var example = Dictionary<Int,AnyObject>()
What other languages have this? How is it often used? I've never heard of a similar type in, say, Haskell.
Good, because types and classes are different things despite what languages like Java and my beloved C# would have us to think.
"Object" as in Java is a type for any tagged box type. Primitives, such as "int", don't derive from Object, but can be promoted to a corresponding boxed type, such as "Integer".
The story is a little more complex in C#, where ValueType derives from Object and "value types", both primitive and user-defined, are truly subclasses of Object. Types not derived from ValueType are considered reference types.
In languages where genericity is supported, you don't need a common base class with a pre-defined set of methods, as you can give type constraints.
Java could also have done it with interfaces, but those were the days OO was becoming mainstream and interface (component) based programming wasn't yet well understood.
http://stackoverflow.com/questions/6479444/is-there-a-type-a...
Int is always Int instead of thinking about int and Integer. Scala handles boxing when the JVM requires it, but it is invisible to the programmer.