Re: Extending Arrays
Lew wrote:
Daniel Pitts wrote:
A Java array is actually *not* a real class. It is a special type of
primitive. From the JVM point of view, it does not have a field
called length, there is actually a special op-code to access the array
length...
[snip]
The members of an array type are all of the following:
* The public final field length,
<http://java.sun.com/docs/books/jls/third_edition/html/arrays.html#10.7>
From the Java language point of view, the array most definitely does
have a field called 'length'. It says so right in the JLS.
Yes, but you'll get a surprise if you look for the "Field" using reflection.
Also, an array reference is assignable to Object,
java.io.Serializable, and Clonable reference variables, but in many
regards is very different than other "classes".
Every array has an associated Class object, shared with all other
arrays with the same component type.
<http://java.sun.com/docs/books/jls/third_edition/html/arrays.html#10.8>
The other thing to consider is that arrays are low-level
building-blocks, and you should avoid using them in all but the
lowest-level abstractions (such as Collection API implementations).
Anything else should use abstractions (such as the Collections API) in
place of these primitives.
OK, that's *a* rule of thumb. I would venture to say that there are
many more use cases for arrays. Also, it isn't accurate to refer to
arrays as "primitives"; arrays are reference (i.e., Object) types, not
primitives.
Sorry, my use of the word "primitive" was ambiguous... I meant primitive
as in a low-level building block of the language that couldn't feasibly
be created from within the language itself. I guess you could call it a
second-level primitive, where references and numeric primitives are
first-level.
What other use-case for arrays can you think of that shouldn't be
wrapped by a more specific class?
--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>