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  • Java NullPointerException. Why?

    - by user292844
    I am new to Java. I just read that class variables in Java have default value. I tried the following program. I was expecting to get the output as 0, which is the default value on an integer, but I get the NullPointerException. What am I missing? class Test{ static Integer iVar; public static void main(String...args) { System.out.println(iVar.intValue()); } }

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  • How to detect if collection contain instance of specific type?

    - by KentZhou
    Suppose I create collection like Collection<IMyType> coll; Then I have many implelentations of IMyTypem like, T1, T2, T3... Then I want know if the collection coll contains a instance of type T1. So I want to write a method like public bool ContainType( <T>){...} here the param should be class type, not class instance. How to write code for this kind of issue?

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  • Django: remove all m2m relations

    - by pistacchio
    Hi, if I have two simple models: class Tag(models.Model): name = models.CharField(max_length=100) class Post(models.Model): title = models.CharField(max_length=100) tags = models.ManyToManyField(Tag, blank=True) given a Post object with a number of Tags added to it, I know hot to remove any of them, but how to do a mass remove (remove all)? Thanks

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  • Quick question about jQuery selector content efficiency

    - by serg
    I am loading HTML page through ajax and then doing a bunch of searches using selectors: $.ajax({ ... dataType: "html", success: function(html) { $("#id1", html); $(".class", html); //... } } Should I extract $(html) into a variable and use it as a content, or it doesn't matter (from performance point)? success: function(html) { $html = $(html); $("#id1", $html); $(".class", $html); //... }

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  • c# Lambda Expression built with LinqKit does not compile

    - by Frank Michael Kraft
    This lambda does not compile, but I do not understand why. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; using LinqKit; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { var barModel = new BarModel(); string id = "some"; Console.WriteLine(barModel.subFor(id).ToString()); // output: m => (True AndAlso (m.key == value(ConsoleApplication2.Bar`1+<>c__DisplayClass0[ConsoleApplication2.Model]).id)) Console.ReadKey(); var subworkitems = barModel.list.Where(barModel.subFor(id).Compile()); // Exception {"variable 'm' of type 'ConsoleApplication2.Model' referenced from scope '', but it is not defined"} Console.WriteLine(subworkitems.ToString()); Console.ReadKey(); } } class Bar<TModel> { public Bar(Expression<Func<TModel, string>> foreignKeyExpression) { _foreignKeyExpression = foreignKeyExpression; } private Expression<Func<TModel, string>> _foreignKeyExpression { get; set; } public Expression<Func<TModel, bool>> subFor(string id) { var ex = forTargetId(id); return ex; } public Expression<Func<TModel, bool>> forTargetId(String id) { var fc = _foreignKeyExpression; Expression<Func<TModel, bool>> predicate = m => true; var result = predicate.And(m => fc.Invoke(m) == id).Expand(); return result; } } class Model { public string key; public string value; } class BarModel : Bar<Model> { public List<Model> list; public BarModel() : base(m => m.key) { list = new List<Model>(); } } }

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  • Asp.NET MVC View with different objects

    - by user195910
    If i have a controller action "Create" that returns a view with the following as the Model type: public class PaymentModel { public Model.SummaryInformation SummaryInformation; public Model.CardDetail CardDetail; } If there is a button on this view that POST's to an action "New" and I want that action to recieve a different object e.g. public class PaymentNewModel { public Model.CardDetail CardDetail; } Is this possible? I do not want to use the same Model when the view is rendered to the Model that is POSTed

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  • Django model help

    - by dotty
    Does anyone have any clue why this doesn't work as expected. If i use the python shell and do team.game_set or team.games It returns an error AttributeError: 'Team' object has no attribute 'game' If i create a Game object and call game.home_team it returns the correct team object Heres my model class Team(models.Model): name = models.CharField(blank=True, max_length=100) class Game(models.Model): home_team = models.ForeignKey(Team, related_name="home_team")

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  • Change and Maintain CSS Style of Button State

    - by TDDG
    I have 5 list items that act like tabs for a page stored in a Masterpage in a asp.net application. When the user selects a list item, I would like to redirect the the page, and change the class for that list item (tab) to show the active tab the user is on. What is the best way to dynamically change the class of the list item based on the user interaction with them, and maintain the state?

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  • Override generic methods in c#

    - by Pascal
    I thought I can not override generic methods of a derived class. http://my.safaribooksonline.com/book/programming/csharp/9780071741163/generics/ch18lev1sec13 The code in this link runs fine. The overriden method is called although the instance type of the base class is used and not the instance of the derived type. Now I am confused because a former question of mine Type parameter declaration must be identifier not a type is about calling the overriding generic method with the instance of base type which did NOT work!

