Java: What's the proper term for multidimensional types, one-dimensional types?

In a Java context, what's the proper way to refer to a variable type that can contain multiple objects or primitives, and the proper way to refer to a type that can contain just one?开发者_开发技巧

In general terms, I refer to lists, arrays, vectors, hashtables, trees, etc, as collections; and I refer to primitive types and one-dimensional objects as scalars.

In the wild, I've heard all sorts of combinations of phrases, including a few that are outright misleading:

"I'm storing my key/value pairs in a hashtable vector."

"Why would you need more than one hashtable?"

"What do you mean? I'm only using one hashtable."

Is there a widely-accepted way to refer to these two groupings of types, at a high level?

The Java Language Spec uses the terms "primitive" and "reference" to make that distinction for both variables and values. This might be confusing in the context of a different programming language where "reference" means something else.

However, I can't tell if that is exactly the distinction you're trying to make. If you want to lump strings and object wrappers like Integer in with the Java primitive types like int you might be distinguishing scaler from non-scaler. Not all non-scalers are collections, of course.

I'm not sure that kind of terminology really applies to an OO language like Java. There's a distinction made between primitives, which can only contain a single value, and Objects, however an Object might contain any number of other objects.

Objects whose purpose is to contain zero-or-more instances of some other object are (in my experience) referred to as collections, maybe because of the Collections API or Arrays.

I guess languages where you're dealing explicitly with pointers and the like depend on the distinction more.

I think your question assumes that there are only 2 classes and one of them is what you call Collections. Let me say that I also call lists, maps, sets, etc. Collections because they're part of the Collections API. However, Collection is not on the same abstraction level as a primitive data type like integer. Really, you have primitives and references. References are pointers to objects which are instances of classes. Classes can be classified many ways. One of these classifications is "Collections".

Your friend who says "hashtable vector" is pretty much wrong if there's only one table. A hash table is a hash table, and a vector is a vector. A hashtable vector is a Vector<Hashtable> as far as I'm concerned.

Just use the most specific Java API class name (Collection, List, Object, etc.), without over-specifying, and 99% of all Java developers will understand what you mean.