Possible Duplicate: Java Generics: Why Does Map.get() Ignore Type? Could someone please explain why with Map defines V put(K key,V value); V get(Object key); Why is get not defined as: V get(K key) Similarly, why are these methods typed to Object, and not K and V respectively? boolean containsKey(Object key); // Why no...
Hello all, I need to outline a little bit of background info for context. Please bear with me and I'll try to simplify my question as much as possible: I have one object that inherits from another object. We'll call the first object Fruit and the second Apple. So I've declared Apple as follows: public class Apple : Fruit { public ...
I know that in ASP.NET (talking about 2.0 here primarily) one can set a property on an object that takes a collection of things (an enumerable type I'm guessing is the trigger) and then reference it declaritivly. For example: <ObjectDataSource properties="blahblahblah"> <SelectParameters> <asp:Parameter /> </SelectParam...
I get a warning about unchecked casts on the "return (T) value;" line. Is there a better way to do this, or should I just suppress the warning? class SomeClass<T> { /* ... other methods ... */ private Set<T> aSet; public T filter(Object value) { if (this.aSet.contains(value)) return (T) value; ...
Hello everyone. I'm having a problem that I have encountered before, but I still don't know why it happens. This is the code: package Program; import java.util.ArrayList; import java.util.Iterator; /** * This class will hold the full collection of the user. * * @author Harm De Weirdt */ public class ShowManager { /** * ...
Hello all I have two complex dictionaries in the form Dictionary<string, Dictionary<string, Dictionary<string, List<string>>>> So as you see i've inner dictionaries. I want to write a generic recursive function which can merge two complex dictionaries of this form (or any other complex form of dictionaries), by calling itself passing...
Dynamic Inheritance I have a situation where I want a class (which is a JPA entity) to be able to extend either class A or class B dynamically. My thought was to use Generics, but it looks like generics doesn’t support this. For example: @Entity public abstract class Resource() { ... } @Entity public abstract class Snapshot() { ... }...
I have a recursive object, a linked list really: public class LinkedList { public string UniqueKey { get; set; } public LinkedList LinkedList { get; set; } } LinkedList will have some object graph that will eventually end in LinkedList.LinkedList == null. I would like to take all the objects in the graph and put them into a ...
I am trying to get a generic tree backing-bean to work. I have one generic class called ACLTree, and then an implementation of it. In my JSF document I try to access a value per #{mybackingbean.property}. But I get an ELException: javax.el.ELException: /modules/useradmin/acl.xhtml @30,55 value="#{ACOTree.root}": java.lang.IllegalAccess...
I have several objects in C# that's roughly like this: A: { Id: 1, Parent: { Id: 2, Parent: { Id: 3, Parent: null }}} And, B: { Id: 4 Parent: { Id: 2 Parent: ...
I'm a linq noob.... can someone please some me how to achieve this using linq... I'm trying to compare 2 lists in both directions... internal void UpdateUserTeams(int iUserID) { UserTeamCollection CurrentTeams = GetUserTeams(iUserID); UserTeamCollection UpdatedTeams = this; foreach (UserTeam ut in Curre...
Using Java Generics, I tried to implement a generic console input method. public static <T> T readFromInput(String message, Class<?> c) throws Exception{ System.out.println(message); Scanner scanner = new Scanner(System.in); try { if(c == Integer.class) return (T) Integer.valueOf(scann...
I'm using a HashMap and the method show below to track change listeners for class types. The IDE is giving a warning [rawtypes] found raw type: java.lang.Class missing type parameters for generic class java.lang.Class<T>. What type for Class needs to be specified to resolve the warning? private HashMap<Class, Set<ChangeListener>>...
I'm trying to work with two contexts in a generic repository and I should invoke the static method GetObjectContext() with dynamic type like ObjectContextManager<DynamicType>.GetObjectContext(). private DataContext GetDataContext() { Type type = GetContainerType(); Type paoloGenericClassType = typeof(ObjectContextMan...
I'm developing in Windows 7 64-bit with Visual Studio 2008. I have a collection of class libraries that I merge into a single DLL using ILMerge. When I try to use this merged DLL, however, I get [BadImageFormatException: Could not load file or assembly 'MyMergedDll' or one of its dependencies. An attempt was made to load a program ...
Given a simple generic class: class EqualsQuestion[T]( val value :T ) it seems reasonable that the following code would resolve to "false": val a = new EqualsQuestion[Int]( 5 ) val b = new EqualsQuestion[Long]( 5 ) a == b (Yes, it's a contrived example. In my real code I wanted '==' to fail if the type parameters are different, re...
With an abstract class I want to define a method that returns "this" for the subclasses: public abstract class Foo { ... public <T extends Foo> T eat(String eatCake) { ... return this; } } public class CakeEater extends Foo {} I want to be able to do things like: CakeEater phil = new CakeEater(); phil.e...
I've got a class Foo<T>. How can I say that I want T to be some class implementing BarInterface? Writing simply class Foo<T implements BarInterface> doesn't compile. ...
How can I combine two lambda expressions into one using an OR ? I have tried the following but merging them requires me to pass parameters into the Expression.Invoke calls, however I want the value passed into the new lambda to be passed onto each child-lambda.. Expression<Func<int, bool>> func1 = (x) => x > 5; Expression<Func<int, boo...
I'm currently playing with implementing various sorting algorithms in Java, mostly for fun, but I'm struggling with how to do it 'right'. That is, I want the user to be able to call the sorting algorithm of choice on anything that is comparable - ints, longs, Strings, booleans (actually, are these comparable in Java?), their own classes;...