); } } } At the top of code file I have: path = String.Empty; So why the heck it this failing every single time, even after trying all of the below variations? if(path.Length > 1) // path contains a path. Save changes instead of creating NEW file. { File.WriteAllText(path, content); } else { // no path defined. Create new file and write to it. using(SaveFileDialog saver = new SaveFileDialog()) { if(saver.ShowDialog() == DialogButtons.OK) { File.WriteAllText(saver.Filename, content); } } } and if(String.IsNullOrEmpty(path)) // path contains a path. Save changes instead of creating NEW file. { File.WriteAllText(path, content); } else { // no path defined. Create new file and write to it. using(SaveFileDialog saver = new SaveFileDialog()) { if(saver.ShowDialog() == DialogButtons.OK) { File.WriteAllText(saver.Filename, content); } } } and if(String.IsNullOrWhiteSpace(path)) // path contains a path. Save changes instead of creating NEW file. { File.WriteAllText(path, content); } else { // no path defined. Create new file and write to it. using(SaveFileDialog saver = new SaveFileDialog()) { if(saver.ShowDialog() == DialogButtons.OK) { File.WriteAllText(saver.Filename, content); } } } This is making me very angry. How could this fail? Setting a break point reveals that path is definitely null/"".

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  • How to import org.codehaus.groovy.scriptom.* on Groovy?

    - by Mulone
    Hi guys, I'm trying to run a Groovy app to manipulate Excel files on STS (by SpringSource) 2.3.0. My Groovy version is 1.7. Class: package com.mytool import org.codehaus.groovy.scriptom.ActiveXObject /** * @author Mulone * */ class SurveyTool { static main(args) { print 'test' def wshell = new ActiveXObject('Wscript.Shell') wshell.popup("Scriptom is Groovy") } } Sadly, this is what I get: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed: C:\workspace\SurveyTool\src\com\geoadapta\surveytool\SurveyTool.groovy: 6: unable to resolve class org.codehaus.groovy.scriptom.ActiveXObject @ line 6, column 1. import org.codehaus.groovy.scriptom.ActiveXObject ^ 1 error I also tried to rename ActiveXObject to ActiveXProxy with the same result. I tried to import scriptom manually from the package scriptom-all-assembly-1.6.0 but I didn't work. Any idea? Cheers

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  • Write to static field - is FindBugs wrong in this case?

    - by htorque
    I have a Java class like this: public class Foo { public static int counter = 0; public void bar(int counter) { Foo.counter = counter; } } FindBugs warns me about writing to the static field counter via the instance method bar. However, if I change the code to: public class Foo { public static int counter = 0; public static void setCounter(int counter) { Foo.counter = counter; } public void bar(int counter) { setCounter(counter); } } Then FindBugs won't complain. Isn't that wrong? I'm still writing to a static field from an instance method, just via a static method - no?

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  • Setting the initial value of a property when using DataContractSerializer

    - by Eric
    If I am serializing and later deserializing a class using DataContractSerializer how can I control the initial values of properties that were not serialized? Consider the Person class below. Its data contract is set to serialize the FirstName and LastName properties but not the IsNew property. I want IsNew to initialize to TRUE whether a new Person is being instantiate as a new instance or being deserialized from a file. This is easy to do through the constructor, but as I understand it DataContractSerializer does not call the constructor as they could require parameters. [DataContract(Name="Person")] public class Person { [DataMember(Name="FirstName")] public string FirstName { get; set; } [DataMember(Name = "LastName")] public string LastName { get; set; } public bool IsNew { get; set; } public Person(string first, string last) { this.FirstName = first; this.LastName = last; this.IsNew = true; } }

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  • Invoke an Overloaded Constructor through this keyword (What's the Different between this two Sample code?)

    - by Alireza Dehqani
    using System; namespace ConsoleApplication1 { class Program { static void Main() { // Sample Sample ob = new Sample(); // line1 // Output for line1 /* * Sample(int i) * Sample() / // Sample2 Sample2 ob2 = new Sample2(); // line2 // Output for line2 / * Sample2() */ } } class Sample { // Fields private int a; // Constructors public Sample(int i) // Main Constructor { Console.WriteLine(" Sample(int i)"); a = i; } // Default Constructor public Sample() : this(0) { Console.WriteLine(" Sample()"); } } class Sample2 { // fields private int a; // Constructors public Sample2(int i) { Console.WriteLine("Sample2(int i)"); a = i; } public Sample2() { Console.WriteLine("Sample2()"); a = 0; } } }

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  • Java How to call method of grand parents?

