collections

google collections ordering on map values

I would like to order a map(A,Double) based on the values. Function<Map.Entry<A, Double>, Double> getSimFunction = new Function<Map.Entry<A, Double>, Double>() { public Double apply(Map.Entry<A, Double> entry) { return entry.getValue(); } }; final Ordering<Map.Entry<A, Double>> entryOrdering = Orde...

which collection should I use

Hello, I have a number of custom objects of type X. X has a number of parameters and must be unique in the collection. (I created my own equals method based on the custom parameters to examine this) In each object of type x, I have a list of objects y. I want to add/remove/modify easily an object y. For example: To write the add meth...

Why does the Java Collections Framework offer two different ways to sort?

If I have a list of elements I would like to sort, Java offers two ways to go about this. For example, lets say I have a list of Movie objects and I’d like to sort them by title. One way I could do this is by calling the one-argument version of the static java.util.Collections.sort( ) method with my movie list as the single argument....

Concise C# code for gathering several properties with a non-null value into a collection?

A fairly basic problem for a change. Given a class such as this: public class X { public T A; public T B; public T C; ... // (other fields, properties, and methods are not of interest here) } I am looking for a concise way to code a method that will return all A, B, C, ... that are not null in an enumerable collec...

Java multiple generic collection parameters compile error

So strange! Please have a look the code first: public class A { } public class B extends A { } public class C extends A { } public class TestMain { public <T extends A> void test(T a, T b) { } public <T extends A> void test(List<T> a, List<T> b) { } public void test1(List<? extends A> a, List<? extends A> b) { } public ...

AutoMapping Custom Collections with FluentNHibernate

I am retrofitting a very large application to use NHibernate as it's data access strategy. Everything is going well with AutoMapping. Luckily when the domain layer was built, we used a code generator. The main issue that I am running into now is that every collection is hidden behind a custom class that derives from List<>. For example ...

How do I select XML elements into a strongly-typed collection using LINQ?

I am trying to wrap my brain around using LINQ as a means of working with XML data and I'm having a problem figuring out the best way to select elements into a strongly-typed collection. I'm sure there's some minute detail I'm missing, but I can't seem to see it. Here is a sample of my XML File: <users> <User> <Use...

How to change order in ordered+persisted collection?

I just need to change order of items in a (previously persisted) ordered collection... I tried simply passing the re-arranged collection to a setter: after committing a transaction the collection is gone. Then I tried to clear() the existing collection and addAll() afterwards: clear() makes persistent manager to mark all the elements as...

"Collection was modified..." Issue

Hey guys, I've got a function that checks a list of objects to see if they've been clicked and fires the OnClick events accordingly. I believe the function is working correctly, however I'm having an issue: When I hook onto one of the OnClick events and remove and insert the element into a different position in the list (typical functi...

WPF/MVVM: Delegating a domain Model collection to a ViewModel

A domain model collection (normally a List or IEnumerable) is delegated to a ViewModel. Thats means my CustomerViewModel has a order collection of type List or IEnumerable. No change in the list is recognized by the bound control. But with ObservableCollection it is. This is a problem in the MVVM design pattern. How do you cope with ...

Why does C# not implement GetHashCode for Collections?

I am porting something from Java to C#. In Java the hashcode of a ArrayList depends on the items in it. In C# I always get the same hashcode from a List... Why is this? For some of my objects the hashcode needs to be different because the objects in their list property make the objects non-equal. I would expect that a hashcode is alwa...

Object Design: How to Organize/Structure a "Collection Class"

I'm currently struggling to understand how I should organize/structure a class which I have already created. The class does the following: As its input in the constructor, it takes a collection of logs In the constructor it validates and filters the logs through a series of algorithms implementing my business logic After all filterin...

Return number of matches from c# dictionary

Hello! I have a dictionary with non unique values and I want to count the matches of a string versus the values. Basically I now do dict.ContainsValue(a) to get a bool telling me if the string a exists in dict, but I want to know not only if it exists but how many times it exists (and maybee even get a list of the keys it exists bound ...

NHibernate : Root collection with an root object

Hi, I want to track a list of root objects which are not contained by any element. I want the following pseudo code to work: using (session1 = [...]) { IList<FavoriteItem>list = session1.Linq<FavoriteItem>().ToList(); } list.Add(item1); list.Add(item2); list.Remove(item3); list.Remove(item4); var item5 = list.First(i => i.Name = "Fo...

Is it better to use List or Collection?

I have an object that stores some data in a list. The implementation could change later, and I don't want to expose the internal implementation to the end user. However, the user must have the ability to modify and access this collection of data. Currently I have something like this: public List<SomeDataType> getData() { return this....

How can I reduce the number of loops in this VIEW in Rails when using :collection?

I am using the :collection to go through all the Contacts that are part of a given Campaign. But within that Campaign I check for three different Models (each with their own partial). Feels like I am going through the list of Contacts 3x. How can I make this alot leaner? <h2>These are past due:</h2> <% @campaigns.each do |campaign| ...

Architecture choice about representation of collections in Business Objects

I have made certain choices in my architecture which I request the community to review and comment. I am breaking up the post in smaller sections to make it easier to understand the context and then suggest/comment. I am sorry that the post is long, but is required to explain the context. What am I building A typical business applicati...

WPF: how to define collections for use in xaml

I want to define something like this <myCustomControl> <myCustomControl.Images> <Image Source="{StaticResource LockedIcon16}" /> <Image Source="{StaticResource UnlockedIcon16}"/> <myCustomControl.Images> <myCustomControl/> what property definitions do i need to get that collection (Images) happening? ...

WPF Databinding With A Collection Object

Argh, although I've been googling, I really would appreciate it if someone could break my problem down as all the code examples online are confusing me more than assisting (perhaps it's just late)... I have a simple class as defined below: public class Person { int _id; string _name; public Person() { } public int...

Java Collection performance question

I have created a method that takes two Collection<String> as input and copies one to the other. However, I am not sure if I should check if the collections contain the same elements before I start copying, or if I should just copy regardless. This is the method: /** * Copies from one collection to the other. Does not allow empty st...