In C#, was is the best way to access a property of the derived class when the generic list contains just the base class. public class ClassA : BaseClass { public object PropertyA { get; set; } } public class ClassB: BaseClass { public object PropertyB { get; set; } } public class BaseClass { } public void Main { List<BaseC...
With a TreeMap it's trivial to bypass the keys' natural ordering using a Comparable. HashMaps however cannot be controlled in this manner. I suspect it would be both easy and useful to design an interface and to retrofit this into HashMap (or a new class)? Something like this, except with better names: interface Hasharator<T> { ...
What is the best way to localize a collection (IEnumerable)? From the BL I retrieve a collection of entities which still need to localized, I figured I write a method which extends the IEnumerable and returns the localized list. How can i get the code underneath working? Any ideas? Maybe better options? public static IEnumerable L...
I'm lead to believe that I cannot count on the order of items added to a dictionary for enumeration purposes. Is there a class (generic if possible) to which items may be added with a key and which can be enumerated in addition order or which can be retrieved by key? Clarification: I do not want to enumerate in Key Order. I want to enu...
I often need to run reduce (also called foldl / foldr, depending on your contexts) in java to aggregate elements of an Itterable. Reduce takes a collection/iterable/etc, a function of two parameters, and an optional start value (depending on the implementation details). The function is successively applied to an element of the collec...
Hello everyone. We all know you can't do this: for (Object i : l) if (condition(i)) l.remove(i); ConcurrentModificationException etc... this apparently works sometimes, but not always. Here's some specific code: public static void main(String[] args) { Collection<Integer> l = new ArrayList<Integer>(); for (int i=0; i < 1...
In the spirit of Best Practices: Always return a ____, never a ____, I face a similar question in my upcoming migration from JDK1.4.2 to JDK5 and more. (Yes, I know, JDK1.4.2 is EOL! ;-) ). For functions returning a collection (which are not simple property collections), I always prefer (in JDK1.4.2) returning an Array instead of a gene...
Consider the following code: abstract class SomeClassX<T> { // blah } class SomeClassY: SomeClassX<int> { // blah } class SomeClassZ: SomeClassX<long> { // blah } I want a collection of SomeClassX<T>'s, however, this isn't possible since SomeClassX<int> != SomeClassX<long> and List<SomeClassX<>> isn't allowed. So my solution ...
Using the following code I get a nice formatted string: Request.QueryString.ToString Gives me something like: &hello=worldµsoft=sucks But when I use this code to clone the collection to another object (of the same type) I get the Type() back from the ToString() method instead. System.Collections.Specialized.NameValueCollection ...
I have the following code: class IncidentTag: def __init__(self,tag): self.tag = tag def equals(self,obj): return self.tag.equals(obj.tag) def hashCode(self): return self.tag.hashCode() from java.lang import String from java.util import HashMap from java.util import HashSet tag1 = IncidentTag(Str...
I have what is essentially a jagged array of name value pairs - i need to generate a set of unique name values from this. the jagged array is approx 86,000 x 11 values. It does not matter to me what way I have to store a name value pair (a single string "name=value" or a specialised class for example KeyValuePair). Additional Info: There...
Hi, I have a sorted collection of objects (it can be either SortedList or SortedDictionary, I will use it mainly for reading so add performance is not that important). How can I get the i-th value? So e.g. when I have numbers 1, 2, 3, 4, 5 in the collection and I want the median (so 3 in this example), how can I do it? ...
I have created a class for a dashboard item which will hold information such as placement on the dashboard, description, etc. I am currently using a pair of Collections to hold those dashboard items contained in the "library" and those items showing on the dashboard itself. I have been asked to make this dashboard multi-tab, and my fir...
Is there a way to do this without iterating through the List and adding the items to the ObservableCollection? ...
Something happened that I'm not sure should be possible. Obviously it is, because I've seen it, but I need to find the root cause & I was hoping you all could help. We have a system that looks up latitude & longitude for a zipcode. Rather than access it every time, we cache the results in a cheap in-memory HashTable cache, since the l...
I've got two collections (generic Lists), let's call them ListA and ListB. In ListA I've got a few items of type A. In ListB I've got some items of type B that have the SAME ID (but not same type) as the items in ListA, plus many more. I want to remove all the items from ListB that have the same ID as the ones in ListA. What's the best ...
I often use Dictionary in C#2.0 with the first key as string that was containing a unique identifier. I am learning C#3.0+ and it seems that I can now simply use a List and simply do LINQ on that object to get the specific object (with the .where()). So, if I understand well, the Dictionary class has lost its purpose? ...
Excuse me if I'm off on my terminology, I only have around 2.4 years of programming experience, mostly in .NET. Currently I'm one of two .NET developers in a mainframe shop, the other developer set the standards and is a great coder with a lot more experience plus a CS degree(I am 100% self taught). We use custom collections for every...
Is there a way of ordering a list of objects by a count of a property which is a collection? For arguments sake let's say I have a question object with a question name property, a property that is a collection of answer objects and another property that is a collection of user objects. The users join the question table via foreign key ...
I wanted to make Map of Collections in Java, so I can make something like public void add(K key, V value) { if (containsKey(key)) { get(key).add(value); } else { Collection c = new Collection(); c.add(value); put(key, value); } } I've tried to make it with something like public class ...