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  • Selecting by ID in Castle ActiveRecord

    - by ripper234
    How can I write a criteria to return all Orders that belong to a specific User? public class User { [PrimaryKey] public virtual int Id { get; set; } } public class Order { [PrimaryKey] public virtual int Id { get; set; } [BelongsTo("UserId")] public virtual User User { get; set; } } return ActiveRecordMediator<Order>.FindAll( // What criteria should I write here ? );

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  • Django save_m2m() and excluded field

    - by jul
    hi, in a ModelForm I replaced a field by excluding it and adding a new one with the same name, as shown below in AddRestaurantForm. When saving the form with the code shown below, I get an error in form.save_m2m() ("Truncated incorrect DOUBLE value"), which seems to be due to the function to attempt to save the tag field, while it is excluded. Is the save_m2m() function supposed to save excluded fields? Is there anything wrong in my code? Thanks Jul (...) new_restaurant = form.save(commit=False) new_restaurant.city = city new_restaurant.save() tags = form.cleaned_data['tag'] if(tags!=''): tags=tags.split(',') for t in tags: tag, created = Tag.objects.get_or_create(name = t.strip()) tag.save() new_restaurant.tag.add(tag) new_restaurant.save() form.save_m2m() models.py class Tag(models.Model): name = models.CharField(max_length=100, unique=True) class Restaurant(models.Model): name = models.CharField(max_length=50) city=models.ForeignKey(City) category=models.ManyToManyField(Category) tag=models.ManyToManyField(Tag, blank=True, null=True) forms.py class AddRestaurantForm(ModelForm): name = forms.CharField(widget=forms.TextInput(attrs=classtext)) city = forms.CharField(widget=forms.TextInput(attrs=classtext), max_length=100) tag = forms.CharField(widget=forms.TextInput(attrs=classtext), required=False) class Meta: model = Restaurant exclude = ('city','tag') Traceback: File "/var/lib/python-support/python2.5/django/core/handlers/base.py" in get_response 92. response = callback(request, *callback_args, **callback_kwargs) File "/home/jul/atable/../atable/resto/views.py" in addRestaurant 498. form.save_m2m() File "/var/lib/python-support/python2.5/django/forms/models.py" in save_m2m 75. f.save_form_data(instance, cleaned_data[f.name]) File "/var/lib/python-support/python2.5/django/db/models/fields/ related.py" in save_form_data 967. setattr(instance, self.attname, data) File "/var/lib/python-support/python2.5/django/db/models/fields/ related.py" in set 627. manager.add(*value) File "/var/lib/python-support/python2.5/django/db/models/fields/ related.py" in add 430. self._add_items(self.source_col_name, self.target_col_name, *objs) File "/var/lib/python-support/python2.5/django/db/models/fields/ related.py" in _add_items 497. [self._pk_val] + list(new_ids)) File "/var/lib/python-support/python2.5/django/db/backends/util.py" in execute 19. return self.cursor.execute(sql, params) File "/var/lib/python-support/python2.5/django/db/backends/mysql/ base.py" in execute 84. return self.cursor.execute(query, args) File "/var/lib/python-support/python2.5/MySQLdb/cursors.py" in execute 168. if not self._defer_warnings: self._warning_check() File "/var/lib/python-support/python2.5/MySQLdb/cursors.py" in _warning_check 82. warn(w[-1], self.Warning, 3) File "/usr/lib/python2.5/warnings.py" in warn 62. globals) File "/usr/lib/python2.5/warnings.py" in warn_explicit 102. raise message Exception Type: Warning at /restaurant/add/ Exception Value: Truncated incorrect DOUBLE value: 'a'

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  • Unit Testing a CSV Parser and Column Mapping Tool

    - by PieterG
    I am really starting to enjoy unit testing and have the following question to the gurus of unit testing. Let's for example say I have the following class public class FileMapper { public Dictionary<string, string> ReadFile(string filename, string delimeter){} } How do you guys generally go about unit testing a Parser or ReadFile method in my case?

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  • Hibernate one to one with multiple columns

    - by Erdem Emekligil
    How can i bind two columns, using @OneToOne annotation? Lets say I've 2 tables A and B. Table A: id1 (primary key) id2 (pk) other columns Table B: id1 (pk) id2 (pk) other columns In class A i want to write something like this: @OneToOne(fetch = FetchType.EAGER, targetEntity = B.class) @JoinColumn(name = "id1 and id2", referencedColumnName = "id1 and id2") private B b; Is it possible to do this using annotations? Thanks.

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  • Object Deletion: use parent or not

    - by metdos
    Which one do you prefer to delete objects? Especially in QT, but other practices are also welcome. These two alternatives seem same to me, are they? 1.Bound to another class, and destroy when it is destroyed. SomeClass::SomeClass{ socket_ = new QTcpSocket(this); } or 2.Destroy in the destructor of class SomeClass::SomeClass{ socket_ = new QTcpSocket(); } SomeClass::~SomeClass{ delete socket_; }

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  • Variables variable and inheritance

    - by Xack
    I made code like this: class Object { function __get($name){ if(isset($this->{$name})){ return $this->{$name}; } else { return null; } } function __set($name, $value){ $this->{$name} = $value; } } If I extend this class (I don't want to repeat this code every time), it says "Undefined variable". Is there any way to do it?

