Via wikipedia: Early versions of Java and C# did not include generics (a.k.a. parametric polymorphism). In such a setting, making arrays invariant rules out useful polymorphic programs. For example, consider writing a function to shuffle an array, or a function that tests two arrays for equality using the Object.equals method on the elements. The implementation … Read more
Iterate your list in reverse with a for loop: for (int i = safePendingList.Count – 1; i >= 0; i–) { // some code // safePendingList.RemoveAt(i); } Example: var list = new List<int>(Enumerable.Range(1, 10)); for (int i = list.Count – 1; i >= 0; i–) { if (list[i] > 5) list.RemoveAt(i); } list.ForEach(i => Console.WriteLine(i)); … Read more
Here’s a nice 2013 update using FastMember from NuGet: IEnumerable<SomeType> data = … DataTable table = new DataTable(); using(var reader = ObjectReader.Create(data)) { table.Load(reader); } This uses FastMember’s meta-programming API for maximum performance. If you want to restrict it to particular members (or enforce the order), then you can do that too: IEnumerable<SomeType> data = … Read more
This comes up in Java 5 and later if you’re using collections without type specifiers (e.g., Arraylist() instead of ArrayList<String>()). It means that the compiler can’t check that you’re using the collection in a type-safe way, using generics. To get rid of the warning, just be specific about what type of objects you’re storing in … Read more
As mentioned by others, the reason why get(), etc. is not generic because the key of the entry you are retrieving does not have to be the same type as the object that you pass in to get(); the specification of the method only requires that they be equal. This follows from how the equals() … Read more
Since Enum Type implements IConvertible interface, a better implementation should be something like this: public T GetEnumFromString<T>(string value) where T : struct, IConvertible { if (!typeof(T).IsEnum) { throw new ArgumentException(“T must be an enumerated type”); } //… } This will still permit passing of value types implementing IConvertible. The chances are rare though.
The short answer is, that there is no way to find out the runtime type of generic type parameters in Java. I suggest reading the chapter about type erasure in the Java Tutorial for more details. A popular solution to this is to pass the Class of the type parameter into the constructor of the … Read more
You can’t do this without reflection. However, you can do it with reflection. Here’s a complete example: using System; using System.Reflection; public class Generic<T> { public Generic() { Console.WriteLine(“T={0}”, typeof(T)); } } class Test { static void Main() { string typeName = “System.String”; Type typeArgument = Type.GetType(typeName); Type genericClass = typeof(Generic<>); // MakeGenericType is badly … Read more
The easiest way I can think of is to use Linq: List<Order> SortedList = objListOrder.OrderBy(o=>o.OrderDate).ToList();
Generics in Java are an entirely compile-time construct – the compiler turns all generic uses into casts to the right type. This is to maintain backwards compatibility with previous JVM runtimes. This: List<ClassA> list = new ArrayList<ClassA>(); list.add(new ClassA()); ClassA a = list.get(0); gets turned into (roughly): List list = new ArrayList(); list.add(new ClassA()); ClassA … Read more