What is the meaning of the Java warning "Type safety: The cast from Object to List is actually checking against the erased type List"? I get it when I try to cast an Object to a type with generic information, such as in the following code: Object object = getMyList();List<Integer> list = (List<Integer>) object;...
It seems that a List object cannot be stored in a List variable in C#, and can't even be explicitly cast that way. List<string> sl = new List<string>();List<object> ol;ol = sl; results in Cannot implicitly convert type ‘System.Collections.Generic.List’ to ‘System.Collections.Generic.List’ And then... List<string> sl = new List<string...
Hi Guys, Here is the problem I am having, I have a class that I want to use to store "properties" for another class, these properties simply have a name and a value. Ideally, what I would like is to be able to add typed properties, so that the "value" returned is always of the type that I want it to be. The type should always be a pr...
OK, here we go again! Following on from my previous question on Converting to a Generic Type from String, I thought I would ask another Generics-related question! This time, is there a way to enforce/limit the types that are passed to PRIMITIVE's? (bool, int, string, etc) Now, I know you can limit the generic type parameter to a type o...
I am trying to find a generic way of accessing a set of containers. I have a standard vector and list in addition to another custom list. The custom list defines an iterator; class Iterator: public std::iterator<std::forward_iterator_tag, T> { // ... } Iterator begin() { return (Iterator(root)); } Iterator end() { return ...
Suppose you have the following EJB 3 interfaces/classes: public interface Repository<E> { public void delete(E entity); } public abstract class AbstractRepository<E> implements Repository<E> { public void delete(E entity){ //... } } public interface FooRepository<Foo> { //other methods } @Local(FooRepository....
What is the best way to iterate through a strongly-typed generic List in C#.NET and VB.NET? ...
So I came across an interesting problem today. We have a WCF web service that returns an IList. Not really a big deal until I wanted to sort it. Turns out the IList interface doesn't have a sort method built in. I ended up using the ArrayList.Adapter(list).Sort(new MyComparer()) method to solve the problem but it just seemed a bit "gh...
Hi there! My question concerns c# and how to access Static memebers ... Well I don't really know how to explain it (wich kind of is bad for a question isn't it?) I will just give you some sample code: Class test<T>{ int method1(Obj Parameter1){ //in here I want to do something which I would explain as T.TryParse(...
Prior to C# generics, everyone would code collections for their business objects by creating a collection base that implemented IEnumerable IE: public class CollectionBase : IEnumerable and then would derive their Business Object collections from that. public class BusinessObjectCollection : CollectionBase Now with the generic lis...
I have defined a Java function: static <T> List<T> createEmptyList() { return new ArrayList<T>(); } One way to call it is like so: List<Integer> myList = createEmptyList(); // Compiles Why can't I call it by explicitly passing the generic type argument? : Object myObject = createEmtpyList<Integer>(); // Doesn't compile. Why? ...
I have a generic class that should allow any type, primitive or otherwise. The only problem with this is using default(T). When you call default on a value type or a string, it initializes it to a reasonable value (such as empty string). When you call default(T) on an object, it returns null. For various reasons we need to ensure that if...
I mostly use Java and generics are relatively new. I keep reading that Java made the wrong decision or that .NET has better implementations etc. etc. So, what are the main differences between C++, C#, Java in generics? Pros/cons of each? ...
I am using LINQ to query a generic dictionary and then use the result as the datasource for my ListView (WebForms). Simplified code: Dictionary<Guid, Record> dict = GetAllRecords(); myListView.DataSource = dict.Values.Where(rec => rec.Name == "foo"); myListView.DataBind(); I thought that would work but in fact it throws a System.Inva...
Can anyone tell me if there is a way with c# generics to limit a type T to only Int16, Int32, Int64, UInt16, UInt32, UInt64 I'm aware of the where keyword, but can't find an interface for only these types, Something like: static bool IntegerFunction<T>(T value) where T : INumeric Thanks ...
I'm creating an app that holds loads of loads of user data in memory, and it's mostly keeping it all in List<T> structures (and some Dictionary<T,T> when I need lookup). And I'm wondering... How efficient are Lists? How much memory overhead do I get for each of them? (that is, memory space in addition to what the objects they contain w...
Java has the generic keyword and C++ provides a very strong programming model with templates. So then, what is the difference between C++ and Java generics? ...
Is there any shorthand way of defining and using generic definations without having to keep repeating a particular generic description such that if there is a change I don't have to change all definations/usages though out the codebase for example is somethhing like this possible: Typedef myGenDef = < Object1, Object2 >; HashMap< myGen...
Right, I know I am totally going to look an idiot with this one, but my brain is just not kicking in to gear this morning. I want to have a method where I can say "if it goes bad, come back with this type of Exception", right? For example, something like (and this doesn't work): static ExType TestException<ExType>(string message) ...
Does anyone know if you can cast a List<int> to List<string> somehow? I know I could loop through and .ToString() the thing but a cast would be awesome. I'm in c# 2.0 (so no linq) ...