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  • initializing a readonly property. Object c

    - by tak
    i was trying to create a property which is readonly. i wanted to initialize with a value from the class creating an instance of this class.e.g @property (readonly) NSString *firstName; And wanted to initialize it like -(id)initWithName:(NSString *)n{ self.firstName = n; } Once i do this, this compiler shows an error that the readonly property cannot be assigned. So how can i do this?

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  • Qt inheriting from QGraphicsEllipseItem

    - by JHollanti
    I was trying to inherit from QGraphicsEllipseItem 'cause i wanted to add some functionality to it. However i was faced with this error, which probably has something to do with the compiler/precompiler or moc? error: 'staticMetaObject' is not a member of 'QGraphicsEllipseItem' And here's the class code: class MyEllipseItem : public QGraphicsEllipseItem { Q_OBJECT public: MyEllipseItem (const QRectF & outline) : QGraphicsEllipseItem(outline) { } };

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  • Setting Rails Checkbox from Another Model

    - by Kevin
    I have a checkbox that belongs to "Foo" class. I have another "Preferences" class that sets the default for what that checkbox should be. I tried using f.check_box :email_preference, :value => preferences.email_preference but it doesn't work. I use this page to do new record creation as well as edit, so obviously for new records I would want to take the preferences.email_preference setting as a default, then for editing the record use the foo.email_preference. Any suggestions?

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  • C# reflection avoid propertie

    - by ozsenegal
    Im using reflection to acess a class tha represents a table in DB.However,reflection read all properties of that class,and im wondering if there're some atributte in c# we can use to avoid read that propertie. i.e: [AvoidThisPropertie] public string Identity { get; set; }

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  • error of grails project from svn : GroovyObject cannot be resolved

    - by atian25
    when i check out a new grails project from svn, i got some error: 1.The project was not built since its build path is incomplete. Cannot find the class file for groovy.lang.GroovyObject. Fix the build path then try building this project 2.The type groovy.lang.GroovyObject cannot be resolved. It is indirectly referenced from required .class files i had config the grails path, and it can run-app well. but,still error warning.

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  • a constructor as a delegate - is it possible in C#?

    - by akavel
    I have a class like below: class Foo { public Foo(int x) { ... } } and I need to pass to a certain method a delegate like this: delegate Foo FooGenerator(int x); Is it possible to pass the constructor directly as a FooGenerator value, without having to type: delegate(int x) { return new Foo(x); } ? EDIT: For my personal use, the question refers to .NET 2.0, but hints/responses for 3.0+ are welcome as well.

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  • NHibernate does not update entity when repository is passed by constructor

    - by Alex
    Hi everybody, I am developing with NHibernate for the first time in conjunction with ASP.NET MVC and StructureMap. The CodeCampServer serves as a great example for me. I really like the different concepts which were implemented there and I can learn a lot from it. In my controllers I use Constructur Dependency Injection to get an instance of the specific repository needed. My problem is: If I change an attribute of the customer the customer's data is not updated in the database, although Commit() is called on the transaction object (by a HttpModule). public class AccountsController : Controller { private readonly ICustomerRepository repository; public AccountsController(ICustomerRepository repository) { this.repository = repository; } public ActionResult Save(Customer customer) { Customer customerToUpdate = repository .GetById(customer.Id); customerToUpdate.GivenName = "test"; //<-- customer does not get updated in database return View(); } } On the other hand this is working: public class AccountsController : Controller { [LoadCurrentCustomer] public ActionResult Save(Customer customer) { customer.GivenName = "test"; //<-- Customer gets updated return View(); } } public class LoadCurrentCustomer : ActionFilterAttribute { public override void OnActionExecuting(ActionExecutingContext filterContext) { const string parameterName = "Customer"; if (filterContext.ActionParameters.ContainsKey(parameterName)) { if (filterContext.HttpContext.User.Identity.IsAuthenticated) { Customer CurrentCustomer = DependencyResolverFactory .GetDefault() .Resolve<IUserSession>() .GetCurrentUser(); filterContext.ActionParameters[parameterName] = CurrentCustomer; } } base.OnActionExecuting(filterContext); } } public class UserSession : IUserSession { private readonly ICustomerRepository repository; public UserSession(ICustomerRepository customerRepository) { repository = customerRepository; } public Customer GetCurrentUser() { var identity = HttpContext.Current.User.Identity; if (!identity.IsAuthenticated) { return null; } Customer customer = repository.GetByEmailAddress(identity.Name); return customer; } } I also tried to call update on the repository like the following code shows. But this leads to an NHibernateException which says "Illegal attempt to associate a collection with two open sessions". Actually there is only one. public ActionResult Save(Customer customer) { Customer customerToUpdate = repository .GetById(customer.Id); customer.GivenName = "test"; repository.Update(customerToUpdate); return View(); } Does somebody have an idea why the customer is not updated in the first example but is updated in the second example? Why does NHibernate say that there are two open sessions?

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