    - by Arkaha
    Let's assume I have 3 classes A, B and C, each one extending the previous one. How do I call the code in A.myMethod() from C.myMethod() if B also implements myMethod? class A { public void myMethod() { // some stuff for A } } class B extends A { public void myMethod() { // some stuff for B //and than calling A stuff super.myMethod(); } } class C extends B { public void myMethod() { // some stuff for C // i don't need stuff from b, but i need call stuff from A // something like: super.super.myMethod(); ?? how to call A.myMethod(); ?? } }

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  • How do I set a VB.Net ComboBox default value

    - by Mr Ed
    I can not locate the correct method to make the first item in a combo box visible. The app starts with an empty combo box. The user makes a radio box selection then clicks Go! (how original). The combo box is loaded via an LDAP query. All this is working just fine. The problem is the combo box still appears to the user to be empty. They must click the arrow to see the options. How do I make the first option 'visible' after the users clicks Go!? I thought it would be simple... Thanks, Ed

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  • Why is the base() constructor not necessary?

    - by Earlz
    Hello, I have a class structure like abstract class Animal { public Animal(){ //init stuff.. } } class Cat : Animal { public Cat(bool is_keyboard) : base() //NOTE here { //other init stuff } } Now then, look at the noted line. If you remove : base() then it will compile without an error. Why is this? Is there a way to disable this behavior? I have had multiple bugs now from forgetting the base() which I would have thought to be required on such a special thing as a constructor.

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  • Multiple key/value pairs in HTTP POST where key is the same name

    - by randombits
    I'm working on an API that accepts data from remote clients, some of which where the key in an HTTP POST almost functions as an array. In english what this means is say I have a resource on my server called "class". A class in this sense, is the type a student sits in and a teacher educates in. When the user submits an HTTP POST to create a new class for their application, a lot of the key value pairs look like: student_name: Bob Smith student_name: Jane Smith student_name: Chris Smith What's the best way to handle this on both the client side (let's say the client is cURL or ActiveResource, whatever..) and what's a decent way of handling this on the server-side if my server is a Ruby on Rails app? Need a way to allow for multiple keys with the same name and without any namespace clashing or loss of data.

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  • In C#, can I hide/modify accessors in subclasses?

    - by Diego
    I'm not even sure what this principle is called or how to search for it, so I sincerely apologize if it has been brought up before, but the best way to do it is with an example. class Properties { public string Name { get; set; } } class MyClass { class SubProperties: Properties { public override Name { get { return GetActualName(); } set { _value = SetActualName(value); } } } public SubProperties ClassProperties; private GetActualName() { ClassProperties.Name = "name"; } private SetActualName(string s) { ClassProperties.Name = SomeOtherFunction(s); } } The idea is to have any object that instantiates MyClass have a fully accessible property ClassProperties. To that object, it would look exactly like a Properties object, but behind the scenes, MyClass is actually computing and modifying the results of the fields. This method of declaration is obviously wrong since I can't access GetActualName() and SetActualName() from within the SubProperties definition. How would I achieve something like this?

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  • How to save file and read

    - by Jessy
    Hello everyone, I create a program that place random image in grid layout format. The size of the grid layout is 6 x 6 = 36. Only 10 were filled with images (each image was different) and the rest were empty. freeimagehosting.net/uploads/bfb7e85f63.jpg How can I save it to a file and read it again, so it will display the same images with same placement on the grid? Here is the code that I used to save the images: //image file String []arrPic = {"pic1.jpg","pic2.jpg","pic3.jpg","pic4.jpg","pic5.jpg","pic6.jpg","pic7.jpg","pic8.jpg","pic9.jpg","pic10.jpg",,"pic11.jpg","pic12.jpg","pic13.jpg"}; ArrayList<String> pictures = new ArrayList<String>(Arrays.asList(arrPic)); ArrayList<String> file = new ArrayList<String>(); JPanel pDraw = new JPanel(new GridLayout(6,6,2,2)); ... //fill all grids with empty label for (int i =0; i<(6*6); i++){ JLabel lbl = new JLabel(""); pDraw.add(lbl); } ... //Choose random box to be filled with images for(int i=0; i<10; i++){ Boolean number = true; while(number){ int n = rand.nextInt(35); if(!(arraylist.contains(n))) number = false; arraylist.add(n); } //fill the grids with images for(int i=0; i<arraylist.size(); i++){ //select random image from arraylist int index = rand.nextInt (pictures.size()); String fileName = (String) pictures.get(index ); //find the image file icon = createImageIcon(fileName); //save the file in a new file file.add(fileName); //rescaled the image int x = rand.nextInt(50)+50; int y = rand.nextInt(50)+50; Image image = icon.getImage().getScaledInstance(x,y,Image.SCALE_SMOOTH); icon.setImage(image); //remove empty label and replace it with an image int one = (Integer) arraylist.get(i); pDraw.remove(one); final JLabel label; pDraw.add(label,one); }

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  • Use the [Serializable] attribute or subclassing from MarshalByRefObject?

