* List: implemented by ArrayList and LinkedLink
* Set: implemented by HashSet
* Map: implemented by HashMap
All are Collections.
Then it's easy to get immutable versions, synchronized versions, Sorted{Set,Map}s (implemented by Tree{Set,Map}).
They work with Comparator and Iterator in a consistent way.
There is symmetry and unity. I don't even remember the C# analogues, but my recollection is that sometimes they come with an interface, sometimes not, the names are messier, generics are less consistent, and there isn't a unified way to get immutable versions etc.
I don't think C#'s collections were that bad, and probably people here can correct my memory about some of the above, but they weren't as clean, and to me that was a motif throughout the framework. A messy collections API is no big deal really, but when it's the same story for I/O, networking, GUI, etc. . . . (I do think layout was a lot easier in WinForms than Swing though.)
On balance I'd take C#'s rapid evolution over Java's slowness, but what Java got from its conservatism was purity and low cognitive overhead, which as a working programmer was pretty nice.
That said, it'd still be really cool if I could write Rails apps in C# on Linux. With vim. :-)
IList<T>: implemented by List<T> and T[] (arrays)
ISet<T>: implemented by HashSet<T> and SortedSet<T>
IDictionary<T,U>: implemented by Dictionary<T,U>
all implement ICollection<T> and IEnumerable<T>. In the case of dictionary, it implements ICollection<KeyValuePair<T,U>>, IEnumerable<T> (.Keys) and IEnumerable<U> (.Values), etc
It's all basically the same thing. Organized and unified.
IList<T> is actually implemented by a lot of things, and the more general you go, the more things implement it. IEnumerable just allows you to get an iterator that will go through the elements. ICollection adds the ability to add and remove elements. IList further adds indexed access and order. The generic collections and operations on them are one of the best aspects of C# and the standard lib.
Except Map. See the section in the Java Collections API Design FAQ [1] on "Why doesn't Map extend Collection?".
[1] http://docs.oracle.com/javase/8/docs/technotes/guides/collec...
That sums it up for me, too. I'm mostly a Ruby developer, and in C# I get tons of Ruby-like features, plus static typing and better performance. But my years with Java spoiled me for a clean and consistent stdlib. For instance in C# collections are just a mess. If I could build Rails apps in C# and deploy on Linux, I'd probably do it.