Are Basic Types Objects?

There is an advantage of consistency if basic types such as integer and real are objects. However:

• A boxed number requires more storage. (16 bytes for Java Integer vs. 4 bytes for int.)

• A statement i = i + 1 requires allocating a new object (and garbage collecting the old one): a significant performance penalty.

Lisp encodes small integers as special pointer values, eliminating the need to box small integers; reals are boxed.

Java caches and reuses small Integer values from -128 to 127.

An alternative is to have both boxed and unboxed numbers; this improves performance but results in an inconsistent type system. Java uses this method; as a result, a generic method that does comparison, such as sorting, may have to be recoded 6 times to handle different types ( < vs. .compareTo()).