    - by Theo Lenndorff
    I'd like to use an object across AppDomains. For this I can use the [Serializeable] attribute: [Serializable] class MyClass { public string GetSomeString() { return "someString" } } Or subclass from MarshalByRefObject: class MyClass: MarshalByRefObject { public string GetSomeString() { return "someString" } } In both cases I can use the class like this: AppDomain appDomain = AppDomain.CreateDomain("AppDomain"); MyClass myObject = (MyClass)appDomain.CreateInstanceAndUnwrap( typeof(MyClass).Assembly.FullName, typeof(MyClass).FullName); Console.WriteLine(myObject.GetSomeString()); Why do both approaches seem to have the same effect? What is the difference in both approaches? When should I favor the one approach over the other? EDIT: At the surface I know that there are differences between both mechanisms, but if someone jumped out of a bush and asked me the question I couldn't give him a proper answer. The questions are quite open questions. I hoped that someone can explain it better than I could do.

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  • Why should i use EJB?

    - by Nitesh Panchal
    Hello, As we all know that EJB's in 3.1 or 3.0 are simple POJOs. You just need to give annotations here and there and it gets converted to EJB from simple class. So, now my question is why should i use EJBs at all? Can i not do without them? In .Net i created class library and got things done. I never felt the need for anything like EJB. Simple classes were enough. Then, why in Java people stress on EJB? What is difference between a simple POJO and EJB in terms of execution and memory? Further which function should i write in EJB and which should i write in simple class? Should i dump every function in EJB only? or there is some kind of strategy? Does EJB provide anything special?

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  • [Ruby on Rails] scribd_fu gsub error

    - by siulamvictor
    I have an application which allow user upload documents to Scribd. I tried to use scribd_fu in Rails. An error occurred when the controller try to save the model. NoMethodError in DocumentsController#processupload private method `gsub' called for nil:NilClass here is the related controller def processupload @document = Document.new(params[:document]) if @document.save session[:scribdid] = @document.ipaper_access_key else xxxxx and this is the related html form <form action="/documents/processupload" enctype="multipart/form-data" method="post"> <input name="authenticity_token" type="hidden" value="FqTCmlGGIvRjiaiaa+YtF50wgI7FfpxfrZsulLCbXcw=" /> <label class="label_h2">Upload a Document</label> <input id="document_document_upload" name="document[document_upload]" size="30" type="file" /></div> <div class="buttons"><button type="submit" class="positive"><img src="/images/icons/tick.png" alt="Save Document"/>Save Document</button> </form> Is there anything wrong?

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  • Code editor with autocomplete

    - by Andrey
    I need to create a code editor for my own simple language: className.MethodName(parameterName = 2, ... ) I've created the appropriate grammar and autogenerate parser using ANTLR tool. Now I would like to have an autocomplete for class, method, variables and parameter names. This list should be context dependent, f.e. for "class." it should display methods and for "class.Method(" - parameters. I was going to parse the text and display the list depending on in which node the cursor is. The problem is that for incomplete code like "aaa.bbb(" the parser produces an error instead of a syntax tree. Any idea how to solve this problem? Maybe I'm on the wrong way and I shouldn't parse code to display autocomplete?

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  • WebLogic Server internal server error

    - by Abhinav Pandey
    when I deploy a project in Apache Tomcat 6.0 it's working fine. When I deploy the same project in weblogic server 10.3 it's showing an error like below: Error 500--Internal Server Error javax.servlet.ServletException: [HTTP:101249][weblogic.servlet.internal.WebAppServletContext@ae43b8 - appName: '_appsdir_ab_dir', name: 'ab', context-path: '/ab', spec-version: 'null']: Servlet class FirstServlet for servlet FirstServlet could not be loaded because the requested class was not found in the classpath . java.lang.UnsupportedClassVersionError: FirstServlet : Unsupported major.minor version 51.0.

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  • Ruby Metaprogramming

    - by VP
    I'm trying to write a DSL that allows me to do Policy.name do author "Foo" reviewed_by "Bar" end The following code can almost process it: class Policy include Singleton def self.method_missing(name,&block) puts name puts "#{yield}" end def self.author(name) puts name end def self.reviewed_by(name) puts name end end Defining my method as class methods (self.method_name) i can access it using the following syntax: Policy.name do Policy.author "Foo" Policy.reviewed_by "Bar" end If i remove the "self" from the method names, and try to use my desired syntax, then i receive an error "Method not Found" in the Main so it could not find my function until the module Kernel. Its ok, i understand the error. But how can i fix it? How can i fix my class to make it work with my desired syntax that?

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  • Custom Classes Passed from Service to a UI threads via AIDL

    - by Honza Pokorny
    I have a service that regularly queries a web server for new messages. The service stores the new messages in an arrayList. These messages are implemented using a custom class, storing all kinds of metadata (strings and longs). An activity then connects to this service to retrieve those messages and display them to the user. I have an .aidl file that describes the interface that the service exposes. package com.example.package; interface MyInterface { List<Message> getMessages(); } The Message class extends the Parcelable class which should allow for the IPC transfer. The problem is this: Eclipse gives me an error saying that the type of List<Message> is unknown. Any imports are marked as invalid. Ideas? Thanks

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